Science.gov

Sample records for 2d6 cyp2d6 enzyme

  1. The Psychostimulant Khat (Catha edulis) Inhibits CYP2D6 Enzyme Activity in Humans.

    PubMed

    Bedada, Worku; de Andrés, Fernando; Engidawork, Ephrem; Pohanka, Anton; Beck, Olof; Bertilsson, Leif; Llerena, Adrián; Aklillu, Eleni

    2015-12-01

    The use of khat (Catha edulis) while on medication may alter treatment outcome. In particular, the influence of khat on the metabolic activities of drug-metabolizing enzymes is not known. We performed a comparative 1-way crossover study to evaluate the effect of khat on cytochrome P450 (CYP)2D6 and CYP3A4 enzyme activity. After 1 week of khat abstinence, baseline CYP2D6 and CYP3A4 metabolic activities were determined in 40 Ethiopian male volunteers using 30 mg dextromethorphan (DM) as a probe drug and then repeated after 1 week of daily use of 400 g fresh khat leaves. Urinary concentrations of cathinone and cathine were determined to monitor the subjects' compliance to the study protocol. Genotyping for CYP2D6*3 and CYP2D6*4 was done. Plasma DM, dextrorphan and 3-methoxymorphinan concentrations were quantified. CYP2D6 and CYP3A4 enzyme activities were assessed by comparing plasma log DM/dextrorphan and log DM/methoxymorphinan metabolic ratio (MR) respectively in the presence and absence of khat. Cytochrome 2D6 MR was significantly increased from baseline by concurrent khat use (paired t test, P = 0.003; geometric mean ratio, 1.38; 95% confidence interval [95% CI], 1.12-1.53). Moreover, the inhibition of CYP2D6 activity by khat was more pronounced in CYP2D6*1/*1 compared with CYP2D6*1/*4 genotypes (P = 0.01). A marginal inhibition of CYP3A4 activity in the presence of khat was observed (P = 0.24). The mean percentage increase of CYP2D6 and CYP3A4 MR from baseline by khat use was 46% (95% CI, 20-72) and 31% (95% CI, 8-54), respectively. This is the first report linking khat use with significant inhibition of CYP2D6 metabolic activity in humans. PMID:26444948

  2. Evaluation of CYP2D6 enzyme activity using a Dextromethorphan Breath Test in Women Receiving Adjuvant Tamoxifen

    PubMed Central

    Safgren, Stephanie L.; Suman, Vera J.; Kosel, Matthew L.; Gilbert, Judith A; Buhrow, Sarah A.; Black, John L.; Northfelt, Donald W.; Modak, Anil S.; Rosen, David; Ingle, James N.; Ames, Matthew M.; Reid, Joel M.; Goetz, Matthew P.

    2015-01-01

    Background In tamoxifen-treated patients, breast cancer recurrence differs according to CYP2D6 genotype and endoxifen steady state concentrations (Endx Css). The 13Cdextromethorphan breath test (DM-BT), labeled with 13C at the O-CH3 moiety, measures CYP2D6 enzyme activity. We sought to examine the ability of the DM-BT to identify known CYP2D6 genotypic poor metabolizers and examine the correlation between DMBT and Endx Css. Methods DM-BT and tamoxifen pharmacokinetics were obtained at baseline (b), 3 month (3m) and 6 months (6m) following tamoxifen initiation. Potent CYP2D6 inhibitors were prohibited. The correlation between bDM-BT with CYP2D6 genotype and Endx Css was determined. The association between bDM-BT (where values ≤0.9 is an indicator of poor in vivo CYP2D6 metabolism) and Endx Css (using values ≤ 11.2 known to be associated with poorer recurrence free survival) was explored. Results 91 patients were enrolled and 77 were eligible. CYP2D6 genotype was positively correlated with b, 3m and 6m DMBT (r ranging from 0.457-0. 60 p < 0.001). Both CYP2D6 genotype (r = 0.47; 0.56, p <.0001), and bDM-BT (r=0.60; 0.54; p<.001) were associated with 3m and 6m Endx Css respectively. Seven of 9 patients (78%) with low (≤11.2 nM) 3m Endx Css also had low DM-BT (≤0.9) including 2/2 CYP2D6 PM/PM and 5/5 IM/PM. In contrast, 1 of 48 pts (2%) with a low DM-BT had Endx Css > 11.2 nM. Conclusions In patients not taking potent CYP2D6 inhibitors, DM-BT was associated with CYP2D6 genotype and 3m and 6 m Endx Css but did not provide better discrimination of Endx Css compared to CYP2D6 genotype alone. Further studies are needed to identify additional factors which alter Endx Css. PMID:25714002

  3. Functional characterization of CYP2D6 enhancer polymorphisms

    PubMed Central

    Wang, Danxin; Papp, Audrey C.; Sun, Xiaochun

    2015-01-01

    CYP2D6 metabolizes nearly 25% of clinically used drugs. Genetic polymorphisms cause large inter-individual variability in CYP2D6 enzyme activity and are currently used as biomarker to predict CYP2D6 metabolizer phenotype. Previously, we had identified a region 115 kb downstream of CYP2D6 as enhancer for CYP2D6, containing two completely linked single nucleotide polymorphisms (SNPs), rs133333 and rs5758550, associated with enhanced transcription. However, the enhancer effect on CYP2D6 expression, and the causative variant, remained to be ascertained. To characterize the CYP2D6 enhancer element, we applied chromatin conformation capture combined with the next-generation sequencing (4C assays) and chromatin immunoprecipitation with P300 antibody, in HepG2 and human primary culture hepatocytes. The results confirmed the role of the previously identified enhancer region in CYP2D6 expression, expanding the number of candidate variants to three highly linked SNPs (rs133333, rs5758550 and rs4822082). Among these, only rs5758550 demonstrated regulating enhancer activity in a reporter gene assay. Use of clustered regularly interspaced short palindromic repeats mediated genome editing in HepG2 cells targeting suspected enhancer regions decreased CYP2D6 mRNA expression by 70%, only upon deletion of the rs5758550 region. These results demonstrate robust effects of both the enhancer element and SNP rs5758550 on CYP2D6 expression, supporting consideration of rs5758550 for CYP2D6 genotyping panels to yield more accurate phenotype prediction. PMID:25381333

  4. CYP2D6 polymorphism in patients with eating disorders.

    PubMed

    Peñas-Lledó, E M; Dorado, P; Agüera, Z; Gratacós, M; Estivill, X; Fernández-Aranda, F; Llerena, A

    2012-04-01

    CYP2D6 polymorphism is associated with variability in drug response, endogenous metabolism (that is, serotonin), personality, neurocognition and psychopathology. The relationship between CYP2D6 genetic polymorphism and the risk of eating disorders (ED) was analyzed in 267 patients with ED and in 285 controls. A difference in the CYP2D6 active allele distribution was found between these groups. Women carrying more than two active genes (ultrarapid metabolizers) (7.5 vs 4.6%) or two (67 vs 58.9%) active genes were more frequent among patients with ED, whereas those with one (20.6 vs 30.2%) or zero active genes (4.9 vs 6.3%) were more frequent among controls (P<0.05). Although further research is needed, present findings suggest an association between CYP2D6 and ED. CYP2D6 allele distribution in patients with ED seems related to increased enzyme activity. PMID:20877302

  5. Inhibitory effects of phytochemicals on metabolic capabilities of CYP2D6*1 and CYP2D6*10 using cell-based models in vitro

    PubMed Central

    Qu, Qiang; Qu, Jian; Han, Lu; Zhan, Min; Wu, Lan-xiang; Zhang, Yi-wen; Zhang, Wei; Zhou, Hong-hao

    2014-01-01

    Aim: Herbal products have been widely used, and the safety of herb-drug interactions has aroused intensive concerns. This study aimed to investigate the effects of phytochemicals on the catalytic activities of human CYP2D6*1 and CYP2D6*10 in vitro. Methods: HepG2 cells were stably transfected with CYP2D6*1 and CYP2D6*10 expression vectors. The metabolic kinetics of the enzymes was studied using HPLC and fluorimetry. Results: HepG2-CYP2D6*1 and HepG2-CYP2D6*10 cell lines were successfully constructed. Among the 63 phytochemicals screened, 6 compounds, including coptisine sulfate, bilobalide, schizandrin B, luteolin, schizandrin A and puerarin, at 100 μmol/L inhibited CYP2D6*1- and CYP2D6*10-mediated O-demethylation of a coumarin compound AMMC by more than 50%. Furthermore, the inhibition by these compounds was dose-dependent. Eadie-Hofstee plots demonstrated that these compounds competitively inhibited CYP2D6*1 and CYP2D6*10. However, their Ki values for CYP2D6*1 and CYP2D6*10 were very close, suggesting that genotype-dependent herb-drug inhibition was similar between the two variants. Conclusion: Six phytochemicals inhibit CYP2D6*1 and CYP2D6*10-mediated catalytic activities in a dose-dependent manner in vitro. Thus herbal products containing these phytochemicals may inhibit the in vivo metabolism of co-administered drugs whose primary route of elimination is CYP2D6. PMID:24786236

  6. Differential CYP 2D6 Metabolism Alters Primaquine Pharmacokinetics

    PubMed Central

    Potter, Brittney M. J.; Xie, Lisa H.; Vuong, Chau; Zhang, Jing; Zhang, Ping; Duan, Dehui; Luong, Thu-Lan T.; Bandara Herath, H. M. T.; Dhammika Nanayakkara, N. P.; Tekwani, Babu L.; Walker, Larry A.; Nolan, Christina K.; Sciotti, Richard J.; Zottig, Victor E.; Smith, Philip L.; Paris, Robert M.; Read, Lisa T.; Li, Qigui; Pybus, Brandon S.; Sousa, Jason C.; Reichard, Gregory A.

    2015-01-01

    Primaquine (PQ) metabolism by the cytochrome P450 (CYP) 2D family of enzymes is required for antimalarial activity in both humans (2D6) and mice (2D). Human CYP 2D6 is highly polymorphic, and decreased CYP 2D6 enzyme activity has been linked to decreased PQ antimalarial activity. Despite the importance of CYP 2D metabolism in PQ efficacy, the exact role that these enzymes play in PQ metabolism and pharmacokinetics has not been extensively studied in vivo. In this study, a series of PQ pharmacokinetic experiments were conducted in mice with differential CYP 2D metabolism characteristics, including wild-type (WT), CYP 2D knockout (KO), and humanized CYP 2D6 (KO/knock-in [KO/KI]) mice. Plasma and liver pharmacokinetic profiles from a single PQ dose (20 mg/kg of body weight) differed significantly among the strains for PQ and carboxy-PQ. Additionally, due to the suspected role of phenolic metabolites in PQ efficacy, these were probed using reference standards. Levels of phenolic metabolites were highest in mice capable of metabolizing CYP 2D6 substrates (WT and KO/KI 2D6 mice). PQ phenolic metabolites were present in different quantities in the two strains, illustrating species-specific differences in PQ metabolism between the human and mouse enzymes. Taking the data together, this report furthers understanding of PQ pharmacokinetics in the context of differential CYP 2D metabolism and has important implications for PQ administration in humans with different levels of CYP 2D6 enzyme activity. PMID:25645856

  7. CYP2D6 Genetic Polymorphisms and Phenotypes in Different Ethnicities of Malaysian Breast Cancer Patients.

    PubMed

    Chin, Fee Wai; Chan, Soon Choy; Abdul Rahman, Sabariah; Noor Akmal, Sharifah; Rosli, Rozita

    2016-01-01

    The cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6) is an enzyme that is predominantly involved in the metabolism of tamoxifen. Genetic polymorphisms of the CYP2D6 gene may contribute to inter-individual variability in tamoxifen metabolism, which leads to the differences in clinical response to tamoxifen among breast cancer patients. In Malaysia, the knowledge on CYP2D6 genetic polymorphisms as well as metabolizer status in Malaysian breast cancer patients remains unknown. Hence, this study aimed to comprehensively identify CYP2D6 genetic polymorphisms among 80 Malaysian breast cancer patients. The genetic polymorphisms of all the 9 exons of CYP2D6 gene were identified using high-resolution melting analysis and confirmed by DNA sequencing. Seven CYP2D6 alleles consisting of CYP2D6*1, CYP2D6*2, CYP2D6*4, CYP2D6*10, CYP2D6*39, CYP2D6*49, and CYP2D6*75 were identified in this study. Among these alleles, CYP2D6*10 is the most common allele in both Malaysian Malay (54.8%) and Chinese (71.4%) breast cancer patients, whereas CYP2D6*4 in Malaysian Indian (28.6%) breast cancer patients. In relation to CYP2D6 genotype, CYP2D6*10/*10 is more frequently observed in both Malaysian Malay (28.9%) and Chinese (57.1%) breast cancer patients, whereas CYP2D6*4/*10 is more frequently observed in Malaysian Indian (42.8%) breast cancer patients. In terms of CYP2D6 phenotype, 61.5% of Malaysian Malay breast cancer patients are predicted as extensive metabolizers in which they are most likely to respond well to tamoxifen therapy. However, 57.1% of Chinese as well as Indian breast cancer patients are predicted as intermediate metabolizers and they are less likely to gain optimal benefit from the tamoxifen therapy. This is the first report of CYP2D6 genetic polymorphisms and phenotypes in Malaysian breast cancer patients for different ethnicities. These data may aid clinicians in selecting an optimal drug therapy for Malaysian breast cancer patients, hence improve the

  8. Nomenclature for human CYP2D6 alleles.

    PubMed

    Daly, A K; Brockmöller, J; Broly, F; Eichelbaum, M; Evans, W E; Gonzalez, F J; Huang, J D; Idle, J R; Ingelman-Sundberg, M; Ishizaki, T; Jacqz-Aigrain, E; Meyer, U A; Nebert, D W; Steen, V M; Wolf, C R; Zanger, U M

    1996-06-01

    To standardize CYP2D6 allele nomenclature, and to conform with international human gene nomenclature guidelines, an alternative to the current arbitrary system is described. Based on recommendations for human genome nomenclature, we propose that alleles be designated by CYP2D6 followed by an asterisk and a combination of roman letters and arabic numerals distinct for each allele with the number specifying the key mutation and, where appropriate, a letter specifying additional mutations. Criteria for classification as a separate allele and protein nomenclature are also presented. PMID:8807658

  9. Prevalence of CYP2D6*2, CYP2D6*4, CYP2D6*10, and CYP3A5*3 in Thai breast cancer patients undergoing tamoxifen treatment

    PubMed Central

    Charoenchokthavee, Wanaporn; Panomvana, Duangchit; Sriuranpong, Virote; Areepium, Nutthada

    2016-01-01

    Background Tamoxifen (TAM) is used in breast cancer treatment, but interindividual variabilities in TAM-metabolizing enzymes exist and have been linked to single nucleotide polymorphisms in the respective encoding genes. The different alleles and genotypes of these genes have been presented for Caucasians and Asians. This study aimed to explore the prevalence of the incomplete functional alleles and genotypes of the CYP2D6 and CYP3A5 genes in Thai breast cancer patients undergoing TAM treatment. Patients and methods In total, 134 Thai breast cancer patients were randomly invited to join the Thai Tamoxifen Project. Their blood samples were collected and extracted for individual DNA. The alleles and genotypes were determined by real-time polymerase chain reaction with TaqMan® Drug Metabolism Genotyping Assays. Results The patients were aged from 27.0 years to 82.0 years with a body mass index range from 15.4 to 40.0, with the majority (103/134) in the early stage (stages 0–II) of breast cancer. The median duration of TAM administration was 17.2 months (interquartile range 16.1 months). Most (53%) of the patients were premenopausal with an estrogen receptor (ER) and progesterone receptor (PR) status of ER+/PR+ (71.7%), ER+/PR− (26.9%), ER−/PR+ (0.7%), and ER−/PR− (0.7%). The allele frequencies of CYP2D6*1, CYP2D6*2, CYP2D6*4, CYP2D6*10, CYP3A5*1, and CYP3A5*3 were 72.9%, 3.2%, 1.1%, 22.8%, 37.3%, and 62.7%, respectively, while the genotype frequencies of CYP2D6*1/*1, CYP2D6*1/*2, CYP2D6*2/*2, CYP2D6*4/*4, CYP2D6*1/*10, CYP2D6*2/*10, CYP2D6*4/*10, CYP2D6*10/*10, CYP3A5*1/*1, CYP3A5*1/*3, and CYP3A5*3/*3 were 9.7%, 2.2%, 3.7%, 1.5%, 15.7%, 9.7%, 3.7%, 53.7%, 13.4%, 47.8%, and 38.8%, respectively. Conclusion The majority (97.8%) of Thai breast cancer patients undergoing TAM treatment carry at least one incomplete functional allele, including 20.9% of the patients who carry only incomplete functional alleles for both the CYP2D6 and CYP3A5 genes. This research

  10. Coprescription of Tamoxifen and Medications That Inhibit CYP2D6

    PubMed Central

    Sideras, Kostandinos; Ingle, James N.; Ames, Matthew M.; Loprinzi, Charles L.; Mrazek, David P.; Black, John L.; Weinshilboum, Richard M.; Hawse, John R.; Spelsberg, Thomas C.; Goetz, Matthew P.

    2010-01-01

    Evidence has emerged that the clinical benefit of tamoxifen is related to the functional status of the hepatic metabolizing enzyme cytochrome P450 2D6 (CYP2D6). CYP2D6 is the key enzyme responsible for the generation of the potent tamoxifen metabolite, endoxifen. Multiple studies have examined the relationship of CYP2D6 status to breast cancer outcomes in tamoxifen-treated women; the majority of studies demonstrated that women with impaired CYP2D6 metabolism have lower endoxifen concentrations and a greater risk of breast cancer recurrence. As a result, practitioners must be aware that some of the most commonly prescribed medications coadministered with tamoxifen interfere with CYP2D6 function, thereby reducing endoxifen concentrations and potentially increasing the risk of breast cancer recurrence. After reviewing the published data regarding tamoxifen metabolism and the evidence relating CYP2D6 status to breast cancer outcomes in tamoxifen-treated patients, we are providing a guide for the use of medications that inhibit CYP2D6 in patients administered tamoxifen. PMID:20439629

  11. Potential role of CYP2D6 in the central nervous system

    PubMed Central

    Cheng, Jie; Zhen, Yueying; Miksys, Sharon; Beyoğlu, Diren; Krausz, Kristopher W.; Tyndale, Rachel F.; Yu, Aiming; Idle, Jeffrey R.; Gonzalez, Frank J.

    2013-01-01

    Cytochrome P450 2D6 (CYP2D6) is a pivotal enzyme responsible for a major human drug oxidation polymorphism in human populations. Distribution of CYP2D6 in brain and its role in serotonin metabolism suggest this CYP2D6 may have a function in central nervous system. To establish an efficient and accurate platform for the study of CYP2D6 in vivo, a transgenic human CYP2D6 (Tg-2D6) model was generated by transgenesis in wild-type C57BL/6 (WT) mice using a P1 phage artificial chromosome clone containing the complete human CYP2D locus, including CYP2D6 gene and 5’- and 3’- flanking sequences. Human CYP2D6 was expressed not only in the liver, but also in brain. The abundance of serotonin and 5-hydroxyindoleacetic acid in brain of Tg-2D6 is higher than in WT mice either basal levels or after harmaline induction. Metabolomics of brain homogenate and cerebrospinal fluid revealed a significant up-regulation of l-carnitine, acetyl-l-carnitine, pantothenic acid, dCDP, anandamide, N-acetylglucosaminylamine, and a down-regulation of stearoyl-l-carnitine in Tg-2D6 mice compared with WT mice. Anxiety tests indicate Tg-2D6 mice have a higher capability to adapt to anxiety. Overall, these findings indicate that the Tg-2D6 mouse model may serve as a valuable in vivo tool to determine CYP2D6-involved neurophysiological metabolism and function. PMID:23614566

  12. Impact of CYP2D*6 in the adjuvant treatment of breast cancer patients with tamoxifen.

    PubMed

    Markopoulos, Christos; Kykalos, Stylianos; Mantas, Dimitrios

    2014-08-10

    Biotransformation of tamoxifen to the potent antiestrogen endoxifen is performed by cytochrome P450 (CYP) enzymes, in particular the CYP2D6 isoform. CYP2D6*4 is one of the most frequent alleles associated with loss of enzymatic activity. The incidence of CYP2D6*4 among Caucasians is estimated up to 27%, while it is present in up to 90% of all poor metabolizers within the Caucasian population. The hypothesis under question is whether the presence of one or two non-functioning (null) alleles predicts an inferior outcome in postmenopausal women with breast cancer receiving adjuvant treatment with tamoxifen. The numerous existing studies investigating the association of CYP2D6 with treatment failure in breast cancer are inconsistent and give rather conflicting results. Currently, routine CYP2D6 testing among women with breast cancer is not recommended and the significance of CYP2D6 phenotype in decision making regarding the administration of tamoxifen is unclear. The present study summarizes current literature regarding clinical studies on CYP2D6*4, particularly in terms of response to tamoxifen therapy and breast cancer outcome. PMID:25114852

  13. Impact of CYP2D*6 in the adjuvant treatment of breast cancer patients with tamoxifen

    PubMed Central

    Markopoulos, Christos; Kykalos, Stylianos; Mantas, Dimitrios

    2014-01-01

    Biotransformation of tamoxifen to the potent antiestrogen endoxifen is performed by cytochrome P450 (CYP) enzymes, in particular the CYP2D6 isoform. CYP2D6*4 is one of the most frequent alleles associated with loss of enzymatic activity. The incidence of CYP2D6*4 among Caucasians is estimated up to 27%, while it is present in up to 90% of all poor metabolizers within the Caucasian population. The hypothesis under question is whether the presence of one or two non-functioning (null) alleles predicts an inferior outcome in postmenopausal women with breast cancer receiving adjuvant treatment with tamoxifen. The numerous existing studies investigating the association of CYP2D6 with treatment failure in breast cancer are inconsistent and give rather conflicting results. Currently, routine CYP2D6 testing among women with breast cancer is not recommended and the significance of CYP2D6 phenotype in decision making regarding the administration of tamoxifen is unclear. The present study summarizes current literature regarding clinical studies on CYP2D6*4, particularly in terms of response to tamoxifen therapy and breast cancer outcome. PMID:25114852

  14. MDMA, methamphetamine, and CYP2D6 pharmacogenetics: what is clinically relevant?

    PubMed

    de la Torre, Rafael; Yubero-Lahoz, Samanta; Pardo-Lozano, Ricardo; Farré, Magí

    2012-01-01

    In vitro human studies show that the metabolism of most amphetamine-like psychostimulants is regulated by the polymorphic cytochrome P450 isozyme CYP2D6. Two compounds, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA), were selected as archetypes to discuss the translation and clinical significance of in vitro to in vivo findings. Both compounds were chosen based on their differential interaction with CYP2D6 and their high abuse prevalence in society. Methamphetamine behaves as both a weak substrate and competitive inhibitor of CYP2D6, while MDMA acts as a high affinity substrate and potent mechanism-based inhibitor (MBI) of the enzyme. The MBI behavior of MDMA on CYP2D6 implies that subjects, irrespective of their genotype/phenotype, are phenocopied to the poor metabolizer (PM) phenotype. The fraction of metabolic clearance regulated by CYP2D6 for both drugs is substantially lower than expected from in vitro studies. Other isoenzymes of cytochrome P450 and a relevant contribution of renal excretion play a part in their clearance. These facts tune down the potential contribution of CYP2D6 polymorphism in the clinical outcomes of both substances. Globally, the clinical relevance of CYP2D6 polymorphism is lower than that predicted by in vitro studies. PMID:23162568

  15. Distribution of CYP2D6 alleles and phenotypes in the Brazilian population.

    PubMed

    Friedrich, Deise C; Genro, Júlia P; Sortica, Vinicius A; Suarez-Kurtz, Guilherme; de Moraes, Maria Elizabete; Pena, Sergio D J; dos Santos, Andrea K Ribeiro; Romano-Silva, Marco A; Hutz, Mara H

    2014-01-01

    The CYP2D6 enzyme is one of the most important members of the cytochrome P450 superfamily. This enzyme metabolizes approximately 25% of currently prescribed medications. The CYP2D6 gene presents a high allele heterogeneity that determines great inter-individual variation. The aim of this study was to evaluate the variability of CYP2D6 alleles, genotypes and predicted phenotypes in Brazilians. Eleven single nucleotide polymorphisms and CYP2D6 duplications/multiplications were genotyped by TaqMan assays in 1020 individuals from North, Northeast, South, and Southeast Brazil. Eighteen CYP2D6 alleles were identified in the Brazilian population. The CYP2D6*1 and CYP2D6*2 alleles were the most frequent and widely distributed in different geographical regions of Brazil. The highest number of CYPD6 alleles observed was six and the frequency of individuals with more than two copies ranged from 6.3% (in Southern Brazil) to 10.2% (Northern Brazil). The analysis of molecular variance showed that CYP2D6 is homogeneously distributed across different Brazilian regions and most of the differences can be attributed to inter-individual differences. The most frequent predicted metabolic status was EM (83.5%). Overall 2.5% and 3.7% of Brazilians were PMs and UMs respectively. Genomic ancestry proportions differ only in the prevalence of intermediate metabolizers. The IM predicted phenotype is associated with a higher proportion of African ancestry and a lower proportion of European ancestry in Brazilians. PM and UM classes did not vary among regions and/or ancestry proportions therefore unique CYP2D6 testing guidelines for Brazilians are possible and could potentially avoid ineffective or adverse events outcomes due to drug prescriptions. PMID:25329392

  16. Distribution of CYP2D6 Alleles and Phenotypes in the Brazilian Population

    PubMed Central

    Sortica, Vinicius A.; Suarez-Kurtz, Guilherme; de Moraes, Maria Elizabete; Pena, Sergio D. J.; dos Santos, Ândrea K. Ribeiro; Romano-Silva, Marco A.; Hutz, Mara H.

    2014-01-01

    Abstract The CYP2D6 enzyme is one of the most important members of the cytochrome P450 superfamily. This enzyme metabolizes approximately 25% of currently prescribed medications. The CYP2D6 gene presents a high allele heterogeneity that determines great inter-individual variation. The aim of this study was to evaluate the variability of CYP2D6 alleles, genotypes and predicted phenotypes in Brazilians. Eleven single nucleotide polymorphisms and CYP2D6 duplications/multiplications were genotyped by TaqMan assays in 1020 individuals from North, Northeast, South, and Southeast Brazil. Eighteen CYP2D6 alleles were identified in the Brazilian population. The CYP2D6*1 and CYP2D6*2 alleles were the most frequent and widely distributed in different geographical regions of Brazil. The highest number of CYPD6 alleles observed was six and the frequency of individuals with more than two copies ranged from 6.3% (in Southern Brazil) to 10.2% (Northern Brazil). The analysis of molecular variance showed that CYP2D6 is homogeneously distributed across different Brazilian regions and most of the differences can be attributed to inter-individual differences. The most frequent predicted metabolic status was EM (83.5%). Overall 2.5% and 3.7% of Brazilians were PMs and UMs respectively. Genomic ancestry proportions differ only in the prevalence of intermediate metabolizers. The IM predicted phenotype is associated with a higher proportion of African ancestry and a lower proportion of European ancestry in Brazilians. PM and UM classes did not vary among regions and/or ancestry proportions therefore unique CYP2D6 testing guidelines for Brazilians are possible and could potentially avoid ineffective or adverse events outcomes due to drug prescriptions. PMID:25329392

  17. The Effect of CYP2D6 Drug-Drug Interactions on Hydrocodone Effectiveness

    PubMed Central

    Monte, Andrew A.; Heard, Kennon J.; Campbell, Jenny; Hamamura, D.; Weinshilboum, Richard M.; Vasiliou, Vasilis

    2014-01-01

    Objectives The hepatic cytochrome 2D6 (CYP2D6) is a saturable enzyme responsible for metabolism of approximately 25% of known pharmaceuticals. CYP interactions can alter the efficacy of prescribed medications. Hydrocodone is largely dependent on CYP2D6 metabolism for analgesia, ondansetron is inactivated by CYP2D6, and oxycodone analgesia is largely independent of CYP2D6. The objective was to determine if CYP2D6 medication co-ingestion decreases the effectiveness of hydrocodone. Methods This was a prospective observational study conducted in an academic U.S. emergency department (ED). Subjects were included if they had self-reported pain or nausea; and were excluded if they were unable to speak English, were less than 18 years of age, had liver or renal failure, or carried diagnoses of chronic pain or cyclic vomiting. Detailed drug ingestion histories for the preceding 48 hours prior to the ED visit were obtained. The patient's pain and nausea were quantified using a 100-millimeter visual analogue scale (VAS) at baseline prior to drug administration and following doses of hydrocodone, oxycodone, or ondansetron. We used a mixed model with random subject effect to determine the interaction between CYP2D6 drug ingestion and study drug effectiveness. Odds ratios (OR) were calculated to compare clinically significant VAS changes between CYP2D6 users and non-users. Results Two hundred fifty (49.8%) of the 502 subjects enrolled had taken at least one CYP2D6 substrate, inhibitor, or inducing pharmaceutical, supplement, or illicit drug in the 48 hours prior to ED presentation. CYP2D6-drug users were one third as likely to respond to hydrocodone (OR 0.33, 95% CI = 0.1 to 0.8), and more than three times as likely as non-users to respond to ondansetron (OR 3.4, 95% CI = 1.3 to 9.1). There was no significant difference in oxycodone effectiveness between CYP2D6 users and non-users (OR 0.53, 95% CI = 0.3 to 1.1). Conclusions CYP2D6 drug-drug interactions appear to change

  18. Effect of CYP2D6 genetic polymorphism on the metabolism of citalopram in vitro.

    PubMed

    Hu, Xiao-Xia; Yuan, Ling-Jing; Fang, Ping; Mao, Yong-Hui; Zhan, Yun-Yun; Li, Xiang-Yu; Dai, Da-Peng; Cai, Jian-Ping; Hu, Guo-Xin

    2016-04-01

    Genetic polymorphisms of CYP2D6 significantly influence the efficacy and safety of some drugs, which might cause adverse effects and therapeutic failure. We aimed at investigating the role of CYP2D6 in the metabolism of citalopram and identifying the effect of 24 CYP2D6 allelic variants we found in Chinese Han population on the metabolism of citalopram in vitro. These CYP2D6 variants expressed by insect cells system were incubated with 10-1000 μM citalopram for 30 min at 37 °C and the reaction was terminated by cooling to -80 °C immediately. Citalopram and its metabolites were analyzed by high-performance liquid chromatography (HPLC). The intrinsic clearance (Vmax/Km) values of the variants toward citalopram metabolites were significantly altered, 38-129% for demethylcitalopram and 13-138% for citalopram N-oxide when compared with CYP2D6*1. Most of the tested rare alleles exhibited significantly decreased values due to increased Km and/or decreased Vmax values. We conclude that recombinant system could be used to investigate the enzymes involved in drug metabolism and these findings suggest that more attention should be paid to subjects carrying these CYP2D6 alleles when administering citalopram in the clinic. PMID:27016952

  19. Haloperidol plasma concentration in Japanese psychiatric subjects with gene duplication of CYP2D6

    PubMed Central

    Ohnuma, Tohru; Shibata, Nobuto; Matsubara, Yoichiro; Arai, Heii

    2003-01-01

    Aims The cytochrome P-450 2D6 (CYP2D6) gene duplication/multiduplication producing an increase in enzyme activity, and the common Japanese mutation, CYP2D6*10A producing a decrease of enzyme activity were screened in a large number of Japanese psychiatric subjects (n = 111) in order to investigate whether these mutated alleles affected the plasma concentration of haloperidol. Methods Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was performed to identify the CYP2D6*10A and CYP2D6*2 genotypes in subjects who had been taking haloperidol. For the screening of duplicated active CYP2D6 gene, allele-specific long PCR was performed. Plasma concentration of haloperidol was measured by the enzyme immunoassay, and expressed as ‘plasma concentration dose ratio’ to normalize individual differences. Results The plasma concentration–dose ratio showed large interindividual differences of approximately 18-fold. PCR-RFLP methods revealed that 29 (26.1%), 10 (9.0%), 39 (35.1%), 0 (0%), seven (6.3%) and 26 (23.4%) cases possessed the CYP2D6 genotypes *1/*1, *1/*2, *1/*10A, *2/*2, *2/*10A and *10 A/*10A, respectively. Six cases (5.4%) had duplicated CYP2D6 genes. There were no significant differences of plasma concentration–dose ratio between the groups classified by CYP2D6*10A and *2 genotypes (Kruskal–Wallis test; P = 0.37), even in those cases whose daily doses were lower than 20 mg (n = 90, P = 0.91). Subjects having duplicated genes (n = 6) did not show significant differences of plasma concentration–dose ratio by comparison with subjects who had no duplicated genes (Mann–Whitney U-test; P = 0.80). Conclusions Gene duplication, and the common Japanese mutation CYP2D6*10A on CYP2D6 gene are not likely to be the main modulatory factors of plasma concentration of haloperidol in Japanese psychiatric subjects. PMID:12919180

  20. Establishment of CYP2D6 reference samples by multiple validated genotyping platforms.

    PubMed

    Fang, H; Liu, X; Ramírez, J; Choudhury, N; Kubo, M; Im, H K; Konkashbaev, A; Cox, N J; Ratain, M J; Nakamura, Y; O'Donnell, P H

    2014-12-01

    Cytochrome P450 2D6 (cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6)), a highly polymorphic drug-metabolizing enzyme, is involved in the metabolism of one-quarter of the most commonly prescribed medications. Here we have applied multiple genotyping methods and Sanger sequencing to assign precise and reproducible CYP2D6 genotypes, including copy numbers, for 48 HapMap samples. Furthermore, by analyzing a set of 50 human liver microsomes using endoxifen formation from N-desmethyl-tamoxifen as the phenotype of interest, we observed a significant positive correlation between CYP2D6 genotype-assigned activity score and endoxifen formation rate (rs = 0.68 by rank correlation test, P = 5.3 × 10(-8)), which corroborated the genotype-phenotype prediction derived from our genotyping methodologies. In the future, these 48 publicly available HapMap samples characterized by multiple substantiated CYP2D6 genotyping platforms could serve as a reference resource for assay development, validation, quality control and proficiency testing for other CYP2D6 genotyping projects and for programs pursuing clinical pharmacogenomic testing implementation. PMID:24980783

  1. Establishment of CYP2D6 Reference Samples by Multiple Validated Genotyping Platforms

    PubMed Central

    Fang, Hua; Liu, Xiao; Ramírez, Jacqueline; Choudhury, Noura; Kubo, Michiaki; Im, Hae Kyung; Konkashbaev, Anuar; Cox, Nancy J.; Ratain, Mark J.; Nakamura, Yusuke; O’Donnell, Peter H.

    2014-01-01

    Cytochrome P450 2D6 (cytochrome P450, family 2, subfamily D, polypeptide 6, or CYP2D6), a highly polymorphic drug metabolizing enzyme, is involved in the metabolism of one quarter of the most commonly prescribed medications. Here, we have applied multiple genotyping methods and Sanger sequencing to assign precise and reproducible CYP2D6 genotypes, including copy numbers, for 48 HapMap samples. Furthermore, by analyzing a set of 50 human liver microsomes using endoxifen formation from N-desmethyl-tamoxifen as the phenotype of interest, we observed a significant positive correlation between CYP2D6 genotype-assigned activity score and endoxifen formation rate (rs = 0.68 by Rank correlation test, P = 5.3 ×10−8), which corroborated the genotype-phenotype prediction derived from our genotyping methodologies. In the future, these 48 publicly available HapMap samples characterized by multiple substantiated CYP2D6 genotyping platforms could serve as a reference resource for assay development, validation, quality control, and proficiency testing for other CYP2D6 genotyping projects, and for programs pursuing clinical pharmacogenomic testing implementation. PMID:24980783

  2. Clinical Relevance of CYP2D6 Genetics for Tamoxifen Response in Breast Cancer

    PubMed Central

    Brauch, Hiltrud; Schroth, Werner; Eichelbaum, Michel; Schwab, Matthias; Harbeck, Nadia

    2008-01-01

    Summary Tamoxifen is a standard endocrine therapy for the prevention and treatment of steroid hormone receptor-positive breast cancer. Tamoxifen requires enzymatic activation by CYP 450 enzymes for the formation of clinically relevant metabolites, 4-OH-tamoxifen and endoxifen, which both have a greater affinity to the estrogen receptor and ability to inhibit cell proliferation when compared to the parent drug. CYP2D6 is the key enzyme in this biotransformation, and recent mechanistic, pharmacologic, and clinical pharmacogenetic evidence suggests that genetic variants and drug interaction by CYP2D6 inhibitors influence plasma concentrations of active tamoxifen metabolites and outcome of patients treated with adjuvant tamoxifen. Particularly, non-functional (poor metabolizer) and severely impaired (intermediate metabolizer) CYP2D6 variants are associated with higher recurrence rates. Accordingly, CYP2D6 genotyping prior to treatment for prediction of metabolizer status and outcome may open new avenues for the individualization of endocrine treatment choice and benefit. Moreover, strong CYP2D6 inhibitors such as the selective serotonin reuptake inhibitor paroxetine should be avoided as co-medication. PMID:20824020

  3. Understanding CYP2D6 and its role in tamoxifen metabolism.

    PubMed

    Smith, Edith Caroline

    2013-11-01

    The gene CYP2D6 has an extremely important role in drug metabolism. "Cytochrome P450, family 2, subfamily D, polypeptide 6" is the official name of CYP2D6. The gene is located at position 13.1 on the long (q) arm of chromosome 21 and encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases that are heavily involved in drug metabolism (Genetics Home Reference, 2013), and many drugs are activated into their biologically active compounds. Because of numerous polymorphisms, the gene also has significant person-to-person variability. To date, more than 80 distinct CYP2D6 alleles and specific types and frequencies have been associated with different ethnic groups. CYP2D6*4 is the most common variant allele in Caucasians and, in that population, has a frequency of about 25%. On the other hand, CYP2D6*10 is common in the Asian population (Stearns & Rae, 2008). PMID:24161632

  4. CYP2D6 Genotype Dependent Oxycodone Metabolism in Postoperative Patients

    PubMed Central

    Stamer, Ulrike M.; Zhang, Lan; Book, Malte; Lehmann, Lutz E.; Stuber, Frank; Musshoff, Frank

    2013-01-01

    Background The impact of polymorphic cytochrome P450 CYP2D6 enzyme on oxycodone's metabolism and clinical efficacy is currently being discussed. However, there are only spare data from postoperative settings. The hypothesis of this study is that genotype dependent CYP2D6 activity influences plasma concentrations of oxycodone and its metabolites and impacts analgesic consumption. Methods Patients received oxycodone 0.05 mg/kg before emerging from anesthesia and patient-controlled analgesia (PCA) for the subsequent 48 postoperative hours. Blood samples were drawn at 30, 90 and 180 minutes after the initial oxycodone dose. Plasma concentrations of oxycodone and its metabolites oxymorphone, noroxycodone and noroxymorphone were analyzed by liquid chromatography-mass spectrometry with electrospray ionization. CYP2D6 genotyping was performed and 121 patients were allocated to the following genotype groups: PM (poor metabolizer: no functionally active CYP2D6 allele), HZ/IM (heterozygous subjects, intermediate metabolizers with decreased CYP2D6 activity), EM (extensive metabolizers, normal CYP2D6 activity) and UM (ultrarapid metabolizers, increased CYP2D6 activity). Primary endpoint was the genotype dependent metabolite ratio of plasma concentrations oxymorphone/oxycodone. Secondary endpoint was the genotype dependent analgesic consumption with calculation of equianalgesic doses compared to the standard non-CYP dependent opioid piritramide. Results Metabolism differed between CYP2D6 genotypes. Mean (95%-CI) oxymophone/oxycodone ratios were 0.10 (0.02/0.19), 0.13 (0.11/0.16), 0.18 (0.16/0.20) and 0.28 (0.07/0.49) in PM, HZ/IM, EM and UM, respectively (p = 0.005). Oxycodone consumption up to the 12th hour was highest in PM (p = 0.005), resulting in lowest equianalgesic doses of piritramide versus oxycodone for PM (1.6 (1.4/1.8); EM and UM 2.2 (2.1/2.3); p<0.001). Pain scores did not differ between genotypes. Conclusions In this postoperative setting, the number of

  5. Individualization of tamoxifen therapy: much more than just CYP2D6 genotyping.

    PubMed

    Binkhorst, Lisette; Mathijssen, Ron H J; Jager, Agnes; van Gelder, Teun

    2015-03-01

    Clinical response to tamoxifen varies widely among women treated with this drug for hormone receptor-positive breast cancer. The principal active metabolite - endoxifen - is generated through hepatic metabolism of tamoxifen, with key roles for cytochrome P450 (CYP) CYP2D6 and CYP3A. By influencing endoxifen formation, genetic variants of CYP2D6 may affect response to tamoxifen. After a decade of research, examining the effects of CYP2D6 genetic variants on tamoxifen efficacy, there is still no agreement on the clinical utility of CYP2D6 genotype as biomarker for the prediction of breast cancer outcome, because studies revealed conflicting results. However, tamoxifen metabolism is complex and involves several other drug-metabolizing enzymes. Genetic variants of other CYP enzymes, including CYP3A4 and CYP2C9/19, as well as co-medication interfering with the metabolic activity of CYP2D6 and CYP3A4 have been shown to affect endoxifen concentrations and may also contribute to the variability in response to tamoxifen. Phenotyping strategies can predict endoxifen exposure more accurately than CYP2D6 genotype, but do not take into account all factors influencing endoxifen exposure. Therapeutic drug monitoring (TDM) is likely to be the optimal strategy for individualization of tamoxifen treatment. According to a growing amount of literature, endoxifen concentration seems to be a predictor of clinical outcome. The relationship between endoxifen levels and breast cancer outcomes has to be replicated and confirmed and the value of TDM should be evaluated in prospective clinical trials. Caution is advised regarding the concomitant use of medications which could interact with tamoxifen, including inhibitors and inducers of CYP enzymes. PMID:25618289

  6. METOCLOPRAMIDE IS METABOLIZED BY CYP2D6 AND IS A REVERSIBLE INHIBITOR, BUT NOT INACTIVATOR, OF CYP2D6

    PubMed Central

    Nagy, Leslie D.; Fujiwara, Rina; Furge, Laura Lowe

    2014-01-01

    Metoclopramide is a widely used clinical drug in a variety of medical settings with rare acute dystonic events reported. The aim of this study was to assess a previous report of inactivation of CYP2D6 by metoclopramide, to determine the contribution of various CYPs to metoclopramide metabolism, and to identify the mono-oxygenated products of metoclopramide metabolism. Metoclopramide interacted with CYP2D6 with Type I binding and a Ks value of 9.56 ± 1.09 μM. CYP2D6 was the major metabolizer of metoclopramide and the two major products were N-deethylation of the diethyl amine and N-hydroxylation on the phenyl ring amine. CYPs 1A2, 2C9, 2C19, and 3A4 also metabolized metoclopramide. While reversible inhibition of CYP2D6 was noted, CYP2D6 inactivation by metoclopramide was not observed under conditions of varying concentration or varying time using Supersomes™ or pool human liver microsomes. The major metabolites of metoclopramide were N-hydroxylation and N-deethylation formed most efficiently by CYP2D6 but also formed by all CYPs examined. Also, while metoclopramide is metabolized primarily by CYP2D6, it is not a mechanism-based inactivator of CYP2D6 in vitro. PMID:24010633

  7. Metoclopramide is metabolized by CYP2D6 and is a reversible inhibitor, but not inactivator, of CYP2D6.

    PubMed

    Livezey, Mara R; Briggs, Erran D; Bolles, Amanda K; Nagy, Leslie D; Fujiwara, Rina; Furge, Laura Lowe

    2014-04-01

    1. Metoclopramide is a widely used clinical drug in a variety of medical settings with rare acute dystonic events reported. The aim of this study was to assess a previous report of inactivation of CYP2D6 by metoclopramide, to determine the contribution of various CYPs to metoclopramide metabolism, and to identify the mono-oxygenated products of metoclopramide metabolism. 2. Metoclopramide interacted with CYP2D6 with Type I binding and a Ks value of 9.56 ± 1.09 µM. CYP2D6 was the major metabolizer of metoclopramide and the two major products were N-deethylation of the diethyl amine and N-hydroxylation on the phenyl ring amine. CYPs 1A2, 2C9, 2C19, and 3A4 also metabolized metoclopramide. 3. While reversible inhibition of CYP2D6 was noted, CYP2D6 inactivation by metoclopramide was not observed under conditions of varying concentration or varying time using Supersomes(TM) or pooled human liver microsomes. 4. The major metabolites of metoclopramide were N-hydroxylation and N-deethylation formed most efficiently by CYP2D6 but also formed by all CYPs examined. Also, while metoclopramide is metabolized primarily by CYP2D6, it is not a mechanism-based inactivator of CYP2D6 in vitro. PMID:24010633

  8. Challenges in CYP2D6 phenotype assignment from genotype data: a critical assessment and call for standardization.

    PubMed

    Hicks, J Kevin; Swen, Jesse J; Gaedigk, Andrea

    2014-02-01

    The cytochrome P450 2D6 (CYP2D6) enzyme contributes to the metabolism and/or bioactivation of approximately 25% of clinically used drugs. The CYP2D6 gene locus is highly polymorphic and complex, and variants within this gene locus affect CYP2D6 enzymatic function resulting in a wide range of metabolic activity from little to no activity to ultrarapid metabolism. For many of the drugs metabolized by CYP2D6, the variation in metabolic activity is one of the most important factors responsible for interindividual drug response. Therefore, determining an individual's CYP2D6 phenotype, or metabolic status, will help identify individuals that may benefit from a change in drug or drug dosage. Genotype analysis has become the method of choice to predict a person's metabolic status. Numerous reference laboratories now offer CYP2D6 genotyping; however, there can be substantial differences in the number of genetic variants interrogated as well as test interpretation. Furthermore, there is no standardized process of how a CYP2D6 genotype result is translated into a phenotype assignment. This review summarizes the complexity of CYP2D6 genotyping and highlights the major challenges for phenotype classification. We call for the implementation of a universally accepted system for CYP2D6 phenotype assignment to promote consistency of test interpretation among reference laboratories and medical institutions. We propose a system that utilizes the CYP2D6 activity score system to place individuals into a continuum of activity scores - rather than using the traditional poor, intermediate, extensive and ultra-rapid metabolizer categorizations - and directly translating activity scores into clinically actionable recommendations. PMID:24524666

  9. The effects of CYP2D6 and CYP3A activities on the pharmacokinetics of immediate release oxycodone

    PubMed Central

    Samer, CF; Daali, Y; Wagner, M; Hopfgartner, G; Eap, CB; Rebsamen, MC; Rossier, MF; Hochstrasser, D; Dayer, P; Desmeules, JA

    2010-01-01

    Background and purpose: There is high interindividual variability in the activity of drug-metabolizing enzymes catalysing the oxidation of oxycodone [cytochrome P450 (CYP) 2D6 and 3A], due to genetic polymorphisms and/or drug–drug interactions. The effects of CYP2D6 and/or CYP3A activity modulation on the pharmacokinetics of oxycodone remains poorly explored. Experimental approach: A randomized crossover double-blind placebo-controlled study was performed with 10 healthy volunteers genotyped for CYP2D6 [six extensive (EM), two deficient (PM/IM) and two ultrarapid metabolizers (UM)]. The volunteers randomly received on five different occasions: oxycodone 0.2 mg·kg−1 and placebo; oxycodone and quinidine (CYP2D6 inhibitor); oxycodone and ketoconazole (CYP3A inhibitor); oxycodone and quinidine+ketoconazole; placebo. Blood samples for plasma concentrations of oxycodone and metabolites (oxymorphone, noroxycodone and noroxymorphone) were collected for 24 h after dosing. Phenotyping for CYP2D6 (with dextromethorphan) and CYP3A (with midazolam) were assessed at each session. Key results: CYP2D6 activity was correlated with oxymorphone and noroxymorphone AUCs and Cmax (−0.71 < Spearman correlation coefficient ρs < −0.92). Oxymorphone Cmax was 62% and 75% lower in PM than EM and UM. Noroxymorphone Cmax reduction was even more pronounced (90%). In UM, oxymorphone and noroxymorphone concentrations increased whereas noroxycodone exposure was halved. Blocking CYP2D6 (with quinidine) reduced oxymorphone and noroxymorphone Cmax by 40% and 80%, and increased noroxycodone AUC∞ by 70%. Blocking CYP3A4 (with ketoconazole) tripled oxymorphone AUC∞ and reduced noroxycodone and noroxymorphone AUCs by 80%. Shunting to CYP2D6 pathway was observed after CYP3A4 inhibition. Conclusions and implications: Drug–drug interactions via CYP2D6 and CYP3A affected oxycodone pharmacokinetics and its magnitude depended on CYP2D6 genotype. PMID:20590587

  10. Pharmacogenetics of CYP2D6 and tamoxifen therapy: Light at the end of the tunnel?

    PubMed

    Del Re, M; Citi, V; Crucitta, S; Rofi, E; Belcari, F; van Schaik, R H; Danesi, R

    2016-05-01

    The clinical usefulness of assessing the enzymatic activity of CYPD6 in patients taking tamoxifen had been longly debated. In favour of preemptive evaluation of phenotypic profile of patients is the strong pharmacologic rationale, being that the formation of endoxifen, the major and clinically most important metabolite of tamoxifen, is largely dependent on the activity of CYP2D6. This enzyme is highly polymorphic for which the activity is largely depending on genetics, but that can also be inhibited by a number of drugs, i.e. antidepressants, which are frequently used in patients with cancer. Unfortunately, the clinical trials that have been published in the last years are contradicting each other on the association between CYP2D6 and significant clinical endpoints, and for this reason CYP2D6 genotyping is at present not generally recommended. Despite this, the CYP2D6 genotyping test for tamoxifen is available in many laboratories and it may still be an appropriate test to use it in specific cases. PMID:27060675

  11. CYP2D7 Sequence Variation Interferes with TaqMan CYP2D6*15 and *35 Genotyping

    PubMed Central

    Riffel, Amanda K.; Dehghani, Mehdi; Hartshorne, Toinette; Floyd, Kristen C.; Leeder, J. Steven; Rosenblatt, Kevin P.; Gaedigk, Andrea

    2016-01-01

    TaqMan™ genotyping assays are widely used to genotype CYP2D6, which encodes a major drug metabolizing enzyme. Assay design for CYP2D6 can be challenging owing to the presence of two pseudogenes, CYP2D7 and CYP2D8, structural and copy number variation and numerous single nucleotide polymorphisms (SNPs) some of which reflect the wild-type sequence of the CYP2D7 pseudogene. The aim of this study was to identify the mechanism causing false-positive CYP2D6*15 calls and remediate those by redesigning and validating alternative TaqMan genotype assays. Among 13,866 DNA samples genotyped by the CompanionDx® lab on the OpenArray platform, 70 samples were identified as heterozygotes for 137Tins, the key SNP of CYP2D6*15. However, only 15 samples were confirmed when tested with the Luminex xTAG CYP2D6 Kit and sequencing of CYP2D6-specific long range (XL)-PCR products. Genotype and gene resequencing of CYP2D6 and CYP2D7-specific XL-PCR products revealed a CC>GT dinucleotide SNP in exon 1 of CYP2D7 that reverts the sequence to CYP2D6 and allows a TaqMan assay PCR primer to bind. Because CYP2D7 also carries a Tins, a false-positive mutation signal is generated. This CYP2D7 SNP was also responsible for generating false-positive signals for rs769258 (CYP2D6*35) which is also located in exon 1. Although alternative CYP2D6*15 and *35 assays resolved the issue, we discovered a novel CYP2D6*15 subvariant in one sample that carries additional SNPs preventing detection with the alternate assay. The frequency of CYP2D6*15 was 0.1% in this ethnically diverse U.S. population sample. In addition, we also discovered linkage between the CYP2D7 CC>GT dinucleotide SNP and the 77G>A (rs28371696) SNP of CYP2D6*43. The frequency of this tentatively functional allele was 0.2%. Taken together, these findings emphasize that regardless of how careful genotyping assays are designed and evaluated before being commercially marketed, rare or unknown SNPs underneath primer and/or probe regions can impact

  12. CYP2D7 Sequence Variation Interferes with TaqMan CYP2D6 (*) 15 and (*) 35 Genotyping.

    PubMed

    Riffel, Amanda K; Dehghani, Mehdi; Hartshorne, Toinette; Floyd, Kristen C; Leeder, J Steven; Rosenblatt, Kevin P; Gaedigk, Andrea

    2015-01-01

    TaqMan™ genotyping assays are widely used to genotype CYP2D6, which encodes a major drug metabolizing enzyme. Assay design for CYP2D6 can be challenging owing to the presence of two pseudogenes, CYP2D7 and CYP2D8, structural and copy number variation and numerous single nucleotide polymorphisms (SNPs) some of which reflect the wild-type sequence of the CYP2D7 pseudogene. The aim of this study was to identify the mechanism causing false-positive CYP2D6 (*) 15 calls and remediate those by redesigning and validating alternative TaqMan genotype assays. Among 13,866 DNA samples genotyped by the CompanionDx® lab on the OpenArray platform, 70 samples were identified as heterozygotes for 137Tins, the key SNP of CYP2D6 (*) 15. However, only 15 samples were confirmed when tested with the Luminex xTAG CYP2D6 Kit and sequencing of CYP2D6-specific long range (XL)-PCR products. Genotype and gene resequencing of CYP2D6 and CYP2D7-specific XL-PCR products revealed a CC>GT dinucleotide SNP in exon 1 of CYP2D7 that reverts the sequence to CYP2D6 and allows a TaqMan assay PCR primer to bind. Because CYP2D7 also carries a Tins, a false-positive mutation signal is generated. This CYP2D7 SNP was also responsible for generating false-positive signals for rs769258 (CYP2D6 (*) 35) which is also located in exon 1. Although alternative CYP2D6 (*) 15 and (*) 35 assays resolved the issue, we discovered a novel CYP2D6 (*) 15 subvariant in one sample that carries additional SNPs preventing detection with the alternate assay. The frequency of CYP2D6 (*) 15 was 0.1% in this ethnically diverse U.S. population sample. In addition, we also discovered linkage between the CYP2D7 CC>GT dinucleotide SNP and the 77G>A (rs28371696) SNP of CYP2D6 (*) 43. The frequency of this tentatively functional allele was 0.2%. Taken together, these findings emphasize that regardless of how careful genotyping assays are designed and evaluated before being commercially marketed, rare or unknown SNPs underneath primer

  13. META-ANALYSIS OF CYP2D6 METABOLIZER PHENOTYPE AND METOPROLOL PHARMACOKINETICS

    PubMed Central

    Blake, CM; Kharasch, ED; Schwab, M; Nagele, P

    2013-01-01

    Metoprolol, a commonly prescribed beta-blocker, is primarily metabolized by cytochrome P450 2D6 (CYP2D6), an enzyme with substantial genetic heterogeneity. Several smaller studies have shown that metoprolol pharmacokinetics is influenced by CYP2D6 genotype and metabolizer phenotype. To increase robustness of metoprolol pharmacokinetic estimates, a systematic review and meta-analysis of pharmacokinetic studies that administered a single oral dose of immediate release metoprolol was performed. Pooled analysis (n= 264) demonstrated differences in peak plasma metoprolol concentration, area under the concentration-time curve, elimination half-life, and apparent oral clearance that were 2.3-, 4.9-, 2.3-, and 5.9-fold between extensive and poor metabolizers, respectively, and 5.3-, 13-, 2.6-, and 15-fold between ultra-rapid and poor metabolizers (all p<0.001). Enantiomer-specific analysis revealed genotype-dependent enantio-selective metabolism, with nearly 40% greater R- vs S-metoprolol metabolism in ultra-rapid and extensive metabolizers. This study demonstrates a marked effect of CYP2D6 metabolizer phenotype on metoprolol pharmacokinetics and confirms enantiomer specific metabolism of metoprolol. PMID:23665868

  14. Detection of an endogenous urinary biomarker associated with CYP2D6 activity using global metabolomics

    PubMed Central

    Tay-Sontheimer, Jessica; Shireman, Laura M; Beyer, Richard P; Senn, Taurence; Witten, Daniela; Pearce, Robin E; Gaedigk, Andrea; Fomban, Cletus L Gana; Lutz, Justin D; Isoherranen, Nina; Thummel, Kenneth E; Fiehn, Oliver; Leeder, J Steven; Lin, Yvonne S

    2015-01-01

    Aim We sought to discover endogenous urinary biomarkers of human CYP2D6 activity. Patients & methods Healthy pediatric subjects (n = 189) were phenotyped using dextromethorphan and randomized for candidate biomarker selection and validation. Global urinary metabolomics was performed using liquid chromatography quadrupole time-of-flight mass spectrometry. Candidate biomarkers were tested in adults receiving fluoxetine, a CYP2D6 inhibitor. Results A biomarker, M1 (m/z 444.3102) was correlated with CYP2D6 activity in both the pediatric training and validation sets. Poor metabolizers had undetectable levels of M1, whereas it was present in subjects with other phenotypes. In adult subjects, a 9.56-fold decrease in M1 abundance was observed during CYP2D6 inhibition. Conclusion Identification and validation of M1 may provide a noninvasive means of CYP2D6 phenotyping. PMID:25521354

  15. Comparison of Paeoniflorin and Albiflorin on Human CYP3A4 and CYP2D6

    PubMed Central

    Gao, Li-Na; Zhang, Ye; Cui, Yuan-Lu; Akinyi, Olunga Mary

    2015-01-01

    Peony (Paeonia lactiflora Pall-) is a plant medicine and a functional food ingredient with wide application for more than 2000 years. It can be coadministrated with many other drugs, composed of traditional Chinese medicine compound such as shaoyao-gancao decoction. In order to explore the efficacy and safety of peony, effects of paeoniflorin and albiflorin (the principal components of peony) on cytochrome P450 (CYP) 3A4 and CYP2D6 were analyzed in human hepatoma HepG2 cells and evaluated from the level of recombinant CYP enzymes in vitro. The findings indicated that albiflorin possessed stronger regulation on the mRNA expression of CYP3A4 and CYP2D6 than paeoniflorin. For the protein level of CYP3A4, albiflorin showed significant induction or inhibition with the concentration increasing from 10−7 M to 10−5 M, but no remarkable variation was observed in paeoniflorin-treated group. Enzyme activity assay implied that both paeoniflorin and albiflorin could regulate CYP3A4 and CYP2D6 with varying degrees. The results showed that albiflorin should be given more attention because it may play a vital role on the overall efficacy of peony. The whole behavior of both paeoniflorin and albiflorin should be focused on ensuring the rationality and effectiveness of clinical application. PMID:26089940

  16. CYP2D6 variation, behaviour and psychopathology: implications for pharmacogenomics-guided clinical trials

    PubMed Central

    Peñas-LLedó, Eva M; LLerena, Adrián

    2014-01-01

    Individual and population differences in polymorphic cytochrome P450 enzyme function have been known for decades. The biological significance of these differences has now been deciphered with regard to drug metabolism, action and toxicity as well as disposition of endogenous substrates, including neuroactive compounds. While the cytochrome P450 enzymes occur abundantly in the liver, they are expressed in most tissues of the body, albeit in varying amounts, including the brain. The latter location of cytochrome P450s is highly pertinent for susceptibility to neuropsychiatric diseases, not to mention local drug metabolism at the site of psychotropic drug action in the brain. In the current era of personality medicine with companion theranostics (i.e. the fusion of therapeutics with diagnostics), this article underscores that such versatile biological roles of cytochrome P450s offer multiple points of entry for personalized medicine and rational therapeutics. We focus our discussion on CYP2D6, one of the most intensively researched drug and endogenous compound metabolism pathways, with a view to relevance for, and optimization of, pharmacogenomic-guided clinical trials. Working on the premise that CYP2D6 is related to human behaviour and certain personality traits such as serotonin and dopamine system function, we further suggest that the motivation of healthy volunteers to participate in clinical trials may in part be influenced by an under-or over-representation of certain CYP2D6 metabolic groups. PMID:24033670

  17. Population pharmacokinetic analysis of risperidone and 9-hydroxyrisperidone with genetic polymorphisms of CYP2D6 and ABCB1.

    PubMed

    Yoo, Hee-Doo; Cho, Hea-Young; Lee, Sang-No; Yoon, Hwa; Lee, Yong-Bok

    2012-08-01

    This study estimated the population pharmacokinetics of risperidone and its active metabolite, 9-hydroxyrisperidone, according to genetic polymorphisms in the metabolizing enzyme (CYP2D6) and transporter (ABCB1) genes in healthy subjects. Eighty healthy subjects who received a single oral dose of 2 mg risperidone participated in this study. However, eight subjects with rare genotype variants in CYP2D6 alleles were excluded from the final model built in this study. We conducted the population pharmacokinetic analysis of risperidone and 9-hydroxyrisperidone using a nonlinear mixed effects modeling (NONMEM) method and explored the possible influence of genetic polymorphisms in CYP2D6 alleles and ABCB1 (2677G>T/A and 3435C>T) on the population pharmacokinetics of risperidone and 9-hydroxyrisperidone. A two-compartment model with a first-order absorption and lag time fitted well to serum concentration-time curve for risperidone. 9-hydroxyrisperidone was well described by a one-compartment model as an extension of the parent drug (risperidone) model with first-order elimination and absorption partially from the depot. Significant covariates for risperidone clearance were genetic polymorphisms of CYP2D6*10, including CYP2D6*1/*10 (27.5 % decrease) and CYP2D6*10/*10 (63.8 % decrease). There was significant difference in the absorption rate constant (k ( a )) of risperidone among the CYP2D6*10 genotype groups. In addition, combined ABCB1 3435C>T and CYP2D6*10 genotypes had a significant (P < 0.01) effect on the fraction of metabolite absorbed from the depot. The population pharmacokinetic model of risperidone and 9-hydroxyrisperidone including the genetic polymorphisms of CYP2D6*10 and ABCB1 3435C>T as covariates was successfully constructed. The estimated contribution of genetic polymorphisms in CYP2D6*10 and ABCB1 3435C>T to population pharmacokinetics of risperidone and 9-hydroxyrisperidone suggests the interplay of CYP2D6 and ABCB1 on the pharmacokinetics of

  18. Clinical Utility and Economic Impact of CYP2D6 Genotyping.

    PubMed

    Reynolds, Kristen K; McNally, Beth A; Linder, Mark W

    2016-09-01

    Pharmacogenetics examines an individual's genetic makeup to help predict the safety and efficacy of medications. Practical application optimizes treatment selection to decrease the failure rate of medications and improve clinical outcomes. Lack of efficacy is costly due to adverse drug reactions and increased hospital stays. Cytochrome P450 2D6 (CYP2D6) metabolizes roughly 25% of all drugs. Detecting variants that cause altered CYP2D6 enzymatic activity identifies patients at risk of adverse drug reactions or therapeutic failure with standard dosages of medications metabolized by CYP2D6. This article discusses the clinical application of pharmacogenetics to improve care and decrease costs. PMID:27514466

  19. Concordance between CYP2D6 genotypes obtained from tumor-derived and germline DNA.

    PubMed

    Rae, James M; Regan, Meredith M; Thibert, Jacklyn N; Gersch, Christina; Thomas, Dafydd; Leyland-Jones, Brian; Viale, Giuseppe; Pusztai, Lajos; Hayes, Daniel F; Skaar, Todd; Van Poznak, Catherine

    2013-09-01

    Formalin-fixed, paraffin-embedded tumors (FFPETs) are a valuable source of DNA for genotype association studies and are often the only germline DNA resource from cancer clinical trials. The anti-estrogen tamoxifen is metabolized into endoxifen by CYP2D6, leading to the hypothesis that patients with certain CYP2D6 genotypes may not receive benefit because of their inability to activate the drug. Studies testing this hypothesis using FFPETs have provided conflicting results. It has been postulated that CYP2D6 genotype determined using FFPET may not be accurate because of somatic tumor alterations. In this study, we determined the concordance between CYP2D6 genotypes generated using 3 tissue sources (FFPETs; formalin-fixed, paraffin-embedded unaffected lymph nodes [FFPELNs]; and whole blood cells [WBCs]) from 122 breast cancer patients. Compared with WBCs, FFPET and FFPELN genotypes were highly concordant (>94%), as were the predicted CYP2D6 metabolic phenotypes (>97%). We conclude that CYP2D6 genotypes obtained from FFPETs accurately represent the patient's CYP2D6 metabolic phenotype. PMID:23958736

  20. Regional and cellular expression of CYP2D6 in human brain: higher levels in alcoholics.

    PubMed

    Miksys, Sharon; Rao, Yushu; Hoffmann, Ewa; Mash, Deborah C; Tyndale, Rachel F

    2002-09-01

    Cytochrome P450 (CYP) 2D6 is expressed in liver, brain and other extrahepatic tissues where it metabolizes a range of centrally acting drugs and toxins. As ethanol can induce CYP2D in rat brain, we hypothesized that CYP2D6 expression is higher in brains of human alcoholics. We examined regional and cellular expression of CYP2D6 mRNA and protein by RT-PCR, Southern blotting, slot blotting, immunoblotting and immunocytochemistry. A significant correlation was found between mean mRNA and CYP2D6 protein levels across 13 brain regions. Higher expression was detected in 13 brain regions of alcoholics (n = 8) compared to nonalcoholics (n = 5) (anovap < 0.0001). In hippocampus this was localized in CA1-3 pyramidal cells and dentate gyrus granular neurons. In cerebellum this was localized in Purkinje cells and their dendrites. Both of these brain regions, and these same cell-types, are known to be susceptible to alcohol damage. For one case, a poor metabolizer (CYP2D6*4/*4), there was no detectable CYP2D6 protein, confirming the specificity of the antibody used. These data suggest that in alcoholics elevated brain CYP2D6 expression may contribute to altered sensitivity to centrally acting drugs and to the mediation of neurotoxic and behavioral effects of alcohol. PMID:12354285

  1. High Frequency of CYP2D6 Ultrarapid Metabolizer Genotype in the Finnish Population.

    PubMed

    Pietarinen, Paavo; Tornio, Aleksi; Niemi, Mikko

    2016-09-01

    CYP2D6 participates in the biotransformation of many commonly used drugs. Large genetic variability in CYP2D6 results in a wide interindividual variability in the response to CYP2D6 substrate drugs. Previous studies have assessed the phenotype and genotype distributions of CYP2D6 in relatively small Finnish population samples. The aim of our study was to investigate the frequencies of CYP2D6 genotypes in a larger Finnish population cohort of 857 healthy volunteers. The volunteers were genotyped for 10 CYP2D6 genetic variants (*2, *3, *4, *5, *6, *9, *10, *17, *39, *41) and copy number variation performed with TaqMan genotyping assays and copy number assay targeting exon 9. CYP2D6 phenotypes were inferred from the genotype data with the classical and activity score methods. According to the classical method, a large majority of the study cases were extensive metabolizers (EM; 87.3%; 95% confidence interval 84.9-89.3) and the second largest group was ultrarapid metabolizers (UM; 7.2%; 5.7-9.2%). Intermediate (IM) and poor metabolizers (PM) were in clear minority (3.0%; 2.1-4.4% and 2.3%; 1.5-3.6%, respectively). The activity score method yielded similar phenotype predictions. These results show that the frequency of UM genotype is higher and that of PM and IM genotype is lower in the Finnish population than in other North European populations. Accordingly, CYP2D6 genetic profile of the Finnish population differs from its geographically close neighbours, which has implications for the effective and safe use of drugs metabolized by CYP2D6. PMID:27038154

  2. Lack of association between schizophrenia and the CYP2D6 gene polymorphisms

    SciTech Connect

    Pirmohamed, M.; Wild, M.J.; Kitteringham, N.R.

    1996-04-09

    Approximately 5-10% of the Caucasian population lack the P450 isoform, CYP2D6. This polymorphism may be of importance in determining individual susceptibility to Parkinson`s disease. In this journal, Daniels et al. recently reported a negative association between the CYP2D6 gene locus and schizophrenia, a disease characterized by dopamine overactivity. It is important to exclude such an association because CYP2D6 is expressed in the brain and it is involved in dopamine catabolism. Between 1992 and 1993, we also performed a study similar to that, and reached the same conclusion. 7 refs., 1 tab.

  3. Relationship between genotype for the cytochrome P450 CYP2D6 and susceptibility to ankylosing spondylitis and rheumatoid arthritis.

    PubMed Central

    Beyeler, C; Armstrong, M; Bird, H A; Idle, J R; Daly, A K

    1996-01-01

    OBJECTIVES--To determine whether particular genotypes for the cytochrome P450 enzyme CYP2D6, a polymorphic enzyme, are associated with susceptibility to ankylosing spondylitis (AS) and rheumatoid arthritis (RA), or linked with any specific clinical or familial features of the two conditions. METHODS--CYP2D6 genotypes were determined in 54 patients with AS, 53 patients with RA, and 662 healthy controls. Leucocyte DNA was analysed for the presence of mutations by restriction fragment length polymorphism analysis with the restriction enzyme Xbal and by two separate polymerase chain reaction assays. RESULTS--On the basis of odds ratio (OR), individuals with two inactive CYP2D6 alleles were more susceptible to AS than controls (OR 2.71, 95% confidence interval (CI) 1.04 to 7.08), with a stronger effect for the CYP2D6B allele (OR 4.11, 95% CI 1.54 to 11.0). No significant differences in the distribution of overall genotypes and allele frequencies were observed between RA and controls. No significant relationships were found between the skeletal, extraskeletal or familial features of AS or RA (iritis, psoriasis, inflammatory enteropathy and rheumatoid nodules, kerato-conjunctivitis sicca, pleuritis, rheumatoid and antinuclear factors) and the overall genotype. CONCLUSIONS--Our findings suggest a modest association between homozygosity for inactive CYP2D6 alleles, particularly CYP2D6B alleles, and susceptibility to AS. However, our results fail to demonstrate a genetic link between CYP2D6 genotype and RA. PMID:8572738

  4. Design and synthesis of novel tamoxifen analogues that avoid CYP2D6 metabolism.

    PubMed

    Ahmed, Nermin S; Elghazawy, Nehal H; ElHady, Ahmed K; Engel, Matthias; Hartmann, Rolf W; Abadi, Ashraf H

    2016-04-13

    Tamoxifen (TAM) is a widely used drug in the prophylaxis and treatment of breast cancer. TAM is metabolized to the more active 4-hydroxytamoxifen (4-OH-TAM) and endoxifen by cytochrome P450 (CYP) mainly CYP2D6 and CYP3A4 enzymes. Due to the genetic polymorphisms in CYP2D6 genes, high variation in the clinical outcomes of TAM treatment is observed among women of different populations. To address this issue, novel TAM analogues with possible altered activation pathways were synthesized. These analogues were tested for their antiproliferative action on MCF-7 breast cancer cell lines as well as their binding affinity for estrogen receptor (ER) ER-α and ER-β receptors. These entire novel compounds showed better antiproliferative activity than did TAM on the MCF-7 cells. Moreover, compound 10 exhibited a half maximal growth inhibition (GI50) that was 1000 times more potent than that of TAM (GI50 < 0.005 μM vs 1.58 μM, respectively). Along with a broad spectrum activity on various cancer cell lines, all the TAM analogues showed considerable activity on the ER-negative breast cancer cell line. For further study, compound 10 was incubated in human liver microsomes (HLM), human hepatocytes (hHEP) and CYP2D6 supersomes. The active hydroxyl metabolite was detected after incubation in HLM and hHEP, implicating the involvement of other enzymes in its metabolism. These results prove that this novel series of TAM analogues might provide improved clinical outcomes for poor 2D6 metabolizers. PMID:26896706

  5. Genetic polymorphisms of CYP2D6 oxidation in patients with autoimmune bullous diseases

    PubMed Central

    Rychlik-Sych, Mariola; Baranska, Małgorzata; Waszczykowska, Elzbieta; Torzecka, Jolanta Dorota; Skretkowicz, Jadwiga

    2013-01-01

    Introduction Bullous skin diseases, which include, among others pemphigoid, pemphigus, and dermatitis herpetiformis are classified as severe autoimmune dermatoses. It has been shown that a pattern of xenobiotic metabolism may play a role in the pathogenesis of autoimmune diseases. Aim To estimate whether the CYP2D6 genotype may be considered a predisposing factor in autoimmune bullous diseases induction. Material and methods The study included 72 patients with autoimmune bullous diseases: 37 with pemphigoid, 21 with pemphigus, and 14 with dermatitis herpetiformis (DH). The CYP2D6 genotypes were analyzed by the polymerase chain reaction fragment length polymorphism (PCR-RFLP) method. Results Relative risk of DH development for particular genotype carriers expressed by odds ratio (OR) was statistically significantly higher for subjects with CYP2D6*1/CYP2D6*4 (OR = 4.2; p = 0.0104) and 2-fold higher for subjects with CYP2D6*4 (OR = 2.3; p = 0.0351). Conclusions The results of the present study show that the CYP2D6 oxidation polymorphism cannot be considered a risk factor for development of pemphigoid and pemphigus, however it might have an impact on dermatitis herpetiformis. PMID:24278077

  6. Prediction of CYP2D6 drug interactions from in vitro data: evidence for substrate-dependent inhibition.

    PubMed

    VandenBrink, Brooke M; Foti, Robert S; Rock, Dan A; Wienkers, Larry C; Wahlstrom, Jan L

    2012-01-01

    Predicting the magnitude of potential drug-drug interactions is important for underwriting patient safety in the clinical setting. Substrate-dependent inhibition of cytochrome P450 enzymes may confound extrapolation of in vitro results to the in vivo situation. However, the potential for substrate-dependent inhibition with CYP2D6 has not been well characterized. The inhibition profiles of 20 known inhibitors of CYP2D6 were characterized in vitro against four clinically relevant CYP2D6 substrates (desipramine, dextromethorphan, metoprolol, and thioridazine) and bufuralol. Dextromethorphan exhibited the highest sensitivity to in vitro inhibition, whereas metoprolol was the least sensitive. In addition, when metoprolol was the substrate, inhibitors with structurally constrained amino moieties (clozapine, debrisoquine, harmine, quinidine, and yohimbine) exhibited at least a 5-fold decrease in inhibition potency when results were compared with those for dextromethorphan. Atypical inhibition kinetics were observed for these and other inhibitor-substrate pairings. In silico docking studies suggested that interactions with Glu216 and an adjacent hydrophobic binding pocket may influence substrate sensitivity and inhibition potency for CYP2D6. The in vivo sensitivities of the clinically relevant CYP2D6 substrates desipramine, dextromethorphan, and metoprolol were determined on the basis of literature drug-drug interaction (DDI) outcomes. Similar to the in vitro results, dextromethorphan exhibited the highest sensitivity to CYP2D6 inhibition in vivo. Finally, the magnitude of in vivo CYP2D6 DDIs caused by quinidine was predicted using desipramine, dextromethorphan, and metoprolol. Comparisons of the predictions with literature results indicated that the marked decrease in inhibition potency observed for the metoprolol-quinidine interaction in vitro translated to the in vivo situation. PMID:21976621

  7. Aloe vera juice: IC₅₀ and dual mechanistic inhibition of CYP3A4 and CYP2D6.

    PubMed

    Djuv, Ane; Nilsen, Odd Georg

    2012-03-01

    The aim of this study was to evaluate the inhibitory potency (IC₅₀ values) of ethanol extracts of two commercially available aloe vera juice (AVJ) products, on CYP3A4 and CYP2D6 activities in vitro and to determine if such inhibitions could be mechanism-based. Recombinant human CYP3A4 and CYP2D6 enzymes were used and the activities were expressed by the metabolism of testosterone and dextromethorphan with ketoconazole and quinidine as positive inhibitor controls, respectively. The formed metabolites were quantified by validated HPLC techniques. Time- and NADPH- dependent inhibition assays were performed to evaluate a possible mechanism-based inhibition. One of the AVJ extracts showed about twice the inhibitory potency towards both CYP enzymes over the other with IC₅₀ values of 8.35 ± 0.72 and 12.5 ± 2.1 mg/mL for CYP3A4 and CYP2D6, respectively. The AVJ was found to exert both CYP mediated and non-CYP mediated inhibition of both CYP3A4 and CYP2D6. This dual mechanistic inhibition, however, seems to be governed by different mechanisms for CYP3A4 and CYP2D6. Estimated IC₅₀ inhibition values indicate no major interference of AVJ with drug metabolism in man, but the dual mechanistic inhibition of both enzymes might be of clinical significance. PMID:21842479

  8. CYP2D6 phenotype-genotype relationships in African-Americans and Caucasians in Los Angeles.

    PubMed

    Leathart, J B; London, S J; Steward, A; Adams, J D; Idle, J R; Daly, A K

    1998-12-01

    CYP2D6 genotyping (CYP2D6*3, CYP2D6*4, CYP2D6*5, CYP2D6*13, CYP2D6*16 alleles and gene duplications) was previously performed on 1053 Caucasian and African-American lung cancer cases and control individuals and no significant difference in allele frequencies between cases and control individuals detected. We have carried out additional genotyping (CYP2D6*6, CYP2D6*7, CYP2D6*8, CYP2D6*9, CYP2D6*10, CYP2D6*17 alleles) and debrisoquine phenotyping on subgroups from this study to assess phenotype-genotype relationships. African-Americans showed significant differences from Caucasians with respect to frequency of defective CYP2D6 alleles, particularly CYP2D6*4 and CYP2D6*5. The CYP2D6*17 allele occurred at a frequency of 0.26 among 87 African-Americans and appeared to explain higher average metabolic ratios among African-Americans compared with Caucasians. CYP2D6*6, CYP2D6*8, CYP2D6*9 and CYP2D6*10 were rare in both ethnic groups but explained approximately 40% of higher than expected metabolic ratios among extensive metabolizers. Among individuals phenotyped with debrisoquine, 32 out of 359 were in the poor metabolizer range with 24 of these (75%) also showing two defective CYP2D6 alleles. Additional single strand conformational polymorphism analysis screening of samples showing large phenotype-genotype discrepancies resulted in the detection of three novel polymorphisms. If subjects taking potentially interfering drugs were excluded, this additional screening enabled the positive identification of 88% of phenotypic poor metabolizers by genotyping. This sensitivity was comparable with that of phenotyping, which identified 90% of those with two defective alleles as poor metabolizers. PMID:9918137

  9. Effects of CYP2D6 Status on Harmaline Metabolism, Pharmacokinetics and Pharmacodynamics, and a Pharmacogenetics-Based Pharmacokinetic Model

    PubMed Central

    Wu, Chao; Jiang, Xi-Ling; Shen, Hong-Wu; Yu, Ai-Ming

    2009-01-01

    Harmaline is a β-carboline alkaloid showing neuroprotective and neurotoxic properties. Our recent studies have revealed an important role for cytochrome P450 2D6 (CYP2D6) in harmaline O-demethylation. This study, therefore, aimed to delineate the effects of CYP2D6 phenotype/genotype on harmaline metabolism, pharmacokinetics (PK) and pharmacodynamics (PD), and to develop a pharmacogenetics mechanism-based compartmental PK model. In vitro kinetic studies on metabolite formation in human CYP2D6 extensive metabolizer (EM) and poor metabolizer (PM) hepatocytes indicated that harmaline O-demethylase activity (Vmax/Km) was about 9-fold higher in EM hepatocytes. Substrate depletion showed mono-exponential decay trait, and estimated in vitro harmaline clearance (CLint, μL/min/106 cells) was significantly lower in PM hepatocytes (28.5) than EM hepatocytes (71.1). In vivo studies in CYP2D6-humanized and wild-type mouse models showed that wild-type mice were subjected to higher and longer exposure to harmaline (5 and 15 mg/kg; i.v. and i.p.), and more severe hypothermic responses. The PK/PD data were nicely described by our pharmacogenetics-based PK model involving the clearance of drug by CYP2D6 (CLCYP2D6) and other mechanisms (CLother), and an indirect response PD model, respectively. Wild-type mice were also more sensitive to harmaline in marble-burying tests, as manifested by significantly lower ED50 and steeper Hill slope. These findings suggest that distinct CYP2D6 status may cause considerable variations in harmaline metabolism, PK and PD. In addition, the pharmacogenetics-based PK model may be extended to define PK difference caused by other polymorphic drug-metabolizing enzyme in different populations. PMID:19445902

  10. CYP2D6 genotype and adjuvant tamoxifen: meta-analysis of heterogeneous study populations.

    PubMed

    Province, M A; Goetz, M P; Brauch, H; Flockhart, D A; Hebert, J M; Whaley, R; Suman, V J; Schroth, W; Winter, S; Zembutsu, H; Mushiroda, T; Newman, W G; Lee, M-T M; Ambrosone, C B; Beckmann, M W; Choi, J-Y; Dieudonné, A-S; Fasching, P A; Ferraldeschi, R; Gong, L; Haschke-Becher, E; Howell, A; Jordan, L B; Hamann, U; Kiyotani, K; Krippl, P; Lambrechts, D; Latif, A; Langsenlehner, U; Lorizio, W; Neven, P; Nguyen, A T; Park, B-W; Purdie, C A; Quinlan, P; Renner, W; Schmidt, M; Schwab, M; Shin, J-G; Stingl, J C; Wegman, P; Wingren, S; Wu, A H B; Ziv, E; Zirpoli, G; Thompson, A M; Jordan, V C; Nakamura, Y; Altman, R B; Ames, M M; Weinshilboum, R M; Eichelbaum, M; Ingle, J N; Klein, T E

    2014-02-01

    The International Tamoxifen Pharmacogenomics Consortium was established to address the controversy regarding cytochrome P450 2D6 (CYP2D6) status and clinical outcomes in tamoxifen therapy. We performed a meta-analysis on data from 4,973 tamoxifen-treated patients (12 globally distributed sites). Using strict eligibility requirements (postmenopausal women with estrogen receptor-positive breast cancer, receiving 20 mg/day tamoxifen for 5 years, criterion 1); CYP2D6 poor metabolizer status was associated with poorer invasive disease-free survival (IDFS: hazard ratio = 1.25; 95% confidence interval = 1.06, 1.47; P = 0.009). However, CYP2D6 status was not statistically significant when tamoxifen duration, menopausal status, and annual follow-up were not specified (criterion 2, n = 2,443; P = 0.25) or when no exclusions were applied (criterion 3, n = 4,935; P = 0.38). Although CYP2D6 is a strong predictor of IDFS using strict inclusion criteria, because the results are not robust to inclusion criteria (these were not defined a priori), prospective studies are necessary to fully establish the value of CYP2D6 genotyping in tamoxifen therapy. PMID:24060820

  11. Cytochrome P450 CYP2D6 gene polymorphism and lung cancer susceptibility in Caucasians.

    PubMed

    Legrand-Andréoletti, M; Stücker, I; Marez, D; Galais, P; Cosme, J; Sabbagh, N; Spire, C; Cenée, S; Lafitte, J J; Beaune, P; Broly, F

    1998-02-01

    Many studies have been performed in an attempt to establish a link between the polymorphism of the cytochrome P450 CYP2D6 gene and the incidence of lung cancer. Nevertheless, whether or not this genetic polymorphism has a role in the development of the disease remains unclear. Recently, new advances in our knowledge of the CYP2D6 gene and its locus (CYP2D) have been achieved. In particular, CYP2D6 was found to be highly polymorphic and multiple novel mutations and allelic variants of the gene have been identified. In addition, a number of CYP2D rearrangements, including those with amplification of the gene, have been demonstrated. Taking this new information into account, we have reconsidered the potential influence of CYP2D6 polymorphism in lung cancer susceptibility by performing a comparative analysis of the overall mutational spectrum of CYP2D6 and of the rearrangements of CYP2D in 249 patients with lung cancer and in 265 control individuals matched on age, sex, hospital and residence area. For this purpose, a strategy based on SSCP analysis of the entire coding sequence of CYP2D6 and on RFLP analysis of the gene locus was carried out in DNA samples from each individual. Forty mutations occurring in various combinations on 42 alleles of the gene and 82 different genotypes were identified. No significant difference in the distribution of the mutations, alleles or genotypes was observed between the two groups, except a particular genotype (CYP2D6*1A/*2), which was more common in the sub-group of moderate smokers (< 30 pack-years) suffering from small cell carcinoma (Odds Ratio (OR) 3.6, 95% CI 1.1-11.9). When the phenotype was predicted according to genotype, only a trend toward a higher frequency of ultrarapid metabolizers in patients was obtained. In spite of a complete analysis of the CYP2D6 gene and its locus, this case-control study provides elements against an influence of the CYP2D6 polymorphism on lung cancer susceptibility. PMID:9511176

  12. Interpreting the CYP2D6 Results From the International Tamoxifen Pharmacogenetics Consortium

    PubMed Central

    Province, MA; Altman, RB; Klein, TE

    2014-01-01

    Meta-analysis of the entire analyzable cohort of 4,935 tamoxifen-treated breast cancer patients by the International Tamoxifen Pharmacogenetics Consortium (ITPC) (criterion 3) revealed no CYP2D6 effect on outcomes but strong heterogeneity across sites.1 However, a post hoc–defined subgroup (criterion 1: postmenopausal, estrogen receptor positive, receiving 20 mg/day tamoxifen for 5 years; n = 1,996) did find statistically significant effect of CYP2D6 on both invasive disease–free survival as well as breast cancer–free interval, with little site heterogeneity. How should we interpret these discrepant findings? PMID:25056393

  13. Future Trends in the Pharmacogenomics of Brain Disorders and Dementia: Influence of APOE and CYP2D6 Variants

    PubMed Central

    Cacabelos, Ramón; Fernández-Novoa, Lucía; Martínez-Bouza, Rocío; McKay, Adam; Carril, Juan C.; Lombardi, Valter; Corzo, Lola; Carrera, Iván; Tellado, Iván; Nebril, Laura; Alcaraz, Margarita; Rodríguez, Susana; Casas, Ángela; Couceiro, Verónica; Álvarez, Antón

    2010-01-01

    About 80% of functional genes in the human genome are expressed in the brain and over 1,200 different genes have been associated with the pathogenesis of CNS disorders and dementia. Pharmacogenetic studies of psychotropic drug response have focused on determining the relationship between variations in specific candidate genes and the positive and adverse effects of drug treatment. Approximately, 18% of neuroleptics are substrates of CYP1A2 enzymes, 40% of CYP2D6, and 23% of CYP3A4; 24% of antidepressants are substrates of CYP1A2 enzymes, 5% of CYP2B6, 38% of CYP2C19, 85% of CYP2D6, and 38% of CYP3A4; 7% of benzodiazepines are substrates of CYP2C19 enzymes, 20% of CYP2D6, and 95% of CYP3A4. 10-20% of Western populations are defective in genes of the CYP superfamily; and the pharmacogenomic response of psychotropic drugs also depends on genetic variants associated with dementia. Prospective studies with anti-dementia drugs or with multifactorial strategies have revealed that the therapeutic response to conventional drugs in Alzheimer’s disease is genotype-specific. The disease-modifying effects (cognitive performance, biomarker modification) of therapeutic intervention are APOE-dependent, with APOE-4 carriers acting as the worst responders (APOE-3/3 > APOE-3/4 > APOE-4/4). APOE-CYP2D6 interactions also influence the therapeutic outcome in patients with dementia.

  14. Genetic polymorphisms and drug interactions modulating CYP2D6 and CYP3A activities have a major effect on oxycodone analgesic efficacy and safety

    PubMed Central

    Samer, CF; Daali, Y; Wagner, M; Hopfgartner, G; Eap, CB; Rebsamen, MC; Rossier, MF; Hochstrasser, D; Dayer, P; Desmeules, JA

    2010-01-01

    Background and purpose: The major drug-metabolizing enzymes for the oxidation of oxycodone are CYP2D6 and CYP3A. A high interindividual variability in the activity of these enzymes because of genetic polymorphisms and/or drug–drug interactions is well established. The possible role of an active metabolite in the pharmacodynamics of oxycodone has been questioned and the importance of CYP3A-mediated effects on the pharmacokinetics and pharmacodynamics of oxycodone has been poorly explored. Experimental approach: We conducted a randomized crossover (five arms) double-blind placebo-controlled study in 10 healthy volunteers genotyped for CYP2D6. Oral oxycodone (0.2 mg·kg−1) was given alone or after inhibition of CYP2D6 (with quinidine) and/or of CYP3A (with ketoconazole). Experimental pain (cold pressor test, electrical stimulation, thermode), pupil size, psychomotor effects and toxicity were assessed. Key results: CYP2D6 activity was correlated with oxycodone experimental pain assessment. CYP2D6 ultra-rapid metabolizers experienced increased pharmacodynamic effects, whereas cold pressor test and pupil size were unchanged in CYP2D6 poor metabolizers, relative to extensive metabolizers. CYP2D6 blockade reduced subjective pain threshold (SPT) for oxycodone by 30% and the response was similar to placebo. CYP3A4 blockade had a major effect on all pharmacodynamic assessments and SPT increased by 15%. Oxymorphone Cmax was correlated with SPT assessment (ρS= 0.7) and the only independent positive predictor of SPT. Side-effects were observed after CYP3A4 blockade and/or in CYP2D6 ultra-rapid metabolizers. Conclusions and implications: The modulation of CYP2D6 and CYP3A activities had clear effects on oxycodone pharmacodynamics and these effects were dependent on CYP2D6 genetic polymorphism. PMID:20590588

  15. Evaluation of a [13C]-Dextromethorphan Breath Test to Assess CYP2D6 Phenotype

    PubMed Central

    Leeder, J. Steven; Pearce, Robin E.; Gaedigk, Andrea; Modak, Anil; Rosen, David I.

    2016-01-01

    A [13C]-dextromethorphan ([13C]-DM) breath test was evaluated to assess its feasibility as a rapid, phenotyping assay for CYP2D6 activity. [13C]-DM (0.5 mg/kg) was administered orally with water or potassium bicarbonate-sodium bicarbonate to 30 adult Caucasian volunteers (n = 1 each): CYP2D6 poor metabolizers (2 null alleles; PM-0) and extensive metabolizers with 1 (EM-1) or 2 functional alleles (EM-2). CYP2D6 phenotype was determined by 13CO2 enrichment measured by infrared spectrometry (delta-over-baseline [DOB] value) in expired breath samples collected before and up to 240 minutes after [13C]-DM ingestion and by 4-hour urinary metabolite ratio. The PM-0 group was readily distinguishable from either EM group by both the breath test and urinary metabolite ratio. Using a single point determination of phenotype at 40 minutes and defining PMs as subjects with a DOB ≤ 0.5, the sensitivity of the method was 100%; specificity was 95% with 95% accuracy and resulted in the misclassification of 1 EM-1 individual as a PM. Modification of the initial protocol (timing of potassium bicarbonate-sodium bicarbonate administration relative to dose) yielded comparable results, but there was a tendency toward increased DOB values. Although further development is required, these studies suggest that the [13C]-DM breath test offers promise as a rapid, minimally invasive phenotyping assay for CYP2D6 activity. PMID:18728242

  16. Impact of CYP2D6 polymorphisms in tamoxifen adjuvant breast cancer treatment.

    PubMed

    Ramón y Cajal, T; Altés, A; Paré, L; del Rio, E; Alonso, C; Barnadas, A; Baiget, M

    2010-01-01

    The aim of this study is to evaluate the impact of CYP2D6 genotyping in predicting disease-free survival and toxicity in breast cancer patients treated with adjuvant tamoxifen. DNA from 91 patients was genotyped using the AmpliChip CYP450 GeneChip, Roche that facilitates the classification of individuals by testing 27 alleles. When patients were grouped into group 1 (*4/*4, *4/*41, *1/*5 and *2/*5) and group 2 (the remaining genotypes), a significant difference in disease-free survival (DFS) was observed between groups (P = 0.016). The mean DFS in group 1 was 95 months in contrast with 119 months in group 2. No significant relationship was found between the CYP2D6 genotype classification and severe, mild or no toxicity (P = 0.2). Nevertheless, severe, and mild toxicity was more frequent among poor metabolizer patients than in patients with a normal metabolizer pattern (18.8 and 43.8% vs. 10.7 and 36%, respectively). In breast cancer, patients treated with adjuvant tamoxifen, non-functional and severely impaired CYP2D6 variants are associated with a worse DFS and with a higher frequency of severe and mild toxicities. Larger studies of the CYP2D6 genotype-clinical outcomes association are needed to complement initial results. PMID:19189210

  17. Genomics of Dementia: APOE- and CYP2D6-Related Pharmacogenetics

    PubMed Central

    Cacabelos, Ramón; Martínez, Rocío; Fernández-Novoa, Lucía; Carril, Juan C.; Lombardi, Valter; Carrera, Iván; Corzo, Lola; Tellado, Iván; Leszek, Jerzy; McKay, Adam; Takeda, Masatoshi

    2012-01-01

    Dementia is a major problem of health in developed societies. Alzheimer's disease (AD), vascular dementia, and mixed dementia account for over 90% of the most prevalent forms of dementia. Both genetic and environmental factors are determinant for the phenotypic expression of dementia. AD is a complex disorder in which many different gene clusters may be involved. Most genes screened to date belong to different proteomic and metabolomic pathways potentially affecting AD pathogenesis. The ε4 variant of the APOE gene seems to be a major risk factor for both degenerative and vascular dementia. Metabolic factors, cerebrovascular disorders, and epigenetic phenomena also contribute to neurodegeneration. Five categories of genes are mainly involved in pharmacogenomics: genes associated with disease pathogenesis, genes associated with the mechanism of action of a particular drug, genes associated with phase I and phase II metabolic reactions, genes associated with transporters, and pleiotropic genes and/or genes associated with concomitant pathologies. The APOE and CYP2D6 genes have been extensively studied in AD. The therapeutic response to conventional drugs in patients with AD is genotype specific, with CYP2D6-PMs, CYP2D6-UMs, and APOE-4/4 carriers acting as the worst responders. APOE and CYP2D6 may cooperate, as pleiotropic genes, in the metabolism of drugs and hepatic function. The introduction of pharmacogenetic procedures into AD pharmacological treatment may help to optimize therapeutics. PMID:22482072

  18. Clinical inhibition of CYP2D6-catalysed metabolism by the antianginal agent perhexiline

    PubMed Central

    Davies, Benjamin J L; Coller, Janet K; James, Heather M; Gillis, David; Somogyi, Andrew A; Horowitz, John D; Morris, Raymond G; Sallustio, Benedetta C

    2004-01-01

    Aims Perhexiline is an antianginal agent that displays both saturable and polymorphic metabolism via CYP2D6. The aim of this study was to determine whether perhexiline produces clinically significant inhibition of CYP2D6-catalysed metabolism in angina patients. Methods The effects of perhexiline on CYP2D6-catalysed metabolism were investigated by comparing urinary total dextrorphan/dextromethorphan metabolic ratios following a single dose of dextromethorphan (16.4 mg) in eight matched control patients not taking perhexiline and 24 patients taking perhexiline. All of the patients taking perhexiline had blood drawn for CYP2D6 genotyping as well as to measure plasma perhexiline and cis-OH-perhexiline concentrations. Results Median (range) dextrorphan/dextromethorphan metabolic ratios were significantly higher (P < 0.0001) in control patients, 271.1 (40.3–686.1), compared with perhexiline-treated patients, 5.0 (0.3–107.9). In the perhexiline-treated group 10/24 patients had metabolic ratios consistent with poor metabolizer phenotypes; however, none was a genotypic poor metabolizer. Interestingly, 89% of patients who had phenocopied to poor metabolizers had only one functional CYP2D6 gene. There was a significant negative linear correlation between the log of the dextrorphan/dextromethorphan metabolic ratio and plasma perhexiline concentrations (r2 = 0.69, P < 0.0001). Compared with patients with at least two functional CYP2D6 genes, those with one functional gene were on similar perhexiline dosage regimens but had significantly higher plasma perhexiline concentrations, 0.73 (0.21–1.00) vs. 0.36 (0.04–0.69) mg l−1 (P = 0.04), lower cis-OH-perhexiline/perhexiline ratios, 2.85 (0.35–6.10) vs. 6.51 (1.84–11.67) (P = 0.03), and lower dextrorphan/dextromethorphan metabolic ratios, 2.51 (0.33–39.56) vs. 11.80 (2.90–36.93) (P = 0.005). Conclusions Perhexiline significantly inhibits CYP2D6-catalysed metabolism in angina patients. The plasma cis

  19. Relationship between genotypes Sult1a2 and Cyp2d6 and tamoxifen metabolism in breast cancer patients.

    PubMed

    Fernández-Santander, Ana; Gaibar, María; Novillo, Apolonia; Romero-Lorca, Alicia; Rubio, Margarita; Chicharro, Luis Miguel; Tejerina, Armando; Bandrés, Fernando

    2013-01-01

    Tamoxifen is a pro-drug widely used in breast cancer patients to prevent tumor recurrence. Prior work has revealed a role of cytochrome and sulfotransferase enzymes in tamoxifen metabolism. In this descriptive study, correlations were examined between concentrations of tamoxifen metabolites and genotypes for CYP2D6, CYP3A4, CYP3A5, SULT1A1, SULT1A2 and SULT1E1 in 135 patients with estrogen receptor-positive breast cancer. Patients were genotyped using the Roche-AmpliChip® CYP450 Test, and Real-Time and conventional PCR-RFLP. Plasma tamoxifen, 4-hydroxy-tamoxifen, N-desmethyl-tamoxifen, endoxifen and tamoxifen-N-oxide were isolated and quantified using a high-pressure liquid chromatography-tandem mass spectrometry system. Significantly higher endoxifen levels were detected in patients with the wt/wt CYP2D6 compared to the v/v CYP2D6 genotype (p<0.001). No differences were detected in the remaining tamoxifen metabolites among CYP2D6 genotypes. Patients featuring the SULT1A2*2 and SULT1A2*3 alleles showed significantly higher plasma levels of 4-hydroxy-tamoxifen and endoxifen (p = 0.025 and p = 0.006, respectively), as likely substrates of the SULT1A2 enzyme. Our observations indicate that besides the CYP2D6 genotype leading to tamoxifen conversion to potent hydroxylated metabolites in a manner consistent with a gene-dose effect, SULT1A2 also seems to play a role in maintaining optimal levels of both 4-hydroxy-tamoxifen and endoxifen. PMID:23922954

  20. Relationship between Genotypes Sult1a2 and Cyp2d6 and Tamoxifen Metabolism in Breast Cancer Patients

    PubMed Central

    Fernández-Santander, Ana; Gaibar, María; Novillo, Apolonia; Romero-Lorca, Alicia; Rubio, Margarita; Chicharro, Luis Miguel; Tejerina, Armando; Bandrés, Fernando

    2013-01-01

    Tamoxifen is a pro-drug widely used in breast cancer patients to prevent tumor recurrence. Prior work has revealed a role of cytochrome and sulfotransferase enzymes in tamoxifen metabolism. In this descriptive study, correlations were examined between concentrations of tamoxifen metabolites and genotypes for CYP2D6, CYP3A4, CYP3A5, SULT1A1, SULT1A2 and SULT1E1 in 135 patients with estrogen receptor-positive breast cancer. Patients were genotyped using the Roche-AmpliChip® CYP450 Test, and Real-Time and conventional PCR-RFLP. Plasma tamoxifen, 4-hydroxy-tamoxifen, N-desmethyl-tamoxifen, endoxifen and tamoxifen-N-oxide were isolated and quantified using a high-pressure liquid chromatography-tandem mass spectrometry system. Significantly higher endoxifen levels were detected in patients with the wt/wt CYP2D6 compared to the v/v CYP2D6 genotype (p<0.001). No differences were detected in the remaining tamoxifen metabolites among CYP2D6 genotypes. Patients featuring the SULT1A2*2 and SULT1A2*3 alleles showed significantly higher plasma levels of 4-hydroxy-tamoxifen and endoxifen (p = 0.025 and p = 0.006, respectively), as likely substrates of the SULT1A2 enzyme. Our observations indicate that besides the CYP2D6 genotype leading to tamoxifen conversion to potent hydroxylated metabolites in a manner consistent with a gene-dose effect, SULT1A2 also seems to play a role in maintaining optimal levels of both 4-hydroxy-tamoxifen and endoxifen. PMID:23922954

  1. Personalized medicine in breast cancer: tamoxifen, endoxifen, and CYP2D6 in clinical practice.

    PubMed

    Ruddy, Kathryn J; Desantis, Stephen D; Gelman, Rebecca S; Wu, Alan H B; Punglia, Rinaa S; Mayer, Erica L; Tolaney, Sara M; Winer, Eric P; Partridge, Ann H; Burstein, Harold J

    2013-10-01

    Tamoxifen is metabolized into endoxifen, a potent antagonist of the estrogen receptor, in part through cytochrome p450 (CYP) 2D6. Genotypic variation in CYP2D6 affects endoxifen levels, and some have argued that patients who do not efficiently metabolize tamoxifen might wish to consider alternative hormonal treatments. This study evaluated an algorithm in which endoxifen levels and CYP2D6 genotypes were used to make hormonal therapy recommendations for patients on adjuvant tamoxifen for breast cancer. Patients with stage I-III breast cancer who had been taking adjuvant tamoxifen for 8-56 weeks were eligible. At enrollment, baseline whole blood and serum were sent for genotyping by Amplichip and endoxifen measurement, respectively, and endoxifen levels were also measured 3 weeks later. Results were returned to oncologists along with an algorithm-generated treatment recommendation. The algorithm recommended that participants with poor metabolizer genotype and/or baseline endoxifen level <6 ng/mL consider alternative endocrine therapy. A medical record review evaluated actual treatment decisions. Of 99 patients on study, 18 (18 %) had findings that triggered algorithm-based recommendations to consider a change in endocrine therapy due to endoxifen <6 ng/mL (all 18 patients) and/or poor metabolizer CYP2D6 genotype (2 of the 18). Endoxifen levels were ≥6 ng/mL in four of them 3 weeks later. Seven (39 % of 18) switched to a different treatment (one based on toxicity, not the algorithm). Hot flash burden was not found to be significantly associated with endoxifen <6 ng/mL or genotype. Prospective testing of tamoxifen metabolism as gauged by CYP2D6 genotype and serum endoxifen levels is feasible. Future studies of tamoxifen metabolism and efficacy should consider including measurement of serial endoxifen levels. Although clinical evidence at present is insufficient to warrant routine CYP2D6 or endoxifen testing, some clinicians and patients did utilize this

  2. Anthocyanins and anthocyanidins are poor inhibitors of CYP2D6.

    PubMed

    Dreiseitel, Andrea; Schreier, Peter; Oehme, Anett; Locher, Sanja; Rogler, Gerhard; Piberger, Heidi; Hajak, Goeran; Sand, Philipp G

    2009-01-01

    The cytochrome P450 CYP2D6 isoform is involved in the metabolism of about 50% of all psychoactive drugs, including neuroleptic agents, selective serotonin reuptake inhibitors, selective norepinephrine reuptake inhibitors and tricyclic antidepressants. Therefore, inhibition of cytochrome P450 activity by foodstuffs has implications for drug safety. The present study addresses inhibitory effects of polyphenolic anthocyanins and their aglycons that are found in many dietary fruits and vegetables. Using a chemiluminescent assay, we obtained IC(50) values ranging from 55 microM to > 800 microM for 17 individual compounds. According to earlier data on furanocoumarins from grapefruit extract, CYP2D6 inhibition is achieved in the range of 190-900 nM. As the tested anthocyanins and anthocyanidins were shown to be about 1,000-fold less potent, they are unlikely to interfere with drug metabolism by CYP2D6. Further studies are warranted to examine the effects of the above flavonoids on other CYP isoforms for more detailed toxicity profiles. PMID:19357792

  3. Neuroleptic malignant syndrome in an adolescent with CYP2D6 deficiency.

    PubMed

    Butwicka, Agnieszka; Krystyna, Szymańska; Retka, Włodzimierz; Wolańczyk, Tomasz

    2014-12-01

    We describe a patient with dystonia and psychotic symptoms treated with standard doses of antipsychotics, who developed neuroleptic malignant syndrome (NMS). A 16-year-old male with a history of misuse of dextromethorphan and pseudoephedrine for recreational purpose presented with dystonia and a psychotic episode. Following continuous treatment with olanzapine (10 mg/day), repeated injections of levomepromazine (37.5 mg/day), and a single injection of haloperidol (2.5 mg), the patient developed NMS. Muscular rigidity, fever (up to 41 °C), hypotension (100/70 mmHg), tachycardia (120 beats per minute), tachypnea (26 breaths per minute), elevated leukocyte count (up to 16.6 × 10(3)/μL), and elevated serum creatinine phosphokinase (CPK) (up to 15,255 U/L) were observed. A diagnosis of NMS was made according to the DSM-IV TR criteria. Genotyping revealed that he was homozygous for a non-functional CYP2D6*4 allele. The case highlights the importance of therapeutic drug monitoring in identification and differentiation of drug-induced effects in psychiatric disorder to prevent NMS and its complications. In addition, genotyping of CYP2D6 might be considered in patients with symptoms suggestive of drug toxicity who are treated with neuroleptics metabolized via the CYP2D6 pathway, as carriage of one or more non-functional alleles may increase the risk for adverse reactions, such as NMS. PMID:24253372

  4. Practical interpretation of CYP2D6 haplotypes: Comparison and integration of automated and expert calling.

    PubMed

    Ruaño, Gualberto; Kocherla, Mohan; Graydon, James S; Holford, Theodore R; Makowski, Gregory S; Goethe, John W

    2016-05-01

    We describe a population genetic approach to compare samples interpreted with expert calling (EC) versus automated calling (AC) for CYP2D6 haplotyping. The analysis represents 4812 haplotype calls based on signal data generated by the Luminex xMap analyzers from 2406 patients referred to a high-complexity molecular diagnostics laboratory for CYP450 testing. DNA was extracted from buccal swabs. We compared the results of expert calls (EC) and automated calls (AC) with regard to haplotype number and frequency. The ratio of EC to AC was 1:3. Haplotype frequencies from EC and AC samples were convergent across haplotypes, and their distribution was not statistically different between the groups. Most duplications required EC, as only expansions with homozygous or hemizygous haplotypes could be automatedly called. High-complexity laboratories can offer equivalent interpretation to automated calling for non-expanded CYP2D6 loci, and superior interpretation for duplications. We have validated scientific expert calling specified by scoring rules as standard operating procedure integrated with an automated calling algorithm. The integration of EC with AC is a practical strategy for CYP2D6 clinical haplotyping. PMID:26908082

  5. Primaquine pharmacology in the context of CYP 2D6 pharmacogenomics: Current state of the art.

    PubMed

    Marcsisin, Sean R; Reichard, Gregory; Pybus, Brandon S

    2016-05-01

    Primaquine is the only antimalarial drug available to clinicians for the treatment of relapsing forms of malaria. Primaquine development and usage dates back to the 1940s and has been administered to millions of individuals to treat and eliminate malaria infections. Primaquine therapy is not without disadvantages, however, as it can cause life threatening hemolysis in humans with glucose-6-phosphate dehydrogenase (G6PD) deficiency. In addition, the efficacy of primaquine against relapsing malaria was recently linked to CYP 2D6 mediated activation to an active metabolite, the structure of which has escaped definitive identification for over 75years. CYP 2D6 is highly polymorphic among various human populations adding further complexity to a comprehensive understanding of primaquine pharmacology. This review aims to discuss primaquine pharmacology in the context of state of the art understanding of CYP 2D6 mediated 8-aminoquinoline metabolic activation, and shed light on the current knowledge gaps of 8-aminoquinoline mechanistic understanding against relapsing malaria. PMID:27016470

  6. Sequencing CYP2D6 for the detection of poor-metabolizers in post-mortem blood samples with tramadol.

    PubMed

    Fonseca, Suzana; Amorim, António; Costa, Heloísa Afonso; Franco, João; Porto, Maria João; Santos, Jorge Costa; Dias, Mário

    2016-08-01

    Tramadol concentrations and analgesic effect are dependent on the CYP2D6 enzymatic activity. It is well known that some genetic polymorphisms are responsible for the variability in the expression of this enzyme and in the individual drug response. The detection of allelic variants described as non-functional can be useful to explain some circumstances of death in the study of post-mortem cases with tramadol. A Sanger sequencing methodology was developed for the detection of genetic variants that cause absent or reduced CYP2D6 activity, such as *3, *4, *6, *8, *10 and *12 alleles. This methodology, as well as the GC/MS method for the detection and quantification of tramadol and its main metabolites in blood samples was fully validated in accordance with international guidelines. Both methodologies were successfully applied to 100 post-mortem blood samples and the relation between toxicological and genetic results evaluated. Tramadol metabolism, expressed as its metabolites concentration ratio (N-desmethyltramadol/O-desmethyltramadol), has been shown to be correlated with the poor-metabolizer phenotype based on genetic characterization. It was also demonstrated the importance of enzyme inhibitors identification in toxicological analysis. According to our knowledge, this is the first study where a CYP2D6 sequencing methodology is validated and applied to post-mortem samples, in Portugal. The developed methodology allows the data collection of post-mortem cases, which is of primordial importance to enhance the application of these genetic tools to forensic toxicology and pathology. PMID:26926096

  7. Complex Disease–, Gene–, and Drug–Drug Interactions: Impacts of Renal Function, CYP2D6 Phenotype, and OCT2 Activity on Veliparib Pharmacokinetics

    PubMed Central

    Li, Jing; Kim, Seongho; Sha, Xianyi; Wiegand, Richard; Wu, Jianmei; LoRusso, Patricia

    2014-01-01

    Purpose Veliparib, a poly (ADP-ribose) polymerase (PARP) inhibitor, undergoes renal excretion and liver metabolism. This study quantitatively assessed the interactions of veliparib with metabolizing enzyme (CYP2D6) and transporter (OCT2) in disease settings (renal impairment). Experimental Design Veliparib in vitro metabolism was examined in human liver microsomes and recombinant enzymes carrying wild-type CYP2D6 or functional defect variants (CYP2D6*10 and *4). Plasma pharmacokinetics were evaluated in 27 patients with cancer. A parent–metabolite joint population model was developed to characterize veliparib and metabolite (M8) pharmacokinetics and to identify patient factors influencing veliparib disposition. A physiologically based pharmacokinetic model integrated with a mechanistic kidney module was developed to quantitatively predict the individual and combined effects of renal function, CYP2D6 phenotype, and OCT2 activity on veliparib pharmacokinetics. Results In vitro intrinsic clearance of CYP2D6.1 and CYP2D6.10 for veliparib metabolism were 0.055 and 0.017 μL/min/pmol CYP, respectively. Population mean values for veliparib oral clearance and M8 clearance were 13.3 and 8.6 L/h, respectively. Creatinine clearance was identified as the significant covariate on veliparib oral clearance. Moderate renal impairment, CYP2D6 poor metabolizer, and co-administration of OCT2 inhibitor (cimetidine) increased veliparib steady-state exposure by 80%, 20%, and 30%, respectively. These factors collectively led to >2-fold increase in veliparib exposure. Conclusions Renal function (creatinine clearance) is a significant predictor for veliparib exposure in patients with cancer. Although a single factor (i.e., renal impairment, CYP2D6 deficiency, and reduced OCT2 activity) shows a moderate impact, they collectively could result in a significant and potentially clinically relevant increase in veliparib exposure. PMID:24947923

  8. The antitussive effect of dextromethorphan in relation to CYP2D6 activity

    PubMed Central

    Abdul Manap, R; Wright, C E; Gregory, A; Rostami-Hodjegan, A; Meller, S T; Kelm, G R; Lennard, M S; Tucker, G T; Morice, A H

    1999-01-01

    Aims To test the hypothesis that inhibition of cytochrome P450 2D6 (CYP2D6) by quinidine increases the antitussive effect of dextromethorphan (DEX) in an induced cough model. Methods Twenty-two healthy extensive metaboliser phenotypes for CYP2D6 were studied according to a double-blind, randomised cross-over design after administration of: (1) Placebo antitussive preceded at 1 h by placebo inhibitor; (2) 30 mg oral DEX preceded at 1 h by placebo inhibitor (DEX30); (3) 60 mg oral DEX preceded at 1 h by placebo inhibitor (DEX60); (4) 30 mg oral DEX preceded at 1 h by 50 mg oral quinidine sulphate (QDEX30). Cough frequency following inhalation of 10% citric acid was measured at baseline and at intervals up to 12 h. Plasma concentrations of DEX and its metabolites were measured up to 96 h by h.p.l.c. Results Inhibition of CYP2D6 by quinidine caused a significant increase in the mean ratio of DEX to dextrorphan (DEX:DOR) plasma AUC(96) (0.04 vs 1.81, P < 0.001). The mean (±s.d.) decrements in cough frequency below baseline over 12 h (AUEC) were: 8% (11), 17% (14.5), 25% (16.2) and 25% (16.9) for placebo, DEX30, DEX60 and QDEX30 treatments, respectively. Statistically significant differences in antitussive effect were detected for the contrasts between DEX60/placebo (P < 0.001; 95% CI of difference +80, +327) and QDEX30/placebo (P < 0.001, +88, +336), but not for DEX30/placebo, DEX30/DEX60 or DEX30/QDEX30 (P = 0.071, −7, +241; P = 0.254, −37, +211; P = 0.187, −29, +219, respectively). Conclusions A significant antitussive effect was demonstrated after 60 mg dextromethorphan and 30 mg dextromethorphan preceded by 50 mg quinidine using an induced cough model. However, although the study was powered to detect a 10% difference in cough response, the observed differences for other contrasts were less than 10%, such that it was possible only to imply a dose effect (30 vs 60 mg) in the antitussive activity of DEX and enhancement of this effect by CYP2D6 inhibition. PMID

  9. National Prociency Testing Result of CYP2D6*10 Genotyping for Adjuvant Tamoxifen Therapy in China.

    PubMed

    Lin, Guigao; Zhang, Kuo; Yi, Lang; Han, Yanxi; Xie, Jiehong; Li, Jinming

    2016-01-01

    Tamoxifen has been successfully used for treating breast cancer and preventing cancer recurrence. Cytochrome P450 2D6 (CYP2D6) plays a key role in the process of metabolizing tamoxifen to its active moiety, endoxifen. Patients with variants of the CYP2D6 gene may not receive the full benefit of tamoxifen treatment. The CYP2D6*10 variant (the most common variant in Asians) was analyzed to optimize the prescription of tamoxifen in China. To ensure referring clinicians have accurate information for genotype-guided tamoxifen treatment, the Chinese National Center for Clinical Laboratories (NCCL) organized a national proficiency testing (PT) to evaluate the performance of laboratories providing CYP2D6*10 genotyping. Ten genomic DNA samples with CYP2D6 wild-type or CYP2D6*10 variants were validated by PCR-sequencing and sent to 28 participant laboratories. The genotyping results and pharmacogenomic test reports were submitted and evaluated by NCCL experts. Additional information regarding the number of samples tested, the accreditation/certification status, and detecting technology was also requested. Thirty-one data sets were received, with a corresponding analytical sensitivity of 98.2% (548/558 challenges; 95% confidence interval: 96.7-99.1%) and an analytic specificity of 96.5% (675/682; 95% confidence interval: 97.9-99.5%). Overall, 25/28 participants correctly identified CYP2D6*10 status in 10 samples; however, two laboratories made serious genotyping errors. Most of the essential information was included in the 20 submitted CYP2D6*10 test reports. The majority of Chinese laboratories are reliable for detecting the CYP2D6*10 variant; however, several issues revealed in this study underline the importance of PT schemes in continued external assessment and provision of guidelines. PMID:27603206

  10. Loss of Heterozygosity at the CYP2D6 Locus in Breast Cancer: Implications for Germline Pharmacogenetic Studies

    PubMed Central

    Goetz, Matthew P.; Sun, James X.; Suman, Vera J.; Silva, Grace O.; Perou, Charles M.; Nakamura, Yusuke; Cox, Nancy J.; Stephens, Philip J.; Miller, Vincent A.; Ross, Jeffrey S.; Chen, David; Safgren, Stephanie L.; Kuffel, Mary J.; Ames, Matthew M.; Kalari, Krishna R.; Gomez, Henry L.; Gonzalez-Angulo, Ana M.; Burgues, Octavio; Brauch, Hiltrud B.; Ingle, James N.; Ratain, Mark J.; Yelensky, Roman

    2015-01-01

    Background: Controversy exists regarding the impact of CYP2D6 genotype on tamoxifen responsiveness. We examined loss of heterozygosity (LOH) at the CYP2D6 locus and determined its impact on genotyping error when tumor tissue is used as a DNA source. Methods: Genomic tumor data from the adjuvant and metastatic settings (The Cancer Genome Atlas [TCGA] and Foundation Medicine [FM]) were analyzed to characterize the impact of CYP2D6 copy number alterations (CNAs) and LOH on Hardy Weinberg equilibrium (HWE). Additionally, we analyzed CYP2D6 *4 genotype from formalin-fixed paraffin-embedded (FFPE) tumor blocks containing nonmalignant tissue and buccal (germline) samples from patients on the North Central Cancer Treatment Group (NCCTG) 89-30-52 tamoxifen trial. All statistical tests were two-sided. Results: In TCGA samples (n =627), the CYP2D6 LOH rate was similar in estrogen receptor (ER)–positive (41.2%) and ER-negative (35.2%) but lower in HER2-positive tumors (15.1%) (P < .001). In FM ER+ samples (n = 290), similar LOH rates were observed (40.8%). In 190 NCCTG samples, the agreement between CYP2D6 genotypes derived from FFPE tumors and FFPE tumors containing nonmalignant tissue was moderate (weighted Kappa = 0.74; 95% CI = 0.63 to 0.84). Comparing CYP2D6 genotypes derived from buccal cells to FFPE tumor DNA, CYP2D6*4 genotype was discordant in six of 31(19.4%). In contrast, there was no disagreement between CYP2D6 genotypes derived from buccal cells with FFPE tumors containing nonmalignant tissue. Conclusions: LOH at the CYP2D6 locus is common in breast cancer, resulting in potential misclassification of germline CYP2D6 genotypes. Tumor DNA should not be used to determine germline CYP2D6 genotype without sensitive techniques to detect low frequency alleles and quality control procedures appropriate for somatic DNA. PMID:25490892

  11. Liver/kidney microsomal antibody type 1 targets CYP2D6 on hepatocyte plasma membrane

    PubMed Central

    Muratori, L; Parola, M; Ripalti, A; Robino, G; Muratori, P; Bellomo, G; Carini, R; Lenzi, M; Landini, M; Albano, E; Bianchi, F

    2000-01-01

    BACKGROUND—Liver/kidney microsomal antibody type 1 (LKM1) is the marker of type 2 autoimmune hepatitis (AIH) and is detected in up to 6% of patients with hepatitis C virus (HCV) infection. It recognises linear and conformational epitopes of cytochrome P450IID6 (CYP2D6) and may have liver damaging activity, provided that CYP2D6 is accessible to effector mechanisms of autoimmune attack.
METHODS—The presence of LKM1 in the plasma membrane was investigated by indirect immunofluorescence and confocal laser microscopy of isolated rat hepatocytes probed with 10 LKM1 positive sera (five from patients with AIH and five from patients with chronic HCV infection) and a rabbit polyclonal anti-CYP2D6 serum.
RESULTS—Serum from both types of patient stained the plasma membrane of non-permeabilised cells, where the fluorescent signal could be visualised as discrete clumps. Conversely, permeabilised hepatocytes showed diffuse submembranous/cytoplasmic staining. Adsorption with recombinant CYP2D6 substantially reduced plasma membrane staining and LKM1 immunoblot reactivity. Plasma membrane staining of LKM1 colocalised with that of anti-CYP2D6. Immunoprecipitation experiments showed that a single 50 kDa protein recognised by anti-CYP2D6 can be isolated from the plasma membrane of intact hepatocytes.
CONCLUSIONS—AIH and HCV related LKM1 recognise CYP2D6 exposed on the plasma membrane of isolated hepatocytes. This observation supports the notion that anti-CYP2D6 autoreactivity may be involved in the pathogenesis of liver damage.


Keywords: liver/kidney microsomal antibody type 1; autoimmunity; autoimmune hepatitis; hepatitis C virus infection; confocal microscopy PMID:10716687

  12. Risperidone-associated adverse drug reactions and CYP2D6 polymorphisms in a South African cohort

    PubMed Central

    Dodgen, Tyren M.; Eloff, Arinda; Mataboge, Connie; Roos, Louw (.J.L.).; van Staden, Werdie (.C.W.).; Pepper, Michael S.

    2015-01-01

    Background Contradictory information exists regarding the influence of CYP2D6 polymorphisms on adverse drug reactions (ADRs) (extrapyramidal symptoms (EPS) and weight gain) related to risperidone treatment. This prompted us to evaluate the influence of CYP2D6 genetic variation in a cohort of South African patients who presented with marked movement disorders and/or weight gain while on risperidone treatment. Methods Patients who were experiencing marked risperidone ADRs were recruited from Weskoppies Public Psychiatric Hospital. As poor or intermediate metabolism was expected, comprehensive CYP2D6 sequence variations were evaluated using XL-PCR + Sequencing. Results No statistically significant association was found between CYP2D6 poor metabolism and risperidone ADRs. An inverse relationship between EPS and weight gain was however identified. A novel CYP2D6 allele was identified which is unlikely to affect metabolism based on in silico evaluation. Conclusion CYP2D6 variation appeared not to be a good pharmacogenetic marker for predicting risperidone-related ADRs in this naturalistic South African cohort. Evaluation of a larger cohort would be needed to confirm these observations, including an examination of the role of potential intermediaries between the hypothesised genetic and clinical phenotypes. PMID:26937359

  13. Length of psychiatric hospitalization is correlated with CYP2D6 functional status in inpatients with major depressive disorder

    PubMed Central

    Ruaño, Gualberto; Szarek, Bonnie L; Villagra, David; Gorowski, Krystyna; Kocherla, Mohan; Seip, Richard L; Goethe, John W; Schwartz, Harold I

    2016-01-01

    Aim This study aimed to determine the effect of the CYP2D6 genotype on the length of hospitalization stay for patients treated for major depressive disorder. Methods A total of 149 inpatients with a diagnosis of major depressive disorder at the Institute of Living, Hartford Hospital (CT, USA), were genotyped to detect altered alleles in the CYP2D6 gene. Prospectively defined drug metabolism indices (metabolic reserve, metabolic alteration and allele alteration) were determined quantitatively and assessed for their relationship to length of hospitalization stay. Results Hospital stay was significantly longer in deficient CYP2D6 metabolizers (metabolic reserve <2) compared with functional or suprafunctional metabolizers (metabolic reserve ≥2; 7.8 vs 5.7 days, respectively; p = 0.002). Conclusion CYP2D6 enzymatic functional status significantly affected length of hospital stay, perhaps due to reduced efficacy or increased side effects of the medications metabolized by the CYP2D6 isoenzyme. Functional scoring of CYP2D6 alleles may have a substantial impact on the quality of care, patient satisfaction and the economics of psychiatric treatment. PMID:23734807

  14. Determination of CYP2D6 *3, *4, and *10 frequency in women with breast cancer in São Luís, Brazil, and its association with prognostic factors and disease-free survival

    PubMed Central

    Martins, D.M.F.; Vidal, F.C.B.; Souza, R.D.M.; Brusaca, S.A.; Brito, L.M.O.

    2014-01-01

    The CYP2D6 enzyme is crucial for the metabolism of tamoxifen. The CYP2D6 gene is highly polymorphic, and individuals can be extensive, intermediate, or poor tamoxifen metabolizers. The aim of this study was to determine the frequencies of the CYP2D6 *3, *4, and *10 alleles in women with breast cancer who were treated with tamoxifen and analyze the association of enzyme activity with prognostic factors and disease-free survival. We observed a high frequency of CYP2D6 *10, with an allelic frequency of 0.14 (14.4%). The *3 allele was not present in the studied population, and *4 had an allelic frequency of 0.13 (13.8%). We conclude that patients with reduced CYP2D6 activity did not present worse tumor characteristics or decreased disease-free survival than women with normal enzyme activity, as the difference was not statistically significant. We also observed a high frequency of CYP2D6 *10, which had not been previously described in this specific population. This study is the first in north-northeastern Brazil that aimed to contribute to the knowledge of the Brazilian regional profile for CYP2D6 polymorphisms and their phenotypes. These findings add to the knowledge of the distribution of different polymorphic CYP2D6 alleles and the potential role of CYP2D6 genotyping in clinical practice prior to choosing therapeutic protocols. PMID:25296365

  15. No influence of the polymorphisms CYP2C19 and CYP2D6 on the efficacy of cyclophosphamide, thalidomide, and bortezomib in patients with Multiple Myeloma

    PubMed Central

    2010-01-01

    Background The response to treatment varies among patients with multiple myeloma and markers for prediction of treatment outcome are highly needed. Bioactivation of cyclophosphamide and thalidomide, and biodegradation of bortezomib, is dependent on cytochrome P450 metabolism. We explored the potential influence of different polymorphisms in the CYP enzymes on the outcome of treatment. Methods Data was analyzed from 348 patients undergoing high-dose treatment and stem cell support in Denmark in 1994 to 2004. Clinical information on relapse treatment in 243 individual patients was collected. The patients were genotyped for the non-functional alleles CYP2C19*2 and CYP2D6*3, *4, *5 (gene deletion), *6, and CYP2D6 gene duplication. Results In patients who were treated with bortezomib and were carriers of one or two defective CYP2D6 alleles there was a trend towards a better time-to-next treatment. We found no association between the number of functional CYP2C19 and CYP2D6 alleles and outcome of treatment with cyclophosphamide or thalidomide. Neither was the number of functional CYP2C19 and CYP2D6 alleles associated with neurological adverse reactions to thalidomide and bortezomib. Conclusion There was no association between functional CYP2C19 and CYP2D6 alleles and treatment outcome in multiple myeloma patients treated with cyclophosphamide, thalidomide or bortezomib. A larger number of patients treated with bortezomib are needed to determine the role of CYP2D6 alleles in treatment outcome. PMID:20684753

  16. Determinants of the substrate specificity of human cytochrome P-450 CYP2D6: design and construction of a mutant with testosterone hydroxylase activity.

    PubMed Central

    Smith, G; Modi, S; Pillai, I; Lian, L Y; Sutcliffe, M J; Pritchard, M P; Friedberg, T; Roberts, G C; Wolf, C R

    1998-01-01

    Cytochrome P-450 CYP2D6, human debrisoquine hydroxylase, metabolizes more than 30 prescribed drugs, the vast majority of which are small molecules containing a basic nitrogen atom. In contrast, the similar mouse protein Cyp2d-9 was first characterized as a testosterone 16alpha-hydroxylase. No common substrates have been reported for the two enzymes. Here we investigate the structural basis of this difference in substrate specificity. We have earlier used a combination of NMR data and homology modelling to generate a three-dimensional model of CYP2D6 [Modi, Paine, Sutcliffe, Lian, Primrose, Wolf, C.R. and Roberts (1996) Biochemistry 35, 4541-4550]. We have now generated a homology model of Cyp2d-9 and compared the two models to identify specific amino acid residues that we believe form the substrate-binding site in each protein and therefore influence catalytic selectivity. Although there are many similarities in active site structure, the most notable difference is a phenylalanine residue (Phe-483) in CYP2D6, which in the model is located such that the bulky phenyl ring is positioned across the channel mouth, thus limiting the size of substrate that can access the active site. In Cyp2d-9, the corresponding position is occupied by an isoleucine residue, which imposes fewer steric restraints on the size of substrate that can access the active site. To investigate whether the amino acid residue at this position does indeed influence the catalytic selectivity of these enzymes, site-directed mutagenesis was used to change Phe-483 in CYP2D6 to isoleucine and also to tryptophan. CYP2D6, Cyp2d-9 and both mutant CYP2D6 proteins were co-expressed with NADPH cytochrome P-450 reductase as a functional mono-oxygenase system in Escherichia coli and their relative catalytic activities towards bufuralol and testosterone were determined. All four proteins exhibited catalytic activity towards bufuralol but only Cyp2d-9 catalysed the formation of 16alpha-hydroxytesterone. Uniquely

  17. Cyp2D6 catalyzes 5-hydroxylation of 1-(2-pyrimidinyl)-piperazine, an active metabolite of several psychoactive drugs, in human liver microsomes.

    PubMed

    Raghavan, Nirmala; Zhang, Donglu; Zhu, Mingshe; Zeng, Jianing; Christopher, Lisa

    2005-02-01

    1-(2-Pyrimidinyl)-piperazine (1-PP) is an active metabolite of several psychoactive drugs including buspirone. 1-PP is also the major metabolite in the human circulation and in rat brains following oral administration of buspirone. This study was conducted to identify the enzyme responsible for the metabolic conversion of 1-PP to 5-hydroxy-1-(2-pyrimidinyl)-piperazine (HO-1-PP) in human liver microsomes (HLMs). The product HO-1-PP was quantified by a validated liquid chromatography-tandem mass spectrometry method. In the presence of NADPH, 1-PP (100 microM) was incubated separately with human cDNA-expressed cytochrome P450 isozymes (including CYP2D6, 3A4, 1A2, 2A6, 2C9, 2C19, 2E1, and 2B6) at 37 degrees C. CYP2D6 catalyzed the formation of HO-1-PP from 1-PP. This catalytic activity was >95% inhibited by quinidine, a CYP2D6 inhibitor. HO-1-PP formation rates correlated well with the bufuralol 1-hydroxylase (CYP2D6) activities of individual HLMs. The formation of HO-1-PP followed a Michaelis-Menten kinetics with a K(m) of 171 microM and V(max) of 313 pmol/min x mg protein in HLMs. Collectively, these results indicate that polymorphic CYP2D6 is responsible for the conversion of 1-PP to HO-1-PP. PMID:15507542

  18. New aQTL SNPs for the CYP2D6 Identified by a Novel Mediation Analysis of Genome-Wide SNP Arrays, Gene Expression Arrays, and CYP2D6 Activity

    PubMed Central

    Wang, Zhiping; Boustani, Malaz; Liu, Yunlong; Skaar, Todd; Li, Lang

    2013-01-01

    Background. The genome-wide association studies (GWAS) have been successful during the last few years. A key challenge is that the interpretation of the results is not straightforward, especially for transacting SNPs. Integration of transcriptome data into GWAS may provide clues elucidating the mechanisms by which a genetic variant leads to a disease. Methods. Here, we developed a novel mediation analysis approach to identify new expression quantitative trait loci (eQTL) driving CYP2D6 activity by combining genotype, gene expression, and enzyme activity data. Results. 389,573 and 1,214,416 SNP-transcript-CYP2D6 activity trios are found strongly associated (P < 10−5, FDR = 16.6% and 11.7%) for two different genotype platforms, namely, Affymetrix and Illumina, respectively. The majority of eQTLs are trans-SNPs. A single polymorphism leads to widespread downstream changes in the expression of distant genes by affecting major regulators or transcription factors (TFs), which would be visible as an eQTL hotspot and can lead to large and consistent biological effects. Overlapped eQTL hotspots with the mediators lead to the discovery of 64 TFs. Conclusions. Our mediation analysis is a powerful approach in identifying the trans-QTL-phenotype associations. It improves our understanding of the functional genetic variations for the liver metabolism mechanisms. PMID:24232670

  19. Modulation of CYP2D6 and CYP3A4 metabolic activities by Ferula asafetida resin

    PubMed Central

    Al-Jenoobi, Fahad I.; Al-Thukair, Areej A.; Alam, Mohd Aftab; Abbas, Fawkeya A.; Al-Mohizea, Abdullah M.; Alkharfy, Khalid M.; Al-Suwayeh, Saleh A.

    2014-01-01

    Present study investigated the potential effects of Ferula asafetida resin on metabolic activities of human drug metabolizing enzymes: CYP2D6 and CYP3A4. Dextromethorphan (DEX) was used as a marker to assess metabolic activities of these enzymes, based on its CYP2D6 and CYP3A4 mediated metabolism to dextrorphan (DOR) and 3-methoxymorphinan (3-MM), respectively. In vitro study was conducted by incubating DEX with human liver microsomes and NADPH in the presence or absence of Asafetida alcoholic extract. For clinical study, healthy human volunteers received a single dose of DEX alone (phase-I) and repeated the same dose after a washout period and four-day Asafetida treatment (phase-II). Asafetida showed a concentration dependent inhibition on DOR formation (in vitro) and a 33% increase in DEX/DOR urinary metabolic ratio in clinical study. For CYP3A4, formation of 3-MM in microsomes was increased at low Asafetida concentrations (10, 25 and 50 μg/ml) but slightly inhibited at the concentration of 100 μg/ml. On the other hand, in vivo observations revealed that Asafetida significantly increased DEX/3-MM urinary metabolic ratio. The findings of this study suggest that Asafetida may have a significant effect on CYP3A4 metabolic activity. Therefore, using Ferula asafetida with CYP3A4 drug substrates should be cautioned especially those with narrow therapeutic index such as cyclosporine, tacrolimus and carbamazepine. PMID:25561870

  20. Population pharmacokinetic modelling to assess the impact of CYP2D6 and CYP3A metabolic phenotypes on the pharmacokinetics of tamoxifen and endoxifen

    PubMed Central

    ter Heine, Rob; Binkhorst, Lisette; de Graan, Anne Joy M; de Bruijn, Peter; Beijnen, Jos H; Mathijssen, Ron H J; Huitema, Alwin D R

    2014-01-01

    Aims Tamoxifen is considered a pro-drug of its active metabolite endoxifen. The major metabolic enzymes involved in endoxifen formation are CYP2D6 and CYP3A. There is considerable evidence that variability in activity of these enzymes influences endoxifen exposure and thereby may influence the clinical outcome of tamoxifen treatment. We aimed to quantify the impact of metabolic phenotype on the pharmacokinetics of tamoxifen and endoxifen. Methods We assessed the CYP2D6 and CYP3A metabolic phenotypes in 40 breast cancer patients on tamoxifen treatment with a single dose of dextromethorphan as a dual phenotypic probe for CYP2D6 and CYP3A. The pharmacokinetics of dextromethorphan, tamoxifen and their relevant metabolites were analyzed using non-linear mixed effects modelling. Results Population pharmacokinetic models were developed for dextromethorphan, tamoxifen and their metabolites. In the final model for tamoxifen, the dextromethorphan derived metabolic phenotypes for CYP2D6 as well as CYP3A significantly (P < 0.0001) explained 54% of the observed variability in endoxifen formation (inter-individual variability reduced from 55% to 25%). Conclusions We have shown that not only CYP2D6, but also CYP3A enzyme activity influences the tamoxifen to endoxifen conversion in breast cancer patients. Our developed model may be used to assess separately the impact of CYP2D6 and CYP3A mediated drug–drug interactions with tamoxifen without the necessity of administering this anti-oestrogenic drug and to support Bayesian guided therapeutic drug monitoring of tamoxifen in routine clinical practice. PMID:24697814

  1. Aberrant CYP2D6 metabolizer phenotypes do not show increased frequency in patients undergoing ECT after antidepressant therapy.

    PubMed

    Mirzakhani, Hooman; van Dormolen, Juliët; van der Weide, Karen; Guchelaar, Henk-Jan; van Noorden, Martijn S; Swen, Jesse

    2015-10-01

    We investigated the accumulation of aberrant CYP2D6 genotypes and predicted metabolizer phenotypes (ultrarapid metabolizer, intermediate metabolizer and poor metabolizer) potentially affecting the antidepressant treatment response in depressive patients indicated for electroconvulsive therapy (ECT) compared with patients with a single episode of depression. Seventy-six Dutch White patients with unipolar or bipolar treatment-resistant depression who underwent ECT were genotyped using the Amplichip CYP450 Test for CYP2D6. Two hundred and eight patients with a single episode of unipolar or bipolar depression were used as controls. No difference was observed in the prevalence of CYP2D6 phenotypes (poor metabolizer, intermediate metabolizer, extensive metabolizer and ultrarapid metabolizer) between the ECT and the control patients (5.3, 38.7, 56.0 and 0.0% vs. 6.4, 51.0, 42.6 and 0.0%, respectively). The types of depression (odds ratio = 0.33, P = 0.018) and age (odds ratio = 1.55 for a 10-year increase, P < 0.001), but not CYP2D6 phenotype or activity score were associated with the response to antidepressant treatment. In conclusion, preemptive genotyping for CYP2D6 currently appears to have no clinical implications in treatment-resistant depressive patients indicated for ECT. PMID:26230381

  2. Dose-dependent effect of the CYP2D6 genotype on the steady-state fluvoxamine concentration.

    PubMed

    Watanabe, Junzo; Suzuki, Yutaro; Fukui, Naoki; Sugai, Takuro; Ono, Shin; Inoue, Yoshimasa; Someya, Toshiyuki

    2008-12-01

    Several studies have reported that the cytochrome P450 (CYP) 2D6 plays an important role in the fluvoxamine metabolism. However, some other studies have reported that the CYP2D6 genotype has no major impact on the fluvoxamine concentration. This study investigated the dose-dependent effect of CYP2D6-variant alleles on the steady-state fluvoxamine concentration. There were 23 patients whose plasma concentrations of fluvoxamine were measured at 4 doses (50, 100, 150, and 200 mg/d). The differences in the plasma fluvoxamine concentration were analyzed between 2 genotype groups divided by the number of CYP2D6-variant alleles (with 0 and 1 or 2 variant alleles). The results demonstrated the nonlinear kinetics of fluvoxamine metabolism, and the degree of nonlinear kinetics decreased as the dose was increased. Significant differences in fluvoxamine concentration were observed between the subjects with 0 variant alleles and the subjects with 1 or 2 variant alleles (P = 0.044) when they were treated by 50 mg of fluvoxamine. There were no significant differences in the plasma concentration of fluvoxamine at 100, 150, and 200 mg/d. The present study suggests that the effect of the CYP2D6 genotype on fluvoxamine metabolism is greater at lower doses of fluvoxamine. PMID:18978520

  3. Use of pharmacogenetics in bioequivalence studies to reduce sample size: an example with mirtazapine and CYP2D6.

    PubMed

    González-Vacarezza, N; Abad-Santos, F; Carcas-Sansuan, A; Dorado, P; Peñas-Lledó, E; Estévez-Carrizo, F; Llerena, A

    2013-10-01

    In bioequivalence studies, intra-individual variability (CV(w)) is critical in determining sample size. In particular, highly variable drugs may require enrollment of a greater number of subjects. We hypothesize that a strategy to reduce pharmacokinetic CV(w), and hence sample size and costs, would be to include subjects with decreased metabolic enzyme capacity for the drug under study. Therefore, two mirtazapine studies, two-way, two-period crossover design (n=68) were re-analysed to calculate the total CV(w) and the CV(w)s in three different CYP2D6 genotype groups (0, 1 and ≥ 2 active genes). The results showed that a 29.2 or 15.3% sample size reduction would have been possible if the recruitment had been of individuals carrying just 0 or 0 plus 1 CYP2D6 active genes, due to the lower CV(w). This suggests that there may be a role for pharmacogenetics in the design of bioequivalence studies to reduce sample size and costs, thus introducing a new paradigm for the biopharmaceutical evaluation of drug products. PMID:22733239

  4. Tamoxifen metabolite concentrations, CYP2D6 genotype, and breast cancer outcomes.

    PubMed

    Madlensky, L; Natarajan, L; Tchu, S; Pu, M; Mortimer, J; Flatt, S W; Nikoloff, D M; Hillman, G; Fontecha, M R; Lawrence, H J; Parker, B A; Wu, A H B; Pierce, J P

    2011-05-01

    We explored whether breast cancer outcomes are associated with endoxifen and other metabolites of tamoxifen and examined potential correlates of endoxifen concentration levels in serum including cytochrome P450 2D6 (CYP2D6) metabolizer phenotype and body mass index (BMI). Concentration levels of tamoxifen, endoxifen, 4-hydroxytamoxifen (4OH-tamoxifen), and N-desmethyltamoxifen (ND-tamoxifen) were measured from samples taken from 1,370 patients with estrogen receptor (ER)-positive breast cancer who were participating in the Women's Healthy Eating and Living (WHEL) Study. We tested these concentration levels for possible associations with breast cancer outcomes and found that breast cancer outcomes were not associated with the concentration levels of tamoxifen, 4-hydroxytamoxifen, and ND-tamoxifen. For endoxifen, a threshold was identified, with women in the upper four quintiles of endoxifen concentration appearing to have a 26% lower recurrence rate than women in the bottom quintile (hazard ratio (HR) = 0.74; 95% confidence interval (CI), (0.55-1.00)). The predictors of this higher-risk bottom quintile were poor/intermediate metabolizer genotype, higher BMI, and lower tamoxifen concentrations as compared with the mean for the cohort as a whole. This study suggests that there is a minimal concentration threshold above which endoxifen is effective against the recurrence of breast cancer and that ~80% of tamoxifen takers attain this threshold. PMID:21430657

  5. Significant Effect of Polymorphisms in CYP2D6 and ABCC2 on Clinical Outcomes of Adjuvant Tamoxifen Therapy for Breast Cancer Patients

    PubMed Central

    Kiyotani, Kazuma; Mushiroda, Taisei; Imamura, Chiyo K.; Hosono, Naoya; Tsunoda, Tatsuhiko; Kubo, Michiaki; Tanigawara, Yusuke; Flockhart, David A.; Desta, Zeruesenay; Skaar, Todd C.; Aki, Fuminori; Hirata, Koichi; Takatsuka, Yuichi; Okazaki, Minoru; Ohsumi, Shozo; Yamakawa, Takashi; Sasa, Mitsunori; Nakamura, Yusuke; Zembutsu, Hitoshi

    2010-01-01

    Purpose The clinical efficacy of tamoxifen is suspected to be influenced by the activity of drug-metabolizing enzymes and transporters involved in the formation, metabolism, and elimination of its active forms. We investigated relationships of polymorphisms in transporter genes and CYP2D6 to clinical outcome of patients receiving tamoxifen. Patients and Methods We studied 282 patients with hormone receptor–positive, invasive breast cancer receiving tamoxifen monotherapy, including 67 patients who have been previously reported. We investigated the effects of allelic variants of CYP2D6 and haplotype-tagging single nucleotide polymorphisms (tag-SNPs) of ABCB1, ABCC2, and ABCG2 on recurrence-free survival using the Kaplan-Meier method and Cox regression analysis. Plasma concentrations of tamoxifen metabolites were measured in 98 patients receiving tamoxifen 20 mg/d. Results CYP2D6 variants were significantly associated with shorter recurrence-free survival (P = .000036; hazard ratio [HR] = 9.52; 95% CI, 2.79 to 32.45 in patients with two variant alleles v patients without variant alleles). Among 51 tag-SNPs in transporter genes, a significant association was found at rs3740065 in ABCC2 (P = .00017; HR = 10.64; 95% CI, 1.44 to 78.88 in patients with AA v GG genotypes). The number of risk alleles of CYP2D6 and ABCC2 showed cumulative effects on recurrence-free survival (P = .000000055). Patients carrying four risk alleles had 45.25-fold higher risk compared with patients with ≤ one risk allele. CYP2D6 variants were associated with lower plasma levels of endoxifen and 4-hydroxytamoxifen (P = .0000043 and .00052), whereas no significant difference was found among ABCC2 genotype groups. Conclusion Our results suggest that polymorphisms in CYP2D6 and ABCC2 are important predictors for the prognosis of patients with breast cancer treated with tamoxifen. PMID:20124171

  6. Guanfu base A, an antiarrhythmic alkaloid of Aconitum coreanum, Is a CYP2D6 inhibitor of human, monkey, and dog isoforms.

    PubMed

    Sun, Jianguo; Peng, Ying; Wu, Hui; Zhang, Xueyuan; Zhong, Yunxi; Xiao, Yanan; Zhang, Fengyi; Qi, Huanhuan; Shang, Lili; Zhu, Jianping; Sun, Yue; Liu, Ke; Liu, Jinghan; A, Jiye; Ho, Rodney J Y; Wang, Guangji

    2015-05-01

    Guanfu base A (GFA) is a novel heterocyclic antiarrhythmic drug isolated from Aconitum coreanum (Lèvl.) rapaics and is currently in a phase IV clinical trial in China. However, no study has investigated the influence of GFA on cytochrome P450 (P450) drug metabolism. We characterized the potency and specificity of GFA CYP2D inhibition based on dextromethorphan O-demethylation, a CYP2D6 probe substrate of activity in human, mouse, rat, dog, and monkey liver microsomes. In addition, (+)-bufuralol 1'-hydroxylation was used as a CYP2D6 probe for the recombinant form (rCYP2D6), 2D1 (rCYP2D1), and 2D2 (rCYP2D2) activities. Results show that GFA is a potent noncompetitive inhibitor of CYP2D6, with inhibition constant Ki = 1.20 ± 0.33 μM in human liver microsomes (HLMs) and Ki = 0.37 ± 0.16 μM for the human recombinant form (rCYP2D6). GFA is also a potent competitive inhibitor of CYP2D in monkey (Ki = 0.38 ± 0.12 μM) and dog (Ki = 2.4 ± 1.3 μM) microsomes. However, GFA has no inhibitory activity on mouse or rat CYP2Ds. GFA did not exhibit any inhibition activity on human recombinant CYP1A2, 2A6, 2C8, 2C19, 3A4, or 3A5, but showed slight inhibition of 2B6 and 2E1. Preincubation of HLMs and rCYP2D6 resulted in the inactivation of the enzyme, which was attenuated by GFA or quinidine. Beagle dogs treated intravenously with dextromethorphan (2 mg/ml) after pretreatment with GFA injection showed reduced CYP2D metabolic activity, with the Cmax of dextrorphan being one-third that of the saline-treated group and area under the plasma concentration-time curve half that of the saline-treated group. This study suggests that GFA is a specific CYP2D6 inhibitor that might play a role in CYP2D6 medicated drug-drug interaction. PMID:25681130

  7. CYP2D6 genotype- and endoxifen-guided tamoxifen dose escalation increases endoxifen serum concentrations without increasing side effects.

    PubMed

    Dezentjé, V O; Opdam, F L; Gelderblom, H; Hartigh den, J; Van der Straaten, T; Vree, R; Maartense, E; Smorenburg, C H; Putter, H; Dieudonné, A S; Neven, P; Van de Velde, C J H; Nortier, J W R; Guchelaar, H-J

    2015-10-01

    Breast cancer patients with absent or reduced CYP2D6 activity and consequently low endoxifen levels may benefit less from tamoxifen treatment. CYP2D6 poor and intermediate metabolizers may need a personalized increased tamoxifen dose to achieve effective endoxifen serum concentrations, without increasing toxicity. From a prospective study population of early breast cancer patients using tamoxifen (CYPTAM: NTR1509), 12 CYP2D6 poor and 12 intermediate metabolizers were selected and included in a one-step tamoxifen dose escalation study during 2 months. The escalated dose was calculated by multiplying the individual's endoxifen level at baseline relative to the average endoxifen concentration observed in CYP2D6 extensive metabolizers by 20 mg (120 mg maximum). Endoxifen levels and tamoxifen toxicity were determined at baseline and after 2 months, just before patients returned to the standard dose of 20 mg. Tamoxifen dose escalation in CYP2D6 poor and intermediate metabolizers significantly increased endoxifen concentrations (p < 0.001; p = 0.002, respectively) without increasing side effects. In intermediate metabolizers, dose escalation increased endoxifen to levels comparable with those observed in extensive metabolizers. In poor metabolizers, the mean endoxifen level increased from 24 to 81 % of the mean concentration in extensive metabolizers. In all patients, the endoxifen threshold of 5.97 ng/ml (=16.0 nM) reported by Madlensky et al. was reached following dose escalation. CYP2D6 genotype- and endoxifen-guided tamoxifen dose escalation increased endoxifen concentrations without increasing short-term side effects. Whether such tamoxifen dose escalation is effective and safe in view of long-term toxic effects is uncertain and needs to be explored. PMID:26369533

  8. Pharmacokinetics and bioequivalence evaluation of risperidone in healthy male subjects with different CYP2D6 genotypes.

    PubMed

    Cho, Hea-Young; Lee, Yong-Bok

    2006-06-01

    The aim of this study was to evaluate the bioequivalence of risperidone in healthy male subjects representing different CYP2D6 genotypes with respect to risperidone, 9-hydroxyrisperidone (9-OH-risperidone), and active moiety. A total of 506 Korean subjects were genotyped for CYP2D6*10 by means of allele-specific polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Based on the genotype analysis, 24 subjects, 7 homozygous for CYP2D6*1, 10 for *10, and 7 heterozygous for *10, were recruited and received a single oral dose of 2 mg risperidone tablet in this study. Serum concentrations of risperidone and 9-OHrisperidone up to 48 h were simultaneously determined. There were no significant differences of the active moiety, risperidone, and 9-OH-risperidone between the two preparations in AUC0-proportinal to, and Cmax. The 90% confidence intervals (CIs) for the ratio of means of the log-transformed AUC0-proportional to. and Cmax for the active moiety, risperidone, and 9-OH-risperidone were all within the bioequivalence acceptance criteria of 0.80-1.25. The CYP2D6*10 allele particularly was associated with higher serum concentrations of risperidone and the risperidone/9-OH-risperidone ratio compared with the CYP2D6*1 allele. The results demonstrate that the two preparations of risperidone are bioequivalent and it can be assumed that they are therapeutically equivalent and exchangeable in clinical practice. Furthermore, the pharmacokinetic parameters of risperidone and the risperidone/9-OH-risperidone ratio are highly dependent on the CYP2D6 genotypes. PMID:16833023

  9. CYP2D6*2 Polymorphism as a Predictor of Failed Outpatient Tramadol Therapy in Postherpetic Neuralgia Patients.

    PubMed

    Nasare, Namita Vilas; Banerjee, Basu Dev; Suryakantrao Deshmukh, Pravin; Mediratta, Pramod Kumari; Saxena, Ashok Kumar; Ahmed, Rafat Sultana; Bhattacharya, Sambit Nath

    2016-01-01

    Human cytochrome P4502D6 (CYP2D6) gene is highly polymorphic, leading to wide interindividual ethnic differences in CYP2D6-mediated drug metabolism. Its activity ranges from complete deficiency to excessive activity, potentially causing toxicity of the medication or therapeutic failure with recommended drug dosages. The aim of the study was to find the association of CYP2D6*2 polymorphisms with demographic characters (age, sex, and weight), pain intensity scales [numerical rating scale (NRS) sleep, global perceived effect (GPE)], and adverse drug effects in postherpetic neuralgia (PHN) patients receiving tramadol. The study comprised 246 patients [including 123 nonresponders (NRs) and 123 responders (Rs)] with PHN undergoing analgesic treatment at the pain clinic, Out Patient Department, University College of Medical Sciences, Guru Teg Bahadur Hospital, Delhi, India. Patients with any history of diabetes mellitus, human immunodeficiency virus, malignancy, hematological or liver disease, psychiatric illness, alcohol abuse, and tramadol sensitivity were excluded from the study. The NRSs of (resting and movement), NRS-sleep, and GPE were evaluated by the treating physician. Adverse drug effects during the time of the study were recorded. All samples were analyzed for CYP2D6*2 polymorphism using the polymerase chain reaction-restriction fragment length polymorphism method. The genotype distribution did not vary significantly among genders [NR (P = 0.723); R (P = 0.947)] and different age groups in NRs (P = 0.763) and Rs (P = 0.268). Clinically, statistically significant (P < 0.001) results were obtained in both the groups when compared with baseline in the NRS-sleep and GPE scores, whereas no association was found between NRS-sleep and GPE scores when compared with CYP2D6*2 genotype (P > 0.05). In addition, CYP2D6*2 genotype was not related to the adverse effects of analgesic therapy. The overall results suggested that CYP2D6*2 polymorphism plays no role in the PHN

  10. Tamoxifen Metabolite Concentrations, CYP2D6 Genotype and Breast Cancer Outcomes

    PubMed Central

    Madlensky, Lisa; Natarajan, Loki; Tchu, Simone; Pu, Minya; Mortimer, Joanne; Flatt, Shirley W.; Nikoloff, D. Michele; Hillman, Grantland; Fontecha, Marcel R.; Lawrence, H. Jeffrey; Parker, Barbara A.; Wu, Alan H.B.; Pierce, John P.

    2011-01-01

    We explored whether breast cancer outcomes are associated with endoxifen and other metabolites of tamoxifen, and to examine potential correlates of endoxifen concentrations including CYP2D6 metabolizer phenotype and body mass index (BMI). Tamoxifen, endoxifen, 4-hydroxytamoxifen and N-desmethyltamoxifen concentrations were measured from 1370 estrogen receptor positive breast cancer patients participating in the Women’s Healthy Eating and Living (WHEL) Study, and tested for associations with breast cancer outcomes. Breast cancer outcomes were not associated with tamoxifen, 4-hydroxytamoxifen or N-desmethyltamoxifen concentrations. For endoxifen, a threshold was identified suggesting that women in the upper four quintiles of endoxifen had a 26% lower recurrence rate than women in the bottom quintile. (HR=0.74; 95% CI, [0.55, 1.00]). Predictors of membership in this higher risk bottom quintile were poor/intermediate metabolizer genotype, higher BMI, and low tamoxifen concentrations. This study suggests a minimal threshold at which endoxifen is effective against breast cancer recurrence, which 80% of tamoxifen-takers achieve. PMID:21430657

  11. Investigation of CYP3A4 and CYP2D6 Interactions of Withania somnifera and Centella asiatica in Human Liver Microsomes.

    PubMed

    Savai, Jay; Varghese, Alice; Pandita, Nancy; Chintamaneni, Meena

    2015-05-01

    Withania somnifera is commonly used as a rejuvenator, whereas Centella asiatica is well known for its anxiolytic and nootropic effects. The present study aims at investigating the effect of crude extracts and principal phytoconstituents of both the medicinal plants with CYP3A4 and CYP2D6 enzyme activity in human liver microsomes (HLM). Phytoconstituents were quantified in the crude extracts of both the medicinal plants using reverse phase HPLC. Crude extracts and phytoconstituents of W. somnifera showed no significant interaction with both CYP3A4 and CYP2D6 enzymes in HLM. Of the crude extracts of C. asiatica screened in vitro, methanolic extract showed potent noncompetitive inhibition of only CYP3A4 enzyme (Ki-64.36 ± 1.82 µg/mL), whereas ethanol solution extract showed potent noncompetitive inhibition of only CYP2D6 enzyme (Ki-36.3 ± 0.44 µg/mL). The flavonoids, quercetin, and kaempferol showed potent (IC50 values less than 100 μM) inhibition of CYP3A4 activity, whereas quercetin alone showed potent inhibition of CYP2D6 activity in HLM. Because methanolic extract of C. asiatica showed a relatively high percentage content of quercetin and kaempferol than ethanol solution extract, the inhibitory effect of methanolic extract on CYP3A4 enzyme activity could be attributed to the flavonoids. Thus, co-administration of the alcoholic extracts of C. asiatica with drugs that are substrates of CYP3A4 and CYP2D6 enzymes may lead to undesirable herb-drug interactions in humans. PMID:25684704

  12. Effect of Garden Cress Seeds Powder and Its Alcoholic Extract on the Metabolic Activity of CYP2D6 and CYP3A4

    PubMed Central

    Al-Jenoobi, Fahad I.; Al-Thukair, Areej A.; Abbas, Fawkeya A.; Al-Mohizea, Abdullah M.; Alkharfy, Khalid M.; Al-Suwayeh, Saleh A.

    2014-01-01

    The powder and alcoholic extract of dried seeds of garden cress were investigated for their effect on metabolic activity of CYP2D6 and CYP3A4 enzymes. In vitro and clinical studies were conducted on human liver microsomes and healthy human subjects, respectively. Dextromethorphan was used as a common marker for measuring metabolic activity of CYP2D6 and CYP3A4 enzymes. In in vitro studies, microsomes were incubated with NADPH in presence and absence of different concentrations of seeds extract. Clinical investigations were performed in two phases. In phase I, six healthy female volunteers were administered a single dose of dextromethorphan and in phase II volunteers were treated with seeds powder for seven days and dextromethorphan was administered with last dose. The O-demethylated and N-demethylated metabolites of dextromethorphan were measured as dextrorphan (DOR) and 3-methoxymorphinan (3-MM), respectively. Observations suggested that garden cress inhibits the formation of DOR and 3-MM metabolites. This inhibition of metabolite level was attributed to the inhibition of CYP2D6 and CYP3A4 activity. Garden cress decreases the level of DOR and 3-MM in urine and significantly increases the urinary metabolic ratio of DEX/DOR and DEX/3-MM. The findings suggested that garden cress seeds powder and ethanolic extract have the potential to interact with CYP2D6 and CYP3A4 substrates. PMID:24711855

  13. Genetic Polymorphism of CYP2D6 and Clomiphene Concentrations in Infertile Patients with Ovulatory Dysfunction Treated with Clomiphene Citrate

    PubMed Central

    2016-01-01

    CYP2D6 is primarily responsible for the metabolism of clomiphene citrate (CC). The purpose of the present study was to investigate the relationship between CYP2D6 genotypes, concentrations of CC and its major metabolites and drug response in infertility patients. We studied 42 patients with ovulatory dysfunction treated with only CC. Patients received a dose of 100 mg/day CC on days 3-7 of the menstrual cycle. CYP2D6 genotyping and measurement of CC and the major metabolite concentrations were performed. Patients were categorized into CC responders or non-responders according to one cycle response for the ovulation. Thirty-two patients were CC responders and 10 patients were non-responders with 1 cycle treatment. The CC concentrations were highly variable within the same group, but non-responders revealed significantly lower (E)-clomiphene concentration and a trend of decreased concentrations of active metabolites compared to the responders. Nine patients with intermediate metabolizer phenotype were all responders. We confirmed that the CC and the metabolite concentrations were different according to the ovulation status. However, our results do not provide evidence for the contribution of CYP2D6 polymorphism to either drug response or CC concentrations. PMID:26839488

  14. Mechanism-based inhibition of CYP3A4 and CYP2D6 by Indonesian medicinal plants.

    PubMed

    Subehan; Usia, Tepy; Iwata, Hiroshi; Kadota, Shigetoshi; Tezuka, Yasuhiro

    2006-05-24

    Thirty samples of Indonesian medicinal plants were tested for their mechanism-based inhibition on cytochrome P450 3A4 (CYP3A4) and CYP2D6 via erythromycin N-demethylation and dextromethorphan O-demethylation activities in human liver microsomes. From screening with 0 and 20min preincubation at 0.5mg/ml of methanol extracts, five plants (Cinnamomum burmani bark, Foeniculum vulgare seed, Strychnos ligustrina wood, Tinospora crispa stem, and Zingiber cassumunar rhizome) showed more than 30% increase of CYP3A4 inhibition, while three (Alpinia galanga rhizome, Melaleuca leucadendron leaf, and Piper nigrum fruit) showed more than 30% increase of CYP2D6 inhibition. In these eight plants, Foeniculum vulgare seed, Cinnamomum burmani bark, and Strychnos ligustrina wood showed time-dependent inhibition on CYP3A4 and Piper nigrum fruit and Melaleuca leucadendron leaf on CYP2D6. Among these, four plants other than Melaleuca leucadendron revealed NADPH-dependent inhibition. Thus, Foeniculum vulgare, Cinnamomum burmani, and Strychnos ligustrina should contain mechanism-based inhibitors on CYP3A4 and Piper nigrum contain that on CYP2D6. PMID:16414224

  15. Stimulus control by 5methoxy-N,N-dimethyltryptamine in wild-type and CYP2D6-humanized mice

    PubMed Central

    Winter, J. C.; Amorosi, D. J.; Rice, Kenner C.; Cheng, Kejun; Yu, Ai-Ming

    2011-01-01

    In previous studies we have observed that, in comparison with wild type mice, Tg-CYP2D6 mice have increased serum levels of bufotenine [5-hydroxy-N,N-dimethyltryptamine] following the administration of 5-MeO-DMT. Furthermore, following the injection of 5-MeO-DMT, harmaline was observed to increase serum levels of bufotenine and 5-MeO-DMT in both wild-type and Tg-CYP2D6 mice. In the present investigation, 5-MeO-DMT-induced stimulus control was established in wild-type and Tg-CYP2D6 mice. The two groups did not differ in their rate of acquisition of stimulus control. When tested with bufotenine, no 5-MeO-DMT-appropriate responding was observed. In contrast, the more lipid soluble analog of bufotenine, acetylbufotenine, was followed by an intermediate level of responding. The combination of harmaline with 5-MeO-DMT yielded a statistically significant increase in 5-MeO-DMT-appropriate responding in Tg-CYP2D6 mice; a comparable increase occurred in wild-type mice. In addition, it was noted that harmaline alone was followed by a significant degree of 5-MeO-DMT-appropriate responding in Tg-CYP2D6 mice. It is concluded that wild-type and Tg-CYPD2D6 mice do not differ in terms of acquisition of stimulus control by 5-MeO-DMT or in their response to bufotenine and acetylbufotenine. In both groups of mice, harmaline was found to enhance the stimulus effects of 5-MeO-DMT. PMID:21624387

  16. Stimulus control by 5-methoxy-N,N-dimethyltryptamine in wild-type and CYP2D6-humanized mice.

    PubMed

    Winter, J C; Amorosi, D J; Rice, Kenner C; Cheng, Kejun; Yu, Ai-Ming

    2011-09-01

    In previous studies we have observed that, in comparison with wild type mice, Tg-CYP2D6 mice have increased serum levels of bufotenine [5-hydroxy-N,N-dimethyltryptamine] following the administration of 5-MeO-DMT. Furthermore, following the injection of 5-MeO-DMT, harmaline was observed to increase serum levels of bufotenine and 5-MeO-DMT in both wild-type and Tg-CYP2D6 mice. In the present investigation, 5-MeO-DMT-induced stimulus control was established in wild-type and Tg-CYP2D6 mice. The two groups did not differ in their rate of acquisition of stimulus control. When tested with bufotenine, no 5-MeO-DMT-appropriate responding was observed. In contrast, the more lipid soluble analog of bufotenine, acetylbufotenine, was followed by an intermediate level of responding. The combination of harmaline with 5-MeO-DMT yielded a statistically significant increase in 5-MeO-DMT-appropriate responding in Tg-CYP2D6 mice; a comparable increase occurred in wild-type mice. In addition, it was noted that harmaline alone was followed by a significant degree of 5-MeO-DMT-appropriate responding in Tg-CYP2D6 mice. It is concluded that wild-type and Tg-CYPD2D6 mice do not differ in terms of acquisition of stimulus control by 5-MeO-DMT or in their response to bufotenine and acetylbufotenine. In both groups of mice, harmaline was found to enhance the stimulus effects of 5-MeO-DMT. PMID:21624387

  17. Effects of 22 novel CYP2D6 variants found in Chinese population on the metabolism of dapoxetine

    PubMed Central

    Xu, Ren-ai; Gu, Er-min; Zhou, Quan; Yuan, Lingjing; Hu, Xiaoxia; Cai, Jianping; Hu, Guoxin

    2016-01-01

    Background CYP2D6 is one of the most important members of the cytochrome P450 superfamily. Its genetic polymorphism significantly influences the efficacy and safety of some drugs, which might cause adverse effects and therapeutic failure. Methods and results The aim of this research was mainly to explore the catalytic activities of 22 newly reported CYP2D6 isoforms (2D6*87, *88, *89, *90, *91, *92, *93, *94, *95, *96,*97, *98, *R25Q, F164L, E215K, F219S, V327M, D336N, V342M, R344Q, R440C, R497C) on dapoxetine in vitro. The research was designed with an appropriate incubation system in test tubes and carried out in the constant temperature water. Through detecting its two metabolites desmethyldapoxetine and dapoxetine-N-oxide, the available data were obtained to explain the influence of CYP2D6 polymorphism on the substrate drug dapoxetine. As a result, the intrinsic clearance (Vmax/Km) values of most variants were significantly altered when compared with the counterpart of CYP2D6*1, with most of these variants exhibiting either reduced Vmax and/or increased Km values. For dapoxetine demethylation pathway (which produces desmethyldapoxetine), 2D6*89 and E215K exhibited no markedly decreased relative clearance of 92.81% and 97.70%, respectively. The relative clearance of rest 20 variants exhibited decrease in different levels, ranging from 20.44% to 90.90%. For the dapoxetine oxidation pathway (which produces dapoxetine-N-oxide), the relative clearance values of three variants, 2D6*90, *94, and V342M, exhibited no markedly increased relative clearance of 106.17%, 107.78%, and 109.98%, respectively; the rest 19 variants exhibited significantly decreased levels ranging from 27.56% to 84.64%. In addition, the kinetic parameters of two CYP2D6 variants (2D6*92 and 2D6*96) could not be detected, due to the defect of the CYP2D6 gene. Conclusion As the first report of all aforementioned alleles for dapoxetine metabolism, these data may help in the clinical assessment of the

  18. CYP2D6 and CYP2C19 genotypes of patients with terodiline cardiotoxicity identified through the yellow card system

    PubMed Central

    Ford, Gary A; Wood, Susan M; Daly, Ann K

    2000-01-01

    Aims Terodiline has concentration dependent QT prolonging effects and thus the potential for cardiotoxicity. Pharmacogenetic variation in terodiline metabolism could be responsible for cardiotoxicity. We sought to determine whether CYP2D6 (debrisoquine hydroxylase) or CYP2C19 (S-mephenytoin hydroxylase) status is a risk factor for terodiline cardiotoxicity. Methods Using the UK Yellow Card scheme to identify patients, blood samples were obtained from eight patients who survived ventricular tachycardia or torsades de pointes suspected to be due to terodiline, for determination of CYP2D6 and CYP2C19 genotypes. Genotype prevalence was compared with that in published general population groups. Results One patient was a CYP2D6 poor metaboliser (CYP2D6*4 homozygous) and a second was heterozygous for CYP2D6*4, a slightly lower frequency for these genotypes compared with the general population (P = 0.31). In the case of CYP2C19, one patient was a poor metaboliser and four were heterozygous for the variant CYP2C19*2 allele, compared with general population frequencies of 2% and 23%, respectively (P = 0.035). Conclusions These findings suggest that debrisoquine poor metaboliser status is not primarily responsible for terodiline cardiotoxicity. However, possession of the CYP2C19*2 allele appears to contribute to adverse cardiac reactions to terodiline. The present study demonstrates the feasibility of using spontaneous adverse drug reaction reporting schemes to determine the contribution of genotype for metabolizing enzymes to uncommon adverse drug reactions. PMID:10886124

  19. Non-alcoholic fatty liver disease (NAFLD) potentiates autoimmune hepatitis in the CYP2D6 mouse model.

    PubMed

    Müller, Peter; Messmer, Marie; Bayer, Monika; Pfeilschifter, Josef M; Hintermann, Edith; Christen, Urs

    2016-05-01

    Non-alcoholic fatty liver disease (NAFLD) and its more severe development non-alcoholic steatohepatitis (NASH) are increasing worldwide. In particular NASH, which is characterized by an active hepatic inflammation, has often severe consequences including progressive fibrosis, cirrhosis, and eventually hepatocellular carcinoma (HCC). Here we investigated how metabolic liver injury is influencing the pathogenesis of autoimmune hepatitis (AIH). We used the CYP2D6 mouse model in which wild type C57BL/6 mice are infected with an Adenovirus expressing the major liver autoantigen cytochrome P450 2D6 (CYP2D6). Such mice display several features of human AIH, including interface hepatitis, formation of LKM-1 antibodies and CYP2D6-specific T cells, as well as hepatic fibrosis. NAFLD was induced with a high-fat diet (HFD). We found that pre-existing NAFLD potentiates the severity of AIH. Mice fed for 12 weeks with a HFD displayed increased cellular infiltration of the liver, enhanced hepatic fibrosis and elevated numbers of liver autoantigen-specific T cells. Our data suggest that a pre-existing metabolic liver injury constitutes an additional risk for the severity of an autoimmune condition of the liver, such as AIH. PMID:26924542

  20. CYP2D6 Metabolism and Patient Outcome in the Austrian Breast and Colorectal Cancer Study Group Trial (ABCSG) 8

    PubMed Central

    Goetz, Matthew P.; Suman, Vera J.; Hoskin, Tanya L.; Gnant, Michael; Filipits, Martin; Safgren, Stephanie L.; Kuffel, Mary; Jakesz, Raimund; Rudas, Margaretha; Greil, Richard; Dietze, Otto; Lang, Alois; Offner, Felix; Reynolds, Carol A.; Weinshilboum, Richard M.; Ames, Matthew M.; Ingle, James N.

    2012-01-01

    Background Controversy exists regarding CYP2D6 genotype and tamoxifen efficacy. Methods A matched case-control study was conducted utilizing the Austrian Breast and Colorectal Cancer Study Group Trial 8 that randomized post-menopausal women with estrogen receptor positive breast cancer to tamoxifen for 5 years (Arm A) or tamoxifen for 2 years followed by anastrozole for 3 years (Arm B). Cases had disease recurrence, contralateral breast cancer, second non-breast cancer, or died. For each case, controls were identified from the same treatment arm of similar age, surgery/radiation, and TNM stage. Genotyping was performed for alleles associated with no (PM; *3, *4, *6); reduced (IM; *10, and *41); and extensive (EM: absence of these alleles) CYP2D6 metabolism. Findings The common CYP2D6 *4 allele was in Hardy Weinberg Equilibrium. In Arm A during the first 5 years of therapy, women with 2 poor alleles (PM/PM: OR=2.45, 95% CI: 1.05–5.73, p=0.04) and women with one poor allele (PM/IM or PM/EM: OR=1.67, 95% CI: 0.95–2.93, p=0.07) had a higher likelihood of an event than women with two extensive alleles (EM/EM). In years 3–5 when patients remained on tamoxifen (Arm A) or switched to anastrozole (Arm B), PM/PM tended towards a higher likelihood of a disease event relative to EM/EM (OR= 2.40, 95% CI: 0.86–6.66, p=0.09) among women on Arm A but not among women on Arm B (OR= 0.28; 95% CI: 0.03–2.30). Conclusion In ABCSG8, the negative effects of reduced CYP2D6 metabolism were observed only during the period of tamoxifen administration, and not after switching to anastrozole. PMID:23213055

  1. Population pharmacokinetics of nortriptyline during monotherapy and during concomitant treatment with drugs that inhibit CYP2D6--an evaluation with the nonparametric maximum likelihood method.

    PubMed Central

    Jerling, M; Merlé, Y; Mentré, F; Mallet, A

    1994-01-01

    Therapeutic drug monitoring data for nortriptyline (674 analyses from 578 patients) were evaluated with the nonparametric maximum likelihood (NPML) method in order to determine the population kinetic parameters of this drug and their relation to age, body weight and duration of treatment. Clearance of nortriptyline during monotherapy exhibited a large interindividual variability and a skewed distribution. A small, separate fraction with a very high clearance, constituting between 0.5% and 2% of the population, was seen in both men and women. This may be explained by the recent discovery of subjects with multiple copies of the gene encoding the cytochrome-P450-enzyme CYP2D6, which catalyses the hydroxylation of nortriptyline. However, erratic compliance with the prescription may also add to this finding. A separate distribution of low clearance values with a frequency corresponding to that of poor metabolizers of CYP2D6 (circa 7% in Caucasian populations) could not be detected. Concomitant therapy with drugs that inhibit CYP2D6 resulted in a major increase in the plasma nortriptyline concentrations. This was caused by a decrease in nortriptyline clearance, whereas the volume of distribution was unchanged. The demographic factors age and body weight had a minor influence on the clearance of nortriptyline which was also unaffected by the duration of treatment. PMID:7893588

  2. Simulation with cells in vitro of tamoxifen treatment in premenopausal breast cancer patients with different CYP2D6 genotypes

    PubMed Central

    Maximov, Philipp Y; McDaniel, Russell E; Fernandes, Daphne J; Korostyshevskiy, Valeriy R; Bhatta, Puspanjali; Mürdter, Thomas E; Flockhart, David A; Jordan, V Craig

    2014-01-01

    Background and Purpose Tamoxifen is a prodrug that is metabolically activated by 4-hydroxylation to the potent primary metabolite 4-hydroxytamoxifen (4OHT) or via another primary metabolite N-desmethyltamoxifen (NDMTAM) to a biologically active secondary metabolite endoxifen through a cytochrome P450 2D6 variant system (CYP2D6). To elucidate the mechanism of action of tamoxifen and the importance of endoxifen for its effect, we determined the anti-oestrogenic efficacy of tamoxifen and its metabolites, including endoxifen, at concentrations corresponding to serum levels measured in breast cancer patients with various CYP2D6 genotypes (simulating tamoxifen treatment). Experimental Approach The biological effects of tamoxifen and its metabolites on cell growth and oestrogen-responsive gene modulation were evaluated in a panel of oestrogen receptor-positive breast cancer cell lines. Actual clinical levels of tamoxifen metabolites in breast cancer patients were used in vitro along with actual levels of oestrogens observed in premenopausal patients taking tamoxifen. Key Results Tamoxifen and its primary metabolites (4OHT and NDMTAM) only partially inhibited the stimulant effects of oestrogen on cells. The addition of endoxifen at concentrations corresponding to different CYP2D6 genotypes was found to enhance the anti-oestrogenic effect of tamoxifen and its metabolites with an efficacy that correlated with the concentration of endoxifen; at concentrations corresponding to the extensive metabolizer genotype it further inhibited the actions of oestrogen. In contrast, lower concentrations of endoxifen (intermediate and poor metabolizers) had little or no anti-oestrogenic effects. Conclusions and Implications Endoxifen may be a clinically relevant metabolite in premenopausal patients as it provides additional anti-oestrogenic actions during tamoxifen treatment. PMID:25073551

  3. Influence of Cytochrome P450, Family 2, Subfamily D, Polypeptide 6 (CYP2D6) polymorphisms on pain sensitivity and clinical response to weak opioid analgesics.

    PubMed

    Zahari, Zalina; Ismail, Rusli

    2014-01-01

      CYP2D6 polymorphisms show large geographical and interethnic differences. Variations in CYP2D6 activity may impact upon a patient's pain level and may contribute to interindividual variations in the response to opioids. This paper reviews the evidence on how CYP2D6 polymorphisms might influence pain sensitivity and clinical response to codeine and tramadol. For example, it is shown that (1) CYP2D6 poor metabolizers (PMs) may be less efficient at synthesizing endogenous morphine compared with other metabolizers. In contrast, ultra-rapid metabolizers (UMs) may be more efficient than other metabolizers at synthesizing endogenous morphine, thus strengthening endogenous pain modulation. Additionally, for codeine and tramadol that are bioactivated by CYP2D6, PMs may undergo no metabolite formation, leading to inadequate analgesia. Conversely, UMs may experience quicker analgesic effects but be prone to higher mu-opioid-related toxicity. The literature suggested the potential usefulness of the determination of CYP2D6 polymorphisms in elucidating serious adverse events and in preventing subsequent inappropriate selection or doses of codeine and tramadol. Notably, even though many studies investigated a possible role of the CYP2D6 polymorphisms on pain sensitivity, pharmacokinetics and pharmacodynamics of these drugs, the results of analgesia and adverse effects are conflicting. More studies are required to demonstrate genetically determined unresponsiveness and risk of developing serious adverse events for patients with pain and these should involve larger numbers of patients in different population types. PMID:23759977

  4. Pharmacokinetic interaction of flecainide and paroxetine in relation to the CYP2D6*10 allele in healthy Korean subjects

    PubMed Central

    Lim, Kyoung Soo; Cho, Joo-Youn; Jang, In-Jin; Kim, Bo-Hyung; Kim, JaeWoo; Jeon, Ji-Young; Tae, Yu-Mi; Yi, SoJeong; Eum, SoYoung; Shin, Sang-Goo; Yu, Kyung-Sang

    2008-01-01

    WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT The only existing study of CYP2D6*10-associated alterations in flecainide pharmacokinetics was retrospective. Paroxetine has been known as a strong inhibitor of CYP2D6. WHAT THIS STUDY ADDS This study reports that the extent of drug interaction between flecainide and paroxetine is influenced by the CYP2D6*10 allele in healthy subjects, which is frequent in Asians. AIMS The objectives were to evaluate the effect of CYP2D6 genetic polymorphism on the pharmacokinetics of flecainide, and also on the extent of drug interaction with paroxetine as a CYP2D6 inhibitor after a single oral administration in healthy subjects. METHODS An open-label, two-period, single-sequence, cross-over study was performed in 21 healthy Korean male volunteers (seven for CYP2D6*1/*1 or *1/*2, group 1; seven for CYP2D6*1/*10, group 2; seven for CYP2D6*10/*10 or *10/*36, group 3). Subjects were administered 200 mg of flecainide on day 1. After a 7-day wash-out period, subjects were administered 20 mg of paroxetine from day 8 to 14, and 200 mg of flecainide on day 15. Blood sampling was performed up to 72 h after flecainide administration. RESULTS Terminal elimination half-life and mean residence time (MRT) were significantly different among three genotype groups after a single oral administration of flecainide (P = 0.021, 0.011, respectively). Area under the concentration–time curve, terminal elimination half-life and MRT increased significantly after paroxetine co-administration only in groups 1 and 2. CONCLUSIONS This study reports that the extent of drug interaction between flecainide and paroxetine is influenced by the CYP2D6*10 allele in healthy subjects, which is frequent in Asians. PMID:18754843

  5. Association of MDR1, CYP2D6, and CYP2C19 gene polymorphisms with prophylactic migraine treatment response.

    PubMed

    Atasayar, Gulfer; Eryilmaz, Isil Ezgi; Karli, Necdet; Egeli, Unal; Zarifoglu, Mehmet; Cecener, Gulsah; Taskapilioglu, Ozlem; Tunca, Berrin; Yildirim, Oznur; Ak, Secil; Tezcan, Gulcin; Can, Fatma Ezgi

    2016-07-15

    Prophylactic therapy response varies in migraine patients. The present study investigated the relationship between the resistance to the drugs commonly used in prophylactic therapy and the possible polymorphic variants of proteins involved in the metabolism of these drugs. Migraine patients with the MDR1 3435TT genotype exhibited a better treatment response to topiramate than migraine patients with the CC and CT genotypes (p=0.020). The MDR1 C3435T polymorphism was also found to be a higher risk factor for topiramate treatment failure in a comparison of the number of days with migraine (β2=1.152, p=0.015). However, there was no significant relationship between the treatment response to topiramate and either the CYP2D6 or CYP2C19 polymorphism, and there were no significant correlations between the treatment responses to amitriptyline, propranolol, and valproic acid and the MDR1, CYP2D6 and CYP2C19 gene polymorphisms. This is the first study to investigate the effect of the polymorphic variants on prophylactic therapy response in migraine patients. PMID:27288795

  6. Single dose, CYP2D6 genotype-stratified pharmacokinetic study of atomoxetine in children with ADHD.

    PubMed

    Brown, J T; Abdel-Rahman, S M; van Haandel, L; Gaedigk, A; Lin, Y S; Leeder, J S

    2016-06-01

    The effect of CYP2D6 genotype on the dose-exposure relationship for atomoxetine has not been well characterized in children. Children 6-17 years of age diagnosed with attention-deficit hyperactivity disorder (ADHD) were stratified by CYP2D6 genotype into groups with 0 (poor metabolizers [PMs], n = 4), 0.5 (intermediate metabolizers [IMs], n = 3), one (extensive metabolizer [EM]1, n = 8) or two (EM2, n = 8) functional alleles and administered a single 0.5 mg/kg oral dose of atomoxetine (ATX). Plasma and urine samples were collected for 24 (IM, EM1, and EM2) or 72 hours (PMs). Dose-corrected ATX systemic exposure (area under the curve [AUC]0-∞ ) varied 29.6-fold across the study cohort, ranging from 4.4 ± 2.7 μM*h in EM2s to 5.8 ± 1.7 μM*h, 16.3 ± 2.9 μM*h, and 50.2 ± 7.3 μM*h in EM1s, IMs, and PMs, respectively (P < 0.0001). Simulated steady state profiles at the maximum US Food and Drug Administration (FDA)-recommended dose suggest that most patients are unlikely to attain adequate ATX exposures. These data support the need for individualized dosing strategies for more effective use of the medication. PMID:26660002

  7. Clinical assessment of CYP2D6-mediated herb-drug interactions in humans: effects of milk thistle, black cohosh, goldenseal, kava kava, St. John's wort, and Echinacea.

    PubMed

    Gurley, Bill J; Swain, Ashley; Hubbard, Martha A; Williams, D Keith; Barone, Gary; Hartsfield, Faith; Tong, Yudong; Carrier, Danielle J; Cheboyina, Shreekar; Battu, Sunil K

    2008-07-01

    Cytochrome P450 2D6 (CYP2D6), an important CYP isoform with regard to drug-drug interactions, accounts for the metabolism of approximately 30% of all medications. To date, few studies have assessed the effects of botanical supplementation on human CYP2D6 activity in vivo. Six botanical extracts were evaluated in three separate studies (two extracts per study), each incorporating 16 healthy volunteers (eight females). Subjects were randomized to receive a standardized botanical extract for 14 days on separate occasions. A 30-day washout period was interposed between each supplementation phase. In study 1, subjects received milk thistle (Silybum marianum) and black cohosh (Cimicifuga racemosa). In study 2, kava kava (Piper methysticum) and goldenseal (Hydrastis canadensis) extracts were administered, and in study 3 subjects received St. John's wort (Hypericum perforatum) and Echinacea (Echinacea purpurea). The CYP2D6 substrate, debrisoquine (5 mg), was administered before and at the end of supplementation. Pre- and post-supplementation phenotypic trait measurements were determined for CYP2D6 using 8-h debrisoquine urinary recovery ratios (DURR). Comparisons of pre- and post-supplementation DURR revealed significant inhibition (approximately 50%) of CYP2D6 activity for goldenseal, but not for the other extracts. Accordingly, adverse herb-drug interactions may result with concomitant ingestion of goldenseal supplements and drugs that are CYP2D6 substrates. PMID:18214849

  8. Reduced CYP2D6 function is associated with gefitinib-induced rash in patients with non-small cell lung cancer

    PubMed Central

    2012-01-01

    Background Rash, liver dysfunction, and diarrhea are known major adverse events associated with erlotinib and gefitinib. However, clinical trials with gefitinib have reported different proportions of adverse events compared to trials with erlotinib. In an in vitro study, cytochrome P450 (CYP) 2D6 was shown to be involved in the metabolism of gefitinib but not erlotinib. It has been hypothesized that CYP2D6 phenotypes may be implicated in different adverse events associated with gefitinib and erlotinib therapies. Methods The frequency of each adverse event was evaluated during the period in which the patients received gefitinib or erlotinib therapy. CYP2D6 phenotypes were determined by analysis of CYP2D6 genotypes using real-time polymerase chain reaction techniques, which can detect single-nucleotide polymorphisms. The CYP2D6 phenotypes were categorized into 2 groups according to functional or reduced metabolic levels. In addition, we evaluated the odds ratio (OR) of the adverse events associated with each factor, including CYP2D6 activities and treatment types. Results A total of 232 patients received gefitinib therapy, and 86 received erlotinib therapy. Reduced function of CYP2D6 was associated with an increased risk of rash of grade 2 or more (OR, 0.44; 95% confidence interval [CI], 0.21–0.94; *p = 0.03), but not diarrhea ≥ grade 2 (OR, 0.49; 95% CI, 0.17–1.51; *p = 0.20) or liver dysfunction ≥ grade 2 (OR, 1.08; 95% CI, 0.52–2.34; *p = 0.84) in the gefitinib cohort. No associations were observed between any adverse events in the erlotinib cohort and CYP2D6 phenotypes (rash: OR, 1.77; 95% CI, 0.54–6.41; *p = 0.35/diarrhea: OR, 1.08; 95% CI, 0.21–7.43; *p = 0.93/liver dysfunction: OR, 0.93; 95% CI, 0.20–5.07; *p = 0.93). Conclusions The frequency of rash was significantly higher in patients with reduced CYP2D6 activity who treated with gefitinib compared to patients with functional CYP2D6. CYP2D6 phenotypes are a risk factor for the development of

  9. Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2D6 and CYP2C19 Genotypes and Dosing of Selective Serotonin Reuptake Inhibitors.

    PubMed

    Hicks, J K; Bishop, J R; Sangkuhl, K; Müller, D J; Ji, Y; Leckband, S G; Leeder, J S; Graham, R L; Chiulli, D L; LLerena, A; Skaar, T C; Scott, S A; Stingl, J C; Klein, T E; Caudle, K E; Gaedigk, A

    2015-08-01

    Selective serotonin reuptake inhibitors (SSRIs) are primary treatment options for major depressive and anxiety disorders. CYP2D6 and CYP2C19 polymorphisms can influence the metabolism of SSRIs, thereby affecting drug efficacy and safety. We summarize evidence from the published literature supporting these associations and provide dosing recommendations for fluvoxamine, paroxetine, citalopram, escitalopram, and sertraline based on CYP2D6 and/or CYP2C19 genotype (updates at www.pharmgkb.org). PMID:25974703

  10. Systematic and quantitative assessment of the effect of chronic kidney disease on CYP2D6 and CYP3A4/5.

    PubMed

    Yoshida, K; Sun, B; Zhang, L; Zhao, P; Abernethy, D R; Nolin, T D; Rostami-Hodjegan, A; Zineh, I; Huang, S-M

    2016-07-01

    Recent reviews suggest that chronic kidney disease (CKD) can affect the pharmacokinetics of nonrenally eliminated drugs, but the impact of CKD on individual elimination pathways has not been systematically evaluated. In this study we developed a comprehensive dataset of the effect of CKD on the pharmacokinetics of CYP2D6- and CYP3A4/5-metabolized drugs. Drugs for evaluation were selected based on clinical drug-drug interaction (CYP3A4/5 and CYP2D6) and pharmacogenetic (CYP2D6) studies. Information from dedicated CKD studies was available for 13 and 18 of the CYP2D6 and CYP3A4/5 model drugs, respectively. Analysis of these data suggested that CYP2D6-mediated clearance is generally decreased in parallel with the severity of CKD. There was no apparent relationship between the severity of CKD and CYP3A4/5-mediated clearance. The observed elimination-route dependency in CKD effects between CYP2D6 and CYP3A4/5 may inform the need to conduct clinical CKD studies with nonrenally eliminated drugs for optimal use of drugs in patients with CKD. PMID:26800425

  11. Genetic polymorphisms of CYP2D6, CYP1A1 and CYP2E1 in the South-Amerindian population of Chile.

    PubMed

    Muñoz, S; Vollrath, V; Vallejos, M P; Miquel, J F; Covarrubias, C; Raddatz, A; Chianale, J

    1998-08-01

    Polymorphisms of cytochrome P450 genes show pronounced interethnic variation and have not been previously studied in the South-Amerindian population, which probably has an Asian origin. Therefore, a similar distribution of allelic and haplotype frequencies of cytochrome P450 genes to Asian populations might be expected in South-Amerindians. We analysed the allelic frequencies and haplotype distribution for CYP2D6, CYP1A1 and CYP2E1 genes in the South-Amerindian population of Chile (Mapuche, n = 84) by Southern blot or polymerase chain reaction-restriction fragment length polymorphism. Similar allelic frequencies and haplotype distribution for the CYP2E1 gene between Mapuches and Asian populations were observed. Frequencies of the two major functional CYP2D6*1 and CYP2D6*2 alleles and the CYP2D6*5 null allele were similar to most populations world-wide. The alleles CYP2D6*3 and *9, absent in Asians, were not found in Mapuches. The CYP2D6*4 allelic group, uncommon in Asian populations, had a low frequency in Mapuches (0.036). However, the CYP2D6*10 allele (Ch1, Ch2 and J), highly frequent in Asians (0.33-0.50), had a very low frequency (0.018) in our study population. In addition, the presence of the common Chinese 44 kb XbaI fragment of CYP2D6 (0.19-0.31 in Asians) was not detected in South-Amerindians. Interestingly, high frequencies for the rare m2 and Val alleles of the CYP1A1 gene were found in Mapuches (0.821 and 0.91, respectively), and the rare Val/m2 haplotype was significantly higher in Mapuches (0.748) than in Asians (0.24) (P < 0.01). The frequency of this haplotype in Mapuches is the highest frequency reported to date. The population studied was in Hardy-Weinberg equilibrium for these polymorphisms. The major differences between Mapuches and Asians were for CYP2D6*10 and CYP1A1 allelic frequencies, as well as the absence of the common Chinese 44 kb XbaI fragment of CYP2D6. These differences might be interpreted as a consequence of genetic drifts caused

  12. Mutation frequencies of the cytochrome CYP2D6 gene in Parkinson disease patients and in families

    SciTech Connect

    Lucotte, G.; Turpin, J.C.; Gerard, N.

    1996-07-26

    The frequencies of five mutations of the debrisoquine 4-hydroxylase (CYP2D6) gene (mutations D6-A, B, C, D, and T), corresponding to poor metabolizer (PM) phenotypes, were determined by restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR) in 47 patients with Parkinson disease, and compared with the findings in 47 healthy controls. These mutant alleles were about twice as frequent among patients as in controls, with an approximate relative risk ratio of 2.12 (95% confidence interval, 1.41-2.62). There seem to be no significant differences in frequencies of mutant genotypes in patients among gender and modalities of response with levodopa therapy; but frequency of the mutations was slightly enhanced after age-at-onset of 60 years. Mutations D6-B, D, and T were detected in 7 patients belonging to 10 Parkinson pedigrees. 25 refs., 1 fig., 2 tabs.

  13. Physiologically Based Pharmacokinetic Modeling of Tamoxifen and its Metabolites in Women of Different CYP2D6 Phenotypes Provides New Insight into the Tamoxifen Mass Balance

    PubMed Central

    Dickschen, Kristin; Willmann, Stefan; Thelen, Kirstin; Lippert, Jörg; Hempel, Georg; Eissing, Thomas

    2012-01-01

    Tamoxifen is a first-line endocrine agent in the mechanism-based treatment of estrogen receptor positive (ER+) mammary carcinoma and applied to breast cancer patients all over the world. Endoxifen is a secondary and highly active metabolite of tamoxifen that is formed among others by the polymorphic cytochrome P450 2D6 (CYP2D6). It is widely accepted that CYP2D6 poor metabolizers exert a pronounced decrease in endoxifen steady-state plasma concentrations compared to CYP2D6 extensive metabolizers. Nevertheless, an in-depth understanding of the chain of cause and effect between CYP2D6 genotype, endoxifen steady-state plasma concentration, and subsequent tamoxifen treatment benefit still remains to be evolved. In this study, physiologically based pharmacokinetic (PBPK)-modeling was applied to mechanistically investigate the impact of CYP2D6 phenotype on endoxifen formation in female breast cancer patients undergoing tamoxifen therapy. A PBPK-model of tamoxifen and its pharmacologically important metabolites N-desmethyltamoxifen (NDM-TAM), 4-hydroxytamoxifen (4-OH-TAM), and endoxifen was developed and validated. This model is able to simulate the pharmacokinetics (PK) after single and repeated oral tamoxifen doses in female breast cancer patients in dependence of the CYP2D6 phenotype. A detailed model-based analysis of the mass balance offered support for a recent hypothesis stating a more prominent role for endoxifen formation from 4-OH-TAM. In the future this model provides a good basis to further investigate the linkage of PK, mode of action, and treatment outcome in dependence of factors such as phenotype, ethnicity, or co-treatment with CYP2D6 inhibitors. PMID:22661948

  14. Profound reduction in the tamoxifen active metabolite endoxifen in a patient on phenytoin for epilepsy compared with a CYP2D6 genotype matched cohort.

    PubMed

    Gryn, Steven E; Teft, Wendy A; Kim, Richard B

    2014-07-01

    Tamoxifen is a prodrug, requiring cytochrome P450 enzyme-mediated metabolism to form the active metabolite endoxifen. We identified a case of drug-drug interaction involving tamoxifen and phenytoin, associated with a markedly lower endoxifen level than predicted. The patient is a 49-year-old woman, genotyped as a cytochrome P450 2D6 (CYP2D6) extensive metabolizer, chronically taking phenytoin for a seizure disorder. The plasma endoxifen level 2 months after starting tamoxifen was 4.72 nmol/l, the lowest level we have seen in our clinic among patients with CYP2D6 extensive metabolizer genotypes (n=195). To our knowledge, this is the first report documenting the extent of induction in terms of both tamoxifen and endoxifen levels during concomitant phenytoin therapy, and this effect would likely result in loss of therapeutic benefit from tamoxifen. Phenytoin should therefore not be used concurrently with tamoxifen for extended periods of time unless a therapeutic drug (endoxifen) monitoring strategy is utilized. PMID:24915025

  15. Pharmacokinetic interactions between monoamine oxidase A inhibitor harmaline and 5-methoxy-N,N-dimethyltryptamine, and the impact of CYP2D6 status.

    PubMed

    Jiang, Xi-Ling; Shen, Hong-Wu; Mager, Donald E; Yu, Ai-Ming

    2013-05-01

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT or street name "5-MEO") is a newer designer drug belonging to a group of naturally occurring indolealkylamines. Our recent study has demonstrated that coadministration of monoamine oxidase A (MAO-A) inhibitor harmaline (5 mg/kg) increases systemic exposure to 5-MeO-DMT (2 mg/kg) and active metabolite bufotenine. This study is aimed at delineating harmaline and 5-MeO-DMT pharmacokinetic (PK) interactions at multiple dose levels, as well as the impact of CYP2D6 that affects harmaline PK and determines 5-MeO-DMT O-demethylation to produce bufotenine. Our data revealed that inhibition of MAO-A-mediated metabolic elimination by harmaline (2, 5, and 15 mg/kg) led to a sharp increase in systemic and cerebral exposure to 5-MeO-DMT (2 and 10 mg/kg) at all dose combinations. A more pronounced effect on 5-MeO-DMT PK was associated with greater exposure to harmaline in wild-type mice than CYP2D6-humanized (Tg-CYP2D6) mice. Harmaline (5 mg/kg) also increased blood and brain bufotenine concentrations that were generally higher in Tg-CYP2D6 mice. Surprisingly, greater harmaline dose (15 mg/kg) reduced bufotenine levels. The in vivo inhibitory effect of harmaline on CYP2D6-catalyzed bufotenine formation was confirmed by in vitro study using purified CYP2D6. Given these findings, a unified PK model including the inhibition of MAO-A- and CYP2D6-catalyzed 5-MeO-DMT metabolism by harmaline was developed to describe blood harmaline, 5-MeO-DMT, and bufotenine PK profiles in both wild-type and Tg-CYP2D6 mouse models. This PK model may be further employed to predict harmaline and 5-MeO-DMT PK interactions at various doses, define the impact of CYP2D6 status, and drive harmaline-5-MeO-DMT pharmacodynamics. PMID:23393220

  16. Pharmacokinetic Interactions between Monoamine Oxidase A Inhibitor Harmaline and 5-Methoxy-N,N-Dimethyltryptamine, and the Impact of CYP2D6 Status

    PubMed Central

    Jiang, Xi-Ling; Shen, Hong-Wu; Mager, Donald E.

    2013-01-01

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT or street name “5-MEO”) is a newer designer drug belonging to a group of naturally occurring indolealkylamines. Our recent study has demonstrated that coadministration of monoamine oxidase A (MAO-A) inhibitor harmaline (5 mg/kg) increases systemic exposure to 5-MeO-DMT (2 mg/kg) and active metabolite bufotenine. This study is aimed at delineating harmaline and 5-MeO-DMT pharmacokinetic (PK) interactions at multiple dose levels, as well as the impact of CYP2D6 that affects harmaline PK and determines 5-MeO-DMT O-demethylation to produce bufotenine. Our data revealed that inhibition of MAO-A–mediated metabolic elimination by harmaline (2, 5, and 15 mg/kg) led to a sharp increase in systemic and cerebral exposure to 5-MeO-DMT (2 and 10 mg/kg) at all dose combinations. A more pronounced effect on 5-MeO-DMT PK was associated with greater exposure to harmaline in wild-type mice than CYP2D6-humanized (Tg-CYP2D6) mice. Harmaline (5 mg/kg) also increased blood and brain bufotenine concentrations that were generally higher in Tg-CYP2D6 mice. Surprisingly, greater harmaline dose (15 mg/kg) reduced bufotenine levels. The in vivo inhibitory effect of harmaline on CYP2D6-catalyzed bufotenine formation was confirmed by in vitro study using purified CYP2D6. Given these findings, a unified PK model including the inhibition of MAO-A- and CYP2D6-catalyzed 5-MeO-DMT metabolism by harmaline was developed to describe blood harmaline, 5-MeO-DMT, and bufotenine PK profiles in both wild-type and Tg-CYP2D6 mouse models. This PK model may be further employed to predict harmaline and 5-MeO-DMT PK interactions at various doses, define the impact of CYP2D6 status, and drive harmaline–5-MeO-DMT pharmacodynamics. PMID:23393220

  17. CYP2D6 function moderates the pharmacokinetics and pharmacodynamics of 3,4-methylene-dioxymethamphetamine in a controlled study in healthy individuals.

    PubMed

    Schmid, Yasmin; Vizeli, Patrick; Hysek, Cédric M; Prestin, Katharina; Meyer Zu Schwabedissen, Henriette E; Liechti, Matthias E

    2016-08-01

    The role of genetic polymorphisms in cytochrome (CYP) 2D6 involved in the metabolism of 3,4-methylene-dioxymethamphetamine (MDMA, ecstasy) is unclear. Effects of genetic variants in CYP2D6 on the pharmacokinetics and pharmacodynamic effects of MDMA were characterized in 139 healthy individuals (70 men, 69 women) in a pooled analysis of eight double-blind, placebo-controlled crossover studies. In CYP2D6 poor metabolizers, the maximum concentrations (Cmax) of MDMA and its active metabolite 3,4-methylene-dioxyamphetamine were +15 and +50% higher, respectively, compared with extensive metabolizers and the Cmax of the inactive metabolite 4-hydroxy-3-methoxymethamphetamine was 50-70% lower. Blood pressure and subjective drug effects increased more rapidly after MDMA administration in poor metabolizers than in extensive metabolizers. In conclusion, the disposition of MDMA and its effects in humans are altered by polymorphic CYP2D6 activity, but the effects are small because of the autoinhibition of CYP2D6. PMID:27253829

  18. In vitro inhibition of the cytochrome P450 (CYP450) system by the antiplatelet drug ticlopidine: potent effect on CYP2C19 and CYP2D6

    PubMed Central

    Ko, Jae Wook; Desta, Zeruesenay; Soukhova, Nadia V; Tracy, Timothy; Flockhart, David A

    2000-01-01

    Aims To examine the potency of ticlopidine (TCL) as an inhibitor of cytochrome P450s (CYP450s) in vitro using human liver microsomes (HLMs) and recombinant human CYP450s. Methods Isoform-specific substrate probes of CYP1A2, 2C19, 2C9, 2D6, 2E1 and 3A4 were incubated in HLMs or recombinant CYPs with or without TCL. Preliminary data were generated to simulate an appropriate range of substrate and inhibitor concentrations to construct Dixon plots. In order to estimate accurately inhibition constants (Ki values) of TCL and determine the type of inhibition, data from experiments with three different HLMs for each isoform were fitted to relevant nonlinear regression enzyme inhibition models by WinNonlin. Results TCL was a potent, competitive inhibitor of CYP2C19 (Ki = 1.2 ± 0.5 µm) and of CYP2D6 (Ki = 3.4 ± 0.3 µm). These Ki values fell within the therapeutic steady-state plasma concentrations of TCL (1–3 µm). TCL was also a moderate inhibitor of CYP1A2 (Ki = 49 ± 19 µm) and a weak inhibitor of CYP2C9 (Ki > 75 µm), but its effect on the activities of CYP2E1 (Ki = 584 ± 48 µm) and CYP3A (> 1000 µm) was marginal. Conclusions TCL appears to be a broad-spectrum inhibitor of the CYP isoforms, but clinically significant adverse drug interactions are most likely with drugs that are substrates of CYP2C19 or CYP2D6. PMID:10759690

  19. CYP2D6 and UGT2B7 Genotype and Risk of Recurrence in Tamoxifen-Treated Breast Cancer Patients

    PubMed Central

    Drury, Suzy; Hayes, Daniel F.; Stearns, Vered; Thibert, Jacklyn N.; Haynes, Ben P.; Salter, Janine; Sestak, Ivana; Cuzick, Jack; Dowsett, Mitch

    2012-01-01

    Background Adjuvant tamoxifen therapy substantially decreases the risk of recurrence and mortality in women with hormone (estrogen and/or progesterone) receptor–positive breast cancer. Previous studies have suggested that metabolic conversion of tamoxifen to endoxifen by cytochrome P450 2D6 (CYP2D6) is required for patient benefit from tamoxifen therapy. Methods Tumor specimens from a subset of postmenopausal patients with hormone receptor–positive early-stage (stages I, II, and IIIA) breast cancer, who were enrolled in the randomized double-blind Arimidex, Tamoxifen, Alone or in Combination (ATAC) clinical trial, were genotyped for variants in CYP2D6 (N = 1203 patients: anastrozole [trade name: Arimidex] group, n = 615 patients; tamoxifen group, n = 588 patients) and UDP-glucuronosyltransferase-2B7 (UGT2B7), whose gene product inactivates endoxifen (N = 1209 patients; anastrozole group, n = 606 patients; tamoxifen group, n = 603 patients). Genotyping was performed using polymerase chain reaction–based TaqMan assays. Based on the genotypes for CYP2D6, patients were classified as poor metabolizer (PM), intermediate metabolizer (IM), or extensive metabolizer (EM) phenotypes. We evaluated the association of CYP2D6 and UGT2B7 genotype with distant recurrence (primary endpoint) and any recurrence (secondary endpoint) by estimating the hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) using Cox proportional hazards models. All statistical tests were two-sided. Results After a median follow-up of 10 years, no statistically significant associations were observed between CYP2D6 genotype and recurrence in tamoxifen-treated patients (PM vs EM: HR for distant recurrence = 1.25, 95% CI = 0.55 to 3.15, P = .64; HR for any recurrence = 0.99, 95% CI = 0.48 to 2.08, P = .99). A near-null association was observed between UGT2B7 genotype and recurrence in tamoxifen-treated patients. No associations were observed between CYP2D6 and UGT2B7 genotypes and

  20. Role of Pharmacogenetics in Improving the Safety of Psychiatric Care by Predicting the Potential Risks of Mania in CYP2D6 Poor Metabolizers Diagnosed With Bipolar Disorder.

    PubMed

    Sánchez-Iglesias, Santiago; García-Solaesa, Virginia; García-Berrocal, Belén; Sanchez-Martín, Almudena; Lorenzo-Romo, Carolina; Martín-Pinto, Tomás; Gaedigk, Andrea; González-Buitrago, José Manuel; Isidoro-García, María

    2016-02-01

    One of the main concerns in psychiatric care is safety related to drug management. Pharmacogenetics provides an important tool to assess causes that may have contributed the adverse events during psychiatric therapy. This study illustrates the potential of pharmacogenetics to identify those patients for which pharmacogenetic-guided therapy could be appropriate. It aimed to investigate CYP2D6 genotype in our psychiatric population to assess the value of introducing pharmacogenetics as a primary improvement for predicting side effects.A broad series of 224 psychiatric patients comprising psychotic disorders, depressive disturbances, bipolar disorders, and anxiety disorders was included. The patients were genotyped with the AmpliChip CYP450 Test to analyzing 33 allelic variants of the CYP2D6 gene.All bipolar patients with poor metabolizer status showed maniac switching when CYP2D6 substrates such as selective serotonin reuptake inhibitors were prescribed. No specific patterns were identified for adverse events for other disorders.We propose to utilize pharmacogenetic testing as an intervention to aid in the identification of patients who are at risk of developing affective switching in bipolar disorder treated with selective serotonin reuptake inhibitors, CYP2D6 substrates, and inhibitors. PMID:26871771

  1. Role of Pharmacogenetics in Improving the Safety of Psychiatric Care by Predicting the Potential Risks of Mania in CYP2D6 Poor Metabolizers Diagnosed With Bipolar Disorder

    PubMed Central

    Sánchez-Iglesias, Santiago; García-Solaesa, Virginia; García-Berrocal, Belén; Sanchez-Martín, Almudena; Lorenzo-Romo, Carolina; Martín-Pinto, Tomás; Gaedigk, Andrea; González-Buitrago, José Manuel; Isidoro-García, María

    2016-01-01

    Abstract One of the main concerns in psychiatric care is safety related to drug management. Pharmacogenetics provides an important tool to assess causes that may have contributed the adverse events during psychiatric therapy. This study illustrates the potential of pharmacogenetics to identify those patients for which pharmacogenetic-guided therapy could be appropriate. It aimed to investigate CYP2D6 genotype in our psychiatric population to assess the value of introducing pharmacogenetics as a primary improvement for predicting side effects. A broad series of 224 psychiatric patients comprising psychotic disorders, depressive disturbances, bipolar disorders, and anxiety disorders was included. The patients were genotyped with the AmpliChip CYP450 Test to analyzing 33 allelic variants of the CYP2D6 gene. All bipolar patients with poor metabolizer status showed maniac switching when CYP2D6 substrates such as selective serotonin reuptake inhibitors were prescribed. No specific patterns were identified for adverse events for other disorders. We propose to utilize pharmacogenetic testing as an intervention to aid in the identification of patients who are at risk of developing affective switching in bipolar disorder treated with selective serotonin reuptake inhibitors, CYP2D6 substrates, and inhibitors. PMID:26871771

  2. Contribution of ABCB1 and CYP2D6 genotypes to the outcome of tamoxifen adjuvant treatment in premenopausal women with breast cancer.

    PubMed

    Argalácsová, S; Slanař, O; Vítek, P; Tesařová, P; Bakhouche, H; DraŽďáková, M; Bartošová, O; Zima, T; PertuŽelka, L

    2015-01-01

    Recent pre-clinical evidence suggests that the active metabolite of tamoxifen, endoxifen, is a substrate for efflux pump P-glycoprotein. The aim of our study was to evaluate, if the polymoprhisms within ABCB1 gene alter tamoxifen adjuvant treatment efficacy in premenopausal women. Totally 71 premenopausal women with estrogen receptor positive breast cancer indicated for tamoxifen adjuvant treatment were followed retrospectively for median period of 56 months. The gentic polymorphisms of CYP2D6 and ABCB1 were analyzed and potential covariates as tumor grading, staging, age at the diagnosis, comedication, quantitative positivity of ER or PR were also evaluated. Cox proportional-hazards regression model indicated that patients carrying at least one variant allele in ABCB1 rs1045642 had significantly longer time to event survival compared to wild type subjects. Non-significant trend was noted for better treatment outcome of patients carrying at least one variant allele in the SNP rs2032582, while for the CYP2D6 polymorphism poor metabolizer phenotype resulted in worse outcome in comparison to extensive metabolizers subjects with HR of 4.04 (95 % CI 0.31-52.19). Similarly, patients using CYP2D6 inhibitors had non-significantly shorter time-to-event as compared to never users resulting in hazard ratio of 2.06 (95 % CI 0.40-10.63). ABCB1 polymorphisms may affect outcome of tamoxifen adjuvant treatment in premenopausal breast cancer patiens. This factor should be taken into account in addition to the CYP2D6 polymorphism or phenotypic inhibition of CYP2D6 activity. PMID:26681084

  3. Influence of CYP2D6 activity on the pharmacokinetics and pharmacodynamics of a single 20 mg dose of ibogaine in healthy volunteers.

    PubMed

    Glue, Paul; Winter, Helen; Garbe, Kira; Jakobi, Hannah; Lyudin, Alexander; Lenagh-Glue, Zoe; Hung, C Tak

    2015-06-01

    Conversion of ibogaine to its active metabolite noribogaine appears to be mediated primarily by CYP2D6. We compared 168 hours pharmacokinetic profiles of both analytes after a single oral 20 mg dose of ibogaine in 21 healthy subjects who had been pretreated for 6 days with placebo or the CYP2D6 inhibitor paroxetine. In placebo-pretreated subjects, ibogaine was rapidly converted to noribogaine. Median peak noribogaine concentrations occurred at 4 hours. Compared with placebo-pretreated subjects, paroxetine-pretreated subjects had rapid (Tmax  = 1.5 hours) and substantial absorption of ibogaine, with detectable levels out to 72 hours, and an elimination half-life of 10.2 hours. In this group, ibogaine was also rapidly converted to noribogaine with a median Tmax of 3 hours. Extent of noribogaine exposure was similar in both groups. CYP2D6 phenotype was robustly correlated with ibogaine AUC0-t (r = 0.82) and Cmax (r = 0.77). Active moiety (ibogaine plus noribogaine) exposure was ∼2-fold higher in paroxetine-pretreated subjects. Single 20 mg ibogaine doses were safe and well tolerated in all subjects. The doubling of exposure to active moiety in subjects with reduced CYP2D6 activity suggests it may be prudent to genotype patients awaiting ibogaine treatment, and to at least halve the intended dose of ibogaine in CYP2D6 poor metabolizers. PMID:25651476

  4. Role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to organophosphate pesticides

    SciTech Connect

    Singh, Satyender; Kumar, Vivek; Vashisht, Kapil; Singh, Priyanka; Banerjee, Basu Dev; Rautela, Rajender Singh; Grover, Shyam Sunder; Rawat, Devendra Singh; Pasha, Syed Tazeen; Jain, Sudhir Kumar; Rai, Arvind

    2011-11-15

    Organophosphate pesticides (OPs) are primarily metabolized by several xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticide-exposed workers. The present study was designed to determine the role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to OPs. We examined 284 subjects including 150 workers occupationally exposed to OPs and 134 normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using PCR-RFLP. The results revealed that the PONase activity toward paraoxonase and AChE activity was found significantly lowered in workers as compared to control subjects (p < 0.001). Workers showed significantly higher DNA damage compared to control subjects (14.37 {+-} 2.15 vs. 6.24 {+-} 1.37 tail% DNA, p < 0.001). Further, the workers with CYP2D6*3 PM and PON1 (QQ and MM) genotypes were found to have significantly higher DNA damage when compared to other genotypes (p < 0.05). In addition, significant increase in DNA damage was also observed in workers with concomitant presence of certain CYP2D6 and PON1 (Q192R and L55M) genotypes which need further extensive studies. In conclusion, the results indicate that the PON1 and CYP2D6 genotypes can modulate DNA damage elicited by some OPs possibly through gene-environment interactions. -- Highlights: Black-Right-Pointing-Pointer Role of CYP1A1, CYP3A5, CYP2C, CYP2D6 and PON1 genotypes on DNA damage. Black-Right-Pointing-Pointer Workers exposed to some OPs demonstrated increased DNA damage. Black-Right-Pointing-Pointer CYP2D6 *3 PM and PON1 (Q192R and L55M) genotypes are associated with DNA damage. Black-Right-Pointing-Pointer Concomitant presence of certain CYP2D6 and PON1 genotypes can increase DNA damage.

  5. In vitro inhibition of human CYP1A2, CYP2D6, and CYP3A4 by six herbs commonly used in pregnancy.

    PubMed

    Langhammer, Astrid Jordet; Nilsen, Odd Georg

    2014-04-01

    Black elderberry, cranberry, fennel, ginger, horsetail, and raspberry leaf, herbs frequently used in pregnancy, were investigated for their in vitro CYP1A2, 2D6, and 3A4 inhibitory potential. Aqueous or ethanolic extracts were made from commercially available herbal products, and incubations were performed with recombinant cDNA-expressed human CYP enzymes in the presence of positive inhibitory controls. Metabolite formation was determined by validated LCMS/MS or HPLC methodologies. IC50 inhibition constants were estimated from CYP activity inhibition plots using non-linear regression. The most potent inhibition was shown for fennel towards CYP2D6 and 3A4 with respective IC50 constants of 23 ± 2 and 40 ± 4 µg/ml, horsetail towards CYP1A2 with an IC50 constant of 27 ± 1 µg/ml, and raspberry leaf towards CYP1A2, 2D6, and 3A4 with IC50 constants of 44 ± 2, 47 ± 8, and 81 ± 11 µg/ml, respectively. Based on the recommended dosing of the different commercial herbal products, clinically relevant systemic CYP inhibitions could be possible for fennel, horsetail, and raspberry leaf. In addition, fennel and raspberry leaf might cause a clinically relevant inhibition of intestinal CYP3A4. The in vivo inhibitory potential of these herbs towards specific CYP enzymes should be further investigated. PMID:23843424

  6. CYP1A2 and CYP2D6 Gene Polymorphisms in Schizophrenic Patients with Neuroleptic Drug-Induced Side Effects.

    PubMed

    Ivanova, S A; Filipenko, M L; Vyalova, N M; Voronina, E N; Pozhidaev, I V; Osmanova, D Z; Ivanov, M V; Fedorenko, O Yu; Semke, A V; Bokhan, N A

    2016-03-01

    Polymorphic variants of CYP1A2 and CYP2D6 genes of the cytochrome P450 system were studied in patients with schizophrenia with drug-induced motor disorders and hyperprolactinemia against the background of long-term neuroleptic therapy. We revealed an association of polymorphic variant C-163A CYP1A2*1F of CYP1A2 gene with tardive dyskinesia and association of polymorphic variant 1846G>A CY2D6*4 and genotype A/A of CYP2D6 gene (responsible for debrisoquin-4-hydroxylase synthesis) with limbotruncal tardive dyskinesia in patients with schizophrenia receiving neuroleptics for a long time. PMID:27021090

  7. Effects of polymorphisms in CYP2D6 and ABC transporters and side effects induced by gefitinib on the pharmacokinetics of the gefitinib metabolite, O-desmethyl gefitinib.

    PubMed

    Kobayashi, Hiroyuki; Sato, Kazuhiro; Niioka, Takenori; Takeda, Masahide; Okuda, Yuji; Asano, Mariko; Ito, Hiroshi; Miura, Masatomo

    2016-06-01

    We investigated the effects of polymorphisms in CYP2D6, ABCB1, and ABCG2 and the side effects induced by gefitinib on the pharmacokinetics of O-desmethyl gefitinib, the active metabolite of gefitinib. On day 14 after beginning therapy with gefitinib, plasma concentrations of gefitinib and O-desmethyl gefitinib were measured. Patients were grouped into three groups according to their combination of CYP2D6 alleles: homozygous extensive metabolisers (EMs; *1/*1, *1/*2, and *2/*2; n = 13), heterozygous EMs (*1/*5, *2/*5, *1/*10, and *2/*10; n = 18), and intermediate metabolisers (IMs; *5/*10 and *10/*10; n = 5). The median AUC0-24 of O-desmethyl gefitinib in CYP2D6 IMs was 1460 ng h/mL, whereas that in homozygous EMs was 12,523 ng h/mL (P = 0.021 in univariate analysis). The median AUC ratio of O-desmethyl gefitinib to gefitinib differed among homozygous EMs, heterozygous EMs, and IMs at a ratio of 1.41:0.86:0.24 (P = 0.030). On the other hand, there were no significant differences in the AUC0-24 of O-desmethyl gefitinib between ABCB1 and ABCG2 genotypes. In a multivariate analysis, CYP2D6 homozygous EMs (P = 0.012) were predictive for a higher AUC0-24 of O-desmethyl gefitinib. The side effects of diarrhoea, skin rash, and hepatotoxicity induced by gefitinib were unrelated to the AUC0-24 of O-desmethyl gefitinib. CYP2D6 polymorphisms were associated with the formation of O-desmethyl gefitinib from gefitinib. In CYP2D6 homozygous EMs, the plasma concentrations of O-desmethyl gefitinib were higher over 24 h after taking gefitinib than those of the parent compound; however, side effects induced by gefitinib were unrelated to O-desmethyl gefitinib exposure. PMID:27154635

  8. A Physiologically Based Pharmacokinetic Model to Predict Disposition of CYP2D6 and CYP1A2 Metabolized Drugs in Pregnant Women

    PubMed Central

    Ke, Alice Ban; Nallani, Srikanth C.; Zhao, Ping; Rostami-Hodjegan, Amin; Isoherranen, Nina

    2013-01-01

    Conducting pharmacokinetic (PK) studies in pregnant women is challenging. Therefore, we asked if a physiologically based pharmacokinetic (PBPK) model could be used to evaluate different dosing regimens for pregnant women. We refined and verified our previously published pregnancy PBPK model by incorporating cytochrome P450 CYP1A2 suppression (based on caffeine PK) and CYP2D6 induction (based on metoprolol PK) into the model. This model accounts for gestational age–dependent changes in maternal physiology and hepatic CYP3A activity. For verification, the disposition of CYP1A2–metabolized drug theophylline (THEO) and CYP2D6–metabolized drugs paroxetine (PAR), dextromethorphan (DEX), and clonidine (CLO) during pregnancy was predicted. Our PBPK model successfully predicted THEO disposition during the third trimester (T3). Predicted mean postpartum to third trimester (PP:T3) ratios of THEO area under the curve (AUC), maximum plasma concentration, and minimum plasma concentration were 0.76, 0.95, and 0.66 versus observed values 0.75, 0.89, and 0.72, respectively. The predicted mean PAR steady-state plasma concentration (Css) ratio (PP:T3) was 7.1 versus the observed value 3.7. Predicted mean DEX urinary ratio (UR) (PP:T3) was 2.9 versus the observed value 1.9. Predicted mean CLO AUC ratio (PP:T3) was 2.2 versus the observed value 1.7. Sensitivity analysis suggested that a 100% induction of CYP2D6 during T3 was required to recover the observed PP:T3 ratios of PAR Css, DEX UR, and CLO AUC. Based on these data, it is prudent to conclude that the magnitude of hepatic CYP2D6 induction during T3 ranges from 100 to 200%. Our PBPK model can predict the disposition of CYP1A2, 2D6, and 3A drugs during pregnancy. PMID:23355638

  9. A physiologically based pharmacokinetic model to predict disposition of CYP2D6 and CYP1A2 metabolized drugs in pregnant women.

    PubMed

    Ke, Alice Ban; Nallani, Srikanth C; Zhao, Ping; Rostami-Hodjegan, Amin; Isoherranen, Nina; Unadkat, Jashvant D

    2013-04-01

    Conducting pharmacokinetic (PK) studies in pregnant women is challenging. Therefore, we asked if a physiologically based pharmacokinetic (PBPK) model could be used to evaluate different dosing regimens for pregnant women. We refined and verified our previously published pregnancy PBPK model by incorporating cytochrome P450 CYP1A2 suppression (based on caffeine PK) and CYP2D6 induction (based on metoprolol PK) into the model. This model accounts for gestational age-dependent changes in maternal physiology and hepatic CYP3A activity. For verification, the disposition of CYP1A2-metabolized drug theophylline (THEO) and CYP2D6-metabolized drugs paroxetine (PAR), dextromethorphan (DEX), and clonidine (CLO) during pregnancy was predicted. Our PBPK model successfully predicted THEO disposition during the third trimester (T3). Predicted mean postpartum to third trimester (PP:T3) ratios of THEO area under the curve (AUC), maximum plasma concentration, and minimum plasma concentration were 0.76, 0.95, and 0.66 versus observed values 0.75, 0.89, and 0.72, respectively. The predicted mean PAR steady-state plasma concentration (Css) ratio (PP:T3) was 7.1 versus the observed value 3.7. Predicted mean DEX urinary ratio (UR) (PP:T3) was 2.9 versus the observed value 1.9. Predicted mean CLO AUC ratio (PP:T3) was 2.2 versus the observed value 1.7. Sensitivity analysis suggested that a 100% induction of CYP2D6 during T3 was required to recover the observed PP:T3 ratios of PAR Css, DEX UR, and CLO AUC. Based on these data, it is prudent to conclude that the magnitude of hepatic CYP2D6 induction during T3 ranges from 100 to 200%. Our PBPK model can predict the disposition of CYP1A2, 2D6, and 3A drugs during pregnancy. PMID:23355638

  10. No association between schizophrenia and polymorphisms within the genes for debrisoquine 4-hydroxylase (CYP2D6) and the dopamine transporter (DAT)

    SciTech Connect

    Daniels, J.; Williams, J.; Asherson, P.; McGuffin, P.; Owen, M.

    1995-02-27

    It has been suggested that the cytochrome P450 mono-oxygenase, debrisoquine 4-hydroxylase, is involved in the catabolism and processing of neurotransmitters subsequent to their reuptake into target cells. It is also thought to be related to the dopamine transporter that acts to take released dopamine back up into presynaptic terminals. The present study used the association approach to test the hypothesis that mutations in the genes for debrisoquine 4-hydroxylase (CYP2D6) and the dopamine transporter (DAT) confer susceptibility to schizophrenia. There were no differences in allele or genotype frequencies between patients and controls in the mutations causing the poor metaboliser phenotype in CYP2D6. In addition there was no association found between schizophrenia and a 48 bp repeat within the 3{prime} untranslated region of DAT. 18 refs., 2 tabs.

  11. 3,4-DEHYDRODEBRISOQUINE, A NOVEL DEBRISOQUINE METABOLITE FORMED FROM 4-HYDROXYDEBRISOQUINE THAT IMPACTS THE CYP2D6 METABOLIC RATIO

    PubMed Central

    Zhen, Yueying; Slanař, Ondřej; Krausz, Kristopher W.; Chen, Chi; Slavík, Josef; McPhail, Kerry L.; Zabriskie, T. Mark; Perlík, František; Gonzalez, Frank J.; Idle, Jeffrey R.

    2006-01-01

    Considerable unexplained inter-subject variability in the debrisoquine metabolic ratio (urinary debrisoquine/4-hydroxydebrisoquine) exists within individual CYP2D6 genotypes. We speculated that debrisoquine was converted to as yet undisclosed metabolites. Thirteen healthy young volunteers, nine CYP2D6*1 homozygotes (EMs) and four CYP2D6*4 homozygotes (PMs) took 12.8 mg debrisoquine hemisulfate by mouth and collected 0–8 and 8–24 h urines, which were analyzed by GCMS before and after treatment with β-glucuronidase. Authentic 3,4-dehydrodebrisoquine was synthesized and characterized by GCMS, LC-MS/MS and 1H NMR. 3,4-Dehydrodebrisoquine is a novel metabolite of debrisoquine excreted variably in 0–24 h urine, both in EMs (3.1–27.6% dose) and PMs (0–2.1% dose). This metabolite is produced from 4-hydroxydebrisoquine in vitro by human and rat liver microsomes. A single CYP2D6*1 homozygote was administered 10.2 mg 4-hydroxydebrisoquine orally and also excreted 3,4-dehydrodebrisoquine. EMs excreted 6-hydroxydebrisoquine (0–4.8%), 8-hydroxydebrisoquine (0–1.3%) but these phenolic metabolites were not detected in PM urine. Debrisoquine and 4-hydroxydebrisoquine glucuronides were excreted in a highly genotype-dependent manner. A non-cytochrome P450 microsomal activity participates in the further metabolism of 4-hydroxydebrisoquine, which we speculate may also lead to the formation of 1- and 3-hydroxydebrisoquine and their ring-opened products. In conclusion, this study suggests that the traditional metabolic ratio is not a true measure of the debrisoquine 4-hydroxylation capacity of an individual and thus may, in part, explain the wide intragenotype variation in metabolic ratio. PMID:16782768

  12. Influence of ABCB1 genetic polymorphisms on the pharmacokinetics of risperidone in healthy subjects with CYP2D6*10/*10

    PubMed Central

    Yoo, Hee-Doo; Lee, Sang-No; Kang, Hyun-Ah; Cho, Hea-Young; Lee, Il-Kwon; Lee, Yong-Bok

    2011-01-01

    BACKGROUND AND PURPOSE The objective of this study was to investigate the combined influence of genetic polymorphisms in ABCB1 and CYP2D6 genes on risperidone pharmacokinetics. EXPERIMENTAL APPROACH Seventy-two healthy Korean volunteers receiving a single oral dose of 2 mg risperidone were included in this study. KEY RESULTS Significant differences were observed between the ABCB1 3435C>T genotypes for the pharmacokinetic parameters (peak serum concentration) of risperidone and the active moiety (risperidone and its main metabolite, 9-hydroxyrisperidone). There were no significant differences in the area under the serum concentration-time curves of risperidone and the active moiety among the ABCB1 2677G>T/A and 3435C>T genotypes. However, the peak serum concentration and area under the serum concentration-time curves were significantly different among the ABCB1 3435C>T genotypes in CYP2D6*10/*10. CONCLUSIONS AND IMPLICATIONS These findings indicate that polymorphisms of ABCB1 3435C>T in individuals with CYP2D6*10/*10, which has low metabolic activity, could play an important role in the potential adverse effects or toxicity of risperidone. PMID:21449914

  13. Pharmacogenetics in American Indian Populations: Analysis of CYP2D6, CYP3A4, CYP3A5, and CYP2C9 in the Confederated Salish and Kootenai Tribes

    PubMed Central

    Fohner, Alison; Muzquiz, LeeAnna I.; Austin, Melissa A.; Gaedigk, Andrea; Gordon, Adam; Thornton, Timothy; Rieder, Mark J.; Pershouse, Mark A.; Putnam, Elizabeth A.; Howlett, Kevin; Beatty, Patrick; Thummel, Kenneth E.; Woodahl, Erica L.

    2014-01-01

    Objectives Cytochrome P450 enzymes play a dominant role in drug elimination and variation in these genes is a major source of interindividual differences in drug response. Little is known, however, about pharmacogenetic variation in American Indian and Alaska Native (AI/AN) populations. We have developed a partnership with the Confederated Salish and Kootenai Tribes (CSKT) in northwestern Montana to address this knowledge gap. Methods We resequenced CYP2D6 in 187 CSKT subjects and CYP3A4, CYP3A5, and CYP2C9 in 94 CSKT subjects. Results We identified 67 variants in CYP2D6, 15 in CYP3A4, 10 in CYP3A5, and 41 in CYP2C9. The most common CYP2D6 alleles were CYP2D6*4 and *41 (20.86 and 11.23%, respectively). CYP2D6*3, *5, *6, *9, *10, *17, *28, *33, *35, *49, *1xN, *2xN, and *4xN frequencies were less than 2%. CYP3A5*3, CYP3A4*1G, and *1B were detected with frequencies of 92.47, 26.81, and 2.20%, respectively. Allelic variation in CYP2C9 was low: CYP2C9*2 (5.17%) and *3 (2.69%). In general, allele frequencies in CYP2D6, CYP2C9 and CYP3A5 were similar to those observed in European Americans. There was, however, a marked divergence in CYP3A4 for the CYP3A4*1G allele. We also observed low levels of linkage between CYP3A4*1G and CYP3A5*1 in the CSKT. The combination of nonfunctional CYP3A5*3 and putative reduced function CYP3A4*1G alleles may predict diminished clearance of CYP3A substrates. Conclusions These results highlight the importance of conducting pharmacogenomic research in AI/AN populations and demonstrate that extrapolation from other populations is not appropriate. This information could help to optimize drug therapy for the CSKT population. PMID:23778323

  14. Role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to organophosphate pesticides.

    PubMed

    Singh, Satyender; Kumar, Vivek; Vashisht, Kapil; Singh, Priyanka; Banerjee, Basu Dev; Rautela, Rajender Singh; Grover, Shyam Sunder; Rawat, Devendra Singh; Pasha, Syed Tazeen; Jain, Sudhir Kumar; Rai, Arvind

    2011-11-15

    Organophosphate pesticides (OPs) are primarily metabolized by several xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticide-exposed workers. The present study was designed to determine the role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to OPs. We examined 284 subjects including 150 workers occupationally exposed to OPs and 134 normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using PCR-RFLP. The results revealed that the PONase activity toward paraoxonase and AChE activity was found significantly lowered in workers as compared to control subjects (p<0.001). Workers showed significantly higher DNA damage compared to control subjects (14.37±2.15 vs. 6.24±1.37 tail% DNA, p<0.001). Further, the workers with CYP2D6*3PM and PON1 (QQ and MM) genotypes were found to have significantly higher DNA damage when compared to other genotypes (p<0.05). In addition, significant increase in DNA damage was also observed in workers with concomitant presence of certain CYP2D6 and PON1 (Q192R and L55M) genotypes which need further extensive studies. In conclusion, the results indicate that the PON1 and CYP2D6 genotypes can modulate DNA damage elicited by some OPs possibly through gene-environment interactions. PMID:21907728

  15. Utilizing structures of CYP2D6 and BACE1 complexes to reduce risk of drug-drug interactions with a novel series of centrally efficacious BACE1 inhibitors.

    PubMed

    Brodney, Michael A; Beck, Elizabeth M; Butler, Christopher R; Barreiro, Gabriela; Johnson, Eric F; Riddell, David; Parris, Kevin; Nolan, Charles E; Fan, Ying; Atchison, Kevin; Gonzales, Cathleen; Robshaw, Ashley E; Doran, Shawn D; Bundesmann, Mark W; Buzon, Leanne; Dutra, Jason; Henegar, Kevin; LaChapelle, Erik; Hou, Xinjun; Rogers, Bruce N; Pandit, Jayvardhan; Lira, Ricardo; Martinez-Alsina, Luis; Mikochik, Peter; Murray, John C; Ogilvie, Kevin; Price, Loren; Sakya, Subas M; Yu, Aijia; Zhang, Yong; O'Neill, Brian T

    2015-04-01

    In recent years, the first generation of β-secretase (BACE1) inhibitors advanced into clinical development for the treatment of Alzheimer's disease (AD). However, the alignment of drug-like properties and selectivity remains a major challenge. Herein, we describe the discovery of a novel class of potent, low clearance, CNS penetrant BACE1 inhibitors represented by thioamidine 5. Further profiling suggested that a high fraction of the metabolism (>95%) was due to CYP2D6, increasing the potential risk for victim-based drug-drug interactions (DDI) and variable exposure in the clinic due to the polymorphic nature of this enzyme. To guide future design, we solved crystal structures of CYP2D6 complexes with substrate 5 and its corresponding metabolic product pyrazole 6, which provided insight into the binding mode and movements between substrate/inhibitor complexes. Guided by the BACE1 and CYP2D6 crystal structures, we designed and synthesized analogues with reduced risk for DDI, central efficacy, and improved hERG therapeutic margins. PMID:25781223

  16. Utilizing Structures of CYP2D6 and BACE1 Complexes To Reduce Risk of Drug–Drug Interactions with a Novel Series of Centrally Efficacious BACE1 Inhibitors

    PubMed Central

    2016-01-01

    In recent years, the first generation of β-secretase (BACE1) inhibitors advanced into clinical development for the treatment of Alzheimer’s disease (AD). However, the alignment of drug-like properties and selectivity remains a major challenge. Herein, we describe the discovery of a novel class of potent, low clearance, CNS penetrant BACE1 inhibitors represented by thioamidine 5. Further profiling suggested that a high fraction of the metabolism (>95%) was due to CYP2D6, increasing the potential risk for victim-based drug–drug interactions (DDI) and variable exposure in the clinic due to the polymorphic nature of this enzyme. To guide future design, we solved crystal structures of CYP2D6 complexes with substrate 5 and its corresponding metabolic product pyrazole 6, which provided insight into the binding mode and movements between substrate/inhibitor complexes. Guided by the BACE1 and CYP2D6 crystal structures, we designed and synthesized analogues with reduced risk for DDI, central efficacy, and improved hERG therapeutic margins. PMID:25781223

  17. Effects of strong CYP2D6 and 3A4 inhibitors, paroxetine and ketoconazole, on the pharmacokinetics and cardiovascular safety of tamsulosin

    PubMed Central

    Troost, Joachim; Tatami, Shinji; Tsuda, Yasuhiro; Mattheus, Michaela; Mehlburger, Ludwig; Wein, Martina; Michel, Martin C

    2011-01-01

    AIM To determine the effect of the strong CYP2D6 inhibitor paroxetine and strong CYP3A4 inhibitor ketoconazole on the pharmacokinetics and safety (orthostatic challenge) of tamsulosin. METHODS Two open-label, randomized, two-way crossover studies were conducted in healthy male volunteers (extensive CYP2D6 metabolizers). RESULTS Co-administration of multiple oral doses of 20 mg paroxetine once daily with a single oral dose of the 0.4 mg tamsulosin HCl capsule increased the adjusted geometric mean (gMean) values of Cmax and AUC(0,∞) of tamsulosin by factors of 1.34 (90% CI 1.21, 1.49) and 1.64 (90% CI 1.44, 1.85), respectively, and increased the terminal half-life (t1/2) of tamsulosin HCl from 11.4 h to 15.3 h. Co-administration of multiple oral doses of 400 mg ketoconazole once dailywith a single oral dose of the 0.4 mg tamsulosin increased the gMean values of Cmax and AUC(0,∞) of tamsulosin by a factor of 2.20 (90% CI 1.96, 2.45) and 2.80 (90% CI 2.56, 3.07), respectively. The terminal half-life was slightly increased from 10.5 h to 11.8 h. These pharmacokinetic changes were not accompanied by clinically significant alterations of haemodynamic responses during orthostatic stress testing. CONCLUSION The exposure to tamsulosin is increased upon co-administration of strong CYP2D6 inhibitors and even more so of strong 3A4 inhibitors, but neither PK alteration was accompanied by clinically significant haemodynamic changes during orthostatic stress testing. PMID:21496064

  18. Comparative inhibitory potential of selected dietary bioactive polyphenols, phytosterols on CYP3A4 and CYP2D6 with fluorometric high-throughput screening.

    PubMed

    Vijayakumar, Thangavel Mahalingam; Kumar, Ramasamy Mohan; Agrawal, Aruna; Dubey, Govind Prasad; Ilango, Kaliappan

    2015-07-01

    Cytochrome P450 (CYP450) inhibition by the bioactive molecules of dietary supplements or herbal products leading to greater potential for toxicity of co-administered drugs. The present study was aimed to compare the inhibitory potential of selected common dietary bioactive molecules (Gallic acid, Ellagic acid, β-Sitosterol, Stigmasterol, Quercetin and Rutin) on CYP3A4 and CYP2D6 to assess safety through its inhibitory potency and to predict interaction potential with co-administered drugs. CYP450-CO complex assay was carried out for all the selected dietary bioactive molecules in isolated rat microsomes. CYP450 concentration of the rat liver microsome was found to be 0.474 nmol/mg protein, quercetin in DMSO has shown maximum inhibition on CYP450 (51.02 ± 1.24 %) but less when compared with positive control (79.02 ± 1.61 %). In high throughput fluorometric assay, IC50 value of quercetin (49.08 ± 1.02-54.36 ± 0.85 μg/ml) and gallic acid (78.46 ± 1.32-83.84 ± 1.06 μg/ml) was lower than other bioactive compounds on CYP3A4 and CYP2D6 respectively but it was higher than positive controls (06.28 ± 1.76-07.74 ± 1.32 μg/ml). In comparison of in vitro inhibitory potential on CYP3A4 and CYP2D6, consumption of food or herbal or dietary supplements containing quercetin and gallic acid without any limitation should be carefully considered when narrow therapeutic drugs are administered together. PMID:26139922

  19. Genetic polymorphisms of CYP2D6*10 and the effectiveness of combined tamoxifen citrate and testosterone undecanoate treatment in infertile men with idiopathic oligozoospermia*

    PubMed Central

    Tang, Kai-fa; Zhao, Yi-li; Ding, Shang-shu; Wu, Qi-fei; Wang, Xing-yang; Shi, Jia-qi; Sun, Fa; Xing, Jun-ping

    2015-01-01

    Tamoxifen citrate, as the first line of treatment for infertile men with idiopathic oligozoospermia, was proposed by the World Health Organization (WHO), and testosterone undecanoate has shown benefits in semen values. Our objective was to assess the effectiveness of treatment with tamoxifen citrate and testosterone undecanoate in infertile men with idiopathic oligozoospermia, and whether the results would be affected by polymorphisms of CYP2D6*10. A total of 230 infertile men and 147 controls were included in the study. Patients were treated with tamoxifen citrate and testosterone undecanoate. Sex hormone, sperm parameters, and incidence of spontaneous pregnancy were detected. There were no significant differences between the control and patient groups with respect to CYP2D6*10 genotype frequencies (P>0.05). The follicle-stimulation hormone (FSH), luteinizing hormone (LH), and testosterone (T) levels were raised, and sperm concentration and motility were increased at 3 months and became significant at 6 months, and they were higher in the wild-type allele (C/C) than in the heterozygous variant allele (C/T) or homozygous variant allele (T/T) subgroups (P<0.05). In addition, the percentage of normal morphology was raised at 6 months, and represented the highest percentage in the C/C subgroup (P<0.05). The incidence of spontaneous pregnancy in the C/C subgroup was higher than that in the C/T or T/T subgroups (P<0.01). This study showed that the CYP2D6*10 variant genotype demonstrated worse clinical effects in infertile men with idiopathic oligozoospermia. PMID:25743120

  20. Genetic polymorphisms of CYP2D6*10 and the effectiveness of combined tamoxifen citrate and testosterone undecanoate treatment in infertile men with idiopathic oligozoospermia.

    PubMed

    Tang, Kai-fa; Zhao, Yi-li; Ding, Shang-shu; Wu, Qi-fei; Wang, Xing-yang; Shi, Jia-qi; Sun, Fa; Xing, Jun-ping

    2015-03-01

    Tamoxifen citrate, as the first line of treatment for infertile men with idiopathic oligozoospermia, was proposed by the World Health Organization (WHO), and testosterone undecanoate has shown benefits in semen values. Our objective was to assess the effectiveness of treatment with tamoxifen citrate and testosterone undecanoate in infertile men with idiopathic oligozoospermia, and whether the results would be affected by polymorphisms of CYP2D6*10. A total of 230 infertile men and 147 controls were included in the study. Patients were treated with tamoxifen citrate and testosterone undecanoate. Sex hormone, sperm parameters, and incidence of spontaneous pregnancy were detected. There were no significant differences between the control and patient groups with respect to CYP2D6*10 genotype frequencies (P>0.05). The follicle-stimulation hormone (FSH), luteinizing hormone (LH), and testosterone (T) levels were raised, and sperm concentration and motility were increased at 3 months and became significant at 6 months, and they were higher in the wild-type allele (C/C) than in the heterozygous variant allele (C/T) or homozygous variant allele (T/T) subgroups (P<0.05). In addition, the percentage of normal morphology was raised at 6 months, and represented the highest percentage in the C/C subgroup (P<0.05). The incidence of spontaneous pregnancy in the C/C subgroup was higher than that in the C/T or T/T subgroups (P<0.01). This study showed that the CYP2D6*10 variant genotype demonstrated worse clinical effects in infertile men with idiopathic oligozoospermia. PMID:25743120

  1. Cytochrome P450 (CYP2D6) Genotype is Associated with Elevated Systolic Blood Pressure in Preterm Infants Following NICU Discharge

    PubMed Central

    Dagle, John M; Fisher, Tyler J; Haynes, Susan E; Berends, Susan K; Brophy, Patrick D; Morriss, Frank H; Murray, Jeffrey C

    2011-01-01

    Objective To determine genetic and clinical risk factors associated with elevated systolic blood pressure (ESBP) in preterm infants following discharge. Study design A convenience cohort of infants <32 weeks gestational age was followed after discharge; we retrospectively identified a subgroup of subjects with ESBP (SBP > 90th percentile for term infants). Genetic testing identified alleles associated with ESBP. Multivariable logistic regression analysis was performed for the outcome ESBP with clinical characteristics and genotype as independent variables. Results Predictors of ESBP were: CYP2D6 (rs28360521) CC genotype (OR 2.92; 95% CI 1.48, 5.79), adjusted for outpatient oxygen therapy (OR 4.53, 95%CI 2.23, 8.81) and history of urinary tract infection (OR 4.68, 95% CI 1.47, 14.86). Maximum SBP was modeled by multivariable linear regression analysis: Maximum SBP = 84.8 mmHg + 6.8 mmHg (if CYP2D6 CC genotype) + 6.8 mmHg (if discharged on supplemental oxygen) + 4.4 mmHg (if received inpatient glucocorticoids) (p=0.0002). Conclusion ESBP is common among preterm infants with residual lung disease following NICU discharge. This study reveals clinical factors associated with ESBP, identifies a candidate gene for further testing, and supports the recommendation that BP be monitored sooner than at age 3 years as suggested for term infants. PMID:21353244

  2. Steady-state pharmacokinetics of the enantiomers of perhexiline in CYP2D6 poor and extensive metabolizers administered Rac-perhexiline

    PubMed Central

    Davies, Benjamin J; Herbert, Megan K; Coller, Janet K; Somogyi, Andrew A; Milne, Robert W; Sallustio, Benedetta C

    2008-01-01

    Aims To determine the steady-state pharmacokinetics of perhexiline (PHX) enantiomers over one interdosing interval in CYP2D6 extensive and poor metabolizer (EM and PM, respectively) patients administered rac-PHX. To elucidate the processes responsible for enantioselectivity, particularly in PM patients. Methods Blood samples were taken over one interdosing interval from six EM and two PM patients at steady-state with respect to rac-PHX metabolism. Complete urine collections were taken from five EM patients. PHX concentrations in plasma and urine were determined with enantioselective high-performance liquid chromatography methods. Results EM patients had 16- and 10-fold greater median apparent oral clearances of (+)- and (−)-PHX, respectively, than PM patients (P < 0.05 for both) and required significantly larger doses of rac-PHX (69 vs. 4.2 µg kg−1 h−1, P < 0.05) to maintain therapeutic concentrations in plasma. Patient phenotypes were consistent with CYP2D6 genotypes. Both groups displayed enantioselective pharmacokinetics, with higher apparent oral clearances for (−)-PHX compared with (+)-PHX, although PM patients exhibited significantly greater enantioselectivity (P < 0.05). The renal clearance of PHX enantiomers was not enantioselective and accounted for <1% of the median apparent oral clearance of each enantiomer in EM patients. Assuming the same renal clearances for PM patients accounts for approximately 9 and 4% of their median apparent oral clearances of (+)- and (−)-PHX, respectively. Conclusions The enantioselective pharmacokinetics of PHX are primarily due to metabolism by CYP2D6 in EM patients. The mechanism responsible for the enantioselective pharmacokinetics of PHX in PM patients is unknown, but may be due to enantioselective biliary or intestinal excretion. What is already known about this subject Perhexiline (PHX) is administered as a racemic mixture and exhibits enantioselective pharmacokinetics in both poor and extensive metabolizers

  3. Further characterization of a ¹³C-dextromethorphan breath test for CYP2D6 phenotyping in breast cancer patients on tamoxifen therapy.

    PubMed

    Opdam, F L; Modak, A S; Gelderblom, H; Guchelaar, H J

    2015-06-01

    In a previous study, we found that the CYP2D6 phenotype determined by (13)C-dextromethorphan breath test (DM-BT) might be used to predict tamoxifen treatment outcome in breast cancer patients in the adjuvant setting. However, large variation in the delta-over-baseline (DOB) values was observed in the extensive metabolizer predicted phenotype group based on single point measures. In the present work we aimed to analyze the variability of phenotype results and determine reproducibility to further characterize the clinical utility of DM-BT by introducing multiple breath sampling instead of single breath sampling and by administration of a fixed dose of (13)C-DM. PMID:25891764

  4. Progression of cervical intraepithelial neoplasia to cervical cancer: interactions of cytochrome P450 CYP2D6 EM and glutathione s-transferase GSTM1 null genotypes and cigarette smoking.

    PubMed Central

    Warwick, A. P.; Redman, C. W.; Jones, P. W.; Fryer, A. A.; Gilford, J.; Alldersea, J.; Strange, R. C.

    1994-01-01

    The factors that determine progression of cervical intraepithelial neoplasia (CIN) to squamous cell carcinoma (SCC) are unknown. Cigarette smoking is an independent risk factor for cervical neoplasia, suggesting that polymorphism at detoxicating enzyme loci such as cytochrome P450 CYP2D6 and glutathione S-transferase GSTM1 may determine susceptibility to these cancers. We have studied the frequencies of genotypes at these loci in women suffering low-grade CIN, high-grade CIN and SCC. A non-cancer control group was provided by women with normal cervical histology suffering menorrhagia. Comparison of the frequency distributions of the CYP2D6 PM, HET and EM genotypes (G-->A transition at intron 3/exon 4 and base pair deletion in exon 5) revealed no significant differences between the menorrhagia and SCC groups. Frequency distributions in the menorrhagia group, however, were significantly different (P < 0.04) from those in the low- and high-grade CIN groups. Thus, the proportion of EM was significantly larger (P < 0.03) and of HET generally lower. We found that the frequency of GSTM1 null in the menorrhagia and case groups was not significantly different. Interactive effects of enzyme genotypes with cigarette smoking were studied by comparing the multinomial frequency distributions of CYP2D6 EM/GSTM1 null/smoking over mutually exclusive categories. These showed no significant differences between the menorrhagia group and SCC or low-grade CIN groups. The frequency distribution in high-grade CIN, however, was significantly different to that in the menorrhagia group and in both SCC and low-grade CIN groups. This study was identified, for the first time, an inherited characteristic in women with high-grade CIN who appear to be at reduced risk of SCC. Thus, women with CYP2D6 EM who smoke have increased susceptibility to high-grade CIN but are less likely to progress to SCC, possibly because they effectively detoxify an unidentified chemical involved in mediating disease

  5. Modeling chemical interaction profiles: I. Spectral data-activity relationship and structure-activity relationship models for inhibitors and non-inhibitors of cytochrome P450 CYP3A4 and CYP2D6 isozymes.

    PubMed

    McPhail, Brooks; Tie, Yunfeng; Hong, Huixiao; Pearce, Bruce A; Schnackenberg, Laura K; Ge, Weigong; Valerio, Luis G; Fuscoe, James C; Tong, Weida; Buzatu, Dan A; Wilkes, Jon G; Fowler, Bruce A; Demchuk, Eugene; Beger, Richard D

    2012-01-01

    An interagency collaboration was established to model chemical interactions that may cause adverse health effects when an exposure to a mixture of chemicals occurs. Many of these chemicals--drugs, pesticides, and environmental pollutants--interact at the level of metabolic biotransformations mediated by cytochrome P450 (CYP) enzymes. In the present work, spectral data-activity relationship (SDAR) and structure-activity relationship (SAR) approaches were used to develop machine-learning classifiers of inhibitors and non-inhibitors of the CYP3A4 and CYP2D6 isozymes. The models were built upon 602 reference pharmaceutical compounds whose interactions have been deduced from clinical data, and 100 additional chemicals that were used to evaluate model performance in an external validation (EV) test. SDAR is an innovative modeling approach that relies on discriminant analysis applied to binned nuclear magnetic resonance (NMR) spectral descriptors. In the present work, both 1D ¹³C and 1D ¹⁵N-NMR spectra were used together in a novel implementation of the SDAR technique. It was found that increasing the binning size of 1D ¹³C-NMR and ¹⁵N-NMR spectra caused an increase in the tenfold cross-validation (CV) performance in terms of both the rate of correct classification and sensitivity. The results of SDAR modeling were verified using SAR. For SAR modeling, a decision forest approach involving from 6 to 17 Mold2 descriptors in a tree was used. Average rates of correct classification of SDAR and SAR models in a hundred CV tests were 60% and 61% for CYP3A4, and 62% and 70% for CYP2D6, respectively. The rates of correct classification of SDAR and SAR models in the EV test were 73% and 86% for CYP3A4, and 76% and 90% for CYP2D6, respectively. Thus, both SDAR and SAR methods demonstrated a comparable performance in modeling a large set of structurally diverse data. Based on unique NMR structural descriptors, the new SDAR modeling method complements the existing SAR

  6. Contributions of Ionic Interactions and Protein Dynamics to Cytochrome P450 2D6 (CYP2D6) Substrate and Inhibitor Binding*

    PubMed Central

    Wang, An; Stout, C. David; Zhang, Qinghai; Johnson, Eric F.

    2015-01-01

    P450 2D6 contributes significantly to the metabolism of >15% of the 200 most marketed drugs. Open and closed crystal structures of P450 2D6 thioridazine complexes were obtained using different crystallization conditions. The protonated piperidine moiety of thioridazine forms a charge-stabilized hydrogen bond with Asp-301 in the active sites of both complexes. The more open conformation exhibits a second molecule of thioridazine bound in an expanded substrate access channel antechamber with its piperidine moiety forming a charge-stabilized hydrogen bond with Glu-222. Incubation of the crystalline open thioridazine complex with alternative ligands, prinomastat, quinidine, quinine, or ajmalicine, displaced both thioridazines. Quinine and ajmalicine formed charge-stabilized hydrogen bonds with Glu-216, whereas the protonated nitrogen of quinidine is equidistant from Asp-301 and Glu-216 with protonated nitrogen H-bonded to a water molecule in the access channel. Prinomastat is not ionized. Adaptations of active site side-chain rotamers and polypeptide conformations were evident between the complexes, with the binding of ajmalicine eliciting a closure of the open structure reflecting in part the inward movement of Glu-216 to form a hydrogen bond with ajmalicine as well as sparse lattice restraints that would hinder adaptations. These results indicate that P450 2D6 exhibits sufficient elasticity within the crystal lattice to allow the passage of compounds between the active site and bulk solvent and to adopt a more closed form that adapts for binding alternative ligands with different degrees of closure. These crystals provide a means to characterize substrate and inhibitor binding to the enzyme after replacement of thioridazine with alternative compounds. PMID:25555909

  7. Simultaneous genotyping of CYP2D6*3, *4, *5 and *6 polymorphisms in a Spanish population through multiplex long polymerase chain reaction and minisequencing multiplex single base extension analysis.

    PubMed

    Crescenti, A; Mas, S; Gassó, P; Baiget, M; Bernardo, M; Lafuente, A

    2007-10-01

    1. The aim of the present study was to perform a descriptive study of the prevalence of the four major CYP2D6 poor metaboliser (PM) alleles (*3, *4, *5 and *6) in a Spanish population (n = 290) using a method based on a new combination of multiplex long polymerase chain reaction (PCR) and minisequencing through multiplex single base extension (SBE) analysis. 2. The method was validated using different strategies, such as allelic discrimination assay and PCR-restriction fragment length polymorphism (RFLP). 3. The allele frequencies were similar to those described for other Spanish populations, namely 0.9% (95% confidence interval (CI) 0.5-1.3), 16.4% (95% CI 14.9-18.0), 2.7% (95% CI 2.0-3.4) and 0.7% (95% CI 0.3-1.0) for the *3, *4, *5 and *6 alleles, respectively. The results were satisfactory and left little doubt as to the genotypes, which were confirmed either by allelic discrimination assay (*4 and *6) or PCR-RFLP (*3) with 100% concordance. 4. The present study corroborates the low prevalence of the most frequent polymorphism (CYP2D6*4) that leads to null CYP2D6 activity in Spain and the allelic geographical gradient between Caucasian populations in the north and south. The present study reports a technique for the detection of four polymorphisms that account for 98% of the CYP2D6 defect alleles. This multiplex long PCR-SBE technique is a combination of several known methods to genotype CYP2D6 alleles (*3, *4, *5 and*6). Given the importance of CYP2D6 in drug metabolism and the need to genotype a large number of samples, we believe that this method will find broad application. PMID:17714084

  8. Influence of the CYP2D6 Isoenzyme in Patients Treated with Venlafaxine for Major Depressive Disorder: Clinical and Economic Consequences

    PubMed Central

    Sicras-Mainar, Antoni; Guijarro, Pablo; Armada, Beatriz; Blanca-Tamayo, Milagrosa; Navarro-Artieda, Ruth

    2014-01-01

    Background Antidepressant drugs are the mainstay of drug therapy for sustained remission of symptoms. However, the clinical results are not encouraging. This lack of response could be due, among other causes, to factors that alter the metabolism of the antidepressant drug. Objective: to evaluate the impact of concomitant administration of CYP2D6 inhibitors or substrates on the efficacy, tolerability and costs of patients treated with venlafaxine for major depressive disorder in clinical practice. Methods We designed an observational study using the medical records of outpatients. Subjects aged ≥18 years who started taking venlafaxine during 2008–2010 were included. Three study groups were considered: no combinations (reference), venlafaxine-substrate, and venlafaxine-inhibitor. The follow-up period was 12 months. The main variables were: demographic data, comorbidity, remission (Hamilton <7), response to treatment, adverse events and costs. The statistical analysis included logistic regression models and ANCOVA, with p values <0.05 considered significant. Results A total of 1,115 subjects were recruited. The mean age was 61.7 years and 75.1% were female. Approximately 33.3% (95% CI: 30.5 to 36.1) were receiving some kind of drug combination (venlafaxine-substrate: 23.0%, and venlafaxine-inhibitor: 10.3%). Compared with the venlafaxine-substrate and venlafaxine-inhibitor groups, patients not taking concomitant drugs had a better response to therapy (49.1% vs. 39.9% and 34.3%, p<0.01), greater remission of symptoms (59.9% vs. 50.2% and 43.8%, p<0.001), fewer adverse events (1.9% vs. 7.0% and 6.1%, p<0.05) and a lower mean adjusted cost (€2,881.7 vs. €4,963.3 and €7,389.1, p<0.001), respectively. All cost components showed these differences. Conclusions The patients treated with venlafaxine alone showed a better response to anti-depressant treatment, greater remission of symptoms, a lower incidence of adverse events and lower healthcare costs. PMID:25369508

  9. Association of CYP2D6*10, OATP1B1 A388G, and OATP1B1 T521C Polymorphisms and Overall Survival of Breast Cancer Patients after Tamoxifen Therapy

    PubMed Central

    Zhang, Xuefeng; Pu, Zhichen; Ge, Jun; Shen, Jie; Yuan, Xiaolong; Xie, Haitang

    2015-01-01

    Background The global incidence of breast cancer is increasing, mainly due to the sharp rise in breast cancer incidence in Asia. The aim of this study was to evaluate the association of CYP2D6*10 (c.100C>T and c.1039C>T), OATP1B1 A388G, and OATP1B1 T521C polymorphisms with overall survival (OS) for hormone receptor (estrogen receptor or progesterone receptor)-positive tumors (ER+/PR+) breast cancer patients after adjuvant tamoxifen (TAM) therapy. Material/Method We included 296 invasive breast cancer patients with hormone receptor-positive tumors during the period 2002–2009. We collected patient data, including clinical features, TAM therapy, and survival status. Archived paraffin blocks from surgery were the source of tissue for genotyping. CYP2D6*10, OATP1B1 A388G, and T521C polymorphisms were detected by direct sequencing of genomic DNA. OS was assessed with Kaplan-Meier analysis, while the Cox proportional hazards model was used to implement multivariate tests for the prognostic significance. Results There was a significant difference in OS between OATP1B1 T521C wild-type and the mutant genotype C carrier (P=0.034). However, there was no difference in overall survival between wild-type and carrier groups for CYP2D6*10 (P=0.096) and OATP1B1 A388G (P=0.388), respectively. Conclusions These results suggest that the OATP1B1 T521C mutation may be an independent prognostic marker for breast cancer patients using TAM therapy. PMID:25701109

  10. Role of cytochrome P450 2D6 genetic polymorphism in carvedilol hydroxylation in vitro

    PubMed Central

    Wang, Zhe; Wang, Li; Xu, Ren-ai; Zhan, Yun-yun; Huang, Cheng-ke; Dai, Da-peng; Cai, Jian-ping; Hu, Guo-xin

    2016-01-01

    Cytochrome P450 2D6 (CYP2D6) is a highly polymorphic enzyme that catalyzes the metabolism of a great number of therapeutic drugs. Up to now, >100 allelic variants of CYP2D6 have been reported. Recently, we identified 22 novel variants in the Chinese population in these variants. The purpose of this study was to examine the enzymatic activity of the variants toward the CYP2D6 substrate carvedilol in vitro. The CYP2D6 proteins, including CYP2D6.1 (wild type), CYP2D6.2, CYP2D6.10, and 22 other novel CYP2D6 variants, were expressed from insect microsomes and incubated with carvedilol ranging from 1.0 μM to 50 μM at 37°C for 30 minutes. After termination, the carvedilol metabolites were extracted and detected using ultra-performance liquid chromatography tandem mass-spectrometry. Among the 24 CYP2D6 variants, CYP2D6.92 and CYP2D6.96 were catalytically inactive and the remaining 22 variants exhibited significantly decreased intrinsic clearance values (ranging from ~25% to 95%) compared with CYP2D6.1. The present data in vitro suggest that the newly found variants significantly reduced catalytic activities compared with CYP2D6.1. Given that CYP2D6 protein activities could affect carvedilol plasma levels, these findings are greatly relevant to personalized medicine. PMID:27354764

  11. Role of cytochrome P450 2D6 genetic polymorphism in carvedilol hydroxylation in vitro.

    PubMed

    Wang, Zhe; Wang, Li; Xu, Ren-Ai; Zhan, Yun-Yun; Huang, Cheng-Ke; Dai, Da-Peng; Cai, Jian-Ping; Hu, Guo-Xin

    2016-01-01

    Cytochrome P450 2D6 (CYP2D6) is a highly polymorphic enzyme that catalyzes the metabolism of a great number of therapeutic drugs. Up to now, >100 allelic variants of CYP2D6 have been reported. Recently, we identified 22 novel variants in the Chinese population in these variants. The purpose of this study was to examine the enzymatic activity of the variants toward the CYP2D6 substrate carvedilol in vitro. The CYP2D6 proteins, including CYP2D6.1 (wild type), CYP2D6.2, CYP2D6.10, and 22 other novel CYP2D6 variants, were expressed from insect microsomes and incubated with carvedilol ranging from 1.0 μM to 50 μM at 37°C for 30 minutes. After termination, the carvedilol metabolites were extracted and detected using ultra-performance liquid chromatography tandem mass-spectrometry. Among the 24 CYP2D6 variants, CYP2D6.92 and CYP2D6.96 were catalytically inactive and the remaining 22 variants exhibited significantly decreased intrinsic clearance values (ranging from ~25% to 95%) compared with CYP2D6.1. The present data in vitro suggest that the newly found variants significantly reduced catalytic activities compared with CYP2D6.1. Given that CYP2D6 protein activities could affect carvedilol plasma levels, these findings are greatly relevant to personalized medicine. PMID:27354764

  12. Simultaneous determination of metoprolol and its metabolites, α-hydroxymetoprolol and O-desmethylmetoprolol, in human plasma by liquid chromatography with tandem mass spectrometry: Application to the pharmacokinetics of metoprolol associated with CYP2D6 genotypes.

    PubMed

    Bae, Soo Hyeon; Lee, Joeng Kee; Cho, Doo-Yeoun; Bae, Soo Kyung

    2014-06-01

    A rapid and simple LC with MS/MS method for the simultaneous determination of metoprolol and its two CYP2D6-derived metabolites, α-hydroxy- and O-desmethylmetoprolol, in human plasma was established. Metoprolol (MET), its two metabolites, and the internal standard chlorpropamide were extracted from plasma (50 μL) using ethyl acetate. Chromatographic separation was performed on a Luna CN column with an isocratic mobile phase consisting of distilled water and methanol containing 0.1% formic acid (60:40, v/v) at a flow rate of 0.3 mL/min. The total run time was 3.0 min per sample. Mass spectrometric detection was conducted by ESI in positive ion selected-reaction monitoring mode. The linear ranges of concentration for MET, α-hydroxymetoprolol, and O-desmethylmetoprolol were 2-1000, 2-500, and 2-500 ng/mL, respectively, with a lower limit of quantification of 2 ng/mL for all analytes. The coefficient of variation for the assay's precision was ≤ 13.2%, and the accuracy was 89.1-110%. All analytes were stable under various storage and handling conditions and no relevant cross-talk and matrix effect were observed. Finally, this method was successfully applied to assess the influence of CYP2D6 genotypes on the pharmacokinetics of MET after oral administration of 100 mg to healthy Korean volunteers. PMID:24648255

  13. Preemptive Pharmacogenomic Testing for Precision Medicine: A Comprehensive Analysis of Five Actionable Pharmacogenomic Genes Using Next-Generation DNA Sequencing and a Customized CYP2D6 Genotyping Cascade.

    PubMed

    Ji, Yuan; Skierka, Jennifer M; Blommel, Joseph H; Moore, Brenda E; VanCuyk, Douglas L; Bruflat, Jamie K; Peterson, Lisa M; Veldhuizen, Tamra L; Fadra, Numrah; Peterson, Sandra E; Lagerstedt, Susan A; Train, Laura J; Baudhuin, Linnea M; Klee, Eric W; Ferber, Matthew J; Bielinski, Suzette J; Caraballo, Pedro J; Weinshilboum, Richard M; Black, John L

    2016-05-01

    Significant barriers, such as lack of professional guidelines, specialized training for interpretation of pharmacogenomics (PGx) data, and insufficient evidence to support clinical utility, prevent preemptive PGx testing from being widely clinically implemented. The current study, as a pilot project for the Right Drug, Right Dose, Right Time-Using Genomic Data to Individualize Treatment Protocol, was designed to evaluate the impact of preemptive PGx and to optimize the workflow in the clinic setting. We used an 84-gene next-generation sequencing panel that included SLCO1B1, CYP2C19, CYP2C9, and VKORC1 together with a custom-designed CYP2D6 testing cascade to genotype the 1013 subjects in laboratories approved by the Clinical Laboratory Improvement Act. Actionable PGx variants were placed in patient's electronic medical records where integrated clinical decision support rules alert providers when a relevant medication is ordered. The fraction of this cohort carrying actionable PGx variant(s) in individual genes ranged from 30% (SLCO1B1) to 79% (CYP2D6). When considering all five genes together, 99% of the subjects carried an actionable PGx variant(s) in at least one gene. Our study provides evidence in favor of preemptive PGx testing by identifying the risk of a variant being present in the population we studied. PMID:26947514

  14. Cytochrome P450 2D6 enzyme neuroprotects against 1-methyl-4-phenylpyridinium toxicity in SH-SY5Y neuronal cells.

    PubMed

    Mann, Amandeep; Tyndale, Rachel F

    2010-04-01

    Cytochrome P450 (CYP) 2D6 is an enzyme that is expressed in liver and brain. It can inactivate neurotoxins such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, 1,2,3,4-tetrahydroisoquinoline and beta-carbolines. Genetically slow CYP2D6 metabolizers are at higher risk for developing Parkinson's disease, a risk that increases with exposure to pesticides. The goal of this study was to investigate the neuroprotective role of CYP2D6 in an in-vitro neurotoxicity model. SH-SY5Y human neuroblastoma cells express CYP2D6 as determined by western blotting, immunocytochemistry and enzymatic activity. CYP2D6 metabolized 3-[2-(N,N-diethyl-N-methylammonium)ethyl]-7-methoxy-4-methylcoumarin and the CYP2D6-specific inhibitor quinidine (1 microM) blocked 96 +/- 1% of this metabolism, indicating that CYP2D6 is functional in this cell line. Treatment of cells with CYP2D6 inhibitors (quinidine, propanolol, metoprolol or timolol) at varying concentrations significantly increased the neurotoxicity caused by 1-methyl-4-phenylpyridinium (MPP+) at 10 and 25 microM by between 9 +/- 1 and 22 +/- 5% (P < 0.01). We found that CYP3A is also expressed in SH-SY5Y cells and inhibiting CYP3A with ketoconazole significantly increased the cell death caused by 10 and 25 microM of MPP+ by between 8 +/- 1 and 30 +/- 3% (P < 0.001). Inhibiting both CYP2D6 and CYP3A showed an additive effect on MPP+ neurotoxicity. These data further support a possible role for CYP2D6 in neuroprotection from Parkinson's disease-causing neurotoxins, especially in the human brain where expression of CYP2D6 is high in some regions (e.g. substantia nigra). PMID:20345925

  15. The effects of H2S on the activities of CYP2B6, CYP2D6, CYP3A4, CYP2C19 and CYP2C9 in vivo in rat.

    PubMed

    Wang, Xianqin; Han, Anyue; Wen, Congcong; Chen, Mengchun; Chen, Xinxin; Yang, Xuezhi; Ma, Jianshe; Lin, Guanyang

    2013-01-01

    Hydrogen sulfide (H2S) is a colorless, flammable, extremely hazardous gas with a "rotten egg" smell. The human body produces small amounts of H2S and uses it as a signaling molecule. The cocktail method was used to evaluate the influence of H2S on the activities of CYP450 in rats, which were reflected by the changes of pharmacokinetic parameters of five specific probe drugs: bupropion, metroprolol, midazolam, omeprazole and tolbutamide, respectively. The rats were randomly divided into two groups, control group and H2S group. The H2S group rats were given 5 mg/kg NaHS by oral administration once a day for seven days. The mixture of five probes was given to rats through oral administration and the blood samples were obtained at a series of time-points through the caudal vein. The concentrations of probe drugs in rat plasma were measured by LC-MS. In comparing the H2S group with the control group, there was a statistically pharmacokinetics difference for midazolam and tolbutamide; the area under the plasma concentration-time curve (AUC) was decreased for midazolam (p < 0.05) and increased for tolbutamide (p < 0.05); while there was no statistical pharmacokinetics difference for bupropion, metroprolol and omeprazole. H2S could not influence the activities of CYP2B6, CYP2D6 and CYP2C19 in rats, while H2S could induce the activity of CYP3A4 and inhibit the activity of CYP2C9 in rats. PMID:24336065

  16. The Effects of H2S on the Activities of CYP2B6, CYP2D6, CYP3A4, CYP2C19 and CYP2C9 in Vivo in Rat

    PubMed Central

    Wang, Xianqin; Han, Anyue; Wen, Congcong; Chen, Mengchun; Chen, Xinxin; Yang, Xuezhi; Ma, Jianshe; Lin, Guanyang

    2013-01-01

    Hydrogen sulfide (H2S) is a colorless, flammable, extremely hazardous gas with a “rotten egg” smell. The human body produces small amounts of H2S and uses it as a signaling molecule. The cocktail method was used to evaluate the influence of H2S on the activities of CYP450 in rats, which were reflected by the changes of pharmacokinetic parameters of five specific probe drugs: bupropion, metroprolol, midazolam, omeprazole and tolbutamide, respectively. The rats were randomly divided into two groups, control group and H2S group. The H2S group rats were given 5 mg/kg NaHS by oral administration once a day for seven days. The mixture of five probes was given to rats through oral administration and the blood samples were obtained at a series of time-points through the caudal vein. The concentrations of probe drugs in rat plasma were measured by LC-MS. In comparing the H2S group with the control group, there was a statistically pharmacokinetics difference for midazolam and tolbutamide; the area under the plasma concentration-time curve (AUC) was decreased for midazolam (p < 0.05) and increased for tolbutamide (p < 0.05); while there was no statistical pharmacokinetics difference for bupropion, metroprolol and omeprazole. H2S could not influence the activities of CYP2B6, CYP2D6 and CYP2C19 in rats, while H2S could induce the activity of CYP3A4 and inhibit the activity of CYP2C9 in rats. PMID:24336065

  17. Farnesoid X Receptor Agonist Represses Cytochrome P450 2D6 Expression by Upregulating Small Heterodimer Partner.

    PubMed

    Pan, Xian; Lee, Yoon-Kwang; Jeong, Hyunyoung

    2015-07-01

    Cytochrome P450 2D6 (CYP2D6) is a major drug-metabolizing enzyme responsible for eliminating approximately 20% of marketed drugs. Studies have shown that differential transcriptional regulation of CYP2D6 may contribute to large interindividual variability in CYP2D6-mediated drug metabolism. However, the factors governing CYP2D6 transcription are largely unknown. We previously demonstrated small heterodimer partner (SHP) as a novel transcriptional repressor of CYP2D6 expression. SHP is a representative target gene of the farnesoid X receptor (FXR). The objective of this study is to investigate whether an agonist of FXR, 3-(2,6-dichlorophenyl)-4-(3'-carboxy-2-chlorostilben-4-yl)oxymethyl-5-isopropylisoxazole (GW4064), alters CYP2D6 expression and activity. In CYP2D6-humanized transgenic mice, GW4064 decreased hepatic CYP2D6 expression and activity (by 2-fold) while increasing SHP expression (by 2-fold) and SHP recruitment to the CYP2D6 promoter. CYP2D6 repression by GW4064 was abrogated in Shp(-/-);CYP2D6 mice, indicating a critical role of SHP in CYP2D6 regulation by GW4064. Also, GW4064 decreased CYP2D6 expression (by 2-fold) in primary human hepatocytes, suggesting that the results obtained in CYP2D6-humanized transgenic mice can be translated to humans. This proof of concept study provides evidence for CYP2D6 regulation by an inducer of SHP expression, namely, the FXR agonist GW4064. PMID:25926433

  18. Genetic variation in the 3′-UTR of CYP1A2, CYP2B6, CYP2D6, CYP3A4, NR1I2, and UGT2B7: potential effects on regulation by microRNA and pharmacogenomics relevance

    PubMed Central

    Swart, Marelize; Dandara, Collet

    2014-01-01

    Introduction: Pharmacogenomics research has concentrated on variation in genes coding for drug metabolizing enzymes, transporters and nuclear receptors. However, variation affecting microRNA could also play a role in drug response. This project set out to investigate potential microRNA target sites in 11 genes and the extent of variation in the 3′-UTR of six selected genes; CYP1A2, CYP2B6, CYP2D6, CYP3A4, NR1I2, and UGT2B7. Methods: Fifteen microRNA target prediction algorithms were used to identify microRNAs predicted to regulate 11 genes. The 3′-UTR of the 6 genes which topped the list of potential microRNA targets was sequenced in 30 black South Africans. In addition, genetic variants within these genes were investigated for interference with mRNA-microRNA interactions. Potential effects of observed variants were determined using in silico prediction tools. Results: The 11 genes coding for DMEs, transporters and nuclear receptors were predicted to be targets of microRNAs with CYP2B6, NR1I2 (PXR), CYP3A4, and CYP1A2, interacting with the most microRNAs. The majority of identified genetic variants were predicted to interfere with microRNA regulation. For example, the variant, rs1054190C in NR1I2 was predicted to result in the presence of a binding site for the microRNA miR-1250-5p, while the variant rs1054191G was predicted to result in the absence of a recognition site for miR-371b-3p, miR-4258 and miR-4707-3p. Fifteen of the seventeen, novel variants occurred within microRNA target sequences. Conclusion: The 3′-UTR harbors variation that is likely to influence regulation of specific genes by microRNA. In silico prediction followed by functional validation could aid in decoding the contribution of variation in the 3′-UTR, to some unexplained heritability that affects drug response. Understanding the specific role of each microRNA may lead to identification of markers for targeted therapy and therefore improve personalized drug treatment. PMID:24926315

  19. Long-Read Single Molecule Real-Time Full Gene Sequencing of Cytochrome P450-2D6.

    PubMed

    Qiao, Wanqiong; Yang, Yao; Sebra, Robert; Mendiratta, Geetu; Gaedigk, Andrea; Desnick, Robert J; Scott, Stuart A

    2016-03-01

    The cytochrome P450-2D6 (CYP2D6) enzyme metabolizes ∼25% of common medications, yet homologous pseudogenes and copy number variants (CNVs) make interrogating the polymorphic CYP2D6 gene with short-read sequencing challenging. Therefore, we developed a novel long-read, full gene CYP2D6 single molecule real-time (SMRT) sequencing method using the Pacific Biosciences platform. Long-range PCR and CYP2D6 SMRT sequencing of 10 previously genotyped controls identified expected star (*) alleles, but also enabled suballele resolution, diplotype refinement, and discovery of novel alleles. Coupled with an optimized variant-calling pipeline, CYP2D6 SMRT sequencing was highly reproducible as triplicate intra- and inter-run nonreference genotype results were completely concordant. Importantly, targeted SMRT sequencing of upstream and downstream CYP2D6 gene copies characterized the duplicated allele in 15 control samples with CYP2D6 CNVs. The utility of CYP2D6 SMRT sequencing was further underscored by identifying the diplotypes of 14 samples with discordant or unclear CYP2D6 configurations from previous targeted genotyping, which again included suballele resolution, duplicated allele characterization, and discovery of a novel allele and tandem arrangement. Taken together, long-read CYP2D6 SMRT sequencing is an innovative, reproducible, and validated method for full-gene characterization, duplication allele-specific analysis, and novel allele discovery, which will likely improve CYP2D6 metabolizer phenotype prediction for both research and clinical testing applications. PMID:26602992

  20. Cytochrome P450-2D6 Screening Among Elderly Using Antidepressants (CYSCE)

    ClinicalTrials.gov

    2015-12-09

    Depression; Depressive Disorder; Poor Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Intermediate Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Ultrarapid Metabolizer Due to Cytochrome P450 CYP2D6 Variant

  1. Cytochrome P450 2D6 Polymorphisms and Predicted Opioid Metabolism in African-American Children with Sickle Cell Disease

    PubMed Central

    Yee, Marianne McPherson; Josephson, Cassandra; Hill, Charles E.; Harrington, Rosiland; Castillejo, Marta-Inés; Ramjit, Ruan; Osunkwo, Ifeyinwa

    2013-01-01

    The opioid medications codeine and hydrocodone, commonly prescribed in sickle cell disease (SCD), require metabolic conversion by cytochrome P450 2D6 (CYP2D6) to morphine and hydromorphone, respectively, to exert their analgesic effects. The CYP2D6 gene is highly polymorphic, with variant alleles that result in decreased, absent, or ultrarapid enzyme activity. Seventy-five children with SCD were tested for CYP2D6 polymorphisms, and metabolic phenotypes were inferred from the genotypes. The most common variant alleles were CYP2D6*2 (normal activity, 28.7%), CYP2D6*17 (reduced activity, 17.3%), CYP2D6*5 (gene deletion, 8.7%), and CYP2D6*4 (absent function, 8.0%). Normal/extensive metabolizer (EM) genotypes were found in 28/75 (37.5%), intermediate metabolism (IM) in 33/75 (44.0%), poor metabolism (PM) in 4/75 (5.3%), ultrarapid metabolism (UM) in 3/75 (4.0%), indeterminate in 6/75 (8.0%). Allele frequencies did not vary significantly among different hemoglobin genotypes. Identification of variant CYP2D6 genotypes may identify individuals with altered metabolism and therefore altered analgesic response to codeine and hydrocodone, thus providing a personalized medicine approach to treatment of pain in SCD. Further pharmacokinetic and pharmacodynamic studies are needed to define the relationship of CYP2D6 and other gene polymorphisms to individual opioid effect in SCD. PMID:23619115

  2. Effects of monoamine oxidase inhibitor and cytochrome P450 2D6 status on 5-Methoxy-N,N-dimethyltryptamine Metabolism and Pharmacokinetics

    PubMed Central

    Shen, Hong-Wu; Wu, Chao; Jiang, Xi-Ling; Yu, Ai-Ming

    2010-01-01

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a natural psychoactive indolealkylamine drug that has been used for recreational purpose. Our previous study revealed that polymorphic cytochrome P450 2D6 (CYP2D6) catalyzed 5-MeO-DMT O-demethylation to produce active metabolite bufotenine, while 5-MeO-DMT is mainly inactivated through deamination pathway mediated by monoamine oxidase (MAO). This study, therefore, aimed to investigate the impact of CYP2D6 genotype/phenotype status and MAO inhibitor (MAOI) on 5-MeO-DMT metabolism and pharmacokinetics. Enzyme kinetic studies using recombinant CYP2D6 allelic isozymes showed that CYP2D6.2 and CYP2D6.10 exhibited 2.6- and 40-fold lower catalytic efficiency (Vmax/Km), respectively, in producing bufotenine from 5-MeO-DMT, compared with wild-type CYP2D6.1. When co-incubated with MAOI pargyline, 5-MeO-DMT O-demethylation in 10 human liver microsomes showed significantly strong correlation with bufuralol 1’-hydroxylase activities (R² = 0.98; p < 0.0001) and CYP2D6 contents (R² = 0.77; p = 0.0007), whereas no appreciable correlations with enzymatic activities of other P450 enzymes. Furthermore, concurrent MAOI harmaline sharply reduced 5-MeO-DMT depletion and increased bufotenine formation in human CYP2D6 extensive metabolizer hepatocytes. In vivo studies in wild-type and CYP2D6-humanized (Tg-CYP2D6) mouse models showed that Tg-CYP2D6 mice receiving the same dose of 5-MeO-DMT (20 mg/kg, i.p.) had 60% higher systemic exposure to metabolite bufotenine. In addition, pre-treatment of harmaline (5 mg/kg, i.p.) led to 3.6- and 4.4-fold higher systemic exposure to 5-MeO-DMT (2 mg/kg, i.p.), and 9.9- and 6.1-fold higher systemic exposure to bufotenine in Tg-CYP2D6 and wild-type mice, respectively. These findings indicate that MAOI largely affects 5-MeO-DMT metabolism and pharmacokinetics, as well as bufotenine formation that is mediated by CYP2D6. PMID:20206139

  3. Effects of monoamine oxidase inhibitor and cytochrome P450 2D6 status on 5-methoxy-N,N-dimethyltryptamine metabolism and pharmacokinetics.

    PubMed

    Shen, Hong-Wu; Wu, Chao; Jiang, Xi-Ling; Yu, Ai-Ming

    2010-07-01

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a natural psychoactive indolealkylamine drug that has been used for recreational purpose. Our previous study revealed that polymorphic cytochrome P450 2D6 (CYP2D6) catalyzed 5-MeO-DMT O-demethylation to produce active metabolite bufotenine, while 5-MeO-DMT is mainly inactivated through deamination pathway mediated by monoamine oxidase (MAO). This study, therefore, aimed to investigate the impact of CYP2D6 genotype/phenotype status and MAO inhibitor (MAOI) on 5-MeO-DMT metabolism and pharmacokinetics. Enzyme kinetic studies using recombinant CYP2D6 allelic isozymes showed that CYP2D6.2 and CYP2D6.10 exhibited 2.6- and 40-fold lower catalytic efficiency (V(max)/K(m)), respectively, in producing bufotenine from 5-MeO-DMT, compared with wild-type CYP2D6.1. When co-incubated with MAOI pargyline, 5-MeO-DMT O-demethylation in 10 human liver microsomes showed significantly strong correlation with bufuralol 1'-hydroxylase activities (R(2)=0.98; P<0.0001) and CYP2D6 contents (R(2)=0.77; P=0.0007), whereas no appreciable correlations with enzymatic activities of other P450 enzymes. Furthermore, concurrent MAOI harmaline sharply reduced 5-MeO-DMT depletion and increased bufotenine formation in human CYP2D6 extensive metabolizer hepatocytes. In vivo studies in wild-type and CYP2D6-humanized (Tg-CYP2D6) mouse models showed that Tg-CYP2D6 mice receiving the same dose of 5-MeO-DMT (20mg/kg, i.p.) had 60% higher systemic exposure to metabolite bufotenine. In addition, pretreatment of harmaline (5mg/kg, i.p.) led to 3.6- and 4.4-fold higher systemic exposure to 5-MeO-DMT (2mg/kg, i.p.), and 9.9- and 6.1-fold higher systemic exposure to bufotenine in Tg-CYP2D6 and wild-type mice, respectively. These findings indicate that MAOI largely affects 5-MeO-DMT metabolism and pharmacokinetics, as well as bufotenine formation that is mediated by CYP2D6. PMID:20206139

  4. Molecular Dynamics Simulations to Investigate the Influences of Amino Acid Mutations on Protein Three-Dimensional Structures of Cytochrome P450 2D6.1, 2, 10, 14A, 51, and 62

    PubMed Central

    Watanabe, Yurie; Hiratsuka, Masahiro; Yamaotsu, Noriyuki; Hirono, Shuichi; Manabe, Noriyoshi; Takahashi, Ohgi; Oda, Akifumi

    2016-01-01

    Many natural mutants of the drug metabolizing enzyme cytochrome P450 (CYP) 2D6 have been reported. Because the enzymatic activities of many mutants are different from that of the wild type, the genetic polymorphism of CYP2D6 plays an important role in drug metabolism. In this study, the molecular dynamics simulations of the wild type and mutants of CYP2D6, CYP2D6.1, 2, 10, 14A, 51, and 62 were performed, and the predictions of static and dynamic structures within them were conducted. In the mutant CYP2D6.10, 14A, and 61, dynamic properties of the F-G loop, which is one of the components of the active site access channel of CYP2D6, were different from that of the wild type. The F-G loop acted as the “hatch” of the channel, which was closed in those mutants. The structure of CYP2D6.51 was not converged by the simulation, which indicated that the three-dimensional structure of CYP2D6.51 was largely different from that of the wild type. In addition, the intramolecular interaction network of CYP2D6.10, 14A, and 61 was different from that of the wild type, and it is considered that these structural changes are the reason for the decrease or loss of enzymatic activities. On the other hand, the static and dynamic properties of CYP2D6.2, whose activity was normal, were not considerably different from those of the wild type. PMID:27046024

  5. Metabolism of 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine by Mitochondrion-targeted Cytochrome P450 2D6

    PubMed Central

    Bajpai, Prachi; Sangar, Michelle C.; Singh, Shilpee; Tang, Weigang; Bansal, Seema; Chowdhury, Goutam; Cheng, Qian; Fang, Ji-Kang; Martin, Martha V.; Guengerich, F. Peter; Avadhani, Narayan G.

    2013-01-01

    1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxic side product formed in the chemical synthesis of desmethylprodine opioid analgesic, which induces Parkinson disease. Monoamine oxidase B, present in the mitochondrial outer membrane of glial cells, catalyzes the oxidation of MPTP to the toxic 1-methyl-4-phenylpyridinium ion (MPP+), which then targets the dopaminergic neurons causing neuronal death. Here, we demonstrate that mitochondrion-targeted human cytochrome P450 2D6 (CYP2D6), supported by mitochondrial adrenodoxin and adrenodoxin reductase, can efficiently catalyze the metabolism of MPTP to MPP+, as shown with purified enzymes and also in cells expressing mitochondrial CYP2D6. Neuro-2A cells stably expressing predominantly mitochondrion-targeted CYP2D6 were more sensitive to MPTP-mediated mitochondrial respiratory dysfunction and complex I inhibition than cells expressing predominantly endoplasmic reticulum-targeted CYP2D6. Mitochondrial CYP2D6 expressing Neuro-2A cells produced higher levels of reactive oxygen species and showed abnormal mitochondrial structures. MPTP treatment also induced mitochondrial translocation of an autophagic marker, Parkin, and a mitochondrial fission marker, Drp1, in differentiated neurons expressing mitochondrial CYP2D6. MPTP-mediated toxicity in primary dopaminergic neurons was attenuated by CYP2D6 inhibitor, quinidine, and also partly by monoamine oxidase B inhibitors deprenyl and pargyline. These studies show for the first time that dopaminergic neurons expressing mitochondrial CYP2D6 are fully capable of activating the pro-neurotoxin MPTP and inducing neuronal damage, which is effectively prevented by the CYP2D6 inhibitor quinidine. PMID:23258538

  6. Cytochrome P450 2D6 Activity Predicts Discontinuation of Tamoxifen Therapy in Breast Cancer Patients

    PubMed Central

    Rae, James M.; Sikora, Matthew J.; Henry, N. Lynn; Li, Lang; Kim, Seongho; Oesterreich, Steffi; Skaar, Todd; Nguyen, Anne T.; Desta, Zeruesenay; Storniolo, Anna Maria; Flockhart, David A.; Hayes, Daniel F.; Stearns, Vered

    2009-01-01

    The selective estrogen receptor modulator tamoxifen is routinely used for treatment and prevention of estrogen receptor positive breast cancer. Studies of tamoxifen adherence suggest that over half of patients discontinue treatment before the recommended 5 years. We hypothesized that polymorphisms in CYP2D6, the enzyme responsible for tamoxifen activation, predict for tamoxifen discontinuation. Tamoxifen-treated women (n = 297) were genotyped for CYP2D6 variants and assigned a “score” based on predicted allele activities from 0 (no activity) to 2 (high activity). Correlation between CYP2D6 score and discontinuation rates at 4 months were tested. We observed a strong non-linear correlation between higher CYP2D6 score and increased rates of discontinuation (r2 = 0.935, p = 0.018). These data suggest that presence of active CYP2D6 alleles may predict for higher likelihood of tamoxifen discontinuation. Therefore, patients who may be most likely to benefit from tamoxifen may paradoxically be most likely to discontinue treatment prematurely. PMID:19421167

  7. Clinical Pharmacogenetics Implementation Consortium guidelines for cytochrome P450 2D6 genotype and codeine therapy: 2014 update.

    PubMed

    Crews, K R; Gaedigk, A; Dunnenberger, H M; Leeder, J S; Klein, T E; Caudle, K E; Haidar, C E; Shen, D D; Callaghan, J T; Sadhasivam, S; Prows, C A; Kharasch, E D; Skaar, T C

    2014-04-01

    Codeine is bioactivated to morphine, a strong opioid agonist, by the hepatic cytochrome P450 2D6 (CYP2D6); hence, the efficacy and safety of codeine are governed by CYP2D6 activity. Polymorphisms are a major cause of CYP2D6 variability. We summarize evidence from the literature supporting this association and provide therapeutic recommendations for codeine based on CYP2D6 genotype. This document is an update to the 2012 Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines for CYP2D6 genotype and codeine therapy. PMID:24458010

  8. Substituted Imidazole of 5-Fluoro-2-[4-[(2-phenyl-1H-imidazol-5-yl)methyl]-1-piperazinyl]pyrimidine Inactivates Cytochrome P450 2D6 by Protein Adduction

    PubMed Central

    Nagy, Leslie D.; Mocny, Catherine S.; Diffenderfer, Laura E.; Hsi, David J.; Butler, Brendan F.; Arthur, Evan J.; Fletke, Kyle J.; Palamanda, Jairam R.; Nomeir, Amin A.

    2011-01-01

    5-Fluoro-2-[4-[(2-phenyl-1H-imidazol-5-yl)methyl]-1-piperazinyl]pyrimidine (SCH 66712) is a potent mechanism-based inactivator of human cytochrome P450 2D6 that displays type I binding spectra with a Ks of 0.39 ± 0.10 μM. The partition ratio is ∼3, indicating potent inactivation that addition of exogenous nucleophiles does not prevent. Within 15 min of incubation with SCH 66712 and NADPH, ∼90% of CYP2D6 activity is lost with only ∼20% loss in ability to bind CO and ∼25% loss of native heme over the same time. The stoichiometry of binding to the protein was 1.2:1. SDS-polyacrylamide gel electrophoresis with Western blotting and autoradiography analyses of CYP2D6 after incubations with radiolabeled SCH 66712 further support the presence of a protein adduct. Metabolites of SCH 66712 detected by mass spectrometry indicate that the phenyl group on the imidazole ring of SCH 66712 is one site of oxidation by CYP2D6 and could lead to methylene quinone formation. Three other metabolites were also observed. For understanding the metabolic pathway that leads to CYP2D6 inactivation, metabolism studies with CYP2C9 and CYP2C19 were performed because neither of these enzymes is significantly inhibited by SCH 66712. The metabolites formed by CYP2C9 and CYP2C19 are the same as those seen with CYP2D6, although in different abundance. Modeling studies with CYP2D6 revealed potential roles of various active site residues in the oxidation of SCH 66712 and inactivation of CYP2D6 and showed that the phenyl group of SCH 66712 is positioned at 2.2 Å from the heme iron. PMID:21422192

  9. Binding of 7-methoxy-4-(aminomethyl)-coumarin to wild-type and W128F mutant cytochrome P450 2D6 studied by time-resolved fluorescence spectroscopy

    PubMed Central

    Stortelder, Aike; Keizers, Peter H. J.; Oostenbrink, Chris; De Graaf, Chris; De Kruijf, Petra; Vermeulen, Nico P. E.; Gooijer, Cees; Commandeur, Jan N. M.; Van Der Zwan, Gert

    2005-01-01

    Enzyme structure and dynamics may play a main role in substrate binding and the subsequent steps in the CYP (cytochrome P450) catalytic cycle. In the present study, changes in the structure of human CYP2D6 upon binding of the substrate are studied using steady-state and time-resolved fluorescence methods, focusing not only on the emission of the tryptophan residues, but also on emission of the substrate. As a substrate, MAMC [7-methoxy-4-(aminomethyl)-coumarin] was selected, a compound exhibiting native fluorescence. As well as the wild-type, the W128F (Trp128→Phe) mutant of CYP2D6 was studied. After binding, a variety of energy transfer possibilities exist, and molecular dynamics simulations were performed to calculate distances and relative orientations of donors and acceptors. Energy transfer from Trp128 to haem appeared to be important; its emission was related to the shortest of the three average tryptophan fluorescence lifetimes observed for CYP2D6. MAMC to haem energy transfer was very efficient as well: when bound in the active site, the emission of MAMC was fully quenched. Steady-state anisotropy revealed that besides the MAMC in the active site, another 2.4% of MAMC was bound outside of the active site to wild-type CYP2D6. The tryptophan residues in CYP2D6 appeared to be less accessible for the external quenchers iodide and acrylamide in presence of MAMC, indicating a tightening of the enzyme structure upon substrate binding. However, the changes in the overall enzyme structure were not very large, since the emission characteristics of the enzyme were not very different in the presence of MAMC. PMID:16190863

  10. Polymorphism of human cytochrome P450 2D6 and its clinical significance: part II.

    PubMed

    Zhou, Shu-Feng

    2009-01-01

    Part I of this article discussed the potential functional importance of genetic mutations and alleles of the human cytochrome P450 2D6 (CYP2D6) gene. The impact of CYP2D6 polymorphisms on the clearance of and response to a series of cardiovascular drugs was addressed. Since CYP2D6 plays a major role in the metabolism of a large number of other drugs, Part II of the article highlights the impact of CYP2D6 polymorphisms on the response to other groups of clinically used drugs. Although clinical studies have observed a gene-dose effect for some tricyclic antidepressants, it is difficult to establish clear relationships of their pharmacokinetics and pharmacodynamic parameters to genetic variations of CYP2D6; therefore, dosage adjustment based on the CYP2D6 phenotype cannot be recommended at present. There is initial evidence for a gene-dose effect on commonly used selective serotonin reuptake inhibitors (SSRIs), but data on the effect of the CYP2D6 genotype/phenotype on the response to SSRIs and their adverse effects are scanty. Therefore, recommendations for dose adjustment of prescribed SSRIs based on the CYP2D6 genotype/phenotype may be premature. A number of clinical studies have indicated that there are significant relationships between the CYP2D6 genotype and steady-state concentrations of perphenazine, zuclopenthixol, risperidone and haloperidol. However, findings on the relationships between the CYP2D6 genotype and parkinsonism or tardive dyskinesia treatment with traditional antipsychotics are conflicting, probably because of small sample size, inclusion of antipsychotics with variable CYP2D6 metabolism, and co-medication. CYP2D6 phenotyping and genotyping appear to be useful in predicting steady-state concentrations of some classical antipsychotic drugs, but their usefulness in predicting clinical effects must be explored. Therapeutic drug monitoring has been strongly recommended for many antipsychotics, including haloperidol, chlorpromazine, fluphenazine

  11. Comparative aromatic hydroxylation and N-demethylation of MPTP neurotoxin and its analogs, N-methylated {beta}-carboline and isoquinoline alkaloids, by human cytochrome P450 2D6

    SciTech Connect

    Herraiz, Tomas . E-mail: therraiz@ifi.csic.es; Guillen, Hugo; Aran, Vicente J.; Idle, Jeffrey R.; Gonzalez, Frank J.

    2006-11-01

    1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxin is a chemical inducer of Parkinson's disease (PD) whereas N-methylated {beta}-carbolines and isoquinolines are naturally occurring analogues of MPTP involved in PD. This research has studied the oxidation of MPTP by human CYP2D6 (CYP2D6*1 and CYP2D6*10 allelic variants) as well as by a mixture of cytochrome P450s-resembling HLM, and the products generated compared with those afforded by human monoamine oxidase (MAO-B). MPTP was efficiently oxidized by CYP2D6 to two main products: MPTP-OH (p-hydroxylation) and PTP (N-demethylation), with turnover numbers of 10.09 min{sup -1} and K {sub m} of 79.36 {+-} 3 {mu}M (formation of MPTP-OH) and 18.95 min{sup -1} and K {sub m} 69.6 {+-} 2.2 {mu}M (PTP). Small amounts of dehydrogenated toxins MPDP{sup +} and MPP{sup +} were also detected. CYP2D6 competed with MAO-B for the oxidation of MPTP. MPTP oxidation by MAO-B to MPDP{sup +} and MPP{sup +} toxins (bioactivation) was up to 3-fold higher than CYP2D6 detoxification to PTP and MPTP-OH. Several N-methylated {beta}-carbolines and isoquinolines were screened for N-demethylation (detoxification) that was not significantly catalyzed by CYP2D6 or the P450s mixture. In contrast, various {beta}-carbolines were efficiently hydroxylated to hydroxy-{beta}-carbolines by CYP2D6. Thus, N(2)-methyl-1,2,3,4-tetrahydro-{beta}-carboline (a close MPTP analog) was highly hydroxylated to 6-hydroxy-N(2)-methyl-1,2,3,4-tetrahydro-{beta}-carboline and a corresponding 7-hydroxy-derivative. Thus, CYP2D6 could participate in the bioactivation and/or detoxification of these neuroactive compounds by an active hydroxylation pathway. The CYP2D6*1 enzymatic variant exhibited much higher metabolism of both MPTP and N(2)-methyl-1,2,3,4-tetrahydro-{beta}-carboline than the CYP2D6*10 variant, highlighting the importance of CYP2D6 polymorphism in the oxidation of these toxins. Altogether, these results suggest that CYP2D6 can play an important role

  12. Cytochrome P450 bio-affinity detection coupled to gradient HPLC: on-line screening of affinities to cytochrome P4501A2 and 2D6.

    PubMed

    Kool, Jeroen; van Liempd, Sebastiaan M; Harmsen, Stefan; Beckman, Joran; van Elswijk, Danny; Commandeur, Jan N M; Irth, Hubertus; Vermeulen, Nico P E

    2007-10-15

    Here we describe novel on-line human CYP1A2 and CYP2D6 Enzyme Affinity Detection (EAD) systems coupled to gradient HPLC. The use of the systems lies in the detection of individual inhibitory ligands in mixtures (e.g. metabolic mixtures or herbal extracts) towards two relevant drug metabolizing human CYPs. The systems can rapidly detect individual compounds in mixtures with affinities to CYP1A2 or 2D6. The HPLC-EAD systems were first evaluated and validated in flow injection analysis mode. IC50 values of known ligands for both CYPs, tested both in flow injection and in HPLC mode, were well comparable with those measured in microplate reader formats. Both EAD systems were also connected to gradient HPLC and used to screen known compound mixtures for the presence of CYP1A2 and 2D6 inhibitors. Finally, the on-line CYP2D6 EAD system was used to screen for the inhibitory activities of stereoisomers of a mixture of five methylenedioxy-alkylamphetamines (XTC analogs) on a chiral analytical column. PMID:17826363

  13. Characterization of hepatic enzyme activity in older adults with dementia: potential impact on personalizing pharmacotherapy

    PubMed Central

    Campbell, Noll L; Skaar, Todd C; Perkins, Anthony J; Gao, Sujuan; Li, Lang; Khan, Babar A; Boustani, Malaz A

    2015-01-01

    Objective To determine the frequency of pharmacogenomic variants and concurrent medications that may alter the efficacy and tolerability of acetylcholinesterase inhibitors (AChEIs). Materials and methods A multisite cross-sectional study was carried out across four memory care practices in the greater Indianapolis area. Participants were adults aged 65 years and older with a diagnosis of probable or possible Alzheimer’s disease (AD) (n=105). Blood samples and self-reported medication data were collected. Since two of the three AChEIs are metabolized by cytochrome P450 (CYP)-2D6, we determined the frequency of functional genetic variants in the CYP2D6 gene and calculated their predicted CYP2D6-activity scores. Concurrent medication data were collected from self-reported medication surveys, and their predicted effect on the pharmacokinetics of AChEIs was determined based on their known effects on CYP2D6 and CYP3A4/5 enzyme activities. Results Among the 105 subjects enrolled, 72% were female and 36% were African American. Subjects had a mean age of 79.6 years. The population used a mean of eight medications per day (prescription and nonprescription). The CYP2D6 activity score frequencies were 0 (3.8%), 0.5 (4.8%), 1.0 (36.2%), 1.5–2.0 (51.4%), and >2.0 (3.8%). Nineteen subjects (18.1%) used a medication considered a strong or moderate inhibitor of CYP2D6, and eight subjects (7.6%) used a medication considered a strong or moderate inhibitor of CYP3A4/5. In total, 28.6% of the study population was predicted to have reduced activity of the CYP2D6 or CYP3A4/5 enzymes due to either genetic variants or concomitant medications. Conclusion Both pharmacogenetic variants and concurrent drug therapies that are predicted to alter the pharmacokinetics of AChEIs should be evaluated in older adults with AD. Pharmacogenetic and drug-interaction data may help personalize AD therapy and increase adherence by improving tolerability. PMID:25609939

  14. Potent inhibition of human cytochrome P450 3A4, 2D6, and 2C9 isoenzymes by grapefruit juice and its furocoumarins.

    PubMed

    Girennavar, B; Jayaprakasha, G K; Patil, B S

    2007-10-01

    The cytochrome P450 enzyme family is the most abundant and responsible for the metabolism of more than 60% of currently marketed drugs and is considered central in many clinically important drug interactions. Seven different grapefruit and pummelo juices as well as 5 furocoumarins isolated from grapefruit juice were evaluated at different concentration on cytochrome P450 3A4 (CYP3A4), cytochrome P450 2C9 (CYP2C9), and cytochrome P450 2D6 (CYP2D6) isoenzyme activity. Grapefruit and pummelo juices were found to be potent inhibitors of cytochrome CYP3A4 and CYP2C9 isoenzymes at 25% concentration, while CYP2D6 is inhibited significantly low at all the tested concentration of juices (P < 0.05). Among the 5 furocoumarins tested, the inhibitory potency was in the order of paradisin A > dihydroxybergamottin > bergamottin > bergaptol > geranylcoumarin at 0.1 microM to 0.1 mM concentrations. The IC(50) value was lowest for paradisin A for CYP3A4 with 0.11 microM followed by DHB for CYP2C9 with 1.58 microM. PMID:17995595

  15. Inhibitory effect of mitragynine on human cytochrome P450 enzyme activities

    PubMed Central

    Hanapi, N. A.; Ismail, S.; Mansor, S. M.

    2013-01-01

    Context: To date, many findings reveal that most of the modern drugs have the ability to interact with herbal drugs. Aims: This study was conducted to determine the inhibitory effects of mitragynine on cytochrome P450 2C9, 2D6 and 3A4 activities. Methods and Material: The in vitro study was conducted using a high-throughput luminescence assay. Statistical Analysis: Statistical analysis was conducted using one-way ANOVA and Dunnett's test with P < 0.05 vs. control. The IC50 values were calculated using the GraphPad Prism® 5 (Version 5.01, GraphPad Software, Inc., USA). Results: Assessment using recombinant enzymes showed that mitragynine gave the strongest inhibitory effect on CYP2D6 with an IC50 value of 0.45±0.33 mM, followed by CYP2C9 and CYP3A4 with IC50 values of 9.70±4.80 and 41.32±6.74 μM respectively. Positive inhibitors appropriate for CYP2C9, CYP2D6, and CYP3A4 which are sulfaphenazole, quinidine and ketoconazole were used respectively. Vmax values of CYP2C9, CYP2D6 and CYP3A4 were 0.0005, 0.01155 and 0.0137 μM luciferin formed/pmol/min respectively. Km values of CYP2C9, CYP2D6, and CYP3A4 were 32.65, 56.01, and 103.30 μM respectively. Mitragynine noncompetitively inhibits CYP2C9 and CYP2D6 activities with the Ki values of 61.48 and 12.86 μM respectively. On the other hand, mitragynine inhibits CYP3A4 competitively with a Ki value of 379.18 μM. Conclusions: The findings of this study reveal that mitragynine might inhibit cytochrome P450 enzyme activities, specifically CYP2D6. Therefore, administration of mitragynine together with herbal or modern drugs which follow the same metabolic pathway may contribute to herb-drug interactions. PMID:24174816

  16. Development of a V79 cell line expressing human cytochrome P450 2D6 and its application as a metabolic screening tool.

    PubMed

    Rauschenbach, R; Gieschen, H; Salomon, B; Kraus, C; Kühne, G; Hildebrand, M

    1997-02-15

    Expression of human cytochrome P450 (CYP) in heterologous cells is a means of specifically studying the role of these enzymes in drug metabolism. The complete cDNA encoding CYP2D6-VAL(374) was inserted into an expression vector containing the strong mycloproliferative sarcoma virus promotor in combination with the enhancer of the cytomegalovirus and stably expressed in V79 Chinese hamster cells. The presence of genomically integrated CYP2D6 cDNA was confirmed by polymerase chain reaction analysis. The protein expression was shown by Western blotting. Functional expression could be demonstrated by O-demethylation of dextromethorphan to dextrorphan in live cells. The enzymatic activity of 154 ± 16 pmol min(-1) mg(-1) protein was comparable with dextromethorphan-O-demethylation activities of human liver. The metabolism of two dopaminergic ergoline derivatives was investigated in whole recombinant V19 cells. Both lisuride and terguride were monodeethylated; in case of lisuride a correlation to the in vivo situation was demonstrated comparing poor and extensive metabolizers. PMID:21781755

  17. Functional Polymorphisms in Xenobiotic Metabolizing Enzymes and Their Impact on the Therapy of Breast Cancer

    PubMed Central

    Vianna-Jorge, Rosane; Festa-Vasconcellos, Juliana Simões; Goulart-Citrangulo, Sheyla Maria Torres; Leite, Marcelo Sobral

    2013-01-01

    Breast cancer is the top cancer among women, and its incidence is increasing worldwide. Although the mortality tends to decrease due to early detection and treatment, there is great variability in the rates of clinical response and survival, which makes breast cancer one of the most appealing targets for pharmacogenomic studies. The recognition that functional CYP2D6 polymorphisms affect tamoxifen pharmacokinetics has motivated the attempts of using CYP2D6 genotyping for predicting breast cancer outcomes. In addition to tamoxifen, the chemotherapy of breast cancer includes combinations of cytotoxic drugs, which are substrates for various xenobiotic metabolizing enzymes. Because of these drugs’ narrow therapeutic window, it has been postulated that impaired biotransformation could lead to increased toxicity. In the present review, we performed a systematic search of all published data exploring associations between polymorphisms in xenobiotic metabolizing enzymes and clinical outcomes of breast cancer. We retrieved 43 original articles involving either tamoxifen or other chemotherapeutic protocols, and compiled all information regarding response or toxicity. The data indicate that, although CYP2D6 polymorphisms can indeed modify tamoxifen pharmacokinetics, CYP2D6 genotyping alone is not enough for predicting breast cancer outcomes. The studies involving other chemotherapeutic protocols explored a great diversity of pharmacogenetic targets, but the number of studies for each functional polymorphism is still very limited, with usually no confirmation of positive associations. In conclusion, the application of pharmacogenetics to predict breast cancer outcomes and to select one individual’s chemotherapeutic protocol is still far from clinical routine. Although some very interesting results have been produced, no clear practical recommendations are recognized yet. PMID:23346096

  18. Inhibition of human cytochrome P450 enzymes by the natural hepatotoxin safrole.

    PubMed

    Ueng, Yune-Fang; Hsieh, Chih-Hang; Don, Ming-Jaw

    2005-05-01

    The hepatotoxin, safrole is a methylenedioxy phenyl compound, found in sassafras oil and certain other essential oils. Recombinant cytochrome P450 (CYP, P450) and human liver microsomes were studied to investigate the selective inhibitory effects of safrole on human P450 enzymes and the mechanisms of action. Using Escherichia coli-expressed human P450, our results demonstrated that safrole was a non-selective inhibitor of CYP1A2, CYP2A6, CYP2D6, CYP2E1, and CYP3A4 in the IC(50) order CYP2E1 < CYP1A2 < CYP2A6 < CYP3A4 < CYP2D6. Safrole strongly inhibited CYP1A2, CYP2A6, and CYP2E1 activities with IC(50) values less than 20 microM. Safrole caused competitive, non-competitive, and non-competitive inhibition of CYP1A2, CYP2A6 and CYP2E1 activities, respectively. The inhibitor constants were in the order CYP1A2 < CYP2E1 < CYP2A6. In human liver microsomes, 50 microM safrole strongly inhibited 7-ethoxyresorufin O-deethylation, coumarin hydroxylation, and chlorzoxazone hydroxylation activities. These results revealed that safrole was a potent inhibitor of human CYP1A2, CYP2A6, and CYP2E1. With relatively less potency, CYP2D6 and CYP3A4 were also inhibited. PMID:15778010

  19. Inhibition of Recombinant Cytochrome P450 Isoforms 2D6 and 2C9 by Diverse Drug-like Molecules

    PubMed Central

    McMasters, Daniel R.; Torres, Rhonda A.; Crathern, Susan J.; Dooney, Deborah L.; Nachbar, Robert B.; Sheridan, Robert P.; Korzekwa, Kenneth R.

    2008-01-01

    The affinities of a diverse set of 500 drug-like molecules to cytochrome P450 isoforms 2C9 and 2D6 were measured using recombinant expressed enzyme. The dose–response curve of each compound was fitted with a series of equations representing typical or various types of atypical kinetics. Atypical kinetics was identified where the Akaike Information Criterion, plus other criteria, suggested the kinetics was more complex than expected for a Michaelis–Menten model. Approximately 20% of the compounds were excluded due to poor solubility, and approximately 15% were excluded due to fluorescence interference. Of the remaining compounds, roughly half were observed to bind with an affinity of 200 μM or lower for each of the two isoforms. Atypical kinetics were observed in 18 percent of the compounds that bind to cytochrome 2C9 but less than 2 percent for 2D6. The resulting collection of competitive inhibitors and inactive compounds was analyzed for trends in binding affinity. For CYP2D6, a clear relationship between polar surface area and charge was observed, with the most potent inhibitors having a formal positive charge and a low percent polar surface area. For CYP2C9, no clear trend between activity and physicochemical properties could be seen for the group as a whole; however, certain classes of compounds have altered frequencies of activity and atypical kinetics. PMID:17559204

  20. Evaluation of the effects of Mitragyna speciosa alkaloid extract on cytochrome P450 enzymes using a high throughput assay.

    PubMed

    Kong, Wai Mun; Chik, Zamri; Ramachandra, Murali; Subramaniam, Umarani; Aziddin, Raja Elina Raja; Mohamed, Zahurin

    2011-01-01

    The extract from Mitragyna speciosa has been widely used as an opium substitute, mainly due to its morphine-like pharmacological effects. This study investigated the effects of M. speciosa alkaloid extract (MSE) on human recombinant cytochrome P450 (CYP) enzyme activities using a modified Crespi method. As compared with the liquid chromatography-mass spectrometry method, this method has shown to be a fast and cost-effective way to perform CYP inhibition studies. The results indicated that MSE has the most potent inhibitory effect on CYP3A4 and CYP2D6, with apparent half-maximal inhibitory concentration (IC(50)) values of 0.78 µg/mL and 0.636 µg/mL, respectively. In addition, moderate inhibition was observed for CYP1A2, with an IC(50) of 39 µg/mL, and weak inhibition was detected for CYP2C19. The IC(50) of CYP2C19 could not be determined, however, because inhibition was <50%. Competitive inhibition was found for the MSE-treated CYP2D6 inhibition assay, whereas non-competitive inhibition was shown in inhibition assays using CYP3A4, CYP1A2 and CYP2C19. Quinidine (CYP2D6), ketoconazole (CYP3A4), tranylcypromine (CYP2C19) and furafylline (CYP1A2) were ACCESSused as positive controls throughout the experiments. This study shows that MSE may contribute to an herb-drug interaction if administered concomitantly with drugs that are substrates for CYP3A4, CYP2D6 and CYP1A2. PMID:21876481

  1. Impact of Cytochrome P450 2D6 Function on the Chiral Blood Plasma Pharmacokinetics of 3,4-Methylenedioxymethamphetamine (MDMA) and Its Phase I and II Metabolites in Humans.

    PubMed

    Steuer, Andrea E; Schmidhauser, Corina; Tingelhoff, Eva H; Schmid, Yasmin; Rickli, Anna; Kraemer, Thomas; Liechti, Matthias E

    2016-01-01

    3,4-methylenedioxymethamphetamine (MDMA; ecstasy) metabolism is known to be stereoselective, with preference for S-stereoisomers. Its major metabolic step involves CYP2D6-catalyzed demethylenation to 3,4-dihydroxymethamphetamine (DHMA), followed by methylation and conjugation. Alterations in CYP2D6 genotype and/or phenotype have been associated with higher toxicity. Therefore, the impact of CYP2D6 function on the plasma pharmacokinetics of MDMA and its phase I and II metabolites was tested by comparing extensive metabolizers (EMs), intermediate metabolizers (IMs), and EMs that were pretreated with bupropion as a metabolic inhibitor in a controlled MDMA administration study. Blood plasma samples were collected from 16 healthy participants (13 EMs and three IMs) up to 24 h after MDMA administration in a double-blind, placebo-controlled, four-period, cross-over design, with subjects receiving 1 week placebo or bupropion pretreatment followed by a single placebo or MDMA (125 mg) dose. Bupropion pretreatment increased the maximum plasma concentration (Cmax) and area under the plasma concentration-time curve from 0 to 24 h (AUC24) of R-MDMA (9% and 25%, respectively) and S-MDMA (16% and 38%, respectively). Bupropion reduced the Cmax and AUC24 of the CYP2D6-dependently formed metabolite stereoisomers of DHMA 3-sulfate, DHMA 4-sulfate, and 4-hydroxy-3-methoxymethamphetamine (HMMA sulfate and HMMA glucuronide) by approximately 40%. The changes that were observed in IMs were generally comparable to bupropion-pretreated EMs. Although changes in stereoselectivity based on CYP2D6 activity were observed, these likely have low clinical relevance. Bupropion and hydroxybupropion stereoisomer pharmacokinetics were unaltered by MDMA co-administration. The present data might aid further interpretations of toxicity based on CYP2D6-dependent MDMA metabolism. PMID:26967321

  2. Impact of Cytochrome P450 2D6 Function on the Chiral Blood Plasma Pharmacokinetics of 3,4-Methylenedioxymethamphetamine (MDMA) and Its Phase I and II Metabolites in Humans

    PubMed Central

    Steuer, Andrea E.; Schmidhauser, Corina; Tingelhoff, Eva H.; Schmid, Yasmin; Rickli, Anna; Kraemer, Thomas; Liechti, Matthias E.

    2016-01-01

    3,4-methylenedioxymethamphetamine (MDMA; ecstasy) metabolism is known to be stereoselective, with preference for S-stereoisomers. Its major metabolic step involves CYP2D6-catalyzed demethylenation to 3,4-dihydroxymethamphetamine (DHMA), followed by methylation and conjugation. Alterations in CYP2D6 genotype and/or phenotype have been associated with higher toxicity. Therefore, the impact of CYP2D6 function on the plasma pharmacokinetics of MDMA and its phase I and II metabolites was tested by comparing extensive metabolizers (EMs), intermediate metabolizers (IMs), and EMs that were pretreated with bupropion as a metabolic inhibitor in a controlled MDMA administration study. Blood plasma samples were collected from 16 healthy participants (13 EMs and three IMs) up to 24 h after MDMA administration in a double-blind, placebo-controlled, four-period, cross-over design, with subjects receiving 1 week placebo or bupropion pretreatment followed by a single placebo or MDMA (125 mg) dose. Bupropion pretreatment increased the maximum plasma concentration (Cmax) and area under the plasma concentration-time curve from 0 to 24 h (AUC24) of R-MDMA (9% and 25%, respectively) and S-MDMA (16% and 38%, respectively). Bupropion reduced the Cmax and AUC24 of the CYP2D6-dependently formed metabolite stereoisomers of DHMA 3-sulfate, DHMA 4-sulfate, and 4-hydroxy-3-methoxymethamphetamine (HMMA sulfate and HMMA glucuronide) by approximately 40%. The changes that were observed in IMs were generally comparable to bupropion-pretreated EMs. Although changes in stereoselectivity based on CYP2D6 activity were observed, these likely have low clinical relevance. Bupropion and hydroxybupropion stereoisomer pharmacokinetics were unaltered by MDMA co-administration. The present data might aid further interpretations of toxicity based on CYP2D6-dependent MDMA metabolism. PMID:26967321

  3. Drug & Gene Interaction Risk Analysis With & Without Genetic Testing Among Patients Undergoing MTM

    ClinicalTrials.gov

    2016-03-15

    Cytochrome P450 CYP2D6 Enzyme Deficiency; Poor Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Ultrarapid Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Extensive Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Cytochrome P450 CYP2C9 Enzyme Deficiency; Cytochrome P450 CYP2C19 Enzyme Deficiency; Drug Metabolism, Poor, CYP2D6-RELATED; Drug Metabolism, Poor, CYP2C19-RELATED; CYP2D6 Polymorphism

  4. Constituents of Indonesian medicinal plant Averrhoa bilimbi and their cytochrome P450 3A4 and 2D6 inhibitory activities.

    PubMed

    Auw, Lidyawati; Subehan; Sukrasno; Kadota, Shigetoshi; Tezuka, Yasuhiro

    2015-01-01

    As constituents of Averrhoa bilimbi leaves we identified three new compounds (1-3) together with 12 known ones (4-15); their inhibitory activities on cytochrome P450 3A4 (CYP3A4) and 2D6 (CYP2D6) were examined. Among the isolated compounds, the mixture of 1 and 2, and compounds 4 and 9 showed strong inhibition on CYP3A4, but mild or no inhibition on CYP2D6. These compounds revealed the characteristics of 1) time- and concentration-dependent inhibition, 2) requirement of NADPH for the inhibition, 3) no protection by nucleophiles, and 4) suppression of the inhibition by competitive inhibitor. Thus, they are suggested to be mechanism-based inactivators of CYP3A4 and CYP2D6. The kinetic parameters for the inactivation (k(inact) and K(I)) were 0.19 min(-1) and 36.7 μM for the mixture of 1 and 2, 0.126 min(-1) and 10.5 μM for 4, and 0.29 min(-1) and 23.4 μM for 9. PMID:25920220

  5. Pungent ginger components modulates human cytochrome P450 enzymes in vitro

    PubMed Central

    Li, Mian; Chen, Pei-zhan; Yue, Qing-xi; Li, Jing-quan; Chu, Rui-ai; Zhang, Wei; Wang, Hui

    2013-01-01

    Aim: Ginger rhizome is used worldwide as a spicy flavor agent. This study was designed to explore the potential effects of pungent ginger components, 6-, 8-, and 10-gingerol, on human cytochrome P450 (CYP450) enzymes that are responsible for the metabolism of many prescription drugs. Methods: The activities of human CYP2C9, CYP2C19, CYP2D6, and CYP3A4 were analyzed using Vivid P450 assay kits. The mRNA expression of CYP3A4 in human hepatocellular carcinoma cell line HepG2 was measured using quantitative real-time PCR assay. Results: All three gingerols potently inhibited CYP2C9 activity, exerted moderate inhibition on CYP2C19 and CYP3A4, and weak inhibion on CYP2D6. 8-Gingerol was the most potent in inhibition of P450 enzymes with IC50 values of 6.8, 12.5, 8.7, and 42.7 μmol/L for CYP2C9, CYP2C19, CYP3A4, and CYP2D6, respectively. By comparing the effects of gingerols on CYP3A4 with three different fluorescent substrate probes, it was demonstrated that the inhibition of gingerols on CYP3A4 had no substrate-dependence. In HepG2 cells, 8-gingerol and 10-gingerol inhibited, but 6-gingerol induced mRNA expression of CYP3A4. Conclusion: 6-, 8-, and 10-gingerol suppress human cytochrome P450 activity, while 8- and 10-gingerol inhibit CYP3A4 expression. The results may have an implication for the use of ginger or ginger products when combined with therapeutic drugs that are metabolized by cytochrome P450 enzymes. PMID:23770984

  6. Effect of crude extract of Eugenia jambolana Lam. on human cytochrome P450 enzymes.

    PubMed

    Chinni, Santhivardhan; Dubala, Anil; Kosaraju, Jayasankar; Khatwal, Rizwan Basha; Satish Kumar, M N; Kannan, Elango

    2014-11-01

    The fruit of Eugenia jambolana Lam. is very popular for its anti-diabetic property. Previous studies on the crude extract of E. jambolana (EJE) have successfully explored the scientific basis for some of its traditional medicinal uses. Considering its wide use and consumption as a seasonal fruit, the present study investigates the ability of E. jambolana to interact with cytochrome P450 enzymes. The standardized EJE was incubated with pooled human liver microsomes to assess the CYP2C9-, CYP2D6-, and CYP3A4-mediated metabolism of diclofenac, dextromethorphan, and testosterone, respectively. The metabolites formed after the enzymatic reactions were quantified by high performance liquid chromatography. EJE showed differential effect on cytochrome P450 activities with an order of inhibitory potential as CYP2C9 > CYP3A4 > CYP2D6 having IC50 of 76.69, 359.02, and 493.05 µg/mL, respectively. The selectivity of EJE for CYP2C9 rather than CYP3A4 and CYP2D6 led to perform the enzyme kinetics to explicate the mechanism underlying the inhibition of CYP2C9-mediated diclofenac 4'-hydroxylation. EJE was notably potent in inhibiting the reaction in a non-competitive manner with Ki of 84.85 ± 5.27 µg/mL. The results revealed the CYP2C9 inhibitory potential of EJE with lower Ki value suggesting that EJE should be examined for its potential pharmacokinetic and pharmacodynamic interactions when concomitantly administered with other drugs. PMID:24590863

  7. Cytochrome P450-2D6 extensive metabolizers are more vulnerable to methamphetamine-associated neurocognitive impairment: Preliminary findings

    PubMed Central

    CHERNER, MARIANA; BOUSMAN, CHAD; EVERALL, IAN; BARRON, DANIEL; LETENDRE, SCOTT; VAIDA, FLORIN; ATKINSON, J. HAMPTON; HEATON, ROBERT; GRANT, IGOR

    2012-01-01

    While neuropsychological deficits are evident among methamphetamine (meth) addicts, they are often unrelated to meth exposure parameters such as lifetime consumption and length of abstinence. The notion that some meth users develop neuropsychological impairments while others with similar drug exposure do not, suggests that there may be individual differences in vulnerability to the neurotoxic effects of meth. One source of differential vulnerability could come from genotypic variability in metabolic clearance of meth, dependent on the activity of cytochrome P450-2D6 (CYP2D6). We compared neuropsychological performance in 52 individuals with a history of meth dependence according with their CYP2D6 phenotype. All were free of HIV or hepatitis C infection and did not meet dependence criteria for other substances. Extensive metabolizers showed worse overall neuropsychological performance and were three times as likely to be cognitively impaired as intermediate/poor metabolizers. Groups did not differ in their demographic or meth use characteristics, nor did they evidence differences in mood disorder or other substance use. This preliminary study is the first to suggest that efficient meth metabolism is associated with worse neurocognitive outcomes in humans, and implicates the products of oxidative metabolism of meth as a possible source of brain injury. PMID:20727252

  8. Correlation of CpG Island Methylation of the Cytochrome P450 2E1/2D6 Genes with Liver Injury Induced by Anti-Tuberculosis Drugs: A Nested Case-Control Study

    PubMed Central

    Zhang, Jinling; Zhu, Xuebin; Li, Yuhong; Zhu, Lingyan; Li, Shiming; Zheng, Guoying; Ren, Qi; Xiao, Yonghong; Feng, Fumin

    2016-01-01

    This study investigated the role of CpG island methylation of the CYP2E1 and CYP2D6 genes in liver injury induced by anti-TB drugs from an epigenetic perspective in a Chinese cohort. A 1:1 matched nested case-control study design was applied. Pulmonary tuberculosis (TB) patients, who underwent standard anti-TB therapy and developed liver injury were defined as cases, while those who did not develop liver injury were defined as control. The two groups were matched in terms of sex, treatment regimen, and age. In 114 pairs of cases, CpG island methylation levels of the CYP2E1 and CYP2D6 genes in plasma cell-free DNA were found to be significantly correlated with the occurrence of anti-TB drug-induced liver injury (ADLI), with odds ratio (OR) values of 2.429 and 3.500, respectively (p < 0.01). Moreover, through multivariate logistic regression analysis, CpG island methylation of the CYP2E1 and CYP2D6 genes in plasma cell-free DNA were found to be significantly correlated with the occurrence of ADLI, with adjusted OR values of 4.390 (95% confidence interval (CI): 1.982–9.724) and 9.193 (95% CI: 3.624–25.888), respectively (p < 0.001). These results suggest that aberrantly elevated methylation of CpG islands of the CYP2E1 and CYP2D6 genes in plasma cell-free DNA may increase the risk of ADLI in Chinese TB patients. PMID:27490558

  9. Correlation of CpG Island Methylation of the Cytochrome P450 2E1/2D6 Genes with Liver Injury Induced by Anti-Tuberculosis Drugs: A Nested Case-Control Study.

    PubMed

    Zhang, Jinling; Zhu, Xuebin; Li, Yuhong; Zhu, Lingyan; Li, Shiming; Zheng, Guoying; Ren, Qi; Xiao, Yonghong; Feng, Fumin

    2016-01-01

    This study investigated the role of CpG island methylation of the CYP2E1 and CYP2D6 genes in liver injury induced by anti-TB drugs from an epigenetic perspective in a Chinese cohort. A 1:1 matched nested case-control study design was applied. Pulmonary tuberculosis (TB) patients, who underwent standard anti-TB therapy and developed liver injury were defined as cases, while those who did not develop liver injury were defined as control. The two groups were matched in terms of sex, treatment regimen, and age. In 114 pairs of cases, CpG island methylation levels of the CYP2E1 and CYP2D6 genes in plasma cell-free DNA were found to be significantly correlated with the occurrence of anti-TB drug-induced liver injury (ADLI), with odds ratio (OR) values of 2.429 and 3.500, respectively (p < 0.01). Moreover, through multivariate logistic regression analysis, CpG island methylation of the CYP2E1 and CYP2D6 genes in plasma cell-free DNA were found to be significantly correlated with the occurrence of ADLI, with adjusted OR values of 4.390 (95% confidence interval (CI): 1.982-9.724) and 9.193 (95% CI: 3.624-25.888), respectively (p < 0.001). These results suggest that aberrantly elevated methylation of CpG islands of the CYP2E1 and CYP2D6 genes in plasma cell-free DNA may increase the risk of ADLI in Chinese TB patients. PMID:27490558

  10. In vitro metabolic interactions between black cohosh (Cimicifuga racemosa) and tamoxifen via inhibition of cytochromes P450 2D6 and 3A4.

    PubMed

    Li, Jinghu; Gödecke, Tanja; Chen, Shao-Nong; Imai, Ayano; Lankin, David C; Farnsworth, Norman R; Pauli, Guido F; van Breemen, Richard B; Nikolić, Dejan

    2011-08-01

    Women who experience hot flashes as a side effect of tamoxifen (TAM) therapy often try botanical remedies such as black cohosh to alleviate these symptoms. Since pharmacological activity of TAM is dependent on the metabolic conversion into active metabolites by the action of cytochromes P450 2D6 (CYP2D6) and 3A4, the objective of this study was to evaluate whether black cohosh extracts can inhibit formation of active TAM metabolites and possibly reduce its clinical efficacy. At 50 μg/mL, a 75% ethanolic extract of black cohosh inhibited formation of 4-hydroxy- TAM by 66.3%, N-desmethyl TAM by 74.6% and α-hydroxy TAM by 80.3%. In addition, using midazolam and dextromethorphan as probe substrates, this extract inhibited CYP3A4 and CYP2D6 with IC(50) values of 16.5 and 50.1 μg/mL, respectively. Eight triterpene glycosides were identified as competitive CYP3A4 inhibitors with IC(50) values ranging from 2.3-5.1 µM, while the alkaloids protopine and allocryptopine were identified as competitive CYP2D6 inhibitors with K(i) values of 78 and 122 nM, respectively. The results of this study suggests that co-administration of black cohosh with TAM might interfere with the clinical efficacy of this drug. However, additional clinical studies are needed to determine the clinical significance of these in vitro results. PMID:21827327

  11. Concomitant use of selective serotonin reuptake inhibitors with other cytochrome P450 2D6 or 3A4 metabolized medications: how often does it really happen?

    PubMed

    Gregor, K J; Way, K; Young, C H; James, S P

    1997-10-01

    This study retrospectively examines the one-month concomitant use of cytochrome P450 2D6 or 3A4 metabolized medications in 544,309 patients who were also receiving selective serotonin reuptake inhibitors (SSRIs). Overall, 25.53% of SSRI patients experienced concomitant use with at least one of the 33 studied CYP 2D6 or 3A4 metabolized medications. Certain drugs and drug classes were more likely to be used concurrently among SSRI patients (e.g., benzodiazepines, tricyclic antidepressants, calcium channel blockers). Similarly, of the SSRI patients experiencing concomitant use, this concurrent use was twice as likely with cytochrome P450 medications metabolized by the 3A4 isoenzyme as with those metabolized by the 2D6 isoenzyme. Finally, the vast majority (80.9%) of SSRI patients experiencing concomitant use did so with one CYP 2D6 or 3A4 metabolized medication. In sum, concomitant use generally was not extensive and did not appear to be differential among the fluoxetine, paroxetine, or sertraline patient comparison groups. PMID:9387087

  12. Identification of the human liver enzymes involved in the metabolism of the antimigraine agent almotriptan.

    PubMed

    Salva, Miquel; Jansat, Josep M; Martinez-Tobed, Antonio; Palacios, Jose M

    2003-04-01

    Almotriptan is a novel highly selective 5-hydroxytryptamine(1B/1D) agonist developed for the acute oral treatment of migraine. The in vitro metabolism of almotriptan has been investigated using human liver subcellular fractions and cDNA-expressed human enzymes, to study the metabolic pathways and identify the enzymes responsible for the formation of the major metabolites. Specific enzymes were identified by correlation analysis, chemical inhibition studies, and incubation with various cDNA expressed human enzymes. Human liver microsomes and S9 fraction metabolize almotriptan by 2-hydroxylation of the pyrrolidine group to form a carbinolamine metabolite intermediate, a reaction catalyzed by CYP3A4 and CYP2D6. This metabolite is further oxidized by aldehyde dehydrogenase to the open ring gamma-aminobutyric acid metabolite. Almotriptan is also metabolized at the dimethylaminoethyl group by N-demethylation, a reaction that is carried out by five different cytochrome P450s, flavin monooxygenase-3 mediated N-oxidation, and MAO-A catalyzed oxidative deamination to form the indole acetic acid and the indole ethyl alcohol derivatives of almotriptan. The use of human liver mitochondria confirmed the contribution of MAO-A to the metabolism of almotriptan. Both, the gamma-aminobutyric acid and the indole acetic acid metabolites have been found to be the major in vivo metabolites of almotriptan in humans. In addition, different clinical trials conducted to study the effects of CYP3A4, CYP2D6, and MAO-A on the pharmacokinetics of almotriptan confirmed the involvement of these enzymes in the metabolic clearance of this drug and that no dose changes are required in the presence of inhibitors of these enzymes. PMID:12642466

  13. Effects of cigarette smoking and cytochrome P450 2D6 genotype on fluvoxamine concentration in plasma of Japanese patients.

    PubMed

    Katoh, Yasuhiro; Uchida, Shinya; Kawai, Masayoshi; Takei, Noriyoshi; Mori, Norio; Kawakami, Junichi; Kagawa, Yoshiyuki; Yamada, Shizuo; Namiki, Noriyuki; Hashimoto, Hisakuni

    2010-01-01

    Fluvoxamine is a selective serotonin reuptake inhibitor widely used in the treatment of depression and other psychiatric diseases. The aim of this study was to assess the clinical impact of cigarette smoking on plasma fluvoxamine concentration in Japanese patients, and evaluate whether the cytochrome P450 (CYP) 1A2 and CYP2D6 genotypes have effects on that concentration. Thirty-two Japanese patients receiving fluvoxamine were enrolled. They were maintained on the same daily dose of fluvoxamine (mean + or - S.D., 109.4 + or - 66.2 mg/d) for at least 4 weeks to obtain the steady-state plasma concentration. The steady-state plasma concentration-to-dose (C/D) ratio of fluvoxamine in patients who smoked (n = 6, 11.8 + or - 6.5 ng/ml/dose) was significantly lower than that in non-smoker patients (n = 26, 22.8 + or - 11.2 ng/ml/dose). There was no significant difference for the C/D ratio of fluvoxamine in patients with CYP1A2 -3860G/G, -3860G/A, and -3860A/A between non-smokers and smokers. Among non-smoker patients, the C/D ratios of fluvoxamine in those with one and two mutated alleles of CYP2D6 were 1.6- and 1.4-fold higher, respectively, than those with no mutated alleles, though the differences among those three genotype groups were not significant. Furthermore, stepwise multiple regression analysis revealed that cigarette smoking and daily dose had significant positive correlations with the plasma concentration of fluvoxamine. Our findings suggest that cigarette smoking has a significant impact on the steady-state plasma concentration of fluvoxamine in Japanese patients. PMID:20118554

  14. Systematic genetic and genomic analysis of cytochrome P450 enzyme activities in human liver

    PubMed Central

    Yang, Xia; Zhang, Bin; Molony, Cliona; Chudin, Eugene; Hao, Ke; Zhu, Jun; Gaedigk, Andrea; Suver, Christine; Zhong, Hua; Leeder, J. Steven; Guengerich, F. Peter; Strom, Stephen C.; Schuetz, Erin; Rushmore, Thomas H.; Ulrich, Roger G.; Slatter, J. Greg; Schadt, Eric E.; Kasarskis, Andrew; Lum, Pek Yee

    2010-01-01

    Liver cytochrome P450s (P450s) play critical roles in drug metabolism, toxicology, and metabolic processes. Despite rapid progress in the understanding of these enzymes, a systematic investigation of the full spectrum of functionality of individual P450s, the interrelationship or networks connecting them, and the genetic control of each gene/enzyme is lacking. To this end, we genotyped, expression-profiled, and measured P450 activities of 466 human liver samples and applied a systems biology approach via the integration of genetics, gene expression, and enzyme activity measurements. We found that most P450s were positively correlated among themselves and were highly correlated with known regulators as well as thousands of other genes enriched for pathways relevant to the metabolism of drugs, fatty acids, amino acids, and steroids. Genome-wide association analyses between genetic polymorphisms and P450 expression or enzyme activities revealed sets of SNPs associated with P450 traits, and suggested the existence of both cis-regulation of P450 expression (especially for CYP2D6) and more complex trans-regulation of P450 activity. Several novel SNPs associated with CYP2D6 expression and enzyme activity were validated in an independent human cohort. By constructing a weighted coexpression network and a Bayesian regulatory network, we defined the human liver transcriptional network structure, uncovered subnetworks representative of the P450 regulatory system, and identified novel candidate regulatory genes, namely, EHHADH, SLC10A1, and AKR1D1. The P450 subnetworks were then validated using gene signatures responsive to ligands of known P450 regulators in mouse and rat. This systematic survey provides a comprehensive view of the functionality, genetic control, and interactions of P450s. PMID:20538623

  15. Pharmacogenetic profile of xenobiotic enzyme metabolism in survivors of the Spanish toxic oil syndrome.

    PubMed Central

    Ladona, M G; Izquierdo-Martinez, M; Posada de la Paz, M P; de la Torre, R; Ampurdanés, C; Segura, J; Sanz, E J

    2001-01-01

    In 1981, the Spanish toxic oil syndrome (TOS) affected more than 20,000 people, and over 300 deaths were registered. Assessment of genetic polymorphisms on xenobiotic metabolism would indicate the potential metabolic capacity of the victims at the time of the disaster. Thus, impaired metabolic pathways may have contributed to the clearance of the toxicant(s) leading to a low detoxification or accumulation of toxic metabolites contributing to the disease. We conducted a matched case-control study using 72 cases (54 females, 18 males) registered in the Official Census of Affected Patients maintained by the Spanish government. Controls were nonaffected siblings (n =72) living in the same household in 1981 and nonaffected nonrelatives (n = 70) living in the neighborhood at that time, with no ties to TOS. Genotype analyses were performed to assess the metabolic capacity of phase I [cytochrome P450 1A1 (CYP1A1), CYP2D6] and phase II [arylamine N-acetyltransferase-2 (NAT2), GSTM1 (glutathione S-transferase M1) and GSTT1] enzyme polymorphisms. The degree of association of the five metabolic pathways was estimated by calculating their odds ratios (ORs) using conditional logistic regression analysis. In the final model, cases compared with siblings (72 pairs) showed no differences either in CYP2D6 or CYP1A1 polymorphisms, or in conjugation enzyme polymorphisms, whereas cases compared with the unrelated controls (70 pairs) showed an increase in NAT2 defective alleles [OR = 6.96, 95% confidence interval (CI), 1.46-33.20] adjusted by age and sex. Glutathione transferase genetic polymorphisms (GSTM1, GSTT1) showed no association with cases compared with their siblings or unrelated controls. These findings suggest a possible role of impaired acetylation mediating susceptibility in TOS. PMID:11335185

  16. Eletriptan metabolism by human hepatic CYP450 enzymes and transport by human P-glycoprotein.

    PubMed

    Evans, David C; O'Connor, Desmond; Lake, Brian G; Evers, Raymond; Allen, Christopher; Hargreaves, Richard

    2003-07-01

    "Reaction phenotyping" studies were performed with eletriptan (ETT) to determine its propensity to interact with coadministered medications. Its ability to serve as a substrate for human P-glycoprotein (P-gp) was also investigated since a central mechanism of action has been proposed for this "triptan" class of drug. In studies with a characterized bank of human liver microsome preparations, a good correlation (r2 = 0.932) was obtained between formation of N-desmethyl eletriptan (DETT) and CYP3A4-catalyzed testosterone 6 beta-hydroxylation. DETT was selected to be monitored in our studies since it represents a significant ETT metabolite in humans, circulating at concentrations 10 to 20% of those observed for parent drug. ETT was metabolized to DETT by recombinant CYP2D6 (rCYP2D6) and rCYP3A4, and to a lesser extent by rCYP2C9 and rCYP2C19. The metabolism of ETT to DETT in human liver microsomes was markedly inhibited by troleandomycin, erythromycin, miconazole, and an inhibitory antibody to CYP3A4, but not by inhibitors of other major P450 enzymes. ETT had little inhibitory effect on any of the P450 enzymes investigated. ETT was determined to be a good substrate for human P-gp in vitro. In bidirectional transport studies across LLC-MDR1 and LLC-Mdr1a cell monolayers, ETT had a BA/AB transport ratio in the range 9 to 11. This finding had significance in vivo since brain exposure to ETT was reduced 40-fold in Mdr1a+/+ relative to Mdr1a-/- mice. ETT metabolism to DETT is therefore catalyzed primarily by CYP3A4, and plasma concentrations are expected to be increased when coadministered with inhibitors of CYP3A4 and P-gp activity. PMID:12814962

  17. The Effect of Yokukansan, a Traditional Herbal Preparation Used for the Behavioral and Psychological Symptoms of Dementia, on the Drug-Metabolizing Enzyme Activities in Healthy Male Volunteers.

    PubMed

    Soraoka, Hiromi; Oniki, Kentaro; Matsuda, Kazuki; Ono, Tatsumasa; Taharazako, Kosuke; Uchiyashiki, Yoshihiro; Kamihashi, Ryoko; Kita, Ayana; Takashima, Ayaka; Nakagawa, Kazuko; Yasui-Furukori, Norio; Kadowaki, Daisuke; Miyata, Keishi; Saruwatari, Junji

    2016-01-01

    The concomitant use of herb and prescription medications is increasing globally. Herb-drug interactions are therefore a clinically important problem. Yokukansan (YKS), a Japanese traditional herbal medicine, is one of the most frequently used herbal medicines. It is effective for treating the behavioral and psychological symptoms of dementia. We investigated the potential effects of YKS on drug-metabolizing enzyme activities in humans. An open-label repeat-dose study was conducted in 26 healthy Japanese male volunteers (age: 22.7±2.3 years) with no history of smoking. An 8-h urine sample was collected after a 150-mg dose of caffeine and a 30-mg dose of dextromethorphan before and after the administration of YKS (2.5 g, twice a day for 1 week). The activities of cytochrome P450 (CYP) 1A2, CYP2D6, CYP3A, xanthine oxidase (XO) and N-acetyltransferase 2 (NAT2) were assessed based on the urinary metabolic indices of caffeine and dextromethorphan, and the urinary excretion ratio of 6β-hydroxycortisol to cortisol. There were no statistically significant differences in the activities of the examined enzymes before or after the 7-d administration of YKS. Although further studies assessing the influence of YKS on the pharmacokinetics and pharmacodynamics of the substrates of the drug-metabolizing enzymes are needed to verify the present results, YKS is unlikely that a pharmacokinetic interaction will occur with concomitantly administered medications that are predominantly metabolized by the CYP1A2, CYP2D6, CYP3A, XO and NAT2. PMID:27582327

  18. Pharmacogenomics toward personalized tamoxifen therapy for breast cancer.

    PubMed

    Zembutsu, Hitoshi

    2015-01-01

    Tamoxifen has been used not only for the treatment or prevention of recurrence in patients with estrogen receptor positive breast cancers but also for recurrent breast cancer. Because CYP2D6 is known to be an important enzyme responsible for the generation of the potent tamoxifen metabolite, 'endoxifen', lots of studies reported that genetic variation which reduced its enzyme activity were associated with poor clinical outcome of breast cancer patients treated with tamoxifen. However, there are some discrepant reports questioning the association between CYP2D6 genotype and clinical outcome after tamoxifen therapy. Dose-adjustment study of tamoxifen based on CYP2D6 genotypes provides the evidence that dose adjustment is useful for the patients carrying reduced or null allele of CYP2D6 to maintain the effective endoxifen level. This review describes critical issues in pharmacogenomic studies as well as summarizes the results of the association of CYP2D6 genotype with tamoxifen efficacy. PMID:25712191

  19. Effects of methoxychlor and 2,2-bis ( p -hydroxyphenyl)-1,1,1-trichloroethane on cytochrome P450 enzyme activities in human and rat livers.

    PubMed

    Chen, Bingbing; Pan, Peipei; Wang, Li; Chen, Menchun; Dong, Yaoyao; Ge, Ren-Shan; Hu, Guo-Xin

    2015-01-01

    Cytochrome P450 (CYP) enzymes are involved in the metabolism of endogenous and exogenous compounds. Human and rat liver microsomes were used to investigate the inhibitory effects of methoxychlor (MXC) and its metabolite 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE) on the activities of corresponding human and rat CYPs. Probe drugs were used to test the inhibitory effects of MXC and HPTE on human and rat CYPs. The results showed that MXC and HPTE inhibited both human CYP2C9 and rat liver CYP2C11 activity, with half-maximal inhibitory concentration (IC50) values of 15.47 ± 0.36 (MXC) and 8.87 ± 0.53 μmol/l (HPTE) for human CYP2C9, and of 22.45 ± 1.48 (MXC) and 24.63 ± 1.35 μmol/l (HPTE) for rat CYP2C11. MXC and HPTE had no effects on human CYP2C19 activity but inhibited rat CYP2C6 activity with IC50 values of 14.84 ± 0.04 (MXC) and 8.72 ± 0.25 μmol/l (HPTE). With regard to human CYP2D6 and rat CYP2D2 activity, only HPTE potently inhibited human CYP2D6 activity, with an IC50 value of 16.56 ± 0.69 μmol/l. Both chemicals had no effect on human CYP3A4 and rat CYP3A1 activity. In summary, MXC and HPTE are potent inhibitors of some human and rat CYPs. PMID:25833162

  20. The inhibition of major human hepatic cytochrome P450 enzymes by 18 pesticides: comparison of the N-in-one and single substrate approaches.

    PubMed

    Abass, Khaled; Pelkonen, Olavi

    2013-08-01

    In the present study on human hepatic microsomes, the N-in-one assay with ten probe substrates for nine cytochrome-P450 enzymes (CYPs) was compared with the single substrate assays to investigate pesticides-CYP interactions. CYP inhibition was measured by liquid chromatography-tandem mass spectrometry (LC/MS-MS). As illustrated by the initial screening at 100 μM concentration of 18 pesticides, CYPs are more sensitive to organophosphates (OPs) than to other pesticide groups. Chlorpyrifos and fenitrothion were most effective in inhibiting CYP1A1/2, and CYP2B6. Profenofos was also inhibitory towards multiple CYPs. Pyrethroids, e.g. deltamethrin, fenvalerate and lambda-cyhalothrin, potently inhibited CYP2D6. CYP3A4 activity was moderately inhibited by fenvalerate and potently by alpha-cypermethrin. The correlations between IC50 values obtained from the N-in-one and single substrate approaches were highly significant for CYP2Cs (r(2)=0.94), CYP3A4, omeprazole-sulfoxidation, (r(2)=0.89), followed by CYP1A2 and CYP2B6 (r(2)=0.82), and CYP2D6 (r(2)=0.80). In contrast no correlation was observed with CYP2E1 and CYP3A4 (midazolam-1'-hydroxylation). The N-in-one screening assay seems useful and reliable for most CYP activities when a comprehensive and quick evaluation of potential interactions with CYPs is needed. However, at the present moment, it does not enable discrimination on the basis of mechanism of inhibition. A strict comparison between single and N-in-one assays is a prerequisite for more extensive routine use. PMID:22634058

  1. Pharmacogenetic Testing Among Home Health Patients

    ClinicalTrials.gov

    2016-03-15

    Adverse Drug Events; Adverse Drug Reactions; Drug Interaction Potentiation; Drug Metabolism, Poor, CYP2D6-RELATED; Drug Metabolism, Poor, CYP2C19-RELATED; Cytochrome P450 Enzyme Deficiency; Cytochrome P450 CYP2D6 Enzyme Deficiency; Cytochrome P450 CYP2C9 Enzyme Deficiency; Cytochrome P450 CYP2C19 Enzyme Deficiency; Cytochrome P450 CYP3A Enzyme Deficiency; Poor Metabolizer Due to Cytochrome P450 CYP2C9 Variant; Poor Metabolizer Due to Cytochrome p450 CYP2C19 Variant; Poor Metabolizer Due to Cytochrome P450 CYP2D6 Variant

  2. YouScript IMPACT Registry

    ClinicalTrials.gov

    2015-09-10

    Adverse Drug Events; Adverse Drug Reactions; Drug Interaction Potentiation; Drug Metabolism, Poor, CYP2D6-RELATED; Drug Metabolism, Poor, CYP2C19-RELATED; Cytochrome P450 Enzyme Deficiency; Cytochrome P450 CYP2D6 Enzyme Deficiency; Cytochrome P450 CYP2C9 Enzyme Deficiency; Cytochrome P450 CYP2C19 Enzyme Deficiency; Cytochrome P450 CYP3A Enzyme Deficiency; Poor Metabolizer Due to Cytochrome P450 CYP2C9 Variant; Poor Metabolizer Due to Cytochrome P450 CYP2C19 Variant; Poor Metabolizer Due to Cytochrome P450 CYP2D6 Variant

  3. Systematic Functional Study of Cytochrome P450 2D6 Promoter Polymorphisms in the Chinese Han Population

    PubMed Central

    Gong, Xueli; Liu, Yichen; Zhang, Xiaoqing; Wei, Zhiyun; Huo, Ran; Shen, Lu; He, Lin; Qin, Shengying

    2013-01-01

    The promoter polymorphisms of drug-metabolizing genes can lead to interindividual differences in gene expression, which may result in adverse drug effects and therapeutic failure. Based on the database of CYP2D6 gene polymorphisms in the Chinese Han population established by our group, we functionally characterized the single nucleotide polymorphisms (SNPs) of the promoter region and corresponding haplotypes in this population. Using site-directed mutagenesis, all the five SNPs identified and ten haplotypes with a frequency equal to or greater than 0.01 in the population were constructed on a luciferase reporter system. Dual luciferase reporter systems were used to analyze regulatory activity. The activity produced by Haplo3(−2183G>A, −1775A>G, −1589G>C, −1431C>T, −1000G>A, −678A>G), Haplo8(−2065G>A, −2058T>G, −1775A>G, −1589G>C, −1235G>A, −678A>G) and MU3(−498C>A) was 0.7−, 0.7−, 1.2− times respectively compared with the wild type in human hepatoma cell lines(p<0.05). These findings might be useful for optimizing pharmacotherapy and the design of personalized medicine. PMID:23469064

  4. CYP450 Enzyme-Mediated Metabolism of TCAS and Its Inhibitory and Induced Effects on Metabolized Enzymes in Vitro

    PubMed Central

    Shen, Guolin; Wang, Cheng; Zhou, Lili; Li, Lei; Chen, Huiming; Yu, Wenlian; Li, Haishan

    2015-01-01

    In this study, we investigated the enzymes catalyzing the phaseⅠmetabolism of thiacalixarene (TCAS) based on in vitro system including cDNA-expressed P450 enzymes, human liver microsomes plus inhibitors and monoclonal antibodies. In addition, the inhibitory potential of TCAS on major CYP450 drug metabolizing enzymes (CYP1A2, CYP2C9, CYP2B6, CYP2D6 and CYP3A4) was assessed. The results showed that CYP1A2 and CYP2C9 mediated TCAS hydroxylation. IC50 values for TCAS in rat and human liver microsomes were greater than 50 µM, and it demonstrated a weak inhibition of rat and human CYP450 enzymes. Finally, sandwiched hepatocytes were used to evaluate the induction of CYP1A and CYP3A to define the function of TCAS in vivo. The results showed that incubation of TCAS at different concentrations for 72 h failed to induce CYP1A and CYP3A. However, incubation of the cells with 50 and 100 µM TCAS caused a profound decrease in the activities of CYP1A and CYP3A, which was probably due to cytotoxic effects, suggesting that exposure to TCAS might be a health concern. PMID:26404338

  5. The CYP4502D6 *4 and *6 alleles are the molecular genetic markers for drug response: implications in colchicine non-responder FMF patients.

    PubMed

    Yalcıntepe, Sinem; Ozdemır, Ozturk; Sılan, Coskun; Ozen, Filiz; Uludag, Ahmet; Candan, Ferhan; Sılan, Fatma

    2016-06-01

    The cytochrome P450 2D6 (CYP2D6) is a cytochrome P450 enzyme involved in the oxidative biotransformation of the xenobiotics, carcinogens and various clinically important drugs. Patients are evaluated in three sub-groups of extensive (EM), intermediate (IM) and poor metabolizer (PM) phenotypes due to their drug-metabolising ability for the target CYP2D6 gene. Colchicine non-responsive FMF patients were prospectively genotyped for the major CYP2D6 alleles in the current study. Major CYP2D6 alleles of *1, *3, *4, *5, and *6 were genotyped for 30 responsive and 60 non-responsive FMF patients by multiplex PCR-based reverse-hybridization StripAssay and real-time PCR methods. DNA banks isolated from blood-EDTA were retrospectively used in the current patients and results were compared statistically. Increased CYP2D6 *4 and *6 allele frequencies were highly detected in the colchicine non-responsive FMF patients when compared to the responsive group. Results showed the frequencies of major CYP2D6 *1(wild), *3(2637A > delA), *4(G1934A), *5(total gene deletion) and *6(1707T del) alleles in 0.550, 0.042, 0.158, 0.025 and 0.225 for non-responder and 0.880 and 0.120 (CYP2D6*1 and *4) for the responder groups, respectively. Despite small sample size, this study suggests that there is an association between CYP2D6*4 and CYP2D6*6 alleles and drug intoxicants in colchicine non-responder FMF patients. PMID:25645282

  6. Characterisation of the cytochrome P450 enzymes involved in the in vitro metabolism of granisetron.

    PubMed Central

    Bloomer, J C; Baldwin, S J; Smith, G J; Ayrton, A D; Clarke, S E; Chenery, R J

    1994-01-01

    1. The metabolism of granisetron was investigated in human liver microsomes to identify the specific forms of cytochrome P450 responsible. 2. 7-hydroxy and 9'-desmethyl granisetron were identified as the major products of metabolism following incubation of granisetron with human liver microsomes. At low, clinically relevant, concentrations of granisetron the 7-hydroxy metabolite predominated. Rates of granisetron 7-hydroxylation varied over 100-fold in the human livers investigated. 3. Enzyme kinetics demonstrated the involvement of at least two enzymes contributing to the 7-hydroxylation of granisetron, one of which was a high affinity component with a Km of 4 microM. A single, low affinity, enzyme was responsible for the 9'-desmethylation of granisetron. 4. Granisetron caused no inhibition of any of the cytochrome P450 activities investigated (CYP1A2, CYP2A6, CYP2B6, CYP2C9/8, CYP2C19, CYP2D6, CYP2E1 and CYP3A), at concentrations up to 250 microM. 5. Studies using chemical inhibitors selective for individual P450 enzymes indicated the involvement of cytochrome P450 3A (CYP3A), both pathways of granisetron metabolism being very sensitive to ketoconazole inhibition. Correlation data were consistent with the role of CYP3A3/4 in granisetron 9'-desmethylation but indicated that a different enzyme was involved in the 7-hydroxylation. PMID:7888294

  7. Impact of Tetrahydropalmatine on the Pharmacokinetics of Probe Drugs for CYP1A2, 2D6 and 3A Isoenzymes in Beagle Dogs.

    PubMed

    Zhao, Yong; Liang, Aihua; Zhang, Yushi; Li, Chunying; Yi, Yan; Nilsen, Odd Georg

    2016-06-01

    Tetrahydropalmatine (Tet) exhibit multiple pharmacological activities and is used frequently by clinical practitioners. In this study, we evaluate the in vivo effects of single and repeated oral Tet administrations on CYP1A2, 2D6 and 3A activities in six beagle dogs in a randomized, controlled, open-label, crossover study. A cocktail approach, with dosages of the probe drugs caffeine (3.0 mg/kg), metoprolol (2.33 mg/kg) and midazolam (0.45 mg/kg), was used to measure cytochrome P450 (CYP) metabolic activities. The cocktail was administered orally as a single dose (12 mg/kg) 1 day prior to and 4 days after repeated oral Tet administrations (12 mg/kg three times daily). The probe drugs and their metabolites in plasma were quantified simultaneously by a validated HPLC technique, and non-compartmental parameters were used to evaluate metabolic variables for assessment of CYP inhibition or induction. Tet had no or minor impact on the pharmacokinetics and metabolism of the probe drugs caffeine and metoprolol, CYP1A2 and CYP2D6 substrates, respectively. However, Tet increased AUC0-24 h and decreased AUCratio(0-24 h) (1-hydroxymidazolam/midazolam ratio) for midazolam statistically significant, both in single or multiple dosing of Tet, with up to 39 or 57% increase for AUC0-24 h and 29% or 22 decrease for AUCratio(0-24 h), respectively, in line with previous in vitro findings for its CYP3A4 inhibition. The extensive use of Tet and herbal medicines containing Tet makes Tet a candidate for further evaluation of CYP3A-mediated herb-drug interactions. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26990021

  8. Structure-Activity Relationship and Substrate-Dependent Phenomena in Effects of Ginsenosides on Activities of Drug-Metabolizing P450 Enzymes

    PubMed Central

    Hao, Miao; Zhao, Yuqing; Chen, Peizhan; Huang, He; Liu, Hong; Jiang, Hualiang; Zhang, Ruiwen; Wang, Hui

    2008-01-01

    Ginseng, a traditional herbal medicine, may interact with several co-administered drugs in clinical settings, and ginsenosides, the major active components of ginseng, may be responsible for these ginseng-drug interactions (GDIs). Results from previous studies on ginsenosides' effects on human drug-metabolizing P450 enzymes are inconsistent and confusing. Herein, we first evaluated the inhibitory effects of fifteen ginsenosides and sapogenins on human CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 enzymes by using commercially available fluorescent probes. The structure-activity relationship of their effects on the P450s was also explored and a pharmacophore model was established for CYP3A4. Moreover, substrate-dependent phenomena were found in ginsenosides' effects on CYP3A4 when another fluorescent probe was used, and were further confirmed in tests with conventional drug probes and human liver microsomes. These substrate-dependent effects of the ginsenosides may provide an explanation for the inconsistent results obtained in previous GDI reports. PMID:18628990

  9. Genetic variation in metabolizing enzyme and transporter genes: comprehensive assessment in 3 major East Asian subpopulations with comparison to Caucasians and Africans.

    PubMed

    Man, Michael; Farmen, Mark; Dumaual, Carmen; Teng, Choo Hua; Moser, Brian; Irie, Shin; Noh, Gyu Jeong; Njau, Reuben; Close, Sandra; Wise, Stephen; Hockett, Richard

    2010-08-01

    The advent of high-throughput technologies has proven valuable in the assessment of genetic differences and their effects on drug activation, metabolism, disposition, and transport. However, most studies to date have focused on a small number of genes or few alleles, some of which are rare and therefore observed infrequently or lacked rigorous ethnic characterization, thus reducing the ability to extrapolate within and among populations. In this study, the authors comprehensively assessed the allele frequencies of 165 variants comprising 27 drug-metabolizing enzyme and transporter (DMET) genes from 2188 participants across 3 major ethnic populations: Caucasians, Africans, and East Asians. This sample size was sufficiently large to demonstrate genetic differences among these major ethnic groups while concomitantly confirming similarities among East Asian subpopulations (Korean, Han Chinese, and Japanese). A comprehensive presentation of allele and genotype frequencies is included in the online supplement, and 3 of the most widely studied cytochrome P450 (CYP) genes, CYP2D6, CYP2C19, and CYP2C9; 2 non-CYP enzymes, NAT1 and TMPT; and 2 transporter genes, SLCO1B1 and SLCO2B1, are presented herein according to ethnic classification. PMID:20173083

  10. In vitro metabolism of α7 neuronal nicotinic receptor agonist AZD0328 and enzyme identification for its N-oxide metabolite.

    PubMed

    Zhou, Diansong; Zhang, Minli; Ye, Xiaomei; Gu, Chungang; Piser, Timothy M; Lanoue, Bernard A; Schock, Sara A; Cheng, Yi-Fang; Grimm, Scott W

    2011-03-01

    1. AZD0328 was pharmacologically characterized as a α7 neuronal nicotinic receptor agonist intended for treatment of Alzheimer's disease. In vitro AZD0328 cross species metabolite profile and enzyme identification for its N-oxide metabolite were evaluated in this study. 2. AZD0328 was very stable in the human hepatocyte incubation, whereas extensively metabolized in rat, dog and guinea pig hepatocyte incubations. The N-oxidation metabolite (M6) was the only metabolite detected in human hepatocyte incubations, and it also appeared to be the major in vitro metabolic pathway in a number of preclinical species. In addition, N-glucuronide metabolite of AZD0328 was observed in human liver microsomes. 3. Other metabolic pathways in the preclinical species include hydroxylation in azabicyclo octane or furopyridine part of the molecule. Pyridine N-methylation of AZD0328 (M2) was identified as a dog specific metabolite, not observed in human or other preclinical species. 4. Multiple enzymes including CYP2D6, CYP3A4/5, FMO1 and FMO3 catalyzed AZD0328 metabolism. The potential for AZD0328 to be inhibited clinically by co-administered drugs or genetic polymorphism is relative low. PMID:21226652

  11. Effects of capsaicin and dihydrocapsaicin on human and rat liver microsomal CYP450 enzyme activities in vitro and in vivo.

    PubMed

    Zhang, Qing-Hao; Hu, Jin-Ping; Wang, Bao-Lian; Li, Yan

    2012-01-01

    Capsaicin and dihydrocapsaicin, the two most abundant members of capsaicinoids in chili peppers, are widely used as food additives and for other purposes. In this study, we examined the inhibitory potentials of capsaicin and dihydrocapsaicin against CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4/5 activities in human liver microsomes. The effects of these two capsaicinoids on CYP450 enzymes were also evaluated in vivo in rats. The results demonstrated that capsaicin and dihydrocapsaicin moderately inhibited five isozymes (IC₅₀) values ranging from 4.4 to 61.8 μM), with the exception of CYP2E1 (IC₅₀ > 200 μM). Both capsaicinoids exhibited competitive, mixed, and noncompetitive inhibition on these isozymes (K (i) = 3.1 ± 0.5 - 78.6 ± 8.4 μM). Time-dependent inhibition of CYP3A4/5 by capsaicin was found. After multiple administrations of capsaicin and dihydrocapsaicin (1, 4, and 10 mg/kg) to rats, chlorzoxazone 6-hydroxylase activity and the expression of CYP2E1 were increased in liver microsomes. Our findings indicated that the possibility of food-drug interactions mediated by capsaicin and dihydrocapsaicin could not be excluded, and provided the useful information for evaluating the anticarcinogenic potentials of these two capsaicinoids. PMID:22375877

  12. Evolution of the CYP2D gene cluster in humans and four non-human primates.

    PubMed

    Yasukochi, Yoshiki; Satta, Yoko

    2011-01-01

    The human cytochrome P450 2D6 (CYP2D6) is a primary enzyme involved in the metabolism of about 25% of commonly used therapeutic drugs. CYP2D6 belongs to the CYP2D subfamily, a gene cluster located on chromosome 22, which comprises the CYP2D6 gene and pseudogenes CYP2D7P and CYP2D8P. Although the chemical and physiological properties of CYP2D6 have been extensively studied, there has been no study to date on molecular evolution of the CYP2D subfamily in the human genome. Such knowledge could greatly contribute to the understanding of drug metabolism in humans because it makes us to know when and how the current metabolic system has been constructed. The knowledge moreover can be useful to find differences in exogenous substrates in a particular metabolism between human and other animals such as experimental animals. Here, we conducted a preliminary study to investigate the evolution and gene organization of the CYP2D subfamily, focused on humans and four non-human primates (chimpanzees, orangutans, rhesus monkeys, and common marmosets). Our results indicate that CYP2D7P has been duplicated from CYP2D6 before the divergence between humans and great apes, whereas CYP2D6 and CYP2D8P have been already present in the stem lineages of New World monkeys and Catarrhini. Furthermore, the origin of the CYP2D subfamily in the human genome can be traced back to before the divergence between amniotes and amphibians. Our analyses also show that reported chimeric sequences of the CYP2D6 and CYP2D7 genes in the chimpanzee genome appear to be exchanged in its genome database. PMID:21670550

  13. Drug Metabolism Enzyme Expression and Activity in Primary Cultures of Human Proximal Tubular Cells

    PubMed Central

    Lash, Lawrence H.; Putt, David A.; Cai, Hongliang

    2008-01-01

    We previously catalogued expression and activity of organic anion and cation, amino acid, and peptide transporters in primary cultures of human proximal tubular (hPT) cells to establish them as a cellular model to study drug transport in the human kidney [Toxicology 228, 200–218 (2006)]. Here, we extend our analysis to drug metabolism enzymes. Expression of 11 cytochrome P450 (CYP) enzymes was determined with specific antibodies. CYP1B1, CYP3A4, and CYP4A11 were the only CYP enzymes readily detected in total cell extracts. These same CYP enzymes, as well as CYP3A5 and possibly CYP2D6, were detected in microsomes from confluent hPT cells, although expression levels varied among kidney samples. In agreement with Western blot data, only activity of CYP3A4/5 was detected among the enzyme activities measured. Expression of all three glutathione S-transferases (GSTs) known to be found in hPT cells, GSTA, GSTP, and GSTT, was readily detected. Variable expression of three sulfotransferases (SULTs), SULT1A3, SULT1E, and SULT2A1, and three UDP-glucuronosyltransferases (UGTs), UGT1A1, UGT1A6, and UGT2B7, was also detected. When examined over the course of cell growth to confluence, expression of all enzymes was generally maintained at readily measurable levels, although they were often lower than in fresh tissue. These results indicate that primary cultures of hPT cells possess significant capacity to metabolize many classes of drugs, and can be used as an effective model to study drug metabolism. PMID:18055091

  14. Clinically relevant genetic variants of drug-metabolizing enzyme and transporter genes detected in Thai children and adolescents with autism spectrum disorder

    PubMed Central

    Medhasi, Sadeep; Pasomsub, Ekawat; Vanwong, Natchaya; Ngamsamut, Nattawat; Puangpetch, Apichaya; Chamnanphon, Montri; Hongkaew, Yaowaluck; Limsila, Penkhae; Pinthong, Darawan; Sukasem, Chonlaphat

    2016-01-01

    Single-nucleotide polymorphisms (SNPs) among drug-metabolizing enzymes and transporters (DMETs) influence the pharmacokinetic profile of drugs and exhibit intra- and interethnic variations in drug response in terms of efficacy and safety profile. The main objective of this study was to assess the frequency of allelic variants of drug absorption, distribution, metabolism, and elimination-related genes in Thai children and adolescents with autism spectrum disorder. Blood samples were drawn from 119 patients, and DNA was extracted. Genotyping was performed using the DMET Plus microarray platform. The allele frequencies of the DMET markers were generated using the DMET Console software. Thereafter, the genetic variations of significant DMET genes were assessed. The frequencies of SNPs across the genes coding for DMETs were determined. After filtering the SNPs, 489 of the 1,931 SNPs passed quality control. Many clinically relevant SNPs, including CYP2C19*2, CYP2D6*10, CYP3A5*3, and SLCO1B1*5, were found to have frequencies similar to those in the Chinese population. These data are important for further research to investigate the interpatient variability in pharmacokinetics and pharmacodynamics of drugs in clinical practice. PMID:27110117

  15. Inhibitory effects of sanguinarine on human liver cytochrome P450 enzymes.

    PubMed

    Qi, Xiao-Yi; Liang, Si-Cheng; Ge, Guang-Bo; Liu, Yong; Dong, Pei-Pei; Zhang, Jiang-Wei; Wang, Ao-Xue; Hou, Jie; Zhu, Liang-Liang; Yang, Ling; Tu, Cai-Xia

    2013-06-01

    Sanguinarine (SAG) has been recognized as an anticancer drug candidate. However, the drug-drug interactions (DDI) potential for SAG via the inhibition against human cytochrome P450 (CYP) enzymes remains unclear. In the present study, the inhibitory effects of SAG on seven major human CYP isoforms 1A2, 2A6, 2E1, 2D6, 2C8, 2C9 and 3A4 were investigated with human liver microsomes (HLM). The results showed that SAG was a potent noncompetitive inhibitor of CYP2C8 activity (Ki=8.9 μM), and competitive inhibitor of CYP1A2, CYP2C9 and CYP3A4 activities (Ki=2.7, 3.8 and 2.0 μM, respectively). Furthermore, SAG exhibited time- and NADPH-dependent inhibition towards CYP1A2 and CYP3A4 with KI/kinact values of 13.3/0.087 and 5.58/0.029 min(-1) μM(-1), respectively. Weak inhibition of SAG against CYP2E1, CYP2D6 and CYP2A6 was also observed. In vitro-in vivo extrapolation (IV-IVE) from HLM data showed that more than 35.9% of CYP1A2, CYP2C9, CYP2C8 and CYP3A4 activities in vivo could be inhibited by SAG, suggesting that harmful DDIs could occur when SAG or its medical preparations are co-administered with drugs primarily cleared by these CYP isoforms. Further in vivo studies are needed to evaluate the clinical significance of the data presented herein. PMID:23500771

  16. Use of Human Plasma Samples to Identify Circulating Drug Metabolites that Inhibit Cytochrome P450 Enzymes.

    PubMed

    Eng, Heather; Obach, R Scott

    2016-08-01

    Drug interactions elicited through inhibition of cytochrome P450 (P450) enzymes are important in pharmacotherapy. Recently, greater attention has been focused on not only parent drugs inhibiting P450 enzymes but also on possible inhibition of these enzymes by circulating metabolites. In this report, an ex vivo method whereby the potential for circulating metabolites to be inhibitors of P450 enzymes is described. To test this method, seven drugs and their known plasma metabolites were added to control human plasma at concentrations previously reported to occur in humans after administration of the parent drug. A volume of plasma for each drug based on the known inhibitory potency and time-averaged concentration of the parent drug was extracted and fractionated by high-pressure liquid chromatography-mass spectrometry, and the fractions were tested for inhibition of six human P450 enzyme activities (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4). Observation of inhibition in fractions that correspond to the retention times of metabolites indicates that the metabolite has the potential to contribute to P450 inhibition in vivo. Using this approach, norfluoxetine, hydroxyitraconazole, desmethyldiltiazem, desacetyldiltiazem, desethylamiodarone, hydroxybupropion, erythro-dihydrobupropion, and threo-dihydrobupropion were identified as circulating metabolites that inhibit P450 activities at a similar or greater extent as the parent drug. A decision tree is presented outlining how this method can be used to determine when a deeper investigation of the P450 inhibition properties of a drug metabolite is warranted. PMID:27271369

  17. In vitro evaluation of the effects of 4-aminopyridine on cytochrome P450 enzymes

    PubMed Central

    Caggiano, Anthony; Blight, Andrew

    2013-01-01

    Background Dalfampridine extended release tablets (dalfampridine-ER, known as prolonged-, modified, or sustained-release fampridine tablets in some countries) are approved for the improvement of walking in patients with multiple sclerosis (MS). Dalfampridine-ER is an extended release formulation of 4-aminopyridine (4-AP). Dalfampridine-ER is incorporated into MS management strategies that may include disease-modifying and symptomatic therapies. Since several symptomatic therapies are partially or fully metabolized by enzymes of the hepatic cytochrome P450 system (CYP450) it is important to evaluate drug–drug interactions through potential effects of dalfampridine-ER on CYP450. Methods The ability of 4-AP to inhibit CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4/5 in a direct and time-dependent manner was evaluated using pooled human liver microsomes. 4-AP concentrations were 0.03, 0.1, 0.3, 1, 3, 10, and 30 μM, representing 0.1–100-times the average plasma 4-AP concentration (30 ng/mL; 0.32 μM) at therapeutic dosing; the concentration inhibiting 50% of each enzyme activity (IC50) was determined. The ability of 4-AP (0.025, 0.25, 2.5, and 25 μM) to induce the expression of CYP1A2, 2B6, 2C9, 2C19, 2E1, and 3A4/5 enzymes was evaluated using primary cultures of freshly isolated human hepatocytes from non-transplantable livers. The enzyme-inducing effects of 4-AP were compared with the prototypical inducers. Metabolites were assayed using high-performance liquid chromatography-tandem mass spectrometry techniques. All inhibition and induction assays included positive controls. Results 4-AP did not directly inhibit CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, or CYP3A4/5, but at a concentration of 30 μM, CYP2E1 was inhibited by 12%, resulting in an estimated IC50 value of 125 μM. None of the enzymes demonstrated time-dependent inhibition by 4-AP. There was little or no effect by 4-AP on enzyme induction, with

  18. CYP2D60 and Clinical Response to Atomoxetine in Children and Adolescents with ADHD

    ERIC Educational Resources Information Center

    Michelson, David; Read, Holly A.; Ruff, Dustin D.; Witcher, Jennifer; Zhang, Shuyu; McCracken, James

    2007-01-01

    Background: Atomoxetine, a selective norepinephrine reuptake inhibitor effective in the treatment of attention-deficit/hyperactivity disorder (ADHD), is metabolized through the cytochrome P-450 2D6 (CYP2D6) enzyme pathway, which is genetically polymorphic in humans. Variations in plasma atomoxetine exposures can occur because of genetic variation…

  19. The effect of enzyme inhibition on the metabolism and activation of tacrine by human liver microsomes.

    PubMed Central

    Spaldin, V; Madden, S; Pool, W F; Woolf, T F; Park, B K

    1994-01-01

    1. Tacrine (1,2,3,4-tetrahydro-9-aminoacridine-hydrochloride: THA) underwent metabolism in vitro by a panel (n = 12) of human liver microsomes genotyped for CYP2D6, in the presence of NADPH, to both protein-reactive and stable metabolites. 2. There was considerable variation in the extent of THA metabolism amongst human livers. Protein-reactive metabolite formation showed a 10-fold variation (0.6 +/- 0.1%-5.2 +/- 0.8% of incubated radioactivity mg-1 protein) whilst stable metabolites showed a 3-fold variation (24.3 +/- 1.7%-78.6 +/- 2.6% of incubated radioactivity). 3. Using cytochrome P450 isoform specific inhibitors CYP1A2 was identified as the major enzyme involved in all routes of THA metabolism. 4. There was a high correlation between aromatic and alicyclic hydroxylation (r = 0.92, P < 0.0001) consistent with these biotransformations being catalysed by the same enzymes. 5. Enoxacin (ENOX), cimetidine (CIM) and chloroquine (CQ) inhibited THA metabolism by a preferential decrease in the bioactivation to protein-reactive, and hence potentially toxic, species. The inhibitory potency of ENOX and CIM was increased significantly upon pre-incubation with microsomes and NADPH. 6. Covalent binding correlated with 7-OH-THA formation before (r = 0.792, P < 0.0001) and after (r = 0.73, P < 0.0001) inhibition by CIM, consistent with a two-step mechanism in the formation of protein-reactive metabolite(s) via a 7-OH intermediate. 7. The use of enzyme inhibitors may provide a useful tool for examining the relationship between the metabolism and toxicity of THA in vivo. PMID:7946932

  20. Effects of suberoylanilide hydroxamic acid on rat cytochrome P450 enzyme activities

    PubMed Central

    Lin, Kezhi; Zhang, Qingwei; Liu, Zezheng; Yang, Suping; Lin, Yingying; Wen, Congcong; Zheng, Yuancai

    2015-01-01

    Vorinostat (suberoylanilide hydroxamic acid, SAHA) is the first approved histone deacetylase (HDAC) inhibitor for the treatment of cutaneous T-cell lymphoma after progressive disease following two systemic therapies. The rats were randomly divided into SAHA groups (low, medium and high dosage) and control group. The SAHA group rats were given 12.3, 24.5, and 49 mg/kg SAHA, respectively, by continuous intragastric administration for 7 days. The influence of SAHA on the activities of CYP450 isoforms CYP2B6, CYP1A2, CYP2C19, CYP2D6 and CYP2C9 were evaluated by cocktail method, they were responsed by the changes of pharmacokinetic parameters of bupropion, phenacetin, tolbutamide, metroprolol and omeprazole. The five probe drugs were given to rats through intragastric administration, and the plasma concentration were determined by UPLC-MS/MS. The result of SAHA group compared to control group, there were statistical pharmacokinetics difference for bupropion, phenacetin, tolbutamide and metroprolol. Continuous intragastric administration for 7 days may induce the activities of CYP2C19 of rats, inhibit CYP1A2 and slightly inhibit CYP2B6 and CYP2D6 of rats. This may give advising for reasonable drug use after co-used with SAHA. The results indicated that drug co-administrated with SAHA may need dose adjustment. Furthermore, continuous intragastric administration of SAHA for 7 days, liver cell damaged, causing liver cell edema, in liver metabolism process. PMID:26191268

  1. Effects of suberoylanilide hydroxamic acid on rat cytochrome P450 enzyme activities.

    PubMed

    Lin, Kezhi; Zhang, Qingwei; Liu, Zezheng; Yang, Suping; Lin, Yingying; Wen, Congcong; Zheng, Yuancai

    2015-01-01

    Vorinostat (suberoylanilide hydroxamic acid, SAHA) is the first approved histone deacetylase (HDAC) inhibitor for the treatment of cutaneous T-cell lymphoma after progressive disease following two systemic therapies. The rats were randomly divided into SAHA groups (low, medium and high dosage) and control group. The SAHA group rats were given 12.3, 24.5, and 49 mg/kg SAHA, respectively, by continuous intragastric administration for 7 days. The influence of SAHA on the activities of CYP450 isoforms CYP2B6, CYP1A2, CYP2C19, CYP2D6 and CYP2C9 were evaluated by cocktail method, they were responsed by the changes of pharmacokinetic parameters of bupropion, phenacetin, tolbutamide, metroprolol and omeprazole. The five probe drugs were given to rats through intragastric administration, and the plasma concentration were determined by UPLC-MS/MS. The result of SAHA group compared to control group, there were statistical pharmacokinetics difference for bupropion, phenacetin, tolbutamide and metroprolol. Continuous intragastric administration for 7 days may induce the activities of CYP2C19 of rats, inhibit CYP1A2 and slightly inhibit CYP2B6 and CYP2D6 of rats. This may give advising for reasonable drug use after co-used with SAHA. The results indicated that drug co-administrated with SAHA may need dose adjustment. Furthermore, continuous intragastric administration of SAHA for 7 days, liver cell damaged, causing liver cell edema, in liver metabolism process. PMID:26191268

  2. Inhibitory Effects of Aschantin on Cytochrome P450 and Uridine 5'-diphospho-glucuronosyltransferase Enzyme Activities in Human Liver Microsomes.

    PubMed

    Kwon, Soon-Sang; Kim, Ju-Hyun; Jeong, Hyeon-Uk; Cho, Yong Yeon; Oh, Sei-Ryang; Lee, Hye Suk

    2016-01-01

    Aschantin is a bioactive neolignan found in Magnolia flos with antiplasmodial, Ca(2+)-antagonistic, platelet activating factor-antagonistic, and chemopreventive activities. We investigated its inhibitory effects on the activities of eight major human cytochrome P450 (CYP) and uridine 5'-diphospho-glucuronosyltransferase (UGT) enzymes of human liver microsomes to determine if mechanistic aschantin-enzyme interactions were evident. Aschantin potently inhibited CYP2C8-mediated amodiaquine N-de-ethylation, CYP2C9-mediated diclofenac 4'-hydroxylation, CYP2C19-mediated [S]-mephenytoin 4'-hydroxylation, and CYP3A4-mediated midazolam 1'-hydroxylation, with Ki values of 10.2, 3.7, 5.8, and 12.6 µM, respectively. Aschantin at 100 µM negligibly inhibited CYP1A2-mediated phenacetin O-de-ethylation, CYP2A6-mediated coumarin 7-hydroxylation, CYP2B6-mediated bupropion hydroxylation, and CYP2D6-mediated bufuralol 1'-hydroxylation. At 200 µM, it weakly inhibited UGT1A1-catalyzed SN-38 glucuronidation, UGT1A6-catalyzed N-acetylserotonin glucuronidation, and UGT1A9-catalyzed mycophenolic acid glucuronidation, with IC50 values of 131.7, 144.1, and 71.0 µM, respectively, but did not show inhibition against UGT1A3, UGT1A4, or UGT2B7 up to 200 µM. These in vitro results indicate that aschantin should be examined in terms of potential interactions with pharmacokinetic drugs in vivo. It exhibited potent mechanism-based inhibition of CYP2C8, CYP2C9, CYP2C19, and CYP3A4. PMID:27128896

  3. Biological definition of multiple chemical sensitivity from redox state and cytokine profiling and not from polymorphisms of xenobiotic-metabolizing enzymes

    SciTech Connect

    De Luca, Chiara; Scordo, Maria G.; Cesareo, Eleonora; Pastore, Saveria; Mariani, Serena; Maiani, Gianluca; Stancato, Andrea; Loreti, Beatrice; Valacchi, Giuseppe; Lubrano, Carla; Raskovic, Desanka; De Padova, Luigia; Genovesi, Giuseppe; Korkina, Liudmila G.

    2010-11-01

    Background: Multiple chemical sensitivity (MCS) is a poorly clinically and biologically defined environment-associated syndrome. Although dysfunctions of phase I/phase II metabolizing enzymes and redox imbalance have been hypothesized, corresponding genetic and metabolic parameters in MCS have not been systematically examined. Objectives: We sought for genetic, immunological, and metabolic markers in MCS. Methods: We genotyped patients with diagnosis of MCS, suspected MCS and Italian healthy controls for allelic variants of cytochrome P450 isoforms (CYP2C9, CYP2C19, CYP2D6, and CYP3A5), UDP-glucuronosyl transferase (UGT1A1), and glutathione S-transferases (GSTP1, GSTM1, and GSTT1). Erythrocyte membrane fatty acids, antioxidant (catalase, superoxide dismutase (SOD)) and glutathione metabolizing (GST, glutathione peroxidase (Gpx)) enzymes, whole blood chemiluminescence, total antioxidant capacity, levels of nitrites/nitrates, glutathione, HNE-protein adducts, and a wide spectrum of cytokines in the plasma were determined. Results: Allele and genotype frequencies of CYPs, UGT, GSTM, GSTT, and GSTP were similar in the Italian MCS patients and in the control populations. The activities of erythrocyte catalase and GST were lower, whereas Gpx was higher than normal. Both reduced and oxidised glutathione were decreased, whereas nitrites/nitrates were increased in the MCS groups. The MCS fatty acid profile was shifted to saturated compartment and IFNgamma, IL-8, IL-10, MCP-1, PDGFbb, and VEGF were increased. Conclusions: Altered redox and cytokine patterns suggest inhibition of expression/activity of metabolizing and antioxidant enzymes in MCS. Metabolic parameters indicating accelerated lipid oxidation, increased nitric oxide production and glutathione depletion in combination with increased plasma inflammatory cytokines should be considered in biological definition and diagnosis of MCS.

  4. Pharmacogenetics of drug oxidation via cytochrome P450 (CYP) in the populations of Denmark, Faroe Islands and Greenland.

    PubMed

    Brosen, Kim

    2015-09-01

    Denmark, the Faroe Islands and Greenland are three population-wise small countries on the northern part of the Northern Hemisphere, and studies carried out here on the genetic control over drug metabolism via cytochrome P450 have led to several important discoveries. Thus, CYP2D6 catalyzes the 2-hydroxylation, and CYP2C19 in part catalyzes the N-demethylation of imipramine. The phenomenon of phenocopy with regard to CYP2D6 was first described when Danish patients changed phenotype from extensive to poor metabolizers during treatment with quinidine. It was a Danish extensive metabolizer patient that became a poor metabolizer during paroxetine treatment, and this was due to the potent inhibition of CYP2D6 by paroxetine, which is also is metabolized by this enzyme. Fluoxetine and norfluoxetine are also potent inhibitors of CYP2D6, and fluvoxamine is a potent inhibitor of both CYP1A2 and CYP2C19. The bioactivation of proguanil to cycloguanil is impaired in CYP2C19 poor metabolizers. The O-demethylation of codeine and tramadol to their respective my-opioid active metabolites, morphine and (+)-O-desmethyltramadol was markedly impaired in CYP2D6 poor metabolizers compared to extensive metabolizers, and this impairs the hypoalgesic effect of the two drugs in the poor metabolizers. The frequency of CYP2D6 poor metabolizers is 2%-3% in Greenlanders and nearly 15% in the Faroese population. The frequency of CYP2C19 poor metabolizers in East Greenlanders is approximately 10%. A study in Danish mono and dizygotic twins showed that the non-polymorphic 3-N-demethylation of caffeine catalyzed by CYP1A2 is subject to approximately 70% genetic control. PMID:25719307

  5. Screening of Drug Metabolizing Enzymes for the Ginsenoside Compound K In Vitro: An Efficient Anti-Cancer Substance Originating from Panax Ginseng

    PubMed Central

    Lin, Xiu-Xian; Peng, Shi-Fang; Xiao, Mei-Fang; Huang, Wei-Hua; Wang, Yi-Cheng; Peng, Jing-Bo; Zhang, Wei; Ouyang, Dong-Sheng; Chen, Yao

    2016-01-01

    Ginsenoside compound K (CK), a rare ginsenoside originating from Panax Ginseng, has been found to possess unique pharmacological activities specifically as anti-cancers. However, the role of cytochrome P450s (CYPs) in the metabolism of CK is unclear. In this study, we screened the CYPs for the metabolism of CK in vitro using human liver microsomes (HLMs) or human recombinant CYPs. The results showed that CK inhibited the enzyme activities of CYP2C9 and CYP3A4 in the HLMs. The Km and Vmax values of CK were 84.20±21.92 μM and 0.28±0.04 nmol/mg protein/min, respectively, for the HLMs; 34.63±10.48 μM and 0.45±0.05 nmol/nmol P450/min, respectively, for CYP2C9; and 27.03±5.04 μM and 0.68±0.04 nmol/nmol P450/min, respectively, for CYP3A4. The IC50 values were 16.00 μM and 9.83 μM, and Ki values were 14.92 μM and 11.42μM for CYP2C9 and CYP3A4, respectively. Other human CYP isoforms, including CYP1A2, CYP2A6, CYP2D6, CYP2E1, and CYP2C19, showed minimal or no effect on CK metabolism. The results suggested that CK was a substrate and also inhibitors for both CYP2C9 and CYP3A4. Patients using CK in combination with therapeutic drugs that are substrates of CYP2C9 and CYP3A4 for different reasons should be careful, although the inhibiting potency of CK is much poorer than that of enzyme-specific inhibitors. PMID:26845774

  6. Characterization and biological properties of NanoCUR formulation and its effect on major human cytochrome P450 enzymes.

    PubMed

    Shamsi, Suhaili; Chen, Yan; Lim, Lee Yong

    2015-11-10

    Curcumin (CUR) has been formulated into a host of nano-sized formulations in a bid to improve its in vivo solubility, stability and bioavailability. The aim of this study was to investigate whether the encapsulation of CUR in nanocarriers would impede its biological interactivity, specifically its potential anti-cancer adjuvant activity via the modulation of CYP enzymes in vitro. NanoCUR, a micellar dispersion prepared via a thin film method using only Pluronic F127 as excipient, was amenable to lyophilization, and retained its nano-sized spherical dimensions (17-33 nm) upon reconstitution with water followed by dilution to 5 μM with HBSS or EMEM. NanoCUR was a weaker cytotoxic agent compared to CUR in solution (sCUR), affecting HepG2 cell viability only when the incubation time was prolonged from 4h to 48 h. Correlation with 2h uptake data suggests this was due to a lower cellular uptake rate of CUR from NanoCUR than from sCUR. The poorer CUR accessibility might also account for NanoCUR being a weaker inhibitor of CYP2C9 and CYP2D6 than sCUR. NanoCUR was, however, 1.76-fold more potent against the CYP3A4 (IC50 5.13 ± 0.91 μM) metabolic function. The higher activity against CYP3A4 might be attributed to the synergistic action of Pluronic F127, since the blank micellar dispersion also inhibited CYP3A4 activity. Both sCUR and NanoCUR had no effect on the CYP3A4 mRNA levels in the HepG2 cells. NanoCUR therefore, maintained most of the biological activities of CUR in vitro, albeit at a lower potency and response rate. PMID:26319630

  7. Interactions of the hepatitis C virus protease inhibitor faldaprevir with cytochrome P450 enzymes: in vitro and in vivo correlation.

    PubMed

    Sabo, John P; Kort, Jens; Ballow, Charles; Kashuba, Angela D M; Haschke, Manuel; Battegay, Manuel; Girlich, Birgit; Ting, Naitee; Lang, Benjamin; Zhang, Wei; Cooper, Curtis; O'Brien, Drané; Seibert, Eleanore; Chan, Tom S; Tweedie, Donald; Li, Yongmei

    2015-04-01

    The potential inhibition of the major human cytochrome P450 (CYP) enzymes by faldaprevir was evaluated both in vitro and in clinical studies (healthy volunteers and hepatitis C virus [HCV] genotype 1-infected patients). In vitro studies indicated that faldaprevir inhibited CYP2B6, CYP2C9, and CYP3A, and was a weak-to-moderate inactivator of CYP3A4. Faldaprevir 240 mg twice daily in healthy volunteers demonstrated moderate inhibition of hepatic and intestinal CYP3A (oral midazolam: 2.96-fold increase in AUC(0-24 h)), weak inhibition of hepatic CYP3A (intravenous midazolam: 1.56-fold increase in AUC(0-24 h)), weak inhibition of CYP2C9 ([S]-warfarin: 1.29-fold increase in AUC(0-120 h)), and had no relevant effects on CYP1A2, CYP2B6, or CYP2D6. Faldaprevir 120 mg once daily in HCV-infected patients demonstrated weak inhibition of hepatic and intestinal CYP3A (oral midazolam: 1.52-fold increase in AUC(0-∞)), and had no relevant effects on CYP2C9 or CYP1A2. In vitro drug-drug interaction predictions based on inhibitor concentration ([I])/inhibition constant (Ki) ratios tended to overestimate clinical effects and a net-effect model provided a more accurate approach. These studies suggest that faldaprevir shows a dose-dependent inhibition of CYP3A and CYP2C9, and does not induce CYP isoforms. PMID:25449227

  8. Phenotyping studies to assess the effects of phytopharmaceuticals on in vivo activity of main human cytochrome p450 enzymes.

    PubMed

    Zadoyan, Gregor; Fuhr, Uwe

    2012-09-01

    The extensive use of herbal drugs and their multiple components and modes of action suggests that they may also cause drug interactions by changing the activity of human cytochrome P450 enzymes. The purpose of the present review is to present the available data for the top 14 herbal drug sales in the U. S. Studies describing the effects of herbal drugs on phenotyping substrates for individual CYPs were identified by a comprehensive MEDLINE search. Drugs included Allium sativum (Liliaceae), Echinacea purpurea (Asteraceae), Serenoa repens (Arecaceae), Ginkgo biloba (Ginkgoaceae), Vaccinium macrocarpon (Ericaceae), Glycine max (Fabaceae), Panax ginseng (Araliaceae), Actea racemosa (Ranunculaceae), Hypericum perforatum (Hypericaceae), Silybum marianum (Asteraceae), Camellia sinensis (Theaceae), Valeriana officinalis (Valerianaceae), Piper methysticum (Piperaceae), and Hydrastis canadensis (Ranunculaceae) preparations. We identified 70 clinical studies in 69 publications. The majority of the herbal drugs appeared to have no clear effects on most of the CYPs examined. If there was an effect, there was mild inhibition in almost all cases, as seen with garlic or kava effects on CYP2E1 and with soybean components on CYP1A2. The most pronounced effects were induction of CYP3A and other CYPs by St. John's wort and the inhibitory effect of goldenseal on CYP3A and CYP2D6, both being borderline between mild and moderate in magnitude. With the exceptions of St.John's wort and goldenseal, the information currently available suggests that concomitant intake of the herbal drugs addressed here is not a major risk for drugs that are metabolized by CYPs. PMID:22588833

  9. Cytochrome P450 Activity in Ex Vivo Cornea Models and a Human Cornea Construct.

    PubMed

    Kölln, Christian; Reichl, Stephan

    2016-07-01

    The pharmacokinetic behaviors of novel ophthalmic drugs are often preliminarily investigated in preclinical studies using ex vivo animal cornea or corneal cell culture models. During transcorneal passage, topically applied drugs may be affected by drug metabolizing enzymes. The knowledge regarding the functional expression of metabolic enzymes in corneal tissue is marginal; thus, the aim of this study was to investigate cytochrome P450 activity in an organotypic three-dimensional human cornea construct and to compare it with porcine and rabbit corneas, which are commonly used ex vivo cornea models. The total cytochrome P450 activity was determined by measuring the transformation of 7-ethoxycoumarin. Furthermore, the expression of the cytochrome P450 enzyme 2D6 (CYP2D6) was investigated at the protein level using immunohistochemistry and western blotting. CYP2D6 activity measurements were performed using a d-luciferin-based assay. In summary, similar levels of the total cytochrome P450 activity were identified in all 3 cornea models. The protein expression of CYP2D6 was confirmed in the human cornea construct and porcine cornea, whereas the signals in the rabbit cornea were weak. The analysis of the CYP2D6 activity indicated similar values for the human cornea construct and porcine cornea; however, a distinctly lower activity was observed in the rabbit cornea. PMID:27212636

  10. Expansion of a PBPK model to predict disposition in pregnant women of drugs cleared via multiple CYP enzymes, including CYP2B6, CYP2C9 and CYP2C19

    PubMed Central

    Ke, Alice Ban; Nallani, Srikanth C; Zhao, Ping; Rostami-Hodjegan, Amin; Unadkat, Jashvant D

    2014-01-01

    Aim Conducting PK studies in pregnant women is challenging. Therefore, we asked if a physiologically-based pharmacokinetic (PBPK) model could be used to predict the disposition in pregnant women of drugs cleared by multiple CYP enzymes. Methods We expanded and verified our previously published pregnancy PBPK model by incorporating hepatic CYP2B6 induction (based on in vitro data), CYP2C9 induction (based on phenytoin PK) and CYP2C19 suppression (based on proguanil PK), into the model. This model accounted for gestational age-dependent changes in maternal physiology and hepatic CYP3A, CYP1A2 and CYP2D6 activity. For verification, the pregnancy-related changes in the disposition of methadone (cleared by CYP2B6, 3A and 2C19) and glyburide (cleared by CYP3A, 2C9 and 2C19) were predicted. Results Predicted mean post-partum to second trimester (PP : T2) ratios of methadone AUC, Cmax and Cmin were 1.9, 1.7 and 2.0, vs. observed values 2.0, 2.0 and 2.6, respectively. Predicted mean post-partum to third trimester (PP : T3) ratios of methadone AUC, Cmax and Cmin were 2.1, 2.0 and 2.4, vs. observed values 1.7, 1.7 and 1.8, respectively. Predicted PP : T3 ratios of glyburide AUC, Cmax and Cmin were 2.6, 2.2 and 7.0 vs. observed values 2.1, 2.2 and 3.2, respectively. Conclusions Our PBPK model integrating prior physiological knowledge, in vitro and in vivo data, allowed successful prediction of methadone and glyburide disposition during pregnancy. We propose this expanded PBPK model can be used to evaluate different dosing scenarios, during pregnancy, of drugs cleared by single or multiple CYP enzymes. PMID:23834474

  11. In vitro inhibition and induction of human liver cytochrome P450 enzymes by gentiopicroside: potent effect on CYP2A6.

    PubMed

    Deng, Yating; Wang, Lu; Yang, Yong; Sun, Wenji; Xie, Renming; Liu, Xueying; Wang, Qingwei

    2013-01-01

    Gentiopicroside (GE), a naturally occurring iridoid glycoside, has been developed into a Novel Traditional Chinese Drug named gentiopicroside injection, and it was approved for the treatment of acute jaundice and chronic active hepatitis by SFDA. However, the inhibitory and inducible effects of GE on the activity of cytochrome P450 (CYP450) are unclear. The purpose of this study was to evaluate the ability of GE to inhibit and induce human cytochrome P450 enzymes in vitro. In human liver microsomes, GE inhibited CYP2A6 and CYP2E1 in a concentration-dependent manner, with IC₅₀ values of 21.8 µg/ml and 594 µg/ml, respectively, and the IC₅₀ of CYP2A6 was close to the C(max) value observed clinically. GE was a non-competitive inhibitor of CYP2A6 at lower concentrations and a competitive inhibitor at higher concentrations. GE did not produce inhibition of CYP2C9, CYP2D6, CYP1A2 or CYP3A4 activities. However, a significant increase of CYP1A2 and CYP3A4 activity was observed at high concentrations. In cultured human hepatocytes no significant induction of CYP1A2, CYP3A4 or CYP2B6 was observed. Given these results, the in vivo potential inhibition of GE on CYP2A6 deserves further investigation, and it seems that the hepatoprotective effect of GE is irrelevant to its effect on P450s. PMID:23419353

  12. Absolute protein quantification of clinically relevant cytochrome P450 enzymes and UDP-glucuronosyltransferases by mass spectrometry-based targeted proteomics.

    PubMed

    Gröer, C; Busch, D; Patrzyk, M; Beyer, K; Busemann, A; Heidecke, C D; Drozdzik, M; Siegmund, W; Oswald, S

    2014-11-01

    Cytochrome P450 (CYP) enzymes and UDP-glucuronosyltransferases (UGT) are major determinants in the pharmacokinetics of most drugs on the market. To investigate their impact on intestinal and hepatic drug metabolism, we developed and validated quantification methods for nine CYP (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4 and CYP3A5) and four UGT enzymes (UGT1A1, UGT1A3, UGT2B7 and UGT2B15) that have been shown to be of clinical relevance in human drug metabolism. Protein quantification was performed by targeted proteomics using liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based determination of enzyme specific peptides after tryptic digestion using in each case stable isotope labelled peptides as internal standard. The chromatography of the respective peptides was performed with gradient elution using a reversed phase (C18) column (Ascentis(®) Express Peptide ES-C18, 100mm×2.1mm, 2.7μm) and 0.1% formic acid (FA) as well as acetonitrile with 0.1% FA as mobile phases at a flow rate of 300μl/min. The MS/MS detection of all peptides was done simultaneously with a scheduled multiple reaction monitoring (MRM) method in the positive mode by monitoring in each case three mass transitions per proteospecific peptide and the internal standard. The assays were validated according to current bioanalytical guidelines with respect to specificity, linearity (0.25-50nM), within-day and between-day accuracy and precision, digestion efficiency as well as stability. Finally, the developed method was successfully applied to determine the CYP and UGT protein amount in human liver and intestinal microsomes. The method was shown to possess sufficient specificity, sensitivity, accuracy, precision and stability to quantify clinically relevant human CYP and UGT enzymes. PMID:25218440

  13. Radical intermediates in the catalytic oxidation of hydrocarbons by bacterial and human cytochrome P450 enzymes.

    PubMed

    Jiang, Yongying; He, Xiang; Ortiz de Montellano, Paul R

    2006-01-17

    Cytochromes P450cam and P450BM3 oxidize alpha- and beta-thujone into multiple products, including 7-hydroxy-alpha-(or beta-)thujone, 7,8-dehydro-alpha-(or beta-)thujone, 4-hydroxy-alpha-(or beta-)thujone, 2-hydroxy-alpha-(or beta-)thujone, 5-hydroxy-5-isopropyl-2-methyl-2-cyclohexen-1-one, 4,10-dehydrothujone, and carvacrol. Quantitative analysis of the 4-hydroxylated isomers and the ring-opened product indicates that the hydroxylation proceeds via a radical mechanism with a radical recombination rate ranging from 0.7 +/- 0.3 x 10(10) s(-1) to 12.5 +/- 3 x 10(10) s(-1) for the trapping of the carbon radical by the iron-bound hydroxyl radical equivalent. 7-[2H]-alpha-Thujone has been synthesized and used to amplify C-4 hydroxylation in situations where uninformative C-7 hydroxylation is the dominant reaction. The involvement of a carbon radical intermediate is confirmed by the observation of inversion of stereochemistry of the methyl-substituted C-4 carbon during the hydroxylation. With an L244A mutation that slightly increases the P450(cam) active-site volume, this inversion is observed in up to 40% of the C-4 hydroxylated products. The oxidation of alpha-thujone by human CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4 occurs with up to 80% C-4 methyl inversion, in agreement with a dominant radical hydroxylation mechanism. Three minor desaturation products are produced, with at least one of them via a cationic pathway. The cation involved is proposed to form by electron abstraction from a radical intermediate. The absence of a solvent deuterium isotope effect on product distribution in the P450cam reaction precludes a significant role for the P450 ferric hydroperoxide intermediate in substrate hydroxylation. The results indicate that carbon hydroxylation is catalyzed exclusively by a P450 ferryl species via radical intermediates whose detailed properties are substrate- and enzyme-dependent. PMID:16401082

  14. Role of Metabolic Enzymes P450 (CYP) on Activating Procarcinogen and their Polymorphisms on the Risk of Cancers.

    PubMed

    He, Xin; Feng, Shan

    2015-01-01

    Cytochrome P450 (CYP450) enzymes are the most important metabolizing enzyme family exists among all organs. Apart from their role in the deactivation of most endogenous compounds and xenobiotics, they also mediate most procarcinogens oxidation to ultimate carcinogens. There are several modes of CYP450s activation of procarcinogens. 1) Formation of epoxide and diol-epoxides intermediates, such as CYP1A1 and CYP1B1 mediates PAHs oxidation to epoxide intermediates; 2) Formation of diazonium ions, such as CYP2A6, CYP2A13 and CYP2E1 mediates activation of most nitrosamines to unstable metabolites, which can rearrange to give diazonium ions. 3) Formation of reactive semiquinones and quinines, such as CYP1A1 and CYP1B1 transformation of estradiol to catechol estrogens, subsequently formation semiquinones; 4) Formation of toxic O-esterification, such as CYP1A1 and CYP1A2 metabolizes PhIP to N(2)-acetoxy-PhIP and N(2)-sulfonyloxy-PhIP, which are carcinogenic metabolites. 5) Formation of free radical, such as CYP2E1 is involved in activation tetrachloromethane to free radicals. While for CYP2B6 and CYP2D6, only a minor role has been found in procarcinogens activation. In addition, as the gene polymorphisms reflected, the polymorphisms of CYP1A1 (-3801T/C and -4889A/G), CYP1A2 (- 163C/A and -2467T/delT), CYP1B1 (-48G/C, -119G/T and -432G/C), CYP2E1 (-1293G/C and -1053 C/T) have been associated with an increased risk of lung cancer. The polymorphisms CYP1A1 (-3801T/C and -4889A/G), and CYP2E1 (PstI/Rsa and 9-bp insertion) have an association with higher risk colon cancers, whereas CYP1A2 (-163C/A and -3860G/A) polymorphism is found to be among the protective factors. The polymorphisms CYP1A1 (-3801T/C and -4889A/G), CYP1B1 -432G/C, CYP2B6 (-516G/T and -785A/G) may increase the risk of breast cancer. In conclusion, CYP1A1, CYP1A2, CYP1B1, CYP2A6, and CYP2E1 are responsible for most of the procarcinogens activation, and their gene polymorphisms are associated with the risk of

  15. Pharmacogenetics of drug metabolizing enzymes in the United Kingdom population: review of current knowledge and comparison with selected European populations.

    PubMed

    Daly, Ann K

    2015-09-01

    Data on frequency of pharmacogenetic polymorphisms in the UK population are limited. However, availability of whole genome sequencing data on 94 UK controls of European ethnicity from the 1000 genomes project together with similar data on other populations provides a valuable new source of data in this area and allows direct comparison of allele frequencies with those for other European populations. The ethnic diversity of the UK population also needs to be considered, and 1000 genomes includes data on South Asians, the most common ethnic group in the UK after White Europeans. Allele frequencies for polymorphisms in genes relevant to phase I and phase II drug metabolism for UK, Finnish, Spanish and South Asian populations were obtained from the literature and 1000 genomes. Generally there was good agreement between the literature and 1000 genomes reports. CYP2D6*4, the most common CYP2D6 poor metabolizer allele among Europeans, appears more common in the UK than in Spain and Finland, whereas, as suggested previously, CYP2C19*2 and CYP2C9*2 appear more common in Finland and Spain, respectively, than in the UK. South Asians show low frequencies of CYP2C9*2 and CYP2C19*17 but higher frequencies of CYP2C19*2 compared with UK residents of European ethnicity. Though personalizing drug treatment on the basis of individual genotype rather than ethnicity may be more appropriate, differences in allele frequencies across continents should be considered when designing clinical trials of new drugs. PMID:25803091

  16. Immobilized Cytochrome P450 for Monitoring of P450-P450 Interactions and Metabolism.

    PubMed

    Bostick, Chris D; Hickey, Katherine M; Wollenberg, Lance A; Flora, Darcy R; Tracy, Timothy S; Gannett, Peter M

    2016-05-01

    Cytochrome P450 (P450) protein-protein interactions have been shown to alter their catalytic activity. Furthermore, these interactions are isoform specific and can elicit activation, inhibition, or no effect on enzymatic activity. Studies show that these effects are also dependent on the protein partner cytochrome P450 reductase (CPR) and the order of protein addition to purified reconstituted enzyme systems. In this study, we use controlled immobilization of P450s to a gold surface to gain a better understanding of P450-P450 interactions between three key drug-metabolizing isoforms (CYP2C9, CYP3A4, and CYP2D6). Molecular modeling was used to assess the favorability of homomeric/heteromeric P450 complex formation. P450 complex formation in vitro was analyzed in real time utilizing surface plasmon resonance. Finally, the effects of P450 complex formation were investigated utilizing our immobilized platform and reconstituted enzyme systems. Molecular modeling shows favorable binding of CYP2C9-CPR, CYP2C9-CYP2D6, CYP2C9-CYP2C9, and CYP2C9-CYP3A4, in rank order.KDvalues obtained via surface plasmon resonance show strong binding, in the nanomolar range, for the above pairs, with CYP2C9-CYP2D6 yielding the lowestKD, followed by CYP2C9-CYP2C9, CYP2C9-CPR, and CYP2C9-CYP3A4. Metabolic incubations show that immobilized CYP2C9 metabolism was activated by homomeric complex formation. CYP2C9 metabolism was not affected by the presence of CYP3A4 with saturating CPR concentrations. CYP2C9 metabolism was activated by CYP2D6 at saturating CPR concentrations in solution but was inhibited when CYP2C9 was immobilized. The order of addition of proteins (CYP2C9, CYP2D6, CYP3A4, and CPR) influenced the magnitude of inhibition for CYP3A4 and CYP2D6. These results indicate isoform-specific P450 interactions and effects on P450-mediated metabolism. PMID:26961240

  17. Infrared and Ultraviolet Spectra of Diborane(6): B2H6 and B2D6.

    PubMed

    Peng, Yu-Chain; Chou, Sheng-Lung; Lo, Jen-Iu; Lin, Meng-Yeh; Lu, Hsiao-Chi; Cheng, Bing-Ming; Ogilvie, J F

    2016-07-21

    We recorded absorption spectra of diborane(6), B2H6 and B2D6, dispersed in solid neon near 4 K in both mid-infrared and ultraviolet regions. For gaseous B2H6 from 105 to 300 nm, we report quantitative absolute cross sections; for solid B2H6 and for B2H6 dispersed in solid neon, we measured ultraviolet absorbance with relative intensities over a wide range. To assign the mid-infrared spectra to specific isotopic variants, we applied the abundance of (11)B and (10)B in natural proportions; we undertook quantum-chemical calculations of wavenumbers associated with anharmonic vibrational modes and the intensities of the harmonic vibrational modes. To aid an interpretation of the ultraviolet spectra, we calculated the energies of electronically excited singlet and triplet states and oscillator strengths for electronic transitions from the electronic ground state. PMID:27351464

  18. Fast and slow metabolizers of Hoasca.

    PubMed

    Callaway, J C

    2005-06-01

    Harmine, a major alkaloid in ayahuasca (hoasca), is a selective and reversible inhibitor of the enzyme monoamine oxidase-A (MAO-A). It is also a selective inhibitor of the human cytochrome P450 isozyme 2D6 (CYP 2D6), which metabolizes harmine to a more hydrophilic derivative for eventual excretion. CYP 2D6 exhibits a wide range of polymorphisms in human populations, and variations in this enzymatic activity could account for differences in effects between individuals who use hoasca. This report broadly describes two subgroups of CYP 2D6 phenotypes--i.e., fast and slow metabolizers of harmine-in 14 experienced male members of the União do Vegetal (UDV) who received a standardized dosage of hoasca. To compensate for metabolic variations in their normal religious practice, the administered dose of hoasca is always determined by the presiding mestre, who is responsible for deciding the actual amount for each individual. This age-old method compensates for metabolic variations between individuals and variations in both the alkaloid profile and strength of the hoasca. PMID:16149329

  19. Variation in Human Cytochrome P-450 Drug-Metabolism Genes: A Gateway to the Understanding of Plasmodium vivax Relapses

    PubMed Central

    Silvino, Ana Carolina Rios; Costa, Gabriel Luiz; de Araújo, Flávia Carolina Faustino; Ascher, David Benjamin; Pires, Douglas Eduardo Valente; Fontes, Cor Jesus Fernandes; Carvalho, Luzia Helena; de Brito, Cristiana Ferreira Alves; Sousa, Tais Nobrega

    2016-01-01

    Although Plasmodium vivax relapses are classically associated with hypnozoite activation, it has been proposed that a proportion of these cases are due to primaquine (PQ) treatment failure caused by polymorphisms in cytochrome P-450 2D6 (CYP2D6). Here, we present evidence that CYP2D6 polymorphisms are implicated in PQ failure, which was reinforced by findings in genetically similar parasites, and may explain a number of vivax relapses. Using a computational approach, these polymorphisms were predicted to affect the activity of CYP2D6 through changes in the structural stability that could lead to disruption of the PQ-enzyme interactions. Furthermore, because PQ is co-administered with chloroquine (CQ), we investigated whether CQ-impaired metabolism by cytochrome P-450 2C8 (CYP2C8) could also contribute to vivax recurrences. Our results show that CYP2C8-mutated patients frequently relapsed early (<42 days) and had a higher proportion of genetically similar parasites, suggesting the possibility of recrudescence due to CQ therapeutic failure. These results highlight the importance of pharmacogenetic studies as a tool to monitor the efficacy of antimalarial therapy. PMID:27467145

  20. Differential Cytochrome P450 2D Metabolism Alters Tafenoquine Pharmacokinetics

    PubMed Central

    Vuong, Chau; Xie, Lisa H.; Potter, Brittney M. J.; Zhang, Jing; Zhang, Ping; Duan, Dehui; Nolan, Christina K.; Sciotti, Richard J.; Zottig, Victor E.; Nanayakkara, N. P. Dhammika; Tekwani, Babu L.; Walker, Larry A.; Smith, Philip L.; Paris, Robert M.; Read, Lisa T.; Li, Qigui; Pybus, Brandon S.; Sousa, Jason C.; Reichard, Gregory A.; Smith, Bryan

    2015-01-01

    Cytochrome P450 (CYP) 2D metabolism is required for the liver-stage antimalarial efficacy of the 8-aminoquinoline molecule tafenoquine in mice. This could be problematic for Plasmodium vivax radical cure, as the human CYP 2D ortholog (2D6) is highly polymorphic. Diminished CYP 2D6 enzyme activity, as in the poor-metabolizer phenotype, could compromise radical curative efficacy in humans. Despite the importance of CYP 2D metabolism for tafenoquine liver-stage efficacy, the exact role that CYP 2D metabolism plays in the metabolism and pharmacokinetics of tafenoquine and other 8-aminoquinoline molecules has not been extensively studied. In this study, a series of tafenoquine pharmacokinetic experiments were conducted in mice with different CYP 2D metabolism statuses, including wild-type (WT) (reflecting extensive metabolizers for CYP 2D6 substrates) and CYPmouse 2D knockout (KO) (reflecting poor metabolizers for CYP 2D6 substrates) mice. Plasma and liver pharmacokinetic profiles from a single 20-mg/kg of body weight dose of tafenoquine differed between the strains; however, the differences were less striking than previous results obtained for primaquine in the same model. Additionally, the presence of a 5,6-ortho-quinone tafenoquine metabolite was examined in both mouse strains. The 5,6-ortho-quinone species of tafenoquine was observed, and concentrations of the metabolite were highest in the WT extensive-metabolizer phenotype. Altogether, this study indicates that CYP 2D metabolism in mice affects tafenoquine pharmacokinetics and could have implications for human tafenoquine pharmacokinetics in polymorphic CYP 2D6 human populations. PMID:25870069

  1. An evaluation of the cytochrome P450 inhibition potential of selected pesticides in human hepatic microsomes.

    PubMed

    Abass, Khaled; Turpeinen, Miia; Pelkonen, Olavi

    2009-08-01

    The goal of this work was to study the ability of 18 pesticides to inhibit selective model activities for all major xenobiotic-metabolizing enzymes, namely CYP1A1/2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1 and 3A4. Generally organophosphorus insecticides were the most potent and extensive inhibitors, especially towards CYP1A1/2 (IC(50) values of chlorpyrifos, fenitrothion and profenofos approximately 3 micro M), CYP2B6 (IC(50) values of chlorpyrifos and fenitrothion 2.5 micro M), CYP2C8 (fenitrothion 4.3 micro M), CYP2C9 (fenitrothion and malathion 4.8 and 2.5 micro M, respectively), CYP2D6 (chlorpyrifos and phenthoate approximately 3 micro M) and CYP3A4 (chlorpyrifos, fenitrothion and phenthoate 3-4 micro M). Otherwise there were quite considerable differences in potency and extent of inhibition between different organophosphates. Pyrethroids were in general very weak or inactive. Deltamethrin and fenvalerate were potent inhibitors of CYP2D6 (IC(50) values of approximately 3 micro M) while lambda-cyhalothrin potently inhibited both CYP2D6 and CYP3A4-mediated activities (IC(50)'s about 3-4 micro M). Some pesticides caused relatively potent inhibitions sporadically (carbendazim, CYP2D6, IC(50) = 12 micro M; atrazine, CYP3A4, IC(50) = 2.8 micro M; glyphosate, CYP2C9, IC(50) = 3.7 micro M; hexaflumuron, IC(50) = 6.0 micro M). With the exceptions of alpha-cypermethrin, cypermethrin, isoproturon, carbaryl and abamectin, most pesticides inhibited relatively potently at least one CYP-selective activity, which may have relevance for potential interactions in occupational exposures and for further studies on the CYP-associated metabolism of respective pesticides. PMID:20183062

  2. Ophthalmic timolol: plasma concentration and systemic cardiopulmonary effects.

    PubMed

    Nieminen, T; Lehtimäki, T; Mäenpää, J; Ropo, A; Uusitalo, H; Kähönen, M

    2007-01-01

    Timolol maleate is a non-selective beta-adrenoceptor antagonist currently used mainly as an ocular preparation for the treatment of glaucoma and ocular hypertension. Despite the topical administration, ophthalmic timolol causes systemic adrenergic beta-blocking because of absorption from the eye into the systemic circulation. Gel formulations of ophthalmic timolol have been developed to reduce systemic absorption and adverse effects in comparison with conventional aqueous solution formulations. Timolol is metabolized by the polymorphic cytochrome P450 2D6 enzyme (CYP2D6). The changes in heart rate (HR) are the most striking effects of the systematically absorbed fraction of ophthalmic timolol, with 0.5 % aqueous formulations presenting larger effects than 0.1 % hydrogel formulations, especially during exercise. Plasma levels of ophthalmic timolol correlate with the changes in HR. Neither 0.5 % aqueous nor 0.1 % hydrogel formulations of timolol have exerted noteworthy effects on systolic (SAP) or diastolic (DAP) arterial pressures, probably because of a compensatory increase in systemic vascular resistance due to the attenuation of HR. Ophthalmic timolol does not exert remarkable effects on pulmonary parameter peak expiratory flow (PEF) and forced expiratory volume in 1 s (FEV1) in non-asthmatic patients. CYP2D6 activity is clearly associated with the pharmacokinetic parameters, particularly when 0.5 % aqueous solution of timolol is used: peak plasma concentration, elimination half-life and area-under-the-curve are highest in CYP2D6 poor metabolizers. Finally, since there is a correlation between the plasma level of timolol and several haemodynamic effects - especially HR in the state of elevated beta-adrenergic tonus - the CYP2D6 poor metabolizers may be more prone to bradycardia during treatment with (aqueous) ophthalmic timolol. PMID:17366003

  3. New insights into the metabolism of tamoxifen and its role in the treatment and prevention of breast cancer

    PubMed Central

    Jordan, V. Craig

    2009-01-01

    The metabolism of tamoxifen is being redefined in the light of several important pharmacological observations. Recent studies have identified 4-hydroxy N-desmethyl tamoxifen (endoxifen) as an important metabolite of tamoxifen necessary for antitumor actions. The metabolite is formed through the enzymatic product of CYP2D6 which also interacts with specific selective serotonin reuptake inhibitors (SSRIs) used to prevent the hot flashes observed in up to 45% of patients taking tamoxifen. Additionally, the finding that enzyme variants of CYP2D6 do not promote the metabolism of tamoxifen to endoxifen means that significant numbers of women might not receive optimal benefit from tamoxifen treatment. Clearly these are particularly important issues not only for breast cancer treatment but also for selecting premenopausal women, at high risk for breast cancer, as candidates for chemoprevention using tamoxifen. PMID:17765940

  4. In vitro metabolism and pharmacokinetic studies on methylone.

    PubMed

    Pedersen, Anders Just; Petersen, Trine Hedebrink; Linnet, Kristian

    2013-06-01

    Abuse of the stimulant designer drug methylone (methylenedioxymethcathinone) has been documented in most parts of the world. As with many of the new designer drugs that continuously appear in the illicit drug market, little is known about the pharmacokinetics of methylone. Using in vitro studies, CYP2D6 was determined to be the primary enzyme that metabolizes methylone, with minor contributions from CYP1A2, CYP2B6, and CYP2C19. The major metabolite was identified as dihydroxymethcathinone, and the minor metabolites were N-hydroxy-methylone, nor-methylone, and dihydro-methylone. Measuring the formation of the major metabolite, biphasic Michaelis-Menten kinetic parameters were determined: V(max,1) = 0.046 ± 0.005 (S.E.) nmol/min/mg protein, K(m,1) = 19.0 ± 4.2 μM, V(max,2) = 0.22 ± 0.04 nmol/min/mg protein, and K(m,2) = 1953 ± 761 μM; the low-capacity and high-affinity contribution was assigned to the activity of CYP2D6. Additionally, a time-dependent loss of CYP2D6 activity was observed when the enzyme was preincubated with methylone, reaching a maximum rate of inactivation at high methylone concentrations, indicating that methylone is a mechanism-based inhibitor of CYP2D6. The inactivation parameters were determined to be K(I) = 15.1 ± 3.4 (S.E.) μM and k(inact) = 0.075 ± 0.005 minute(-1). PMID:23545806

  5. Molecular Evolution of the CYP2D Subfamily in Primates: Purifying Selection on Substrate Recognition Sites without the Frequent or Long-Tract Gene Conversion

    PubMed Central

    Yasukochi, Yoshiki; Satta, Yoko

    2015-01-01

    The human cytochrome P450 (CYP) 2D6 gene is a member of the CYP2D gene subfamily, along with the CYP2D7P and CYP2D8P pseudogenes. Although the CYP2D6 enzyme has been studied extensively because of its clinical importance, the evolution of the CYP2D subfamily has not yet been fully understood. Therefore, the goal of this study was to reveal the evolutionary process of the human drug metabolic system. Here, we investigate molecular evolution of the CYP2D subfamily in primates by comparing 14 CYP2D sequences from humans to New World monkey genomes. Window analysis and statistical tests revealed that entire genomic sequences of paralogous genes were extensively homogenized by gene conversion during molecular evolution of CYP2D genes in primates. A neighbor-joining tree based on genomic sequences at the nonsubstrate recognition sites showed that CYP2D6 and CYP2D8 genes were clustered together due to gene conversion. In contrast, a phylogenetic tree using amino acid sequences at substrate recognition sites did not cluster the CYP2D6 and CYP2D8 genes, suggesting that the functional constraint on substrate specificity is one of the causes for purifying selection at the substrate recognition sites. Our results suggest that the CYP2D gene subfamily in primates has evolved to maintain the regioselectivity for a substrate hydroxylation activity between individual enzymes, even though extensive gene conversion has occurred across CYP2D coding sequences. PMID:25808902

  6. Role of cytochrome P450 genotype in the steps toward personalized drug therapy

    PubMed Central

    Cavallari, Larisa H; Jeong, Hyunyoung; Bress, Adam

    2011-01-01

    Genetic polymorphism for cytochrome 450 (P450) enzymes leads to interindividual variability in the plasma concentrations of many drugs. In some cases, P450 genotype results in decreased enzyme activity and an increased risk for adverse drug effects. For example, individuals with the CYP2D6 loss-of-function genotype are at increased risk for ventricular arrhythmia if treated with usual does of thioridazine. In other cases, P450 genotype may influence the dose of a drug required to achieve a desired effect. This is the case with warfarin, with lower doses often necessary in carriers of a variant CYP2C9*2 or *3 allele to avoid supratherapeutic anticoagulation. When a prodrug, such as clopidogrel or codeine, must undergo hepatic biotransformation to its active form, a loss-of-function P450 genotype leads to reduced concentrations of the active drug and decreased drug efficacy. In contrast, patients with multiple CYP2D6 gene copies are at risk for opioid-related toxicity if treated with usual doses of codeine-containing analgesics. At least 25 drugs contain information in their US Food and Drug Administration-approved labeling regarding P450 genotype. The CYP2C9, CYP2C19, and CYP2D6 genes are the P450 genes most often cited. To date, integration of P450 genetic information into clinical decision making is limited. However, some institutions are beginning to embrace routine P450 genotyping to assist in the treatment of their patients. Genotyping for P450 variants may carry less risk for discrimination compared with genotyping for disease-associated variants. As such, P450 genotyping is likely to lead the way in the clinical implementation of pharmacogenomics. This review discusses variability in the CYP2C9, CYP2C19, and CYP2D6 genes and the implications of this for drug efficacy and safety. PMID:23226058

  7. Intronic polymorphisms of cytochromes P450

    PubMed Central

    2010-01-01

    The cytochrome P450 enzymes active in drug metabolism are highly polymorphic. Most allelic variants have been described for enzymes encoded by the cytochrome P450 family 2 (CYP2) gene family, which has 252 different alleles. The intronic polymorphisms in the cytochrome P450 genes account for only a small number of the important variant alleles; however, the most important ones are CYP2D6*4 and CYP2D6*41, which cause abolished and reduced CYP2D6 activity, respectively, and CYP3A5*3 and CYP3A5*5, common in Caucasian populations, which cause almost null activity. Their discoveries have been based on phenotypic alterations within individuals in a population, and their identification has, in several cases, been difficult and taken a long time. In light of the next-generation sequencing projects, it is anticipated that further alleles with intronic mutations will be identified that can explain the hitherto unidentified genetic basis of inter-individual differences in cytochrome P450-mediated drug and steroid metabolism. PMID:20846929

  8. Boronic prodrug of endoxifen as an effective hormone therapy for breast cancer.

    PubMed

    Zhang, Changde; Zhong, Qiu; Zhang, Qiang; Zheng, Shilong; Miele, Lucio; Wang, Guangdi

    2015-07-01

    As a prodrug, tamoxifen is activated by the P450 enzyme CYP2D6 that is responsible for converting it to the active metabolites, 4-hydroxytamoxifen and endoxifen. Patients with genetic polymorphisms of CYP2D6 may not receive the full benefit of tamoxifen therapy. There is increasing evidence that poor metabolizer patients have lower plasma concentrations of endoxifen and suffer worse disease outcome, although some clinical studies reported no correlation between CYP2D6 polymorphism and tamoxifen therapy outcome. Endoxifen is currently undergoing clinical trials as a potentially improved and more potent SERM (Selective Estrogen Receptor Modulator) for endocrine therapy that is independent of CYP2D6 status in patients. However, direct administration of endoxifen may present the problem of low bioavailability due to its rapid first-pass metabolism via O-glucuronidation. We have designed and synthesized ZB483, a boronic prodrug of endoxifen suitable for oral administration with greatly enhanced bioavailability by increasing the concentration of endoxifen in mouse blood. Our study demonstrated that ZB483 potently inhibited growth of ER+ breast cancer cells in vitro and was efficiently converted to endoxifen in cell culture media by oxidative deboronation. This metabolic conversion is equally efficient in vivo as indicated in the pharmacokinetic study in mice. Moreover, when administered at the same dose, oral ZB483 afforded a 30- to 40-fold higher plasma level of endoxifen in mice than oral administration of endoxifen. The significantly enhanced bioavailability of endoxifen conferred by the boronic prodrug was further validated in an in vivo efficacy study. ZB483 was demonstrated to be more efficacious than endoxifen in inhibiting xenograft tumor growth in mice at equal dosage but more so at lower dosage. Together, these preclinical studies demonstrate that ZB483 is a promising endocrine therapy agent with markedly enhanced bioavailability in systemic circulation and

  9. In vitro metabolism of l-corydalmine, a potent analgesic drug, in human, cynomolgus monkey, beagle dog, rat and mouse liver microsomes.

    PubMed

    Tang, Xiange; Di, Xinyu; Zhong, Zeyu; Xie, Qiushi; Chen, Yang; Wang, Fan; Ling, Zhaoli; Xu, Ping; Zhao, Kaijing; Wang, Zhongjian; Liu, Li; Liu, Xiaodong

    2016-09-01

    l-Corydalmine (l-CDL) was under development as an oral analgesic agent, exhibiting potent analgesic activity in preclinical models. The objective of this study was to compare metabolic profiles of l-CDL in liver microsomes from mouse, rat, monkey, dog and human. Six metabolites (M1-M6) were identified using LC-Q/TOF in liver microsomes from the five species. The metabolism of l-CDL included O-demethylation (M1-3) and hydroxylation (M4-6). The desmethyl metabolites were the major ones among the five species, which accounted for more than 84%. Data from chemical inhibition in human liver microsomes (HLM) and human recombinant CYP450s demonstrated that CYP2D6 exhibited strong catalytic activity towards M1 and M2 formations, while CYP2C9 and CYP2C19 also catalyzed M2 formation. Formations of M3 and hydroxyl metabolites (M4 and M5) were mainly catalyzed by CYP3A4. Further studies showed that M1 and M2 were main metabolites in HLM. The kinetics of M1 and M2 formations in HLM and recombinant CYP450s were also investigated. The results showed that M1 and M2 formations in HLM and recombinant CYP2D6 characterized biphasic kinetics, whereas sigmoid Vmax model was better used to fit M2 formation by recombinant CYP2C9 and CYP2C19. The contributions of CYP2D6 to M1 and M2 formations in HLM were estimated to be 75.3% and 50.7%, respectively. However, the contributions of CYP2C9 and CYP2C19 to M2 formation were only 5.0% and 4.1%, respectively. All these data indicated that M1 and M2 were main metabolites in HLM, and CYP2D6 was the primary enzyme responsible for their formations. PMID:27239758

  10. Nonlinear pharmacokinetics of 5-methoxy-N,N-dimethyltryptamine in mice.

    PubMed

    Shen, Hong-Wu; Jiang, Xi-Ling; Yu, Ai-Ming

    2011-07-01

    5-Methoxy-N,N,-dimethyltryptamine (5-MeO-DMT), an abused serotonergic indolealkylamine drug, was placed into Schedule I controlled substance status in the United States as of January 19, 2011. In previous studies, we have shown the impact of monoamine oxidase A and cytochrome P450 2D6 enzymes on 5-MeO-DMT metabolism and pharmacokinetics. The aim of this study was to investigate 5-MeO-DMT pharmacokinetic properties after intravenous or intraperitoneal administration of three different doses (2, 10, and 20 mg/kg) to CYP2D6-humanized (Tg-CYP2D6) and wild-type control mice. Systemic exposure [area under the curve (AUC)] to 5-MeO-DMT was increased nonproportionally with the increase in dose. The existence of nonlinearity in serum 5-MeO-DMT pharmacokinetics was clearly manifested by dose-normalized AUC values, which were approximately 1.5- to 2.0-fold (intravenous) and 1.8- to 2.7-fold (intraperitoneal) higher in wild-type or Tg-CYP2D6 mice dosed with 10 and 20 mg/kg 5-MeO-DMT, respectively, than those in mice treated with 2 mg/kg 5-MeO-DMT. Furthermore, a two-compartment model including first-order absorption, nonlinear (Michaelis-Menten) elimination, and CYP2D6-dependent linear elimination from the central compartment was developed to characterize the intravenous and intraperitoneal pharmacokinetic data for 5-MeO-DMT in wild-type and Tg-CYP2D6 mice. In addition, 5-MeO-DMT was readily detected in mouse brain after drug treatment, and brain 5-MeO-DMT concentrations were also increased nonproportionally with the increase of dose. The results establish a nonlinear pharmacokinetic property for 5-MeO-DMT in mice, suggesting that the risk of 5-MeO-DMT intoxication may be increased nonproportionally at higher doses. PMID:21464174

  11. Nonlinear Pharmacokinetics of 5-Methoxy-N,N-dimethyltryptamine in MiceS⃞

    PubMed Central

    Shen, Hong-Wu; Jiang, Xi-Ling

    2011-01-01

    5-Methoxy-N,N,-dimethyltryptamine (5-MeO-DMT), an abused serotonergic indolealkylamine drug, was placed into Schedule I controlled substance status in the United States as of January 19, 2011. In previous studies, we have shown the impact of monoamine oxidase A and cytochrome P450 2D6 enzymes on 5-MeO-DMT metabolism and pharmacokinetics. The aim of this study was to investigate 5-MeO-DMT pharmacokinetic properties after intravenous or intraperitoneal administration of three different doses (2, 10, and 20 mg/kg) to CYP2D6-humanized (Tg-CYP2D6) and wild-type control mice. Systemic exposure [area under the curve (AUC)] to 5-MeO-DMT was increased nonproportionally with the increase in dose. The existence of nonlinearity in serum 5-MeO-DMT pharmacokinetics was clearly manifested by dose-normalized AUC values, which were approximately 1.5- to 2.0-fold (intravenous) and 1.8- to 2.7-fold (intraperitoneal) higher in wild-type or Tg-CYP2D6 mice dosed with 10 and 20 mg/kg 5-MeO-DMT, respectively, than those in mice treated with 2 mg/kg 5-MeO-DMT. Furthermore, a two-compartment model including first-order absorption, nonlinear (Michaelis-Menten) elimination, and CYP2D6-dependent linear elimination from the central compartment was developed to characterize the intravenous and intraperitoneal pharmacokinetic data for 5-MeO-DMT in wild-type and Tg-CYP2D6 mice. In addition, 5-MeO-DMT was readily detected in mouse brain after drug treatment, and brain 5-MeO-DMT concentrations were also increased nonproportionally with the increase of dose. The results establish a nonlinear pharmacokinetic property for 5-MeO-DMT in mice, suggesting that the risk of 5-MeO-DMT intoxication may be increased nonproportionally at higher doses. PMID:21464174

  12. Duloxetine: clinical pharmacokinetics and drug interactions.

    PubMed

    Knadler, Mary Pat; Lobo, Evelyn; Chappell, Jill; Bergstrom, Richard

    2011-05-01

    that duloxetine may enhance the effects of benzodiazepines, but not alcohol or warfarin. An increase in gastric pH produced by histamine H(2)-receptor antagonists or antacids did not impact the absorption of duloxetine. While duloxetine is generally well tolerated, it is important to be knowledgeable about the potential for pharmacokinetic interactions between duloxetine and drugs that inhibit CYP1A2 or drugs that are metabolized by CYP2D6 enzymes. PMID:21366359

  13. Applications of CYP450 testing in the clinical setting.

    PubMed

    Samer, C F; Lorenzini, K Ing; Rollason, V; Daali, Y; Desmeules, J A

    2013-06-01

    Interindividual variability in drug response is a major clinical problem. Polymedication and genetic polymorphisms modulating drug-metabolising enzyme activities (cytochromes P450, CYP) are identified sources of variability in drug responses. We present here the relevant data on the clinical impact of the major CYP polymorphisms (CYP2D6, CYP2C19 and CYP2C9) on drug therapy where genotyping and phenotyping may be considered, and the guidelines developed when available. CYP2D6 is responsible for the oxidative metabolism of up to 25% of commonly prescribed drugs such as antidepressants, antipsychotics, opioids, antiarrythmics and tamoxifen. The ultrarapid metaboliser (UM) phenotype is recognised as a cause of therapeutic inefficacy of antidepressant, whereas an increased risk of toxicity has been reported in poor metabolisers (PMs) with several psychotropics (desipramine, venlafaxine, amitriptyline, haloperidol). CYP2D6 polymorphism influences the analgesic response to prodrug opioids (codeine, tramadol and oxycodone). In PMs for CYP2D6, reduced analgesic effects have been observed, whereas in UMs cases of life-threatening toxicity have been reported with tramadol and codeine. CYP2D6 PM phenotype has been associated with an increased risk of toxicity of metoprolol, timolol, carvedilol and propafenone. Although conflicting results have been reported regarding the association between CYP2D6 genotype and tamoxifen effects, CYP2D6 genotyping may be useful in selecting adjuvant hormonal therapy in postmenopausal women. CYP2C19 is responsible for metabolising clopidogrel, proton pump inhibitors (PPIs) and some antidepressants. Carriers of CYP2C19 variant alleles exhibit a reduced capacity to produce the active metabolite of clopidogrel, and are at increased risk of adverse cardiovascular events. For PPIs, it has been shown that the mean intragastric pH values and the Helicobacter pylori eradication rates were higher in carriers of CYP2C19 variant alleles. CYP2C19 is

  14. Enzyme

    MedlinePlus

    Enzymes are complex proteins that cause a specific chemical change in all parts of the body. For ... use them. Blood clotting is another example of enzymes at work. Enzymes are needed for all body ...

  15. Association between CYP2C19*17 and metabolism of amitriptyline, citalopram and clomipramine in Dutch hospitalized patients.

    PubMed

    de Vos, A; van der Weide, J; Loovers, H M

    2011-10-01

    Polymorphisms in genes coding for drug metabolizing enzymes, such as the cytochrome P450 enzymes CYP2C19 and CYP2D6, can lead to therapy failure and side effects. In earlier studies, the novel variant CYP2C19*17 increased metabolism of several CYP2C19 substrates. The objective of this study was to evaluate the impact of CYP2C19*17 on the metabolism of amitriptyline (AT), citalopram (CIT), and clomipramine (CLOM). Six-hundred and seventy-eight patients were included in this study, based on availability of DNA and serum levels of parent drug and main metabolite. We investigated the relationship between CYP2C19 genotypes and metabolic parameters, including serum levels corrected for dose and metabolic ratio (MR). The CYP2C19*17 allele was significantly associated with decreased MR for CIT (CYP2C19*1/*17 mean MR=2.3, compared with CYP2C19*1/*1 mean MR=2.8) and AT (CYP2C19*17/*17 mean MR=0.8, compared with CYP2C19*1/*1 mean MR=3.7 in the CYP2D6*1/*1 subgroup). Furthermore, significant association of CYP2D6 genotype with AT, CIT, and CLOM metabolism was observed. No clear correlation was found between CYP2C19 genotype and CLOM metabolism. This study confirms the increased activity of the CYP2C19*17 allele and shows increased metabolism of drugs that are metabolized by CYP2C19, including AT and CIT. However, the clinical relevance of CYP2C19*17 is probably limited for AT, CIT, and CLOM. PMID:20531370

  16. P450-Based Drug-Drug Interactions of Amiodarone and its Metabolites: Diversity of Inhibitory Mechanisms.

    PubMed

    McDonald, Matthew G; Au, Nicholas T; Rettie, Allan E

    2015-11-01

    In this study, IC50 shift and time-dependent inhibition (TDI) experiments were carried out to measure the ability of amiodarone (AMIO), and its circulating human metabolites, to reversibly and irreversibly inhibit CYP1A2, CYP2C9, CYP2D6, and CYP3A4 activities in human liver microsomes. The [I]u/Ki,u values were calculated and used to predict in vivo AMIO drug-drug interactions (DDIs) for pharmaceuticals metabolized by these four enzymes. Based on these values, the minor metabolite N,N-didesethylamiodarone (DDEA) is predicted to be the major cause of DDIs with xenobiotics primarily metabolized by CYP1A2, CYP2C9, or CYP3A4, while AMIO and its N-monodesethylamiodarone (MDEA) derivative are the most likely cause of interactions involving inhibition of CYP2D6 metabolism. AMIO drug interactions predicted from the reversible inhibition of the four P450 activities were found to be in good agreement with the magnitude of reported clinical DDIs with lidocaine, warfarin, metoprolol, and simvastatin. The TDI experiments showed DDEA to be a potent inactivator of CYP1A2 (KI = 0.46 μM, kinact = 0.030 minute(-1)), while MDEA was a moderate inactivator of both CYP2D6 (KI = 2.7 μM, kinact = 0.018 minute(-1)) and CYP3A4 (KI = 2.6 μM, kinact = 0.016 minute(-1)). For DDEA and MDEA, mechanism-based inactivation appears to occur through formation of a metabolic intermediate complex. Additional metabolic studies strongly suggest that CYP3A4 is the primary microsomal enzyme involved in the metabolism of AMIO to both MDEA and DDEA. In summary, these studies demonstrate both the diversity of inhibitory mechanisms with AMIO and the need to consider metabolites as the culprit in inhibitory P450-based DDIs. PMID:26296708

  17. Inhibitory and inductive effects of Phikud Navakot extract on human cytochrome P450.

    PubMed

    Chiangsom, Abhiruj; Lawanprasert, Somsong; Oda, Shingo; Kulthong, Kornphimol; Luechapudiporn, Rataya; Yokoi, Tsuyoshi; Maniratanachote, Rawiwan

    2016-06-01

    Effects of the hydroethanolic extract of Phikud Navakot (PN), a Thai traditional remedy, on human cytochrome P450s (CYPs) were investigated in vitro. Selective substrates of CYPs were used to investigate the effects and kinetics of PN on CYP inhibition using human liver microsomes. Primary human hepatocytes were used to assess the inductive effects of PN on CYP enzyme activities and protein expressions. The results showed that PN inhibited the activities of CYP1A2, CYP2C9, CYP2D6, and CYP3A4 with half maximal inhibitory concentration (IC50) values of 13, 62, 67, and 88 μg/mL, respectively. Meanwhile, it had no effect on the activities of CYP2C19 and CYP2E1 (IC50 > 1 mg/mL). PN exhibited competitive inhibition of CYP1A2 (Ki = 34 μg/mL), mixed type inhibition of CYP2C9 and CYP2D6 (Ki = 80 and 12 μg/mL, respectively), and uncompetitive inhibition of CYP3A4 (Ki = 150 μg/mL). PN did not have an inductive effect on CYP1A2, CYP2C9, CYP2C19 and CYP3A4 in primary human hepatocytes, which is an advantageous characteristic of the extract. However the extract may cause herb-drug interactions via inhibition of CYP1A2, CYP2C9, CYP2D6 and CYP3A4, and precautions should be taken when PN is coadministered with drugs that are metabolized by these CYP enzymes. PMID:27212065

  18. Development of a complex parent-metabolite joint population pharmacokinetic model.

    PubMed

    Bertrand, Julie; Laffont, Céline M; Mentré, France; Chenel, Marylore; Comets, Emmanuelle

    2011-09-01

    This study aimed to develop a joint population pharmacokinetic model for an antipsychotic agent in development (S33138) and its active metabolite (S35424) produced by reversible metabolism. Because such a model leads to identifiability problems and numerical difficulties, the model building was performed using the FOCE-I and the Stochastic Approximation Expectation Maximization (SAEM) estimation algorithms in NONMEM and MONOLIX, respectively. Four different structural models were compared based on Bayesian information criteria. Models were first written as ordinary differential equations systems and then in closed form (CF) to facilitate further analyses. The impact of polymorphisms on genes coding for the CYP2C19 and CYP2D6 enzymes, respectively involved in the parent drug and the metabolite elimination were investigated using permutation Wald test. The parent drug and metabolite plasma concentrations of 101 patients were analyzed on two occasions after 4 and 8 weeks of treatment at 1, 3, 6, and 24 h following daily oral administration. All configurations led to a two compartment model with back-transformation of the metabolite into the parent drug and a first-pass effect. The elimination clearance of the metabolite through other processes than back-transformation was decreased by 35% [9-53%] in CYP2D6 poor metabolizer. Permutation tests were performed to ensure the robustness of the analysis, using SAEM and CF. In conclusion, we developed a complex joint pharmacokinetic model adequately predicting the impact of CYP2D6 polymorphisms on the parent drug and its metabolite concentrations through the back-transformation mechanism. PMID:21618059

  19. Tamoxifen-associated hot flash severity is inversely correlated with endoxifen concentration and CYP3A4*22.

    PubMed

    Baxter, Simon D; Teft, Wendy A; Choi, Yun-Hee; Winquist, Eric; Kim, Richard B

    2014-06-01

    Tamoxifen use is often limited in some patients due to adverse effects including severe hot flash symptoms. Tamoxifen undergoes hepatic bioactivation by CYP2D6 and CYP3A4 to form the active metabolite endoxifen. It remains unclear whether the extent of attained endoxifen level or genetic polymorphisms in drug metabolizing enzymes is associated with the frequency and severity of hot flashes. We conducted a prospective study using self-reported surveys to assess tamoxifen side effects experienced during the week prior to clinic visits of 132 female breast cancer patients on tamoxifen therapy, and hot flash severity scores were tabulated. At the time of clinic visit, blood samples were obtained to determine tamoxifen and its metabolite levels and to determine CYP2D6 and CYP3A4 genotypes. The majority of participants (77 %) experienced hot flashes, with 11 % experiencing severe or very severe symptoms. We observed an inverse correlation between endoxifen concentration and hot flash severity score following adjustment for age, BMI, and menopausal status in patients with non-zero scores (p < 0.001). Interestingly, CYP2D6 genotype was not significantly associated with hot flash scores in patients on no known inhibitory medications. However, CYP3A4*22 carriers were less likely to have hot flashes with an odds ratio of 8.87 (p < 0.01) even when compared to a cohort with similar endoxifen levels. Our data demonstrate that patients with higher endoxifen levels tended to predict lower hot flash severity scores. Importantly, this is the first study to show CYP3A4*22 genotype as an independent predictor of hot flash severity during tamoxifen therapy. PMID:24744093

  20. Effect of Single Nucleotide Polymorphisms in Cytochrome P450 Isoenzyme and N-Acetyltransferase 2 Genes on the Metabolism of Artemisinin-Based Combination Therapies in Malaria Patients from Cambodia and Tanzania

    PubMed Central

    Staehli Hodel, Eva Maria; Csajka, Chantal; Ariey, Frédéric; Guidi, Monia; Kabanywanyi, Abdunoor Mulokozi; Duong, Socheat; Decosterd, Laurent Arthur; Olliaro, Piero; Genton, Blaise

    2013-01-01

    The pharmacogenetics of antimalarial agents are poorly known, although the application of pharmacogenetics might be critical in optimizing treatment. This population pharmacokinetic-pharmacogenetic study aimed at assessing the effects of single nucleotide polymorphisms (SNPs) in cytochrome P450 isoenzyme genes (CYP, namely, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4, and CYP3A5) and the N-acetyltransferase 2 gene (NAT2) on the pharmacokinetics of artemisinin-based combination therapies in 150 Tanzanian patients treated with artemether-lumefantrine, 64 Cambodian patients treated with artesunate-mefloquine, and 61 Cambodian patients treated with dihydroartemisinin-piperaquine. The frequency of SNPs varied with the enzyme and the population. Higher frequencies of mutant alleles were found in Cambodians than Tanzanians for CYP2C9*3, CYP2D6*10 (100C→T), CYP3A5*3, NAT2*6, and NAT2*7. In contrast, higher frequencies of mutant alleles were found in Tanzanians for CYP2D6*17 (1023C→T and 2850C→T), CYP3A4*1B, NAT2*5, and NAT2*14. For 8 SNPs, no significant differences in frequencies were observed. In the genetic-based population pharmacokinetic analyses, none of the SNPs improved model fit. This suggests that pharmacogenetic data need not be included in appropriate first-line treatments with the current artemisinin derivatives and quinolines for uncomplicated malaria in specific populations. However, it cannot be ruled out that our results represent isolated findings, and therefore more studies in different populations, ideally with the same artemisinin-based combination therapies, are needed to evaluate the influence of pharmacogenetic factors on the clearance of antimalarials. PMID:23229480

  1. Identification and characterization of the 2D6 and Mr 23,000 antigens on the plasma membrane of rat spermatozoa.

    PubMed Central

    Jones, R; Brown, C R

    1987-01-01

    Previous investigations [Jones, Brown, von Glos & Gaunt (1985) Exp. Cell Res. 156, 31-44] have demonstrated the appearance of a new antigenic determinant (recognized by monoclonal antibody 2D6) on the plasma membrane of rat spermatozoa during post-testicular maturation in the epididymis. Identification of the 2D6 antigen on Western blots from one-dimensional SDS/polyacrylamide gels revealed that it co-migrated with a membrane protein (designated Mr 23,000 antigen) present on testicular and immature germ cells, suggesting that one antigen might be a modified version of the other. In the present work, however, we demonstrate that, although they have similar Mr and are present in soluble and membrane-bound forms, the 2D6 and Mr 23,000 antigens are biochemically and immunologically distinct molecules. The properties of the antigens are described and compared. The Mr 23,000 antigen is present on both testicular and cauda epididymidal spermatozoa, has a pI of 6.1, contains no detectable carbohydrate, is not tissue-specific and is degraded by V8 protease. By contrast, the 2D6 antigen is glycosylated, has a broad pI from 4.5 to 6.1, is tissue- and species-specific and is resistant to digestion with V8 protease. Its role in sperm-egg recognition is discussed. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. PMID:2439064

  2. Xenobiotic Sensor- and Metabolism-Related Gene Variants in Environmental Sensitivity-Related Illnesses: A Survey on the Italian Population

    PubMed Central

    Caccamo, Daniela; Cesareo, Eleonora; Mariani, Serena; Raskovic, Desanka; Ientile, Riccardo; Currò, Monica; Korkina, Liudmila; De Luca, Chiara

    2013-01-01

    In the environmental sensitivity-related illnesses (SRIs), multiple chemical sensitivity (MCS), chronic fatigue syndrome (FCS), and fibromyalgia (FM), the search for genetic polymorphisms of phase I/II xenobiotic-metabolizing enzymes as suitable diagnostic biomarkers produced so far inconclusive results, due to patient heterogeneity, geographic/ethnic differences in genetic backgrounds, and different methodological approaches. Here, we compared the frequency of gene polymorphisms of selected cytochrome P450 (CYP) metabolizing enzymes and, for the first time, the frequency of the xenobiotic sensor Aryl hydrocarbon receptor (AHR) in the three cohorts of 156 diagnosed MCS, 94 suspected MCS, and 80 FM/FCS patients versus 113 healthy controls. We found significantly higher frequency of polymorphisms CYP2C9∗2, CYP2C9∗3, CYP2C19∗2, CYP2D6∗4 and CYP2D6∗41 in patients compared with controls. This confirms that these genetic variants represent a genetic risk factor for SRI. Moreover, the compound heterozygosity for CYP2C9∗2 and ∗3 variants was useful to discriminate between either MCS or FM/CFS versus SMCS, while the PM ∗41/∗41 genotype discriminated between MCS and either SMCS or FM/CFS. The compound heterozygosity for CYP2C9 ∗1/∗3 and CYP2D6 ∗1/∗4 differentiated MCS and SMCS cases from FM/CFS ones. Interestingly, despite the distribution of the AHR Arg554Lys variant did not result significantly different between SRI cases and controls, it resulted useful for the discrimination between MCS and SMCS cases when considered within haplotypes in combination with CYP2C19 ∗1/∗2 and CYP2D6 ∗1/∗4. Results allowed us to propose the genotyping for these specific CYP variants, together with the AHR Arg554Lys variant, as reliable, cost-effective genetic parameters to be included in the still undefined biomarkers' panel for laboratory diagnosis of the main types of environmental-borne SRI. PMID:23936614

  3. Importance of pharmacogenetics in the treatment of children with attention deficit hyperactive disorder: a case report

    PubMed Central

    Tan-kam, Teerarat; Suthisisang, Chutamanee; Pavasuthipaisit, Chosita; Limsila, Penkhae; Puangpetch, Apichaya; Sukasem, Chonlaphat

    2013-01-01

    This case report highlights the importance of pharmacogenetic testing in the treatment of attention deficit hyperactive disorder (ADHD). A 6-year-old boy diagnosed with ADHD was prescribed methylphenidate 5 mg twice daily (7 am and noon) and the family was compliant with administration of this medication. On the first day of treatment, the patient had an adverse reaction, becoming disobedient, more mischievous, erratic, resistant to discipline, would not go to sleep until midnight, and had a poor appetite. The All-In-One PGX (All-In-One Pharmacogenetics for Antipsychotics test for CYP2D6, CYP2C19, and CYP2C9) was performed using microarray-based and real-time polymerase chain reaction techniques. The genotype of our patient was identified to be CYP2D6*2/*10, with isoforms of the enzyme consistent with a predicted cytochrome P450 2D6 intermediate metabolizer phenotype. Consequently, the physician adjusted the methylphenidate dose to 2.5 mg once daily in the morning. At this dosage, the patient had a good response without any further adverse reactions. Pharmacogenetic testing should be included in the management plan for ADHD. In this case, cooperation between the medical team and the patients’ relatives was key to successful treatment. PMID:23526481

  4. Factors affecting the development of adverse drug reactions to β-blockers in hospitalized cardiac patient population

    PubMed Central

    Mugoša, Snežana; Djordjević, Nataša; Djukanović, Nina; Protić, Dragana; Bukumirić, Zoran; Radosavljević, Ivan; Bošković, Aneta; Todorović, Zoran

    2016-01-01

    The aim of the present study was to undertake a study on the prevalence of cytochrome P450 2D6 (CYP2D6) poor metabolizer alleles (*3, *4, *5, and *6) on a Montenegrin population and its impact on developing adverse drug reactions (ADRs) of β-blockers in a hospitalized cardiac patient population. A prospective study was conducted in the Cardiology Center of the Clinical Center of Montenegro and included 138 patients who had received any β-blocker in their therapy. ADRs were collected using a specially designed questionnaire, based on the symptom list and any signs that could point to eventual ADRs. Data from patients’ medical charts, laboratory tests, and other available parameters were observed and combined with the data from the questionnaire. ADRs to β-blockers were observed in 15 (10.9%) patients. There was a statistically significant difference in the frequency of ADRs in relation to genetically determined enzymatic activity (P<0.001), with ADRs’ occurrence significantly correlating with slower CYP2D6 metabolism. Our study showed that the adverse reactions to β-blockers could be predicted by the length of hospitalization, CYP2D6 poor metabolizer phenotype, and the concomitant use of other CYP2D6-metabolizing drugs. Therefore, in hospitalized patients with polypharmacy CYP2D6 genotyping might be useful in detecting those at risk of ADRs. PMID:27536078

  5. Cytochrome P450 induction properties of food and herbal-derived compounds using a novel multiplex RT-qPCR in vitro assay, a drug-food interaction prediction tool.

    PubMed

    Koe, Xue Fen; Tengku Muhammad, Tengku Sifzizul; Chong, Alexander Shu-Chien; Wahab, Habibah Abdul; Tan, Mei Lan

    2014-09-01

    A multiplex RT-qPCR was developed to examine CYP1A2, CYP2D6, and CYP3A4 induction properties of compounds from food and herbal sources. The induction of drug metabolizing enzymes is an important pharmacokinetic interaction with unique features in comparison with inhibition of metabolizing enzymes. Cytochrome induction can lead to serious drug-drug or drug-food interactions, especially if the coadministered drug plasma level is critical as it can reduce therapeutic effects and cause complications. Using this optimized multiplex RT-qPCR, cytochrome induction properties of andrographolide, curcumin, lycopene, bergamottin, and resveratrol were determined. Andrographolide, curcumin, and lycopene produced no significant induction effects on CYP1A2, CYP2D6, and CYP3A4. However, bergamottin appeared to be a significant in vitro CYP1A2 inducer starting from 5 to 50 μmol/L with induction ranging from 60 to 100-fold changes. On the other hand, resveratrol is a weak in vitro CYP1A2 inducer. Examining the cytochrome induction properties of food and herbal compounds help complement CYP inhibition studies and provide labeling and safety caution for such products. PMID:25473508

  6. Evaluation of genipin on human cytochrome P450 isoenzymes and P-glycoprotein in vitro.

    PubMed

    Gao, Li-Na; Zhang, Ye; Cui, Yuan-Lu; Yan, Kuo

    2014-10-01

    Genipin is obtained from the fruit of Gardenia jasminoides Ellis and acts as an herbal medicine or functional food in East Asia. In addition to produce natural colorant, it possesses widely antiinflammatory, antithrombotic, antidepressive and anticarcinogenic activities. However, little research focuses on the potential of genipin for drug-drug interactions. In this study, effects of genipin on mRNA and protein expression of cytochrome P450 (CYP) 2C19, CYP2D6 and CYP3A4 were detected by real-time reverse-transcription polymerase chain reaction (real-time RT-PCR) and Western blot, respectively, in human hepatoma HepG2 cells. Enzyme activities of which were detected by luminogenic CYP assay in vitro. Moreover, effect of genipin on P-glycoprotein expression was analyzed by Western blot. Results showed that genipin possessed a significant induction on CYP2D6 and a remarkable inhibition on CYP2C19 and CYP3A4 not only from the expression of mRNA and protein (P<0.05 or P<0.01), but the level of enzyme activity. Moreover, a concentration-dependent induction of genipin on P-glycoprotein expression was observed. In conclusion, caution should be exercised with respect to the induction or inhibition of genipin on CYP isoenzymes and the strong induction on P-glycoprotein. PMID:25073096

  7. [Codeine--Restrictions on use for children and teenagers].

    PubMed

    Stingl, Julia C; Rotthauwe, Jens

    2015-07-01

    The Pharmacovigilance Risk Assessment Committee (PRAC) of the European Medicines Agency has issued European-wide restrictions on the use of codeine-containing medicines for cough and cold in children at the age of 0-12 because of the risk of serious side effects, including the risk of breathing problems. The PRAC further recommended that "codeine must not be used in people of any age who are known to convert codeine into morphine at a faster rate than normal ('ultra-rapid metabolisers')". The reasons for this variability in codeine biotransformation lay in a genetic polymorphism in the liver enzyme CYP2D6 leading to 3% of the northern European population being ultrarapid metabolisers due to a gene duplication of the enzyme.This is the first restriction of a common drug in CYP2D6 ultrarapid metabolizers, and more use of pharmacogenetic biomarkers for stratified benefit-risk assessment in drug regulation can be expected and will be a first step to Individualized Medicine Regulation. PMID:26182260

  8. Cytochrome P450 induction properties of food and herbal-derived compounds using a novel multiplex RT-qPCR in vitro assay, a drug–food interaction prediction tool

    PubMed Central

    Koe, Xue Fen; Tengku Muhammad, Tengku Sifzizul; Chong, Alexander Shu-Chien; Wahab, Habibah Abdul; Tan, Mei Lan

    2014-01-01

    A multiplex RT-qPCR was developed to examine CYP1A2, CYP2D6, and CYP3A4 induction properties of compounds from food and herbal sources. The induction of drug metabolizing enzymes is an important pharmacokinetic interaction with unique features in comparison with inhibition of metabolizing enzymes. Cytochrome induction can lead to serious drug–drug or drug–food interactions, especially if the coadministered drug plasma level is critical as it can reduce therapeutic effects and cause complications. Using this optimized multiplex RT-qPCR, cytochrome induction properties of andrographolide, curcumin, lycopene, bergamottin, and resveratrol were determined. Andrographolide, curcumin, and lycopene produced no significant induction effects on CYP1A2, CYP2D6, and CYP3A4. However, bergamottin appeared to be a significant in vitro CYP1A2 inducer starting from 5 to 50 μmol/L with induction ranging from 60 to 100-fold changes. On the other hand, resveratrol is a weak in vitro CYP1A2 inducer. Examining the cytochrome induction properties of food and herbal compounds help complement CYP inhibition studies and provide labeling and safety caution for such products. PMID:25473508

  9. Tamoxifen metabolism predicts drug concentrations and outcome in premenopausal patients with early breast cancer.

    PubMed

    Saladores, P; Mürdter, T; Eccles, D; Chowbay, B; Zgheib, N K; Winter, S; Ganchev, B; Eccles, B; Gerty, S; Tfayli, A; Lim, J S L; Yap, Y S; Ng, R C H; Wong, N S; Dent, R; Habbal, M Z; Schaeffeler, E; Eichelbaum, M; Schroth, W; Schwab, M; Brauch, H

    2015-02-01

    Tamoxifen is the standard-of-care treatment for estrogen receptor-positive premenopausal breast cancer. We examined tamoxifen metabolism via blood metabolite concentrations and germline variations of CYP3A5, CYP2C9, CYP2C19 and CYP2D6 in 587 premenopausal patients (Asians, Middle Eastern Arabs, Caucasian-UK; median age 39 years) and clinical outcome in 306 patients. N-desmethyltamoxifen (DM-Tam)/(Z)-endoxifen and CYP2D6 phenotype significantly correlated across ethnicities (R(2): 53%, P<10(-77)). CYP2C19 and CYP2C9 correlated with norendoxifen and (Z)-4-hydroxytamoxifen concentrations, respectively (P<0.001). DM-Tam was influenced by body mass index (P<0.001). Improved distant relapse-free survival (DRFS) was associated with decreasing DM-Tam/(Z)-endoxifen (P=0.036) and increasing CYP2D6 activity score (hazard ratio (HR)=0.62; 95% confidence interval (CI), 0.43-0.91; P=0.013). Low (<14 nM) compared with high (>35 nM) endoxifen concentrations were associated with shorter DRFS (univariate P=0.03; multivariate HR=1.94; 95% CI, 1.04-4.14; P=0.064). Our data indicate that endoxifen formation in premenopausal women depends on CYP2D6 irrespective of ethnicity. Low endoxifen concentration/formation and decreased CYP2D6 activity predict shorter DRFS. PMID:25091503

  10. Tamoxifen metabolism predicts drug concentrations and outcome in premenopausal patients with early breast cancer

    PubMed Central

    Saladores, P; Mürdter, T; Eccles, D; Chowbay, B; Zgheib, N K; Winter, S; Ganchev, B; Eccles, B; Gerty, S; Tfayli, A; Lim, J S L; Yap, Y S; Ng, R C H; Wong, N S; Dent, R; Habbal, M Z; Schaeffeler, E; Eichelbaum, M; Schroth, W; Schwab, M; Brauch, H

    2015-01-01

    Tamoxifen is the standard-of-care treatment for estrogen receptor-positive premenopausal breast cancer. We examined tamoxifen metabolism via blood metabolite concentrations and germline variations of CYP3A5, CYP2C9, CYP2C19 and CYP2D6 in 587 premenopausal patients (Asians, Middle Eastern Arabs, Caucasian-UK; median age 39 years) and clinical outcome in 306 patients. N-desmethyltamoxifen (DM-Tam)/(Z)-endoxifen and CYP2D6 phenotype significantly correlated across ethnicities (R2: 53%, P<10−77). CYP2C19 and CYP2C9 correlated with norendoxifen and (Z)-4-hydroxytamoxifen concentrations, respectively (P<0.001). DM-Tam was influenced by body mass index (P<0.001). Improved distant relapse-free survival (DRFS) was associated with decreasing DM-Tam/(Z)-endoxifen (P=0.036) and increasing CYP2D6 activity score (hazard ratio (HR)=0.62; 95% confidence interval (CI), 0.43–0.91; P=0.013). Low (<14 nM) compared with high (>35 nM) endoxifen concentrations were associated with shorter DRFS (univariate P=0.03; multivariate HR=1.94; 95% CI, 1.04–4.14; P=0.064). Our data indicate that endoxifen formation in premenopausal women depends on CYP2D6 irrespective of ethnicity. Low endoxifen concentration/formation and decreased CYP2D6 activity predict shorter DRFS. PMID:25091503

  11. Atomoxetine: A Review of Its Pharmacokinetics and Pharmacogenomics Relative to Drug Disposition.

    PubMed

    Yu, Guo; Li, Guo-Fu; Markowitz, John S

    2016-05-01

    Atomoxetine is a selective norepinephrine (NE) reuptake inhibitor approved for the treatment of attention-deficit/hyperactivity disorder (ADHD) in children (≥6 years of age), adolescents, and adults. Its metabolism and disposition are fairly complex, and primarily governed by cytochrome P450 (CYP) 2D6 (CYP2D6), whose protein expression varies substantially from person to person, and by race and ethnicity because of genetic polymorphism. These differences can be substantial, resulting in 8-10-fold differences in atomoxetine exposure between CYP2D6 poor metabolizers and extensive metabolizers. In this review, we have attempted to revisit and analyze all published clinical pharmacokinetic data on atomoxetine inclusive of public access documents from the new drug application submitted to the United States Food and Drug Administration (FDA). The present review focuses on atomoxetine metabolism, disposition, and genetic polymorphisms of CYP2D6 as they specifically relate to atomoxetine, and provides an in-depth discussion of the fundamental pharmacokinetics of the drug including its absorption, distribution, metabolism, and excretion in pediatric and adult populations. Further, a summary of relationships between genetic variants of CYP2D6 and to some degree, CYP2C19, are provided with respect to atomoxetine plasma concentrations, central nervous system (CNS) pharmacokinetics, and associated clinical implications for pharmacotherapy. Lastly, dosage adjustments based on pharmacokinetic principles are discussed. PMID:26859445

  12. Inhibition of dextromethorphan metabolism by moclobemide.

    PubMed

    Härtter, S; Dingemanse, J; Baier, D; Ziegler, G; Hiemke, C

    1998-01-01

    This pilot study was conducted to evaluate the potential of the new antidepressant moclobemide to inhibit the cytochrome enzyme P4502D6 (CYP2D6) using the cough suppressant dextromethorphan as a substrate in four extensive metabolizers (EM) of debrisoquine. The subjects received seven oral doses of 20 mg dextromethorphan at 4-h intervals over 2 days (1 and 2) and subsequently moclobemide (300 mg b.i.d.) for 9 days. On days 10 and 11, they received seven doses of 20 mg dextromethorphan in addition to moclobemide. During monotreatment and combined treatment, blood was collected on days 2 and 11, respectively, for determination of dextromethorphan and its demethylated metabolites using automated high-performance liquid chromatography with column switching. Concurrent administration of moclobemide markedly reduced the O-demethylation of dextromethorphan, whereas the N-demethylation of dextrorphan to hydroxymorphinan was not affected. The findings indicate that moclobemide can affect the pharmacokinetics of drugs that are mainly metabolized by CYP2D6. PMID:9489930

  13. [Effect of oligosaccharide esters and polygalaxanthone Ill from Polygala tenuifolia willd towards cytochrome P450].

    PubMed

    Li, Zhao-liang; Dong, Xian-zhe; Wang, Dong-xiao; Dong, Rui-hua; Guo, Ting-ting; Sun, Yan; Liu, Ping

    2014-11-01

    Five compounds (tenuifoliside C, tenuifoliside D, telephiose A, telephiose C and polygalaxanthone III) from polygala tenuifolia wild were incubated together with CYP probe substrate in human liver microsomes to investigate the inhibitory effect towards CYP450 enzyme. Phenacetin (CYP1A2), coumarin (CYP2A6), paclitaxel (CYP2C8), diclofenac (CYP2C9), S-mepheriytoin (CYP2C19), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1), midazolam (CYP3A) were selected as the isoforfn specific substrate. And the formation of paracetamol, 7-hydroxycoumarin, 6alpha-hydroxy paclitaxel, 4'-hydroxydiclofenac, dextrorphan, 6-hydroxychlorzoxazone, 1'-hydroxymidazolam, 4'-hydroxymephenytoin were detected respectively to measure the effect towards CYP450 by high-pressure liquid chromatography (HPLC). The result shows that five compounds from polygala tenuifolia willd significantly inhibit chlorzoxazone 6-hydroxylation catalyzed by CYP2E1, while showed no effect towards CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A. And IC50 value was 38.73, 54.14, 61.77, 62.22, 50.56 micromol x L(-1), respectively. PMID:25850285

  14. The Effect of Vinpocetine on Human Cytochrome P450 Isoenzymes by Using a Cocktail Method

    PubMed Central

    Kong, Lingti; Song, Chunli; Ye, Linhu; Guo, Daohua; Yu, Meiling; Xing, Rong

    2016-01-01

    Vinpocetine is a derivative of the alkaloid vincamine, which had been prescribed for chronic cerebral vascular ischemia and acute ischemic stroke or used as a dietary supplement for its several different mechanisms of biological activities. However, information on the cytochrome P450 (CYP) enzyme-mediated drug metabolism has not been previously studied. The present study was performed to investigate the effects of vinpocetine on CYPs activity, and cocktail method was used, respectively. To evaluate the effects of vinpocetine on the activity of human CYP3A4, CYP2C9, CYP2C19, CYP2D6, and CYP2E1, human liver microsomes were utilized to incubate with the mixed CYPs probe substrates and the target components. The results indicate that vinpocetine exhibited weak inhibitory effect on the CYP2C9, where the IC50 value is 68.96 μM, whereas the IC50 values for CYP3A4, CYP2C19, CYP2D6, and CYP2E1 were all over range of 100 μM, which showed that vinpocetine had no apparent inhibitory effects on these CYPs. In conclusion, the results indicated that drugs metabolized by CYP2C9 coadministrated with vinpocetine may require attention or dose adjustment. PMID:27006677

  15. The Effect of Vinpocetine on Human Cytochrome P450 Isoenzymes by Using a Cocktail Method.

    PubMed

    Kong, Lingti; Song, Chunli; Ye, Linhu; Guo, Daohua; Yu, Meiling; Xing, Rong

    2016-01-01

    Vinpocetine is a derivative of the alkaloid vincamine, which had been prescribed for chronic cerebral vascular ischemia and acute ischemic stroke or used as a dietary supplement for its several different mechanisms of biological activities. However, information on the cytochrome P450 (CYP) enzyme-mediated drug metabolism has not been previously studied. The present study was performed to investigate the effects of vinpocetine on CYPs activity, and cocktail method was used, respectively. To evaluate the effects of vinpocetine on the activity of human CYP3A4, CYP2C9, CYP2C19, CYP2D6, and CYP2E1, human liver microsomes were utilized to incubate with the mixed CYPs probe substrates and the target components. The results indicate that vinpocetine exhibited weak inhibitory effect on the CYP2C9, where the IC50 value is 68.96 μM, whereas the IC50 values for CYP3A4, CYP2C19, CYP2D6, and CYP2E1 were all over range of 100 μM, which showed that vinpocetine had no apparent inhibitory effects on these CYPs. In conclusion, the results indicated that drugs metabolized by CYP2C9 coadministrated with vinpocetine may require attention or dose adjustment. PMID:27006677

  16. Heritability of metoprolol and torsemide pharmacokinetics.

    PubMed

    Matthaei, J; Brockmöller, J; Tzvetkov, M V; Sehrt, D; Sachse-Seeboth, C; Hjelmborg, J B; Möller, S; Halekoh, U; Hofmann, U; Schwab, M; Kerb, R

    2015-12-01

    Genetic variation in the pharmacokinetics of metoprolol and torsemide due to polymorphisms in CYP2D6, CYP2C9, and OATP1B1 has been extensively studied. However, it is still unknown how much of the variation in pharmacokinetics of these two clinically important drugs in total is due to genetic factors. Metoprolol and torsemide were intravenously administered to 44 monozygotic and 14 dizygotic twin pairs. Metoprolol area under the curve (AUC) varied 4.7-fold and torsemide AUC 3.5-fold. A very high fraction of AUC variations, 91% of metoprolol and 86% of torsemide, were found to be due to additive genetic effects. However, known genetic variants of CYP2D6, -2C9, and OATP1B1 explained only 39%, 2%, and 39% of that variation, respectively. Comparable results for genetically explained variation in pharmacokinetics and pharmacodynamics have been found for other substrates of these enzymes earlier. These findings indicate that a substantial fraction of the heritable variability in the pharmacokinetics of metoprolol and torsemide remains to be elucidated. PMID:26344676

  17. An experimental and theoretical study on the kinetic isotope effect of C2H6 and C2D6 reaction with OH

    NASA Astrophysics Data System (ADS)

    Khaled, Fethi; Giri, Binod Raj; Szőri, Milán; Viskolcz, Béla; Farooq, Aamir

    2015-11-01

    We report experimental and theoretical results for the deuterated kinetic isotope effect (DKIE) of the reaction of OH with ethane (C2H6) and deuterated ethane (C2D6). The reactions were investigated behind reflected shock waves over 800-1350 K by monitoring OH radicals near 306.69 nm using laser absorption. In addition, high level CCSD(T)/cc-pV(T,Q)Z//MP2/cc-pVTZ quantum chemical and statistical rate theory calculations were performed which agreed very well with the experimental findings. The results reported herein provide the first experimental evidence that DKIE asymptotes to a value of 1.4 at high temperatures.

  18. Berberine

    MedlinePlus

    ... health provider.Medications changed by the liver (Cytochrome P450 2C9 [CYP2C9] substrates)Some medications are changed and ... health provider.Medications changed by the liver (Cytochrome P450 2D6 [CYP2D6] substrates)Some medications are changed and ...

  19. Inhibitory Mechanisms of Human CYPs by Three Alkaloids Isolated from Traditional Chinese Herbs.

    PubMed

    Zhao, Yong; Hellum, Bent Håvard; Liang, Aihua; Nilsen, Odd Georg

    2015-06-01

    The three purified herbal compounds tetrahydropalmatine (Tet), neferine and berberine (Ber) were explored in vitro for basic inhibition mechanisms towards recombinant human CYP1A2, CYP2D6 and CYP3A4 metabolic activities. Phenacetin, dextromethorphan and testosterone, respectively, were used as CYP1A2, CYP2D6 and CYP3A4 substrates, and their metabolites were determined by validated HPLC methodologies. Positive inhibition controls were used. Mechanism-based (irreversible) inhibition was assessed by time-dependent and nicotinamide adenine dinucleotide phosphate-dependent and reversible inhibition by Lineweaver-Burk plot assessments. Inhibition mechanisms were also assessed by computerized interaction prediction by using the Discovery Studio CDOCKER software (Accelrys, San Diego, CA, USA). Tetrahydropalmatine showed a mechanism-based inhibition of both CYP1A2 and CYP2D6, and Ber of CYP2D6. Neferine and Ber both showed a nonmechanistic inhibition of CYP1A2. All compounds showed a similar and significant mechanism-based inhibition of CYP3A4. Tetrahydropalmatine and Ber demonstrated both reversible and irreversible inhibition of CYP2D6 and CYP3A4. Tetrahydropalmatine and Ber displayed H-bond and several Pi-bond connections with specific amino acid residues of CYP1A2, CYP2D6 and CYP3A4, giving further knowledge to the identified reversible and irreversible herb-drug interactions. Tetrahydropalmatine and Ber should be considered for herb-drug interactions in clinical therapy until relevant clinical studies are available. PMID:25640685

  20. A case with occurring adverse effects when cross-over titration from fluvoxamine to paroxetine associated with increasing the plasma fluvoxamine level in major depressive disorder.

    PubMed

    Hori, Hikaru; Yoshimura, Reiji; Ueda, Nobuhisa; Ikenouchi-Sugita, Atsuko; Umene-Nakano, Wakako; Nakamura, Jun

    2009-01-01

    Selective serotonin reuptake inhibitors (SSRIs) are first line drugs for treating not only depressive disorder but also anxiety disorder. Fluvoxamine, a SSRI, is mainly metabolized by cytochrome P450 (CYP) 2D6 and 1A2. However, paroxetine, an another SSRI is potent inhibitor for CYP 2D6. We report a case with depression whose plasma fluvoxamine level rapidly increased after the addition of paroxetine while switching from fluvoxamine to paroxetine. The case indicates that emerging adverse effects via the pharmacokinetic interaction of these drugs when switching patients from fluvoxamine to paroxetine can occur. PMID:18609433

  1. Frequencies of 23 functionally significant variant alleles related with metabolism of antineoplastic drugs in the chilean population: comparison with caucasian and asian populations.

    PubMed

    Roco, Angela; Quiñones, Luis; Agúndez, José A G; García-Martín, Elena; Squicciarini, Valentina; Miranda, Carla; Garay, Joselyn; Farfán, Nancy; Saavedra, Iván; Cáceres, Dante; Ibarra, Carol; Varela, Nelson

    2012-01-01

    Cancer is a leading cause of death worldwide. The cancer incidence rate in Chile is 133.7/100,000 inhabitants and it is the second cause of death, after cardiovascular diseases. Most of the antineoplastic drugs are metabolized to be detoxified, and some of them to be activated. Genetic polymorphisms of drug-metabolizing enzymes can induce deep changes in enzyme activity, leading to individual variability in drug efficacy and/or toxicity. The present research describes the presence of genetic polymorphisms in the Chilean population, which might be useful in public health programs for personalized treatment of cancer, and compares these frequencies with those reported for Asian and Caucasian populations, as a contribution to the evaluation of ethnic differences in the response to chemotherapy. We analyzed 23 polymorphisms in a group of 253 unrelated Chilean volunteers from the general population. The results showed that CYP2A6*2, CYP2A6*3, CYP2D6*3, CYP2C19*3, and CYP3A4*17 variant alleles are virtually absent in Chileans. CYP1A1*2A allele frequency (0.37) is similar to that of Caucasians and higher than that reported for Japanese people. Allele frequencies for CYP3A5*3(0.76) and CYP2C9*3(0.04) are similar to those observed in Japanese people. CYP1A1*2C(0.32), CYP1A2*1F(0.77), CYP3A4*1B(0.06), CYP2D6*2(0.41), and MTHFR T(0.52) allele frequencies are higher than the observed either in Caucasian or in Japanese populations. Conversely, CYP2C19*2 allelic frequency (0.12), and genotype frequencies for GSTT1 null (0.11) and GSTM1 null (0.36) are lower than those observed in both populations. Finally, allele frequencies for CYP2A6*4(0.04), CYP2C8*3(0.06), CYP2C9*2(0.06), CYP2D6*4(0.12), CYP2E1*5B(0.14), CYP2E1*6(0.19), and UGT2B7*2(0.40) are intermediate in relation to those described in Caucasian and in Japanese populations, as expected according to the ethnic origin of the Chilean population. In conclusion, our findings support the idea that ethnic variability must be

  2. Frequencies of 23 Functionally Significant Variant Alleles Related with Metabolism of Antineoplastic Drugs in the Chilean Population: Comparison with Caucasian and Asian Populations

    PubMed Central

    Roco, Ángela; Quiñones, Luis; Agúndez, José A. G.; García-Martín, Elena; Squicciarini, Valentina; Miranda, Carla; Garay, Joselyn; Farfán, Nancy; Saavedra, Iván; Cáceres, Dante; Ibarra, Carol; Varela, Nelson

    2012-01-01

    Cancer is a leading cause of death worldwide. The cancer incidence rate in Chile is 133.7/100,000 inhabitants and it is the second cause of death, after cardiovascular diseases. Most of the antineoplastic drugs are metabolized to be detoxified, and some of them to be activated. Genetic polymorphisms of drug-metabolizing enzymes can induce deep changes in enzyme activity, leading to individual variability in drug efficacy and/or toxicity. The present research describes the presence of genetic polymorphisms in the Chilean population, which might be useful in public health programs for personalized treatment of cancer, and compares these frequencies with those reported for Asian and Caucasian populations, as a contribution to the evaluation of ethnic differences in the response to chemotherapy. We analyzed 23 polymorphisms in a group of 253 unrelated Chilean volunteers from the general population. The results showed that CYP2A6*2, CYP2A6*3, CYP2D6*3, CYP2C19*3, and CYP3A4*17 variant alleles are virtually absent in Chileans. CYP1A1*2A allele frequency (0.37) is similar to that of Caucasians and higher than that reported for Japanese people. Allele frequencies for CYP3A5*3(0.76) and CYP2C9*3(0.04) are similar to those observed in Japanese people. CYP1A1*2C(0.32), CYP1A2*1F(0.77), CYP3A4*1B(0.06), CYP2D6*2(0.41), and MTHFR T(0.52) allele frequencies are higher than the observed either in Caucasian or in Japanese populations. Conversely, CYP2C19*2 allelic frequency (0.12), and genotype frequencies for GSTT1 null (0.11) and GSTM1 null (0.36) are lower than those observed in both populations. Finally, allele frequencies for CYP2A6*4(0.04), CYP2C8*3(0.06), CYP2C9*2(0.06), CYP2D6*4(0.12), CYP2E1*5B(0.14), CYP2E1*6(0.19), and UGT2B7*2(0.40) are intermediate in relation to those described in Caucasian and in Japanese populations, as expected according to the ethnic origin of the Chilean population. In conclusion, our findings support the idea that ethnic variability must be

  3. Psychedelic 5-Methoxy-N,N-dimethyltryptamine: Metabolism, Pharmacokinetics, Drug Interactions, and Pharmacological Actions

    PubMed Central

    Shen, Hong-Wu; Jiang, Xi-Ling; Winter, Jerrold C.; Yu, Ai-Ming

    2011-01-01

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) belongs to a group of naturally-occurring psychoactive indolealkylamine drugs. It acts as a nonselective serotonin (5-HT) agonist and causes many physiological and behavioral changes. 5-MeO-DMT is O-demethylated by polymorphic cytochrome P450 2D6 (CYP2D6) to an active metabolite, bufotenine, while it is mainly inactivated through the deamination pathway mediated by monoamine oxidase A (MAO-A). 5-MeO-DMT is often used with MAO-A inhibitors such as harmaline. Concurrent use of harmaline reduces 5-MeO-DMT deamination metabolism and leads to a prolonged and increased exposure to the parent drug 5-MeO-DMT, as well as the active metabolite bufotenine. Harmaline, 5-MeO-DMT and bufotenine act agonistically on serotonergic systems and may result in hyperserotonergic effects or serotonin toxicity. Interestingly, CYP2D6 also has important contribution to harmaline metabolism, and CYP2D6 genetic polymorphism may cause considerable variability in the metabolism, pharmacokinetics and dynamics of harmaline and its interaction with 5-MeO-DMT. Therefore, this review summarizes recent findings on biotransformation, pharmacokinetics, and pharmacological actions of 5-MeO-DMT. In addition, the pharmacokinetic and pharmacodynamic drug-drug interactions between harmaline and 5-MeO-DMT, potential involvement of CYP2D6 pharmacogenetics, and risks of 5-MeO-DMT intoxication are discussed. PMID:20942780

  4. Psychedelic 5-methoxy-N,N-dimethyltryptamine: metabolism, pharmacokinetics, drug interactions, and pharmacological actions.

    PubMed

    Shen, Hong-Wu; Jiang, Xi-Ling; Winter, Jerrold C; Yu, Ai-Ming

    2010-10-01

    5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) belongs to a group of naturally-occurring psychoactive indolealkylamine drugs. It acts as a nonselective serotonin (5-HT) agonist and causes many physiological and behavioral changes. 5-MeO-DMT is O-demethylated by polymorphic cytochrome P450 2D6 (CYP2D6) to an active metabolite, bufotenine, while it is mainly inactivated through the deamination pathway mediated by monoamine oxidase A (MAO-A). 5-MeO-DMT is often used with MAO-A inhibitors such as harmaline. Concurrent use of harmaline reduces 5-MeO-DMT deamination metabolism and leads to a prolonged and increased exposure to the parent drug 5-MeO-DMT, as well as the active metabolite bufotenine. Harmaline, 5-MeO-DMT and bufotenine act agonistically on serotonergic systems and may result in hyperserotonergic effects or serotonin toxicity. Interestingly, CYP2D6 also has important contribution to harmaline metabolism, and CYP2D6 genetic polymorphism may cause considerable variability in the metabolism, pharmacokinetics and dynamics of harmaline and its interaction with 5-MeO-DMT. Therefore, this review summarizes recent findings on biotransformation, pharmacokinetics, and pharmacological actions of 5-MeO-DMT. In addition, the pharmacokinetic and pharmacodynamic drug-drug interactions between harmaline and 5-MeO-DMT, potential involvement of CYP2D6 pharmacogenetics, and risks of 5-MeO-DMT intoxication are discussed. PMID:20942780

  5. Effects of Pharmacogenetics on the Pharmacokinetics and Pharmacodynamics of Tamoxifen.

    PubMed

    de Vries Schultink, Aurelia H M; Zwart, Wilbert; Linn, Sabine C; Beijnen, Jos H; Huitema, Alwin D R

    2015-08-01

    The antiestrogenic drug tamoxifen is widely used in the treatment of estrogen receptor-α-positive breast cancer and substantially decreases recurrence and mortality rates. However, high interindividual variability in response is observed, calling for a personalized approach to tamoxifen treatment. Tamoxifen is bioactivated by cytochrome P450 (CYP) enzymes such as CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP3A4/5, resulting in the formation of active metabolites, including 4-hydroxy-tamoxifen and endoxifen. Therefore, polymorphisms in the genes encoding these enzymes are proposed to influence tamoxifen and active tamoxifen metabolites in the serum and consequently affect patient response rates. To tailor tamoxifen treatment, multiple studies have been performed to clarify the influence of polymorphisms on its pharmacokinetics and pharmacodynamics. Nevertheless, personalized treatment of tamoxifen based on genotyping has not yet met consensus. This article critically reviews the published data on the effect of various genetic polymorphisms on the pharmacokinetics and pharmacodynamics of tamoxifen, and reviews the clinical implications of its findings. For each CYP enzyme, the influence of polymorphisms on pharmacokinetic and pharmacodynamic outcome measures is described throughout this review. No clear effects on pharmacokinetics and pharmacodynamics were seen for various polymorphisms in the CYP encoding genes CYP2B6, CYP2C9, CYP2C19 and CYP3A4/5. For CYP2D6, there was a clear gene-exposure effect that was able to partially explain the interindividual variability in plasma concentrations of the pharmacologically most active metabolite endoxifen; however, a clear exposure-response effect remained controversial. These controversial findings and the partial contribution of genotype in explaining interindividual variability in plasma concentrations of, in particular, endoxifen, imply that tailored tamoxifen treatment may not be fully realized through pharmacogenetics of

  6. Complex Drug Interactions of HIV Protease Inhibitors 2: In Vivo Induction and In Vitro to In Vivo Correlation of Induction of Cytochrome P450 1A2, 2B6, and 2C9 by Ritonavir or Nelfinavir

    PubMed Central

    Kirby, Brian J.; Collier, Ann C.; Kharasch, Evan D.; Dixit, Vaishali; Desai, Pankaj; Whittington, Dale; Thummel, Kenneth E.

    2011-01-01

    Drug-drug interactions (DDIs) with the HIV protease inhibitors (PIs) are complex, paradoxical (e.g., ritonavir/alprazolam), and involve multiple mechanisms. As part of a larger study to better understand these DDIs and to devise a framework for in vitro to in vivo prediction of these DDIs, we determined the inductive effect of ∼2 weeks of administration of two prototypic PIs, nelfinavir (NFV), ritonavir (RTV), and rifampin (RIF; induction positive control) on the cytochrome P450 enzymes CYP1A2, CYP2B6, CYP2C9, and CYP2D6 and the inductive or inductive plus inhibitory effect of NFV, RTV, or RIF on CYP3A and P-glycoprotein in healthy human volunteers. Statistically significant induction of CYP1A2 (2.1-, 2.9-, and 2.2-fold), CYP2B6 (1.8-, 2.4-, and 4-fold), and CYP2C9 (1.3-, 1.8-, and 2.6-fold) was observed after NFV, RTV, or RIF treatment, respectively (as expected, CYP2D6 was not induced). Moreover, we accurately predicted the in vivo induction of these enzymes by quantifying their induction by the PIs in human hepatocytes and by using RIF as an in vitro to in vivo scalar. On the basis of the modest in vivo induction of CYP1A2, CYP2B6, or CYP2C9, the in vivo paradoxical DDIs with the PIs are likely explained by mechanisms other than induction of these enzymes such as induction of other metabolic enzymes, transporters, or both. PMID:21930825

  7. Enhanced Methamphetamine Metabolism in Rhesus Macaque as Compared with Human: An Analysis Using a Novel Method of Liquid Chromatography with Tandem Mass Spectrometry, Kinetic Study, and Substrate Docking

    PubMed Central

    Wang, Lei; Bosinger, Steven; Li, Junhao; Shah, Ankit; Gangwani, Mohitkumar; Nookala, Anantha; Liu, Xun; Cao, Lu; Jackson, Austin; Silverstein, Peter S.; Fox, Howard S.; Li, Weihua; Kumar, Anil

    2014-01-01

    Methamphetamine (MA), which remains one of the widely used drugs of abuse, is metabolized by the cytochrome P450 (P450) family of enzymes in humans. However, metabolism of methamphetamine in macaques is poorly understood. Therefore, we first developed and validated a very sensitive liquid chromatography with tandem mass spectrometry (LC-MS/MS) method using solid phase extraction of rhesus plasma with a lower limit of quantitation at 1.09 ng/ml for MA and its metabolites, 4-hydroxy methamphetamine (4-OH MA), amphetamine (AM), 4-OH amphetamine (4-OH AM), and norephedrine. We then analyzed plasma samples of MA-treated rhesus, which showed >10-fold higher concentrations of AM (∼29 ng/ml) and 4-OH AM (∼28 ng/ml) than MA (∼2 ng/ml). Because the plasma levels of MA metabolites in rhesus were much higher than in human samples, we examined MA metabolism in human and rhesus microsomes. Interestingly, the results showed that AM and 4-OH AM were formed more rapidly and that the catalytic efficiency (Vmax/Km) for the formation of AM was ∼8-fold higher in rhesus than in human microsomes. We further examined the differences in these kinetic characteristics using three selective inhibitors of each human CYP2D6 and CYP3A4 enzymes. The results showed that each of these inhibitors inhibited both d- and l-MA metabolism by 20%–60% in human microsomes but not in rhesus microsomes. The differences between human and rhesus CYP2D6 and CYP3A4 enzymes were further assessed by docking studies for both d and l-MA. In conclusion, our results demonstrated an enhanced MA metabolism in rhesus compared with humans, which is likely to be caused by differences in MA-metabolizing P450 enzymes between these species. PMID:25301936

  8. Interactions of Papua New Guinea medicinal plant extracts with antiretroviral therapy

    PubMed Central

    Larson, Erica C.; Hathaway, Laura B.; Lamb, John G.; Pond, Chris D.; Rai, Prem P.; Matainaho, Teatulohi K.; Piskaut, Pius; Barrows, Louis R.; Franklin, Michael R.

    2014-01-01

    Ethnopharmacological relevance A substantial proportion of the population in Papua New Guinea (PNG) lives with human immunodeficiency virus (HIV). Treatment requires lifelong use of antiretroviral therapy (ART). The majority of people in PNG use traditional medicines (TM) derived from plants for all types of health promotions. Consequently, there is a concern that herb-drug interactions may impact the efficacy of ART. Herb-drug, or drug-drug, interactions occur at the level of metabolism through two major mechanisms: enzyme induction or enzyme inhibition. In this study, extracts of commonly-used medicinal plants from PNG were screened for herb-drug interactions related to cytochrome P450s (CYPs). Materials and Methods Sixty nine methanol extracts of TM plants were screened for their ability to induce CYPs by human aryl hydrocarbon receptor- (hAhR-) and human pregnane X receptor- (hPXR-) dependent mechanisms, utilizing a commercially available cell-based luciferase reporter system. Inhibition of three major CYPs, CYP1A2, CYP3A4, and CYP2D6, was determined using human liver microsomes and enzyme-selective model substrates. Results Almost one third of the TM plant extracts induced the hAhR-dependent expression of CYP1A2, the hPXR-dependent expression of CYP3A4, or both. Almost two thirds inhibited CYP1A2, CYP3A4, or CYP2D6, or combinations thereof. Many plant extracts exhibited both induction and inhibition properties. Conclusions We demonstrated that the potent and selective ability of extracts from PNG medicinal plants to affect drug metabolizing enzymes through induction and/or inhibition is a common phenomenon. Use of traditional medicines concomitantly with ART could dramatically alter the concentrations of antiretroviral drugs in the body; and their efficacy. PNG healthcare providers should counsel HIV patients because of this consequence. PMID:25138353

  9. Pharmacological Relevance of Endoxifen in a Laboratory Simulation of Breast Cancer in Postmenopausal Patients

    PubMed Central

    Maximov, Philipp Y.; McDaniel, Russell E.; Fernandes, Daphne J.; Bhatta, Puspanjali; Korostyshevskiy, Valeriy R.; Curpan, Ramona F.

    2014-01-01

    Background Tamoxifen is metabolically activated via a CYP2D6 enzyme system to the more potent hydroxylated derivatives 4-hydroxytamoxifen and endoxifen. This study addresses the pharmacological importance of endoxifen by simulating clinical scenarios in vitro. Methods Clinical levels of tamoxifen metabolites in postmenopausal breast cancer patients previously genotyped for CYP2D6 were used in vitro along with clinical estrogen levels (estrone and estradiol) in postmenopausal patients determined in previous studies. The biological effects on cell growth were evaluated in a panel of estrogen receptor–positive breast cancer cell lines via cell proliferation assays and real-time polymerase chain reaction (PCR). Data were analyzed with one- and two-way analysis of variance and Student’s t test. All statistical tests were two-sided. Results Postmenopausal levels of estrogen-induced proliferation of all test breast cancer cell lines (mean fold induction ± SD vs vehicle control: MCF-7 = 11±1.74, P < .001; T47D = 7.52±0.72, P < .001; BT474 = 1.75±0.23, P < .001; ZR-75-1 = 5.5±1.95, P = .001. Tamoxifen and primary metabolites completely inhibited cell growth regardless of the CYP2D6 genotype in all cell lines (mean fold induction ± SD vs vehicle control: MCF-7 = 1.57±0.38, P = .54; T47D = 1.17±0.23, P = .79; BT474 = 0.96±0.2, P = .98; ZR-75-1 = 0.86±0.67, P = .99). Interestingly, tamoxifen and its primary metabolites were not able to fully inhibit the estrogen-stimulated expression of estrogen-responsive genes in MCF-7 cells (P < .05 for all genes), but the addition of endoxifen was able to produce additional antiestrogenic effect on these genes. Conclusions The results indicate that tamoxifen and other metabolites, excluding endoxifen, completely inhibit estrogen-stimulated growth in all cell lines, but additional antiestrogenic action from endoxifen is necessary for complete blockade of estrogen-stimulated genes. Endoxifen is of supportive importance for the

  10. Pharmacokinetics of dextromethorphan after single or multiple dosing in combination with quinidine in extensive and poor metabolizers.

    PubMed

    Pope, Laura E; Khalil, M H; Berg, James E; Stiles, Mark; Yakatan, Gerald J; Sellers, Edward M

    2004-10-01

    Dextromethorphan (DM) pharmacological properties predict that the widely used cough suppressant could be used to treat several neuronal disorders, but it is rapidly metabolized after oral dosing. To find out whether quinidine (Q), a CYP2D6 inhibitor, could elevate and prolong DM plasma profiles, 2 multiple-dose studies identified the lowest oral dose of Q that could be used in a fixed combination with 3 doses of DM. A multiple-dose study in healthy subjects with an extensive or a poor enzyme metabolizer phenotype evaluated the safety and pharmacokinetic profile of a selected fixed-dose combination (AVP-923). Study 1 randomized 46 healthy subjects, who were extensive CYP2D6 metabolizers, to receive 0, 2.5, 10, 25, 50, or 75 mg Q twice daily in combination with 30 mg DM for 7 days. Plasma and urine samples were collected after the first and last doses for the assay of DM, dextrorphan (DX), and Q. Study 2 randomized 65 healthy extensive CYP2D6 metabolizers to 8 groups given twice-daily 45- or 60-mg DM doses combined with 0, 30, 45, or 60 mg Q for 7 days. The effects of increasing Q were not different with doses greater than 25 mg, whereas lower doses showed a dose-related increase in plasma DM concentrations. Urinary ratios of DM/DX showed a Q dose- and time-related increase in the number of subjects converted to the poor metabolizer phenotype that reached 100% on day 3 of dosing with 25 mg Q. Results from both studies indicated that 25 to 30 mg Q is adequate to maximally suppress O-demethylation of DM. Study 3 evaluated 7 extensive metabolizers and 2 poor metabolizers given an oral capsule every 12 hours containing 30 mg Q combined with 30 mg DM. DM plasma AUC values increased in both groups of subjects during the 8-day study. The mean urinary metabolic ratio (DM/DX) increased at least 27-fold in extensive metabolizers by day 8. There was no effect of Q on urinary metabolic ratios in poor metabolizers. Safety evaluations, including electrocardiograms, indicated that

  11. Breath tests to phenotype drug disposition in oncology.

    PubMed

    Opdam, Frans L; Modak, Anil S; Gelderblom, Hans; Guchelaar, Henk-Jan

    2013-11-01

    Breath tests (BTs) have been investigated as diagnostic tools to phenotype drug disposition in cancer patients in the pursuit to individualize drug treatment. The choice of the right phenotype probe is crucial and depends on the metabolic pathway of the anticancer agent of interest. BTs using orally or intravenously administered selective non-radioactive (13)C-labeled probes to non-invasively evaluate dihydropyrimidine dehydrogenase, cytochrome P450 (CYP) 3A4, and CYP2D6 enzyme activity have been published. Clinically, a (13)C-dextromethorphan BT to predict endoxifen levels in breast cancer patients and a (13)C-uracil BT to predict fluoropyrimidine toxicity in colorectal cancer patients are most promising. However, the clinical benefit and cost effectiveness of these phenotype BTs need to be determined in order to make the transition from an experimental setting to clinical practice as companion diagnostic tests. PMID:23868281

  12. Clinical response to eliglustat in treatment-naïve patients with Gaucher disease type 1: Post-hoc comparison to imiglucerase-treated patients enrolled in the International Collaborative Gaucher Group Gaucher Registry.

    PubMed

    Ibrahim, Jennifer; Underhill, Lisa H; Taylor, John S; Angell, Jennifer; Peterschmitt, M Judith

    2016-09-01

    Eliglustat is a recently approved oral therapy in the United States and Europe for adults with Gaucher disease type 1 who are CYP2D6 extensive, intermediate, or poor metabolizers (> 90% of patients) that has been shown to decrease spleen and liver volume and increase hemoglobin concentrations and platelet counts in untreated adults with Gaucher disease type 1 and maintain these parameters in patients previously stabilized on enzyme replacement therapy. In a post-hoc analysis, we compared the results of eliglustat treatment in treatment-naïve patients in two clinical studies with the results of imiglucerase treatment among a cohort of treatment-naïve patients with comparable baseline hematologic and visceral parameters in the International Collaborative Gaucher Group Gaucher Registry. Organ volumes and hematologic parameters improved from baseline in both treatment groups, with a time course and degree of improvement in eliglustat-treated patients similar to imiglucerase-treated patients. PMID:27408819

  13. Detection of DNA sequence polymorphisms in carcinogen metabolism genes by polymerase chain reaction.

    PubMed

    Bell, D A

    1991-01-01

    The glutathione transferase mu gene (GST1) and the debrisoquine hydroxylase gene (CYP2D6) are known to be polymorphic in the human population and have been associated with increased susceptibility to cancer. Smokers with low lymphocyte GST mu activity are at higher risk for lung cancer, while low debrisoquine hydroxylase activity has been correlated with lower risk for lung and bladder cancer. Phenotypic characterization of these polymorphisms by lymphocyte enzyme activity (GST) and urine metabolite ratios (debrisoquine) is cumbersome for population studies. Recent cloning and sequencing of the mutant alleles of these genes has allowed genotyping via the polymerase chain reaction (PCR). Advantages of PCR approaches are speed, technical simplicity, and minimal sample requirements. This article reviews the PCR-based methods for detection of genetic polymorphisms in human cancer susceptibility genes. PMID:1684153

  14. Metabolites profiling of 10 bufadienolides in human liver microsomes and their cytotoxicity variation in HepG2 cell.

    PubMed

    Han, Lingyu; Wang, Hongjie; Si, Nan; Ren, Wei; Gao, Bo; Li, Yan; Yang, Jian; Xu, Miao; Zhao, Haiyu; Bian, Baolin

    2016-04-01

    Bufadienolides, a class of polyhydroxy steroids, exhibit significant antitumor activity. In this study, a total of 39 metabolites from 10 bufadienolides were detected and identified by ultrahigh-performance liquid chromatography (UHPLC) coupled with an LTQ Orbitrap mass spectrometer. The results showed that hydroxylation and dehydrogenation were the major metabolic pathways of bufadienolides in human liver microsomes (HLMs). CYP3A4 was found to be the major metabolic enzyme and CYP2D6 only mediated the dehydrogenation reaction. A systematic validated cytotoxicity evaluation method for bufadienolide metabolites at equal equivalents was established. Hellebrigenin (1), hellebrigenol (2), arenobufagin (3), bufotalin (5), and bufalin (6) were selected to determine their cytotoxicity against HepG2 cells before and after incubation in HLMs. All the test samples were enriched by a validated solid-phase extraction (SPE) method. Although the cytotoxicities of metabolites were weaker than those of the parent compounds to different degrees, their effects were still strong. PMID:26869342

  15. Comparative metabolic study between two selective estrogen receptor modulators, toremifene and tamoxifen, in human liver microsomes.

    PubMed

    Watanabe, Miyuki; Watanabe, Noriko; Maruyama, Sakiko; Kawashiro, Takashi

    2015-10-01

    Toremifene (TOR) and Tamoxifen (TAM) are widely used as endocrine therapy for estrogen receptor positive breast cancer. Poor metabolizers of TAM are likely to have worse clinical outcomes than patients who exhibit normal TAM metabolism due to lower plasma level of its active metabolite, 4-hydroxy-N-desmethyl (4OH-NDM) tamoxifen (endoxifen). In this study, we examined the role of individual cytochrome P450 (CYP) isoforms in the metabolism of TOR to N-desmethyl (NDM), 4-hydroxy (4OH) and 4OH-NDM metabolites in comparison with TAM using human liver microsomes (HLMs) with selective chemical inhibitors for each CYP isoform and recombinant CYP proteins. Similar levels of NDM metabolites were formed for both TOR and TAM, and N-demethylation of both compounds was primarily carried out by CYP3A4. We found that the formation of 4OH-NDM-TOR was catalyzed both by CYP2C9 and CYP2D6, whereas the formation of 4OH-TAM and endoxifen was specifically catalyzed by CYP2D6 in HLMs. Our results suggest that the potential contribution of CYP2D6 in the bioactivation pathway of TOR may be lower compared to TAM, and may have a different impact on clinical outcome than CYP2D6 polymorphisms. PMID:26423799

  16. Allele and genotype frequencies of metabolic genes in Native Americans from Argentina and Paraguay.

    PubMed

    Bailliet, G; Santos, M R; Alfaro, E L; Dipierri, J E; Demarchi, D A; Carnese, F R; Bianchi, N O

    2007-03-01

    Interethnic differences in the allele frequencies of CYP2D6, NAT2, GSTM1 and GSTT1 deletions have been documented for Caucasians, Asians, and Africans population. On the other hand, data on Amerindians are scanty and limited to a few populations from southern areas of South America. In this report we analyze the frequencies of 11 allele variants of CYP2D6 and 4 allele variants of NAT2 genes, and the frequency of GSTM1 and GSTT1 homozygous deleted genotypes in a sample of 90 donors representing 8 Native American populations from Argentina and Paraguay, identified as Amerindians on the basis of their geographic location, genealogical data, mitochondrial- and Y-chromosome DNA markers. For CYP2D6, 88.6% of the total allele frequency corresponded to *1, *2, *4 and *10 variants. Average frequencies for NAT2 *4, *5, *6 and *7 alleles were 51.2%, 25%, 6.1%, and 20.1%, respectively. GSTM1 deletion ranged from 20% to 66%, while GSTT1 deletion was present in four populations in less than 50%. We assume that CYP2D6 *2, *4, *10, *14; NAT2 *5, *7 alleles and GSTM1 and GSTT1 *0/*0 genotypes are founder variants brought to America by the first Asian settlers. PMID:17194620

  17. Assessment of effect of Zhu-tan Tong-luo decoction on CYP450 isoforms activity of rats

    PubMed Central

    Jin, Yongxi; Shao, Lingjiu; Li, Gaowen; Shao, Mengmeng; Zhi, Yinghao; Zhu, Wenzong

    2015-01-01

    In order to investigate the effects of Zhu-tan Tong-luo decoction on the metabolic capacity of cytochrome P450 (CYP) enzymes, a cocktail method was employed to evaluate the activities of CYP2B6, CYP2C19, CYP1A2, CYP3A4, CYP2C9, CYP2D6. The rats were randomly divided into acute Zhu-Tan Tong-Luo decoction group (Low, High), chronic Zhu-Tan Tong-Luo decoction group (Low, High) and control group. The acute group rats were given 0.6, 1.2 g/kg (Low, High) Zhu-tan Tong-luo decoction by intragastric administration for 1 day, and the chronic group for 14 days. Six probe drugs bupropion, omeprazole, phenacetin, testosterone, tolbutamide, and metroprolol were given to rats through intragastric administration, and the plasma concentrations were determined by UPLC-MS/MS. There statistical pharmacokinetics differences for omeprazole, phenacetin, testosterone, tolbutamide, and metroprolol in rats were observed by comparing acute Zhu-tan Tong-luo decoction group with control group; and statistical pharmacokinetics differences for bupropion, omeprazole, phenacetin, testosterone, tolbutamide, and metroprolol were observed by comparing chronic Zhu-Tan Tong-Luo decoction group with control group. After intragastric administration of Zhu-Tan Tong-Luo decoction may slightly induce the activities of CYP2B6, CYP2C19, CYP1A2, CYP3A4, CYP2C9, CYP2D6 of rats. Induction of drug metabolizing enzyme by Zhu-Tan Tong-Luo decoction would reduce the efficacy of other drug. Additional, there no statistical difference for biochemical results after 1 or 14 intragastric administration of Zhu-Tan Tong-Luo decoction. PMID:26629097

  18. The Effects of Milk Thistle (Silybum marianum) on Human Cytochrome P450 Activity

    PubMed Central

    Kawaguchi-Suzuki, Marina; Frye, Reginald F.; Zhu, Hao-Jie; Brinda, Bryan J.; Chavin, Kenneth D.; Bernstein, Hilary J.

    2014-01-01

    Milk thistle (Silybum marianum) extracts are widely used as a complementary and alternative treatment of various hepatic conditions and a host of other diseases/disorders. The active constituents of milk thistle supplements are believed to be the flavonolignans contained within the extracts. In vitro studies have suggested that some milk thistle components may significantly inhibit specific cytochrome P450 (P450) enzymes. However, determining the potential for clinically significant drug interactions with milk thistle products has been complicated by inconsistencies between in vitro and in vivo study results. The aim of the present study was to determine the effect of a standardized milk thistle supplement on major P450 drug-metabolizing enzymes after a 14-day exposure period. CYP1A2, CYP2C9, CYP2D6, and CYP3A4/5 activities were measured by simultaneously administering the four probe drugs, caffeine, tolbutamide, dextromethorphan, and midazolam, to nine healthy volunteers before and after exposure to a standardized milk thistle extract given thrice daily for 14 days. The three most abundant falvonolignans found in plasma, following exposure to milk thistle extracts, were silybin A, silybin B, and isosilybin B. The concentrations of these three major constituents were individually measured in study subjects as potential perpetrators. The peak concentrations and areas under the time-concentration curves of the four probe drugs were determined with the milk thistle administration. Exposure to milk thistle extract produced no significant influence on CYP1A2, CYP2C9, CYP2D6, or CYP3A4/5 activities. PMID:25028567

  19. Modulation of CYPs, P-gp, and PXR by Eschscholzia californica (California Poppy) and Its Alkaloids.

    PubMed

    Manda, Vamshi K; Ibrahim, Mohamed A; Dale, Olivia R; Kumarihamy, Mallika; Cutler, Stephen J; Khan, Ikhlas A; Walker, Larry A; Muhammad, Ilias; Khan, Shabana I

    2016-04-01

    Eschscholzia californica, a native US plant, is traditionally used as a sedative, analgesic, and anxiolytic herb. With the rapid rise in the use of herbal supplements together with over-the-counter and prescription drugs, the risk for potential herb-drug interactions is also increasing. Most of the clinically relevant pharmacokinetic drug interactions occur due to modulation of cytochrome P450 enzymes (CYPs), P-glycoprotein, and the pregnane X receptor by concomitantly used herbs. This study aimed to determine the effects of an EtOH extract, aqueous extract (tea), basic CHCl3 fractions, and isolated major alkaloids, namely protopine (1), escholtzine (2), allocryptopine (3), and californidine (4), of E. californica on the activity of cytochrome P450s, P-glycoprotein and the pregnane X receptor. The EtOH extract and fractions showed strong time-dependent inhibition of CYP 3A4, CYP 2C9, and CYP 2C19, and reversible inhibition of CYP 2D6. Among the alkaloids, escholtzine (2) and allocryptopine (3) exhibited time-dependent inhibition of CYP 3A4, CYP 2C9, and CYP 2C19 (IC50 shift ratio > 2), while protopine (1) and allocryptopine (3) showed reversible inhibition of CYP 2D6 enzyme. A significant activation of the pregnane X receptor (> 2-fold) was observed with the EtOH extract, basic CHCl3 fraction, and alkaloids (except protopine), which resulted into an increased expression of mRNA and the activity of CYP 3A4 and CYP 1A2. The expression of P-glycoprotein was unaffected. However, aqueous extract (tea) and its main alkaloid californidine (4) did not affect cytochrome P450s, P-glycoprotein, or the pregnane X receptor. This data suggests that EtOH extract of E. californica and its major alkaloids have a potential of causing interactions with drugs that are metabolized by cytochrome P450s, while the tea seems to be safer. PMID:27054913

  20. Assessment of the stereoselective metabolism of methaqualone in man by capillary electrophoresis.

    PubMed

    Prost, Francine; Thormann, Wolfgang

    2003-08-01

    Methaqualone (MQ) and its hydroxylated metabolites are quinazoline derivatives that exhibit atropisomerism. As a continuation of our previous work with these compounds (Electrophoresis 2001, 22, 3270-3280), chiral capillary zone electrophoresis with hydroxypropyl-beta-cyclodextrin as buffer additive and multiwavelength absorbance detection is shown to be an effective tool to provide insight into the stereoselectivity of the MQ metabolism. The five major monohydroxy MQ metabolites formed during biotransformation do not show enantiomerization at temperatures up to 85 degrees C. Enzymatic and acidic hydrolysis of urines that were collected after concomitant administration of 250 mg of MQ and 25 mg diphenhydramine (DH) chloride are both shown to provide stereoselective metabolic patterns with 4'-hydroxymethaqualone, the major urinary metabolite, being excreted almost exclusively as a single enantiomer. A stereoselectivity in the formation of 2'-hydroxymethaqualone and 2-hydroxymethaqualone was also observed in vitro using human liver microsomes and preparations containing the cytochrome P450 enzyme (CYP) CYP3A4 only. The presence of DH during incubation with human liver microsomes did not reveal a difference in the metabolic pattern obtained. Furthermore, CYP2D6 and CYP2C19 do not significantly contribute to the metabolism of MQ. This was independently observed in vitro and via analysis of urines of individuals that are either efficient metabolizer phenotypes or poor metabolizer phenotypes for the two polymorphic enzymes. Although interindividual differences in the monitored metabolic patterns were noted, no marked difference could be related to a CYP2D6 or CYP2C19 polymorphism. PMID:12900872

  1. Methadone dose in heroin-dependent patients: role of clinical factors, comedications, genetic polymorphisms and enzyme activity

    PubMed Central

    Mouly, Stéphane; Bloch, Vanessa; Peoc'h, Katell; Houze, Pascal; Labat, Laurence; Ksouda, Kamilia; Simoneau, Guy; Declèves, Xavier; Bergmann, Jean Francois; Scherrmann, Jean-Michel; Laplanche, Jean-Louis; Lepine, Jean-Pierre; Vorspan, Florence

    2015-01-01

    Aims Methadone is characterized by wide intersubject variability regarding the dose needed to obtain full therapeutic response. We assessed the influence of sociodemographic, ethnic, clinical, metabolic and genotypic variables on methadone maintenance dose requirement in opioid-dependent responder patients. Methods Eighty-one stable patients (60 men and 21 women, 43.7 ± 8.1 years old, 63.1 ± 50.9 mg day−1 methadone), divided into quartiles with respect to the median daily dose, were enrolled and underwent clinical examination, treatment history and determination of liver/intestinal cytochrome P450 (CYP) 3A4 activity measured by the midazolam test, R,S-methadone trough concentration and clinically significant polymorphisms of the OPRM1, DRD2, COMT, ABCB1, CYP2B6, CYP3A5, CYP2C19 and CYP2D6 genes. Results Methadone maintenance dose was correlated to the highest dose ever used (r2 = 0.57, P < 0.0001). Fractioned methadone intake (odds ratio 4.87, 95% confidence interval 1.27–18.6, P = 0.02), bodyweight (odds ratio 1.57, 95% confidence interval 1.01–2.44, P = 0.04), history of cocaine dependence (80 vs. 44 mg day−1 in never-addict patients, P = 0.005) and ethnicity (Asian > Caucasian > African, P = 0.04) were independently associated with high-dose methadone in multiple regression analysis. A modest correlation was observed between liver/intestinal CYP3A4 activity and methadone dose at steady state (Spearman rank correlation coefficient [rs] = 0.21, P = 0.06) but not with highest dose ever used (rs = 0.15, P = 0.18) or dose-normalized R,S-methadone trough concentrations (rs = −0.05, P = 0.64). Concomitant CYP3A4 inhibitors only affected the relationship between methadone dose and R,S-methadone trough concentration. None of the genetic polymorphisms explored was predictive of the methadone maintenance dose. Conclusions Methadone maintenance dose was predicted by sociodemographic and clinical variables rather than genetic polymorphisms or liver/intestinal CYP

  2. Pharmacogenomic diversity of tamoxifen metabolites and estrogen receptor genes in Hispanics and non-Hispanic whites with breast cancer.

    PubMed

    Rangel, Leticia B A; Taraba, Jodi L; Frei, Christopher R; Smith, Lon; Rodriguez, Gladys; Kuhn, John G

    2014-12-01

    Ethnic differences in patient genetics and breast cancer (BC) biology contribute to ethnic disparities in cancer presentation and patient outcome. We prospectively evaluated SNPs within phase I and phase II tamoxifen (TAM) metabolizing enzymes, and the estrogen receptor gene (ESR1), aiming to identify potential pharmacogenomic ethnicity patterns in an ER-positive BC cohort constituted of Hispanic and Non-Hispanic White (NHW) women in South Texas. Plasma concentrations of TAM/metabolites were measured using HPLC. CYP2C9, CYP2D6 and SULT1A1 genotypes were determined by DNA sequencing/Pyrosequencing technology. ESR1 PvuII and XbaI SNPs were genotyped using Applied Biosystems Taqman Allelic Discrimination Assay. Hispanics had higher levels of TAM, 4-hydroxytamoxifen, and endoxifen than NHWs. There was a higher prevalence of CYP2D6 EM within Hispanics than NHWs, which corresponded to higher endoxifen levels, but no differences were verified with regard to CYP2C9 and SULT1A1. We found a higher incidence of the wild type forms of the ESR1 in Hispanics than NHWs. The performance status, the disease stage at diagnosis, and the use of aromatase inhibitors might have overcome the overall favorable pharmacogenomics profile of Hispanics when compared to NHWs in relation to TAM therapy responsiveness. Our data strongly point to ethnical peculiarities related to pharmacogenomics and demographic features of TAM treated Hispanics and NHWs. In the era of pharmacogenomics and its ultimate goal of individualized, efficacious and safe therapy, cancer studies focused on the Hispanic population are warranted because this is the fastest growing major demographic group, and an understudied segment in the U.S. PMID:25395315

  3. Pharmacogenomic diversity of tamoxifen metabolites and estrogen receptor genes in Hispanics and non-Hispanic whites with breast cancer

    PubMed Central

    Rangel, Leticia B. A.; Taraba, Jodi L.; Frei, Christopher R.; Smith, Lon; Rodriguez, Gladys

    2015-01-01

    Ethnic differences in patient genetics and breast cancer (BC) biology contribute to ethnic disparities in cancer presentation and patient outcome. We prospectively evaluated SNPs within phase I and phase II tamoxifen (TAM) metabolizing enzymes, and the estrogen receptor gene (ESR1), aiming to identify potential pharmacogenomic ethnicity patterns in an ER-positive BC cohort constituted of Hispanic and Non-Hispanic White (NHW) women in South Texas. Plasma concentrations of TAM/metabolites were measured using HPLC. CYP2C9, CYP2D6 and SULT1A1 genotypes were determined by DNA sequencing/Pyrosequencing technology. ESR1 PvuII and XbaI SNPs were genotyped using Applied Biosystems Taqman® Allelic Discrimination Assay. Hispanics had higher levels of TAM, 4-hydroxytamoxifen, and endoxifen than NHWs. There was a higher prevalence of CYP2D6 EM within Hispanics than NHWs, which corresponded to higher endoxifen levels, but no differences were verified with regard to CYP2C9 and SULT1A1. We found a higher incidence of the wild type forms of the ESR1 in Hispanics than NHWs. The performance status, the disease stage at diagnosis, and the use of aromatase inhibitors might have overcome the overall favorable pharmacogenomics profile of Hispanics when compared to NHWs in relation to TAM therapy responsiveness. Our data strongly point to ethnical peculiarities related to pharmacogenomics and demographic features of TAM treated Hispanics and NHWs. In the era of pharmacogenomics and its ultimate goal of individualized, efficacious and safe therapy, cancer studies focused on the Hispanic population are warranted because this is the fastest growing major demographic group, and an understudied segment in the U.S. PMID:25395315

  4. Simultaneous interstitial pneumonitis and cardiomyopathy induced by venlafaxine* **

    PubMed Central

    Ferreira, Pedro Gonçalo; Costa, Susana; Dias, Nuno; Ferreira, António Jorge; Franco, Fátima

    2014-01-01

    Venlafaxine is a serotonin-norepinephrine reuptake inhibitor used as an antidepressant. Interindividual variability and herb-drug interactions can lead to drug-induced toxicity. We report the case of a 35-year-old female patient diagnosed with synchronous pneumonitis and acute cardiomyopathy attributed to venlafaxine. The patient sought medical attention due to dyspnea and dry cough that started three months after initiating treatment with venlafaxine for depression. The patient was concomitantly taking Centella asiatica and Fucus vesiculosus as phytotherapeutic agents. Chest CT angiography and chest X-ray revealed parenchymal lung disease (diffuse micronodules and focal ground-glass opacities) and simultaneous dilated cardiomyopathy. Ecocardiography revealed a left ventricular ejection fraction (LVEF) of 21%. A thorough investigation was carried out, including BAL, imaging studies, autoimmune testing, right heart catheterization, and myocardial biopsy. After excluding other etiologies and applying the Naranjo Adverse Drug Reaction Probability Scale, a diagnosis of synchronous pneumonitis/cardiomyopathy associated with venlafaxine was assumed. The herbal supplements taken by the patient have a known potential to inhibit cytochrome P450 enzyme complex, which is responsible for the metabolization of venlafaxine. After venlafaxine discontinuation, there was rapid improvement, with regression of the radiological abnormalities and normalization of the LVEF. This was an important case of drug-induced cardiopulmonary toxicity. The circumstantial intake of inhibitors of the CYP2D6 isoenzyme and the presence of a CYP2D6 slow metabolism phenotype might have resulted in the toxic accumulation of venlafaxine and the subsequent clinical manifestations. Here, we also discuss why macrophage-dominant phospholipidosis was the most likely mechanism of toxicity in this case. PMID:25029655

  5. Short-term fasting alters cytochrome P450-mediated drug metabolism in humans.

    PubMed

    Lammers, Laureen A; Achterbergh, Roos; de Vries, Emmely M; van Nierop, F Samuel; Klümpen, Heinz-Josef; Soeters, Maarten R; Boelen, Anita; Romijn, Johannes A; Mathôt, Ron A A

    2015-06-01

    Experimental studies indicate that short-term fasting alters drug metabolism. However, the effects of short-term fasting on drug metabolism in humans need further investigation. Therefore, the aim of this study was to evaluate the effects of short-term fasting (36 h) on P450-mediated drug metabolism. In a randomized crossover study design, nine healthy subjects ingested a cocktail consisting of five P450-specific probe drugs [caffeine (CYP1A2), S-warfarin (CYP2C9), omeprazole (CYP2C19), metoprolol (CYP2D6), and midazolam (CYP3A4)] on two occasions (control study after an overnight fast and after 36 h of fasting). Blood samples were drawn for pharmacokinetic analysis using nonlinear mixed effects modeling. In addition, we studied in Wistar rats the effects of short-term fasting on hepatic mRNA expression of P450 isoforms corresponding with the five studied P450 enzymes in humans. In the healthy subjects, short-term fasting increased oral caffeine clearance by 20% (P = 0.03) and decreased oral S-warfarin clearance by 25% (P < 0.001). In rats, short-term fasting increased mRNA expression of the orthologs of human CYP1A2, CYP2C19, CYP2D6, and CYP3A4 (P < 0.05), and decreased the mRNA expression of the ortholog of CYP2C9 (P < 0.001) compared with the postabsorptive state. These results demonstrate that short-term fasting alters cytochrome P450-mediated drug metabolism in a nonuniform pattern. Therefore, short-term fasting is another factor affecting cytochrome P450-mediated drug metabolism in humans. PMID:25795462

  6. Evaluation of inhibitory effects of caffeic acid and quercetin on human liver cytochrome p450 activities.

    PubMed

    Rastogi, Himanshu; Jana, Snehasis

    2014-12-01

    When herbal drugs and conventional allopathic drugs are used together, they can interact in our body which can lead to the potential for herb-drug interactions. This work was conducted to evaluate the herb-drug interaction potential of caffeic acid and quercetin mediated by cytochrome P450 (CYP) inhibition. Human liver microsomes (HLMs) were added to each selective probe substrates of cytochrome P450 enzymes with or without of caffeic acid and quercetin. IC50 , Ki values, and the types of inhibition were determined. Both caffeic acid and quercetin were potent competitive inhibitors of CYP1A2 (Ki = 1.16 and 0.93 μM, respectively) and CYP2C9 (Ki = 0.95 and 1.67 μM, respectively). Caffeic acid was a potent competitive inhibitor of CYP2D6 (Ki = 1.10 μM) and a weak inhibitor of CYP2C19 and CYP3A4 (IC50  > 100 μM). Quercetin was a potent competitive inhibitor of CYP 2C19 and CYP3A4 (Ki = 1.74 and 4.12 μM, respectively) and a moderate competitive inhibitor of CYP2D6 (Ki = 18.72 μM). These findings might be helpful for safe and effective use of polyphenols in clinical practice. Our data indicated that it is necessary to study the in vivo interactions between drugs and pharmaceuticals with dietary polyphenols. PMID:25196644

  7. Prediction of Cytochrome P450 Profiles of Environmental Chemicals with QSAR Models Built from Drug-like Molecules

    PubMed Central

    Sun, Hongmao; Veith, Henrike; Xia, Menghang; Austin, Christopher P.; Tice, Raymond R.; Huang, Ruili

    2012-01-01

    The human cytochrome P450 (CYP) enzyme family is involved in the biotransformation of many xenobiotics. As part of the U.S. Tox21 Phase I effort, we profiled the CYP activity of approximately three thousand compounds, primarily those of environmental concern, against human CYP1A2, CYP2C19, CYP2C9, CYP2D6, and CYP3A4 isoforms in a quantitative high throughput screening (qHTS) format. In order to evaluate the extent to which computational models built from a drug-like library screened in these five CYP assays under the same conditions can accurately predict the outcome of an environmental compound library, five support vector machines (SVM) models built from over 17,000 drug-like compounds were challenged to predict the CYP activities of the Tox21 compound collection. Although a large fraction of the test compounds fall outside of the applicability domain (AD) of the models, as measured by k-nearest neighbor (k-NN) similarities, the predictions were largely accurate for CYP1A2, CYP2C9, and CYP3A4 ioszymes with area under the receiver operator characteristic curves (AUC-ROC) ranging between 0.82 and 0.84. The lower predictive power of the CYP2C19 model (AUC-ROC = 0.76) is caused by experimental errors and that of the CYP2D6 model (AUC-ROC = 0.76) can be rescued by rebalancing the training data. Our results demonstrate that decomposing molecules into atom types enhanced the coverage of the AD and that computational models built from drug-like molecules can be used to predict the ability of non-drug like compounds to interact with these CYPs. PMID:23459712

  8. In vitro oxidative metabolism of cajaninstilbene Acid by human liver microsomes and hepatocytes: involvement of cytochrome p450 reaction phenotyping, inhibition, and induction studies.

    PubMed

    Hua, Xin; Peng, Xiao; Tan, Shengnan; Li, Chunying; Wang, Wei; Luo, Meng; Fu, Yujie; Zu, Yuangang; Smyth, Hugh

    2014-10-29

    Cajaninstilbene acid (CSA, 3-hydroxy-4-prenyl-5-methoxystilbene-2-carboxylic acid), an active constituent of pigeonpea leaves, an important tropical crop, is known for its clinical effects in the treatment of diabetes, hepatitis, and measles and its potential antitumor effect. In this study, the effect of the cytochrome P450 isozymes on the activity of CSA was investigated. Two hydroxylation metabolites were identified in the study. The reaction phenotype study showed that CYP3A4, CYP2C9, and CYP1A2 were the major cytochrome P450 isozymes in the metabolism of CSA. The metabolic food-drug interaction potential was also evaluated in vitro. The effect of CSA inhibition/induction of enzymatic activities of seven drug-metabolizing CYP450 isozymes in vitro was estimated by high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry analytical techniques. CSA showed different inhibitory effects on different isozymes. CSA reversibly inhibited CYP3A4 and CYP2C9 activities in human liver microsomes with IC50 values of 28.3 and 31.3 μM, respectively, but exhibited no inhibition activities to CYP1A2, CYP2A6, CYP2C19, CYP2D6, and CYP2E1. CSA showed a weak effect on CYP450 enzymes in a time-dependent manner. CSA did not substantially induce CYP1A2, CYP2A6, CYP2B6, CYP2E1, CYP2C9, CYP2C19, CYP2D6, or CYP3A4 at concentrations up to 30 μM in primary human hepatocytes. The results of our experiments may be helpful to predict clinically significant food-drug interactions when other drugs are administered in combination with CSA. PMID:25272989

  9. Gene polymorphisms and contents of cytochrome P450s have only limited effects on metabolic activities in human liver microsomes.

    PubMed

    Gao, Na; Tian, Xin; Fang, Yan; Zhou, Jun; Zhang, Haifeng; Wen, Qiang; Jia, Linjing; Gao, Jie; Sun, Bao; Wei, Jingyao; Zhang, Yunfei; Cui, Mingzhu; Qiao, Hailing

    2016-09-20

    Extensive inter-individual variations in pharmacokinetics are considered as a major reason for unpredictable drug responses. As the most important drug metabolic enzymes, inter-individual variations of cytochrome P450 (CYP) activities are not clear in human liver. In this paper, metabolic activities, gene polymorphisms and protein contents of 10 CYPs were determined in 105 human normal liver microsomes. The results indicated substantial inter-individual variations in CYP activities, with the greatest being CYP2C19 activity (>600-fold). Only half of 10 CYP isoforms and 26 gene polymorphism sites had limited effects on metabolic activities, such as CYP2A6, CYP2B6, CYP2C9, CYP2D6 and CYP3A4/5, others had almost no effects. Compared with their respective wild type, Km, Vmax, and CLint decreased by 51.6%, 88.7% and 70.7% in CYP2A6*1/*4 genotype, Vmax and CLint decreased by 32.8% and 60.2% in CYP2C9*1/*3 genotype, Km increased by 118.4% and CLint decreased by 65.2% in CYP2D6 100TT genotype, respectively. Moreover, there were only 4 CYP isoforms, CYP1A2, CYP2A6, CYP2E1 and CYP3A5, which had moderate or weak correlations between Vmax values and corresponding contents. In conclusions, the genotypes and contents of some CYPs have only limited effects on metabolic activities, which imply that there are other more important factors to influence inter-individual variations. PMID:27339126

  10. Evidence for polymorphism in the cytochrome P450 2D50 gene in horses.

    PubMed

    Corado, C R; McKemie, D S; Young, A; Knych, H K

    2016-06-01

    Metabolism is an essential factor in the clearance of many drugs and as such plays a major role in the establishment of dosage regimens and withdrawal times. CYP2D6, the human orthologue to equine CYP2D50, is a drug-metabolizing enzyme that is highly polymorphic in humans leading to widely differing levels of metabolic activity. As CYP2D6 is highly polymorphic, in this study it was hypothesized that the gene coding for the equine orthologue, CYP2D50, may also be prone to polymorphism. Blood samples were collected from 150 horses, the CYP2D50 gene was cloned and sequenced; and full-length sequences were analyzed for single nucleotide polymorphisms (SNPs), deletions, or insertions. Pharmacokinetic data were collected from a subset of horses following the administration of a single oral dose of tramadol and probit analysis used to calculate metabolic ratios. Prior to drug administration, the ability of recombinant CYP2D50 to metabolize tramadol to O-desmethyltramadol was confirmed. Sequencing of CYP2D50 identified 126 exonic SNPs, with 31 of those appearing in multiple horses. Oral administration of tramadol to a subset of these horses revealed variable metabolic ratios (tramadol: O-desmethyltramadol) in individual horses and separation into three metabolic groups. While a limited number of horses of primarily a single breed were studied, the variability in tramadol metabolism to O-desmethyltramadol between horses and preliminary evidence of what appears to be poor, extensive, and ultra-rapid metabolizers supports further study of the potential for genetic polymorphisms in the CYP2D50 gene in horses. PMID:26441153

  11. Successful use of agomelatine in the treatment of major depression in a woman taking tamoxifen: a case report.

    PubMed

    De Berardis, Domenico; Brucchi, Maurizio; Serroni, Nicola; Valchera, Alessandro; Fornaro, Michele; Mazza, Monica; Martinotti, Giovanni; Di Giannantonio, Massimo

    2014-01-01

    The selective estrogen receptor modulator, tamoxifen, is extensively used for the endocrine treatment of all stages of hormone receptor-positive breast cancer. Tamoxifen is a mainly inactive prodrug, necessitating metabolism by the cytochrome P450 (CYP450) pathway, predominantly the Cytochrome P450 2D6 (CYP2D6), into the active metabolites 4-hydroxytamoxifen and, in particular, endoxifen to achieve its therapeutic effect. As several women treated with tamoxifen may experience depressive symptoms or may have a previous or actual major depressive episode with ongoing antidepressant treatment or need for a new-onset therapy, the coprescription of an antidepressant drug may be particularly problematic as several antidepressants are potent CYP2D6-inhibiting drugs. We herein report a case of a patient with major depression and concurrent tamoxifen therapy successfully treated with agomelatine monotherapy. PMID:24434530

  12. Characterization of Atomoxetine Biotransformation and Implications for Development of PBPK Models for Dose Individualization in Children.

    PubMed

    Dinh, Jean C; Pearce, Robin E; Van Haandel, Leon; Gaedigk, Andrea; Leeder, J Steven

    2016-07-01

    Atomoxetine (ATX) is a second-line nonstimulant medication used to control symptoms of attention deficit hyperactivity disorder (ADHD). Inconsistent therapeutic efficacy has been reported with ATX, which may be related to variable CYP2D6-mediated drug clearance. We characterized ATX metabolism in a panel of human liver samples as a basis for a bottom-up PBPK model to aid in ATX exposure prediction and control. Km, Vmax, and Clint values in pooled human liver microsomes (HLMs) were 2.4 µM, 479 pmol/min/mg protein, and 202 µl/min/mg protein, respectively. Mean population values of kinetic parameters are not adequate to describe variability in a population, given that Km, Vmax, and Clint values from single-donor HLMs ranged from 0.93 to 79.2 µM, 20.0 to 1600 pmol/min/mg protein, and 0.3 to 936 µl/min/mg protein. All kinetic parameters were calculated from 4-hydroxyatomoxetine (4-OH-ATX) formation. CYP2E1 and CYP3A contributed to 4-OH-ATX formation in livers with CYP2D6 intermediate and poor metabolizer status. In HLMs with lower CYP2D6 activity levels, 2-hydroxymethylatomoxetine (2-CH2OH-ATX) formation became a more predominant pathway of metabolism, which appeared to be catalyzed by CYP2B6. ATX biotransformation at clinically relevant plasma concentrations was characterized in a panel of pediatric HLM (n = 116) samples by evaluating primary metabolites. Competing pathways of ATX metabolism [N-desmethylatomoxetine (NDM-ATX) and 2-CH2OH-ATX formation] had increasing importance in livers with lesser CYP2D6 activity, but, overall ATX clearance was still compromised. Modeling ATX exposure to individualize therapy would require comprehensive knowledge of factors that affect CYP2D6 activity as well as an understanding of competing pathways, particularly for individuals with lower CYP2D6 activity. PMID:27052878

  13. CYP3A4 Mediates Oxidative Metabolism of the Synthetic Cannabinoid AKB-48.

    PubMed

    Holm, Niels Bjerre; Nielsen, Line Marie; Linnet, Kristian

    2015-09-01

    Synthetic cannabinoid designer drugs have emerged as drugs of abuse during the last decade, and acute intoxication cases are documented in the scientific literature. Synthetic cannabinoids are extensively metabolized, but our knowledge of the involved enzymes is limited. Here, we investigated the metabolism of N-(1-adamantyl)-1-pentyl-1H-indazole-3-carboxamide (AKB-48), a compound identified in herbal blends from 2012 and onwards. We screened for metabolite formation using a panel of nine recombinant cytochrome P450 (CYP) enzymes (CYP1A2, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, and 3A4) and compared the formed metabolites to human liver microsomal (HLM) incubations with specific inhibitors against CYP2D6, 2C19, and 3A4, respectively. The data reported here demonstrate CYP3A4 to be the major CYP enzyme responsible for the oxidative metabolism of AKB-48, preferentially performing the oxidation on the adamantyl moiety. Genetic polymorphisms are likely not important with regard to toxicity given the major involvement of CYP3A4. Adverse drug-drug interactions (DDIs) could potentially occur in cases with co-intake of strong CYP3A4 inhibitors, e.g., HIV antivirals and azole antifungal agents. PMID:26002511

  14. Evaluation of human hepatocytes cultured by three-dimensional spheroid systems for drug metabolism.

    PubMed

    Ohkura, Takako; Ohta, Kunihiro; Nagao, Takuya; Kusumoto, Kumiko; Koeda, Akiko; Ueda, Tadayoshi; Jomura, Tomoko; Ikeya, Takeshi; Ozeki, Emiko; Wada, Kazuki; Naitoh, Kazushi; Inoue, Yukiko; Takahashi, Naoki; Iwai, Hisakazu; Arakawa, Hiroshi; Ogihara, Takuo

    2014-01-01

    We investigated the utility of three-dimensional (3D) spheroid cultures of human hepatocytes in discovering drug metabolites. Metabolites of acetaminophen, diclofenac, lamotrigine, midazolam, propranolol and salbutamol were analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS) to measure enzyme activities in this system cultured for 2 and 7 days. Sequential metabolic reactions by Phase I and then Phase II enzymes were found in diclofenac [CYP2C9 and UDP-glucuronyltransferases (UGTs)], midazolam (CYP3A4 and UGTs) and propranolol (CYP1A2/2D6 and UGTs). Moreover, lamotrigine and salbutamol were metabolized to lamotrigine-N-glucuronide and salbutamol 4-O-sulfate, respectively. These metabolites, which are human specific, could be observed in clinical studies, but not in conventional hepatic culture systems as in previous reports. Acetaminophen was metabolized to glucuronide and sulfate conjugates, and N-acetyl-p-benzo-quinoneimine (NAPQI) and its metabolites were not observed. In addition, mRNA of drug-metabolism enzymes [CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, UGT1A1, UGT2B7, sulfotransferase 1A1 (SULT1A1) and glutathione S-transferase pi 1 (GSTP1)], which were measured by qRT-PCR, were expressed in the human hepatocyte spheroids. In conclusion, these results suggest that human hepatocyte spheroids are useful in discovering drug metabolites. PMID:24695277

  15. Effects of gestational and overt diabetes on placental cytochromes P450 and glutathione S-transferase.

    PubMed

    Glover; McRobie; Tracy

    1998-07-01

    Objective: Animal and in vivo human studies have observed that diabetes alters the expression of hepatic metabolizing cytochrome P450 (CYP) and glutathione S-transferase (GST) enzymes. The placenta has the ability to metabolize a number of xenobiotic and endogenous compounds by processes similar to those seen in the liver. Our objective was to compare placental xenobiotic metabolizing activity in diabetics to matched non-diabetic controls to determine if the presence of diabetes alters placental xenobiotic metabolizing activity.Methods: The catalytic activities of 7-ethoxyresorufin-O-deethylation [EROD] (CYP1A1), chlorzoxazone 6-hydroxylation (CYP2E1), dextromethorphan N-demethylation (CYP3A4), dextromethorphan O-demethylation (CYP2D6), and 1-chloro-2,4-dinitrobenzene (CDNB) conjugation with glutathione (GST) from placentas of diet controlled (class A1) and insulin-dependent (class A2) gestational diabetics and overt diabetics were compared to matched controls.Results: No differences in EROD activity were observed among overt or gestational diabetics and their respectively matched controls. CYP2E1, 2D6, and 3A4 enzyme activity were not detected in human placentas. In contrast, GST activity was significantly reduced by 30% (P <.05) in overt diabetics as compared to their matched controls and gestational diabetics.Conclusion: Pregnant women with overt diabetes have reduced GST activity in the placenta, which could potentially result in exposure of the fetus to harmful reactive electrophilic metabolites. PMID:10838356

  16. Prolonged Drug-Drug Interaction between Terbinafine and Perphenazine.

    PubMed

    Park, Young-Min

    2012-12-01

    I report here an elderly woman receiving perphenazine together with terbinafine. After 1 week of terbinafine treatment she experienced extrapyramidal symptoms and, in particular, akathisia. Her symptoms did not disappear for 6 weeks, and so at 2 weeks prior to this most recent admission she had stopped taking terbinafine. However, these symptoms persisted for 3 weeks after discontinuing terbinafine. It is well known that terbinafine inhibits CYP2D6 and that perphenazine is metabolized mainly by CYP2D6. Thus, when terbinafine and perphenazine are coadministrated, the subsequent increase in the concentration of perphenazine may induce extrapyramidal symptoms. Thus, terbinafine therapy may be associated with the induction and persistence of extrapyramidal symptoms, including akathisia. This case report emphasizes the importance of monitoring drug-drug interactions in patients undergoing terbinafine and perphenazine therapy. PMID:23251210

  17. Prolonged Drug-Drug Interaction between Terbinafine and Perphenazine

    PubMed Central

    2012-01-01

    I report here an elderly woman receiving perphenazine together with terbinafine. After 1 week of terbinafine treatment she experienced extrapyramidal symptoms and, in particular, akathisia. Her symptoms did not disappear for 6 weeks, and so at 2 weeks prior to this most recent admission she had stopped taking terbinafine. However, these symptoms persisted for 3 weeks after discontinuing terbinafine. It is well known that terbinafine inhibits CYP2D6 and that perphenazine is metabolized mainly by CYP2D6. Thus, when terbinafine and perphenazine are coadministrated, the subsequent increase in the concentration of perphenazine may induce extrapyramidal symptoms. Thus, terbinafine therapy may be associated with the induction and persistence of extrapyramidal symptoms, including akathisia. This case report emphasizes the importance of monitoring drug-drug interactions in patients undergoing terbinafine and perphenazine therapy. PMID:23251210

  18. CYP isoform specificity toward drug metabolism: analysis using common feature hypothesis.

    PubMed

    Ramesh, M; Bharatam, Prasad V

    2012-02-01

    Three dimensional pharmacophoric maps were generated for each isoforms of CYP2C9, CYP2D6 and CYP3A4 separately using independent training sets consist of highly potent substrates (seven substrates for each isoform). HipHop module of CATALYST software was used in the generation of pharmacophore models. The best pharmacophore model was chosen out of the several models on the basis of (i) highest ranking score, (ii) better fit value among training set, (iii) capability to screen substrates from data set and (iv) efficiency to identify the isoform specificity. The individual pharmacophore models (CYP2C9-hypo1, CYP2D6-hypo1 and CYP3A4-hypo1) are characterized by the pharmacophoric features XZDH, RPZH and XYZHH for the CYP2C9, CYP2D6 and CYP3A4 respectively. Each of the chosen models was validated by using data sets of CYP substrates. This comparative study of CYP substrates demonstrates the importance of acidic character along with HBD and HBAl features for CYP2C9, basic character with ring aromatic features for CYP2D6 and hydrophobic features for CYP3A4. Acidity, basicity and hydrophobicity features arising from the functional groups of the substrates are also responsible for demonstrating CYP isoform specificity. Hence, these chemical features are incorporated in the decision tree along with pharmacophore maps. Finally, a decision tree based on chemical features and pharmacophore features was generated to identify the isoform specificity of novel query molecule toward the three isoforms. PMID:21562823

  19. Polymorphism in the metabolism of drugs, including antidepressant drugs: comments on phenotyping.

    PubMed Central

    Coutts, R T

    1994-01-01

    In neurochemistry there are advantages in determining how patients are likely to react to psychoactive drugs prior to the commencement of drug therapy. Explanations of a patient's nonresponse, or unexpected adverse reactions to drugs are required. In many instances, a knowledge of the drug metabolism status of a patient can be helpful in the selection of a drug and its dosage regimen, and in the prediction of possible drug/drug interactions when two or more drugs have to be administered concomitantly. Important information on these topics may be obtained by phenotyping patients prior to drug therapy. The metabolism of various antidepressant and neuroleptic drugs is catalyzed by CYP2D6, a cytochrome P450 isozyme (also named P450IID6), whereas the metabolism of other drugs may involve different cytochromes P450. The properties of CYP2D6 and four other isozymes (CYP1A1, CYP1A2, CYP2C8/9 and CYP3A4) are described, and substrates identified. Phenotyping of patients for CYP2D6 activity and mephenytoin hydroxylase activity is described. PMID:8148364

  20. Profound metoprolol-induced bradycardia precipitated by acetaminophen-propoxyphene.

    PubMed

    Marraffa, Jeanna M; Lang, Li; Ong, Gilbert; Lehmann, David F

    2006-03-01

    Pharmacokinetic studies demonstrate that propoxyphene is a potent inhibitor of cytochrome P450 (CYP) 2D6. Clinically significant sequelae have not been previously reported. We report a case of this inhibition manifested by life-threatening bradycardia in a patient receiving a CYP2D6 substrate, metoprolol. A 48-year-old man came to the emergency department complaining of dizziness 3 hours after ingesting metoprolol, at his usual dose, and 2 tablets of propoxyphene, newly begun postoperatively. Four hours after ingestion of both drugs, the patient was noted to have a ventricular rate of about 30 beats/min with underlying atrial fibrillation. The patient's ventricular response returned to normal within 11 hours of ingestion. We have demonstrated the clinical importance of the interaction between propoxyphene and metoprolol likely resulting from inhibition of hepatic clearance of metoprolol by propoxyphene. Underscoring the clinical relevance of CYP2D6 inhibition by an analgesic of questionable efficacy should proscribe its use. PMID:16513452

  1. Contribution of human hepatic cytochrome p450 isoforms to the metabolism of psychotropic drugs.

    PubMed

    Niwa, Toshiro; Shiraga, Toshifumi; Ishii, Ikuko; Kagayama, Akira; Takagi, Akira

    2005-09-01

    The metabolic activities of six psychotropic drugs, diazepam, clotiazepam, tofisopam, etizolam, tandospirone, and imipramine, were determined for 14 isoforms of recombinant human hepatic cytochrome P450s (CYPs) and human liver microsomes by measuring the disappearance rate of parent compounds. In vitro kinetic studies revealed that Vmax/Km values in human liver microsomes were the highest for tofisopam, followed by tandospirone>clotiazepam>imipramine, diazepam, and etizolam. Among the recombinant CYPs, CYP3A4 exhibited the highest metabolic activities of all compounds except for clotiazepam and imipramine. The metabolism of clotiazepam was catalyzed by CYP2B6, CYP3A4, CYP2C18, and CYP2C19, and imipramine was metabolized by CYP2D6 most efficiently. In addition, the metabolic activities of diazepam, clotiazepam, and etizolam in human liver microsomes were inhibited by 2.5 microM ketoconazole, a CYP3A4 inhibitor, by 97.5%, 65.1%, and 83.5%, respectively, and the imipramine metabolism was not detected after the addition of 1 or 10 microM quinidine, a CYP2D6 inhibitor. These results suggest that the psychotropic drugs investigated are metabolized predominantly by CYP3A4, except that CYP2D6 catalyzes the metabolism of imipramine. In addition, this approach based on the disappearance rate appears to be useful for the identification of the responsible CYP isoform(s) of older drugs, for which metabolic profiles have not been reported. PMID:16141545

  2. Pharmacogenomic considerations in opioid analgesia

    PubMed Central

    Vuilleumier, Pascal H; Stamer, Ulrike M; Landau, Ruth

    2012-01-01

    Translating pharmacogenetics to clinical practice has been particularly challenging in the context of pain, due to the complexity of this multifaceted phenotype and the overall subjective nature of pain perception and response to analgesia. Overall, numerous genes involved with the pharmacokinetics and dynamics of opioids response are candidate genes in the context of opioid analgesia. The clinical relevance of CYP2D6 genotyping to predict analgesic outcomes is still relatively unknown; the two extremes in CYP2D6 genotype (ultrarapid and poor metabolism) seem to predict pain response and/or adverse effects. Overall, the level of evidence linking genetic variability (CYP2D6 and CYP3A4) to oxycodone response and phenotype (altered biotransformation of oxycodone into oxymorphone and overall clearance of oxycodone and oxymorphone) is strong; however, there has been no randomized clinical trial on the benefits of genetic testing prior to oxycodone therapy. On the other hand, predicting the analgesic response to morphine based on pharmacogenetic testing is more complex; though there was hope that simple genetic testing would allow tailoring morphine doses to provide optimal analgesia, this is unlikely to occur. A variety of polymorphisms clearly influence pain perception and behavior in response to pain. However, the response to analgesics also differs depending on the pain modality and the potential for repeated noxious stimuli, the opioid prescribed, and even its route of administration. PMID:23226064

  3. Potentiation of 5-methoxy-N,N-dimethyltryptamine-induced hyperthermia by harmaline and the involvement of activation of 5-HT1A and 5-HT2A receptors.

    PubMed

    Jiang, Xi-Ling; Shen, Hong-Wu; Yu, Ai-Ming

    2015-02-01

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and harmaline are serotonin (5-HT) analogs often abused together, which alters thermoregulation that may indicate the severity of serotonin toxicity. Our recent studies have revealed that co-administration of monoamine oxidase inhibitor harmaline leads to greater and prolonged exposure to 5-HT agonist 5-MeO-DMT that might be influenced by cytochrome P450 2D6 (CYP2D6) status. This study was to define the effects of harmaline and 5-MeO-DMT on thermoregulation in wild-type and CYP2D6-humanized (Tg-CYP2D6) mice, as well as the involvement of 5-HT receptors. Animal core body temperatures were monitored noninvasively in the home cages after implantation of telemetry transmitters and administration of drugs. Harmaline (5 and 15 mg/kg, i.p.) alone was shown to induce hypothermia that was significantly affected by CYP2D6 status. In contrast, higher doses of 5-MeO-DMT (10 and 20 mg/kg) alone caused hyperthermia. Co-administration of harmaline (2, 5 or 15 mg/kg) remarkably potentiated the hyperthermia elicited by 5-MeO-DMT (2 or 10 mg/kg), which might be influenced by CYP2D6 status at certain dose combination. Interestingly, harmaline-induced hypothermia was only attenuated by 5-HT1A receptor antagonist WAY-100635, whereas 5-MeO-DMT- and harmaline-5-MeO-DMT-induced hyperthermia could be suppressed by either WAY-100635 or 5-HT2A receptor antagonists (MDL-100907 and ketanserin). Moreover, stress-induced hyperthermia under home cage conditions was not affected by WAY-100635 but surprisingly attenuated by MDL-100907 and ketanserin. Our results indicate that co-administration of monoamine oxidase inhibitor largely potentiates 5-MeO-DMT-induced hyperthermia that involves the activation of both 5-HT1A and 5-HT2A receptors. These findings shall provide insights into development of anxiolytic drugs and new strategies to relieve the lethal hyperthermia in serotonin toxicity. PMID:25446678

  4. Potentiation of 5-methoxy-N,N-dimethyltryptamine-induced hyperthermia by harmaline and the involvement of activation of 5-HT1A and 5-HT2A receptors

    PubMed Central

    Jiang, Xi-Ling; Shen, Hong-Wu; Yu, Ai-Ming

    2014-01-01

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and harmaline are serotonin (5-HT) analogs often abused together, which alters thermoregulation that may indicate the severity of serotonin toxicity. Our recent studies have revealed that co-administration of monoamine oxidase inhibitor harmaline leads to greater and prolonged exposure to 5-HT agonist 5-MeO-DMT that might be influenced by cytochrome P450 2D6 (CYP2D6) status. This study was to define the effects of harmaline and 5-MeO-DMT on thermoregulation in wild-type and CYP2D6-humanized (Tg-CYP2D6) mice, as well as the involvement of 5-HT receptors. Animal core body temperatures were monitored noninvasively in the home cages after implantation of telemetry transmitters and administration of drugs. Harmaline (5 and 15 mg/kg, i.p.) alone was shown to induce hypothermia that was significantly affected by CYP2D6 status. In contrast, higher doses of 5-MeO-DMT (10 and 20 mg/kg) alone caused hyperthermia. Co-administration of harmaline (2, 5 or 15 mg/kg) remarkably potentiated the hyperthermia elicited by 5-MeO-DMT (2 or 10 mg/kg), which might be influenced by CYP2D6 status at certain dose combination. Interestingly, harmaline-induced hypothermia was only attenuated by 5-HT1A receptor antagonist WAY-100635, whereas 5-MeO-DMT- and harmaline-5-MeO-DMT-induced hyperthermia could be suppressed by either WAY-100635 or 5-HT2A receptor antagonists (MDL-100907 and ketanserin). Moreover, stress-induced hyperthermia under home cage conditions was not affected by WAY-100635 but surprisingly attenuated by MDL-100907 and ketanserin. Our results indicate that co-administration of monoamine oxidase inhibitor largely potentiates 5-MeO-DMT-induced hyperthermia that involves the activation of both 5-HT1A and 5-HT2A receptors. These findings shall provide insights into development of anxiolytic drugs and new strategies to relieve the lethal hyperthermia in serotonin toxicity. PMID:25446678

  5. High-Throughput and Combinatorial Gene Expression on a Chip for Metabolism-Induced Toxicology Screening

    PubMed Central

    Kwon, Seok Joon; Lee, Dong Woo; Shah, Dhiral A.; Ku, Bosung; Jeon, Sang Youl; Solanki, Kusum; Ryan, Jessica D.; Clark, Douglas S.; Dordick, Jonathan S.; Lee, Moo-Yeal

    2014-01-01

    Differential expression of various drug-metabolizing enzymes in the human liver may cause deviations of pharmacokinetic profiles, resulting in inter-individual variability of drug toxicity and/or efficacy. Here we present the “Transfected Enzyme and Metabolism Chip” (TeamChip), which predicts potential metabolism-induced drug or drug-candidate toxicity. The TeamChip is prepared by delivering genes into miniaturized three-dimensional cellular microarrays on a micropillar chip using recombinant adenoviruses in a complementary microwell chip. The device enables users to manipulate the expression of individual and multiple human metabolizing-enzyme genes (such as CYP3A4, CYP2D6, CYP2C9, CYP1A2, CYP2E1, and UGT1A4) in THLE-2 cell microarrays. To identify specific enzymes involved in drug detoxification, we created 84 combinations of metabolic-gene expressions in a combinatorial fashion on a single microarray. Thus, the TeamChip platform can provide critical information necessary for evaluating metabolism-induced toxicity in a high-throughput manner. PMID:24799042

  6. Significance of metabolism in the disposition and action of the antidysrhythmic drug, dofetilide. In vitro studies and correlation with in vivo data.

    PubMed

    Walker, D K; Alabaster, C T; Congrave, G S; Hargreaves, M B; Hyland, R; Jones, B C; Reed, L J; Smith, D A

    1996-04-01

    Dofetilide, a class III antidysrhythmic agent, undergoes both renal and metabolic clearance. Characterization of the metabolism in vitro allows explanation of species differences, whereas identification of the human enzymes involved permits assessment of potential drug interaction. In liver microsomes, the rate of oxidative metabolism of dofetilide is in the order: male rat > female rat > dog > humans, which correlates with the metabolic clearance seen in vivo. In vitro products of oxidative metabolism, formed by N-dealkylation, are the same as those formed in vivo, with the N-desmethyl being the major product. This route of dofetilide metabolism is mediated by cytochrome P450 (CYP). In humans, N-demethylation has a high KM of 657 +/- 116 microM, indicating low affinity for the enzyme's active site. In a number of human liver microsomal preparations, this rate correlated (r = 0.903) with the activity of CYP3A4. There was no correlation with the activities of other isozymes. Specific isozyme inhibitors also indicated the involvement of CYP3A4, with partial inhibition being observed with ketoconazole and troleandeomycin, whereas the activator, alpha-naphthaflavone, caused increased turnover. No inhibition was observed with specific inhibitors or competing substrates for other isozymes. Dofetilide did not significantly inhibit CYP2C9, CYP2D6, or CYP3A4 at concentrations up to 100 microM in vitro. In contrast, amiodarone (IC50, 25 microM) and flecainide (49 microM) inhibited CYP2C9 and quinidine (0.26 microM), and flecainide (0.44 microM) inhibited CYP2D6. Many antidysrhythmic drugs have active, circulating metabolites, complicating the relationship of dose and clinical response. In vitro pharmacology studies allow assessment of the potential contribution to the pharmacological profile by metabolites. Potency of dofetilide and metabolites has been compared for class III (K+ channel blockade) and class I (Na+ channel blockade) antidysrhythmic activities. Three of the

  7. Donepezil in Alzheimer’s disease: From conventional trials to pharmacogenetics

    PubMed Central

    Cacabelos, Ramón

    2007-01-01

    Donepezil is the leading compound for the treatment of Alzheimer’s disease (AD) in more than 50 countries. As compared with other conventional acetylcholinesterase inhibitors (AChEIs), donepezil is a highly selective and reversible piperidine derivative with AChEI activity that exhibits the best pharmacological profile in terms of cognitive improvement, responders rate (40%–58%), dropout cases (5%–13%), and side-effects (6%–13%) in AD. Although donepezil represents a non cost-effective treatment, most studies convey that this drug can provide a modest benefit on cognition, behavior, and activities of the daily living in both moderate and severe AD, contributing to slow down disease progression and, to a lesser exetnt, to delay institutionalization. Patients with vascular dementia might also benefit from donepezil in a similar fashion to AD patients. Some potential effects of donepezil on the AD brain, leading to reduced cortico-hippocampal atrophy, include the following: AChE inhibition, enhancement of cholinergic neurotransmission and putative modulation of other neurotransmitter systems, protection against glutamate-induced excitotoxicity, activation of neurotrophic mechanisms, promotion of non-amyloidodgenic pathways for APP processing, and indirect effects on cerebrovascular function improving brain perfusion. Recent studies demonstrate that the therapeutic response in AD is genotype-specific. Donepezil is metabolized via CYP-related enzymes, especially CYP2D6, CYP3A4, and CYP1A2. Approximately, 15%–20% of the AD population may exhibit an abnormal metabolism of AChEIs; about 50% of this population cluster would show an ultrarapid metabolism, requiring higher doses of AChEIs to reach a therapeutic threshold, whereas the other 50% of the cluster would exhibit a poor metabolism, displaying potential adverse events at low doses. In AD patients treated with a multifactorial therapy, including donepezil, the best responders are the CYP2D6-related extensive

  8. Clinical validity: Combinatorial pharmacogenomics predicts antidepressant responses and healthcare utilizations better than single gene phenotypes.

    PubMed

    Altar, C A; Carhart, J M; Allen, J D; Hall-Flavin, D K; Dechairo, B M; Winner, J G

    2015-10-01

    In four previous studies, a combinatorial multigene pharmacogenomic test (GeneSight) predicted those patients whose antidepressant treatment for major depressive disorder resulted in poorer efficacy and increased health-care resource utilizations. Here, we extended the analysis of clinical validity to the combined data from these studies. We also compared the outcome predictions of the combinatorial use of allelic variations in genes for four cytochrome P450 (CYP) enzymes (CYP2D6, CYP2C19, CYP2C9 and CYP1A2), the serotonin transporter (SLC6A4) and serotonin 2A receptor (HTR2A) with the outcome predictions for the very same subjects using traditional, single-gene analysis. Depression scores were measured at baseline and 8-10 weeks later for the 119 fully blinded subjects who received treatment as usual (TAU) with antidepressant standard of care, without the benefit of pharmacogenomic medication guidance. For another 96 TAU subjects, health-care utilizations were recorded in a 1-year, retrospective chart review. All subjects were genotyped after the clinical study period, and phenotype subgroups were created among those who had been prescribed a GeneSight panel medication that is a substrate for either CYP enzyme or serotonin effector protein. On the basis of medications prescribed for each subject at baseline, the combinatorial pharmacogenomic (CPGx™) GeneSight method categorized each subject into either a green ('use as directed'), yellow ('use with caution') or red category ('use with increased caution and with more frequent monitoring') phenotype, whereas the single-gene method categorized the same subjects with the traditional phenotype (for example, poor, intermediate, extensive or ultrarapid CYP metabolizer). The GeneSight combinatorial categorization approach discriminated and predicted poorer outcomes for red category patients prescribed medications metabolized by CYP2D6, CYP2C19 and CYP1A2 (P=0.0034, P=0.04 and P=0.03, respectively), whereas the single

  9. Pharmacokinetic interaction profile of riociguat, a new soluble guanylate cyclase stimulator, in vitro.

    PubMed

    Rickert, Verena; Haefeli, Walter Emil; Weiss, Johanna

    2014-08-01

    Riociguat is a new soluble guanylate cyclase stimulator under development for pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. So far, the interaction potential of riociguat with other drugs is nearly unknown. Therefore, we assessed in vitro the potency of riociguat to inhibit important drug metabolising enzymes (cytochrome P450 (CYP) 3A4, CYP2C19, and CYP2D6) and drug transporters (P-glycoprotein (P-gp/ABCB1), breast cancer resistance protein (BCRP/ABCG2), and organic anion transporting polypeptides (OATP) 1B1 and 1B3). In addition we evaluated its substrate characteristics for P-gp, BCRP, and the multidrug resistance-associated protein 1 (MRP1/ABCC1). We also assessed riociguat's inducing properties on important drug metabolising enzymes and transporters and investigated its ability to activate the pregnane-X-receptor (PXR). Riociguat was identified as a weak to moderate inhibitor of P-gp (f2-value: 11.7 ± 4.8 μM), BCRP (IC50 = 46.2 ± 20.3 μM), OATP1B1 (IC50 = 34.1 ± 3.15 μM), OATP1B3 (IC50 = 50.3 ± 7.5 μM), CYP2D6 (IC50 = 12.4 ± 0.74 μM), and CYP2C19 (IC50 = 46.1 ± 7.14 μM). Furthermore, it induced mRNA expression of BCRP/ABCG2 (3-fold at 20 μM) and to a lesser extent of CYP3A4 (2.3-fold at 20 μM), UGT1A4, and ABCB11. The only weak inducing properties were confirmed by weak activation of PXR. Considering its systemic concentrations its interaction potential as a perpetrator drug seems to be low. In contrast, our data suggest that riociguat is a P-gp substrate and might therefore act as a victim drug when co-administered with strong P-gp inductors or inhibitors. PMID:24657506

  10. Enantiomers of Naringenin as Pleiotropic, Stereoselective Inhibitors of Cytochrome P450 Isoforms

    PubMed Central

    Lu, Wenjie Jessie; Ferlito, Valentina; Xu, Cong; Flockhart, David A; Caccamese, Salvatore

    2011-01-01

    Interactions between naringenin and the cytochrome P450 (CYP) system have been of interest since the first demonstration that grapefruit juice reduced CYP3A activity. The effects of naringenin on other CYP isoforms have been less investigated. In addition, it is well known that interactions with enzymes are often stereospecific, but due to the lack of readily available, chirally pure naringenin enantiomers, the enantioselectivity of its effects has not been characterized. We isolated pure naringenin enantiomers by chiral HPLC and tested the ability of (R)-, (S)-and rac-naringenin to inhibit several important drug-metabolizing CYP isoforms using recombinant enzymes and pooled human liver microsomes. Naringenin was able to inhibit CYP19, CYP2C9 and CYP2C19 with IC50 values below 5 μM. No appreciable inhibition of CYP2B6 or CYP2D6 was observed at concentrations up to 10 μM. While (S)-naringenin was 2-fold more potent as an inhibitor of CYP19 and CYP2C19 than (R)-naringenin, (R)-naringenin was 2-fold more potent for CYP2C9 and CYP3A. Chiral flavanones like naringenin are difficult to separate into their enantiomeric forms, but enantioselective effects may be observed that ultimately impact clinical effects. Inhibition of specific drug metabolizing enzymes by naringenin observed in vitro may be exploited to understand pharmacokinetic changes seen in vivo. PMID:21953762

  11. The role of CYP2C9 genetic polymorphism in carvedilol O-desmethylation in vitro.

    PubMed

    Pan, Pei-Pei; Weng, Qing-Hua; Zhou, Chen-Jian; Wei, Yan-Li; Wang, Li; Dai, Da-Peng; Cai, Jian-Ping; Hu, Guo-Xin

    2016-02-01

    We aimed at investigating the role of CYP2C9 in carvedilol O-desmethylation and identifying the effect of 35 CYP2C9 allelic variants we found in Chinese Han population on the in vitro metabolism of carvedilol. Recombinant CYP2C9 and CYP2D6 microsomes of the wild type were used to test and verify the enzymes involved in carvedilol O-desmethylation. Recombinant CYP2C9 microsomes of distinguished genotypes were used to characterize the corresponding enzyme activity toward carvedilol. 2-100 μM carvedilol was incubated for 30 min at 37 °C. The products were detected using high-performance liquid chromatography. CYP2C9 plays a certain role in carvedilol metabolism. Compared with wild-type CYP2C9*1, the intrinsic clearance (V max/K m) values of all variants toward carvedilol O-desmethylation were significantly altered. The variants exhibited significantly decreased values (from 30 to 99.8 %) due to increased K m and/or decreased V max values. We conclude that recombinant system could be used to investigate the enzymes involved in drug metabolism and these findings complement the database where CYP2C9 polymorphism interacts with biotransformation of exogenous substances like drugs and toxins. PMID:25476996

  12. Characterization of inhibitory effects of perfluorooctane sulfonate on human hepatic cytochrome P450 isoenzymes: focusing on CYP2A6.

    PubMed

    Narimatsu, Shizuo; Nakanishi, Ryoko; Hanioka, Nobumitsu; Saito, Keita; Kataoka, Hiroyuki

    2011-11-15

    Perfluorooctane sulfonate (PFOS) is a chemically stable compound extensively used as oil and water repellent, surface active agents in our daily life. Accumulative research evidence gradually appears the toxicity of PFOS against mammals, but the whole figure remains to be elucidated. The present study was conducted to know the effects of PFOS on human hepatic drug metabolizing-type cytochrome P450 (CYP) isoenzymes such as CYP1A2 (7-ethoxyresorufin as a substrate), CYP2A6 (coumarin), CYP2B6 (7-ethoxy-4-trifluoromethylcoumarin), CYP2C8 (paclitaxel), CYP2C9 (diclofenac), CYP2C19 (S-mephenytoin), CYP2D6 (bufuralol), CYP2E1 (chlorzoxazone) and CYP3A4 (testosterone) in human livers employing their typical substrates. Although all of the oxidation reactions tested were more or less inhibited by PFOS, diclofenac 4'-hydroxylation mediated mainly by CYP2C9 was most strongly inhibited (K(i) value of 40 nM), followed by paclitaxel 6α-hydroxylation mediated mainly by CYP2C8 (K(i) value of 4 μM). The substrate oxidation reactions catalyzed by CYP2A6, CYP2B6, CYP2C19 and CYP3A4 were moderately (K(i) values of 35 to 45 μM), and those by CYP1A2, CYP2D6 and CYP2E1 were weakly inhibited by PFOS (K(i) values of 190-300 μM). The inhibition by PFOS for coumarin 7-hydroxylation mainly catalyzed by human liver microsomal CYP2A6 as well as by the recombinant enzyme was found to be enhanced by the preincubation of PFOS with human liver microsomes and NADPH as compared to the case without preincubation. The inhibition of the human liver microsomal cumarin 7-hydroxylation was PFOS concentration-dependent, and exhibited pseudo-first-order kinetics with respect to preincubation time, yielding K(inact) and K(I) values of 0.06 min(-1) and 23 μM, respectively. These results suggest that the metabolism of medicines which are substrates for CYP2C9 may be altered by PFOS in human bodies, and that PFOS is a mechanism-based inhibitor of CYP2A6. PMID:21964418

  13. ABCB1 and ABCC2 and the risk of distant metastasis in Thai breast cancer patients treated with tamoxifen

    PubMed Central

    Sensorn, Insee; Sukasem, Chonlaphat; Sirachainan, Ekaphop; Chamnanphon, Montri; Pasomsub, Ekawat; Trachu, Narumol; Supavilai, Porntip; Pinthong, Darawan; Wongwaisayawan, Sansanee

    2016-01-01

    Background Genetic polymorphisms of drug-metabolizing enzymes and transporters have been extensively studied with regard to tamoxifen treatment outcomes. However, the results are inconclusive. Analysis of organ-specific metastasis may reveal the association of these pharmacogenetic factors. The aim of this study is to investigate the impact of CYP3A5, CYP2D6, ABCB1, and ABCC2 polymorphisms on the risk of all distant and organ-specific metastases in Thai patients who received tamoxifen adjuvant therapy. Methods Genomic DNA was extracted from blood samples of 73 patients with breast cancer who received tamoxifen adjuvant therapy. CYP3A5 (6986A>G), CYP2D6 (100C>T), ABCB1 (3435C>T), and ABCC2 (−24C>T) were genotyped using allelic discrimination real-time polymerase chain reaction assays. The impacts of prognostic clinical factors and genetic variants on disease-free survival were analyzed using the Kaplan–Meier method and Cox regression analysis. Results In the univariate analysis, primary tumor size >5 cm was significantly associated with increased risk of distant metastasis (P=0.004; hazard ratio [HR] =3.05; 95% confidence interval [CI], 1.44–6.47). In the multivariate analysis, tumor size >5 cm remained predictive of distant metastasis (P<0.001; HR=5.49; 95% CI, 2.30–13.10). ABCC2 −24CC were shown to be associated with increased risk of distant metastasis (P=0.040; adjusted HR=2.34; 95% CI, 1.04–5.27). The combined genotype of ABCC2 −24CC − ABCB1 3435 CT+TT was associated with increased risk of distant and bone metastasis (P=0.020; adjusted HR=2.46; 95% CI, 1.15–5.26 and P=0.040; adjusted HR=3.70; 95% CI, 1.06–12.89, respectively). Conclusion This study indicates that polymorphisms of ABCC2 and ABCB1 are independently associated with bone metastasis. Further prospective studies with larger sample sizes are needed to verify this finding. PMID:27110128

  14. Evaluation of the Transport, In Vitro Metabolism and Pharmacokinetics of Salvinorin A, a Potent Hallucinogen

    PubMed Central

    Teksin, Zeynep S.; Lee, Insong J.; Nemieboka, Noble N.; Othman, Ahmed A.; Upreti, Vijay V.; Hassan, Hazem E.; Syed, Shariq S.; Prisinzano, Thomas E.; Eddington, Natalie D.

    2009-01-01

    Salvinorin A is an unregulated potent hallucinogen isolated from the leaves of Salvia divinorum. It is the only known non-nitrogenous kappa-opioid selective agonist and rivals synthetic lysergic acid diethylamide (LSD) in potency. This objective of this study was to characterize the in vitro transport, in vitro metabolism, and pharmacokinetic properties of Salvinorin A. The transport characteristics of Salvinorin A were assessed using MDCK-MDR1 cell monolayers. The P-glycoprotein (P-gp) affinity status was assessed by the P-gp ATPase assay. In vitro metabolism studies were performed with various specific human CYP450 isoforms and UGT2B7 to assess the metabolic characteristics of Salvinorin A. Cohorts (n=3) of male Sprague Dawley rats were used to evaluate the pharmacokinetics and brain distribution of Salvinorin A (10 mg/kg, intraperitonal (i.p.) over a 240 min period. A validated UV-HPLC and LC/MS/MS method was used to quantify the hallucinogen concentrations obtained from the in vitro and in vivo studies, respectively. Salvinorin A displayed a high secretory transport in the MDCK-MDR1 cells (4.07±1.34 × 10-5 cm/s). Salvinorin A also stimulated the P-gp ATPase activity in a concentration (5-10 μm) dependent manner, suggesting that it may be a substrate of P-gp. A significant decrease in Salvinorin A concentration ranging from 14.7±0.80 % to 31.1±1.20 % was observed after incubation with CYP2D6, CYP1A1, CYP2C18, and CYP2E1, respectively. A significant decrease was also observed after incubation with UGT2B7. These results suggest that Salvinorin A may be a substrate of UGT2B7, CYP2D6, CYP1A1, CYP2E1 and CYP2C18. The in vivo pharmacokinetic study showed a relatively fast elimination with a half-life (t1/2) of 75 min and a clearance (Cl/F) of 26 L/h/kg. The distribution was extensive (Vd of 47.1 L/kg), however the brain to plasma ratio was 0.050. Accordingly, the brain half life was relatively short, 36 min. Salvinorin A is rapidly eliminated after i.p. dosing

  15. Integrated in vitro analysis for the in vivo prediction of cytochrome P450-mediated drug-drug interactions.

    PubMed

    McGinnity, Dermot F; Waters, Nigel J; Tucker, James; Riley, Robert J

    2008-06-01

    Unbound IC(50) (IC(50,u)) values of 15 drugs were determined in eight recombinantly expressed human cytochromes P450 (P450s) and human hepatocytes, and the data were used to simulate clinical area under the plasma concentration-time curve changes (deltaAUC) on coadministration with prototypic CYP2D6 substrates. Significant differences in IC(50,u) values between enzyme sources were observed for quinidine (0.02 microM in recombinant CYP2D6 versus 0.5 microM in hepatocytes) and propafenone (0.02 versus 4.1 microM). The relative contribution of individual P450s toward the oxidative metabolism of clinical probes desipramine, imipramine, tolterodine, propranolol, and metoprolol was estimated via determinations of intrinsic clearance using recombinant P450s (rP450s). Simulated deltaAUC were compared with those observed in vivo via the ratios of unbound inhibitor concentration at the entrance to the liver to inhibition constants determined against rP450s ([I](in,u)/K(i)) and incorporating parallel substrate elimination pathways. For this dataset, there were 20% false negatives (observed deltaAUC >or= 2, predicted deltaAUC < 2), 77% correct predictions, and 3% false positives. Thus, the [I](in,u)/K(i) approach appears relatively successful at estimating the degree of clinical interactions and can be incorporated into drug discovery strategies. Using a Simcyp ADME (absorption, metabolism, distribution, elimination) simulator (Simcyp Ltd., Sheffield, UK), there were 3% false negatives, 94% correct simulations, and 3% false positives. False-negative predictions were rationalized as a result of mechanism-based inhibition, production of inhibitory metabolites, and/or hepatic uptake. Integrating inhibition and reaction phenotyping data from automated rP450 screens have shown applicability to predict the occurrence and degree of in vivo drug-drug interactions, and such data may identify the clinical consequences for candidate drugs as both "perpetrators" and "victims" of P450

  16. Predictors of Blood Trihalomethane Concentrations in NHANES 1999–2006

    PubMed Central

    Dhingra, Radhika; Blount, Benjamin C.; Steenland, Kyle

    2014-01-01

    Background: Trihalomethanes (THMs) are water disinfection by-products that have been associated with bladder cancer and adverse birth outcomes. Four THMs (bromoform, chloroform, bromodichloromethane, dibromochloromethane) were measured in blood and tap water of U.S. adults in the National Health and Nutrition Examination Survey (NHANES) 1999–2006. THMs are metabolized to potentially toxic/mutagenic intermediates by cytochrome p450 (CYP) 2D6 and CYP2E1 enzymes. Objectives: We conducted exploratory analyses of blood THMs, including factors affecting CYP2D6 and CYP2E1 activity. Methods: We used weighted multivariable regressions to evaluate associations between blood THMs and water concentrations, survey year, and other factors potentially affecting THM exposure or metabolism (e.g., prescription medications, cruciferous vegetables, diabetes, fasting, pregnancy, swimming). Results: From 1999 to 2006, geometric mean blood and water THM levels dropped in parallel, with decreases of 32%–76% in blood and 38%–52% in water, likely resulting, in part, from the lowering of the total THM drinking water standard in 2002–2004. The strongest predictors of blood THM levels were survey year and water concentration (n = 4,232 total THM; n = 4,080 bromoform; n = 4,582 chloroform; n = 4,374 bromodichloromethane; n = 4,464 dibromochloromethane). We detected statistically significant inverse associations with diabetes and eating cruciferous vegetables in all but the bromoform model. Medications did not consistently predict blood levels. Afternoon/evening blood samples had lower THM concentrations than morning samples. In a subsample (n = 230), air chloroform better predicted blood chloroform than water chloroform, suggesting showering/bathing was a more important source than drinking. Conclusions: We identified several factors associated with blood THMs that may affect their metabolism. The potential health implications require further study. Citation: Riederer AM, Dhingra R

  17. Enzyme markers

    MedlinePlus

    ... or defects passed down through families (inherited) can affect how enzymes work. Some enzymes are affected by several genes. Test results are usually reported as a percentage of normal enzyme activity.

  18. Metabolism and Disposition of Prescription Opioids: A Review.

    PubMed

    DePriest, A Z; Puet, B L; Holt, A C; Roberts, A; Cone, E J

    2015-07-01

    Opioid analgesics are commonly prescribed for acute and chronic pain, but are subject to abuse. Consequently, toxicology testing programs are frequently implemented for both forensic and clinical applications. Understanding opioid metabolism and disposition is essential for assessing risk of toxicity and, in some cases, providing additional information regarding risk of therapeutic failure. Opioids significantly metabolized by the cytochromeP450 (CYP450) enzyme system maybe subjectto drug-drug interactions, including codeine, hydrocodone, oxycodone, fentanyl, meperidine, methadone, buprenorphine, and tramadol. CYP2D6 metabolism is polymorphic, and pharmacogenetic testing has been investigated for codeine, tramadol, oxycodone, and hydrocodone. CYP2B6 pharmacogenetic testing of methadone may reduce the risk of cardiac toxicity associated with the S-enantiomer. Opioids metabolized primarily by uridine 5'-diphospho-glucuronsyltransferase (UGT) enzymes include morphine, hydromorphone, dihydrocodeine, oxymorphone, levorphanol, and tapentadol. Parent and metabolite disposition is described for blood, oral fluid, and urine. Parent drug is most commonly detected in blood and oral fluid, whereas metabolites typically predominate in urine. Oral fluid/blood ratios exceed 1 for most opioids, making this an excellent alternative matrix for testing of this drug class. Metabolites of codeine, hydrocodone, and oxycodone are commercially available, and knowledge of metabolism is necessary for correct interpretation. PMID:26227254

  19. Cytochrome P450 humanised mice

    PubMed Central

    2004-01-01

    Humans are exposed to countless foreign compounds, typically referred to as xenobiotics. These can include clinically used drugs, environmental pollutants, food additives, pesticides, herbicides and even natural plant compounds. Xenobiotics are metabolised primarily in the liver, but also in the gut and other organs, to derivatives that are more easily eliminated from the body. In some cases, however, a compound is converted to an electrophile that can cause cell toxicity and transformation leading to cancer. Among the most important xenobiotic-metabolising enzymes are the cytochromes P450 (P450s). These enzymes represent a superfamily of multiple forms that exhibit marked species differences in their expression and catalytic activities. To predict how humans will metabolise xenobiotics, including drugs, human liver extracts and recombinant P450s have been used. New humanised mouse models are being developed which will be of great value in the study of drug metabolism, pharmacokinetics and pharmacodynamics in vivo, and in carrying out human risk assessment of xenobiotics. Humanised mice expressing CYP2D6 and CYP3A4, two major drug-metabolising P450s, have revealed the feasibility of this approach. PMID:15588489

  20. Promising Tools in Prostate Cancer Research: Selective Non-Steroidal Cytochrome P450 17A1 Inhibitors.

    PubMed

    Bonomo, Silvia; Hansen, Cecilie H; Petrunak, Elyse M; Scott, Emily E; Styrishave, Bjarne; Jørgensen, Flemming Steen; Olsen, Lars

    2016-01-01

    Cytochrome P450 17A1 (CYP17A1) is an important target in the treatment of prostate cancer because it produces androgens required for tumour growth. The FDA has approved only one CYP17A1 inhibitor, abiraterone, which contains a steroidal scaffold similar to the endogenous CYP17A1 substrates. Abiraterone is structurally similar to the substrates of other cytochrome P450 enzymes involved in steroidogenesis, and interference can pose a liability in terms of side effects. Using non-steroidal scaffolds is expected to enable the design of compounds that interact more selectively with CYP17A1. Therefore, we combined a structure-based virtual screening approach with density functional theory (DFT) calculations to suggest non-steroidal compounds selective for CYP17A1. In vitro assays demonstrated that two such compounds selectively inhibited CYP17A1 17α-hydroxylase and 17,20-lyase activities with IC50 values in the nanomolar range, without affinity for the major drug-metabolizing CYP2D6 and CYP3A4 enzymes and CYP21A2, with the latter result confirmed in human H295R cells. PMID:27406023

  1. The effects of antiepileptic inducers in neuropsychopharmacology, a neglected issue. Part II: Pharmacological issues and further understanding.

    PubMed

    de Leon, Jose

    2015-01-01

    The literature on inducers in epilepsy and bipolar disorder is seriously contaminated by false negative findings. Part II of this comprehensive review on antiepileptic drug (AED) inducers provides clinicians with further educational material about the complexity of interpreting AED drug-drug interactions. The basic pharmacology of induction is reviewed including the cytochrome P450 (CYP) isoenzymes, the Uridine Diphosphate Glucuronosyltransferases (UGTs), and P-glycoprotein (P-gp). CYP2B6 and CYP3A4 are very sensitive to induction. CYP1A2 is moderately sensitive while CYP2C9 and CYP2C19 are only mildly sensitive. CYP2D6 cannot be induced by medications. Induction of UGT and P-gp are poorly understood. The induction of metabolic enzymes such as CYPs and UGTs, and transporters such as P-gp, implies that the amount of these proteins increases when they are induced; this is almost always explained by increasing synthesis mediated by the so-called nuclear receptors (constitutive androstane, estrogen, glucocorticoid receptors and pregnaneX receptors). Although parti provides correction factors for AEDs, extrapolation from an average to an individual patient may be influenced by administration route, absence of metabolic enzyme for genetic reasons, and presence of inhibitors or other inducers. AED pharmacodynamic DDIs may also be important. Six patients with extreme sensitivity to AED inductive effects are described. PMID:26111722

  2. Enhancing cytochrome P450-mediated conversions in P. pastoris through RAD52 over-expression and optimizing the cultivation conditions.

    PubMed

    Wriessnegger, Tamara; Moser, Sandra; Emmerstorfer-Augustin, Anita; Leitner, Erich; Müller, Monika; Kaluzna, Iwona; Schürmann, Martin; Mink, Daniel; Pichler, Harald

    2016-04-01

    Cytochrome P450 enzymes (CYPs) play an essential role in the biosynthesis of various natural compounds by catalyzing regio- and stereospecific hydroxylation reactions. Thus, CYP activities are of great interest in the production of fine chemicals, pharmaceutical compounds or flavors and fragrances. Industrial applicability of CYPs has driven extensive research efforts aimed at improving the performance of these enzymes to generate robust biocatalysts. Recently, our group has identified CYP-mediated hydroxylation of (+)-valencene as a major bottleneck in the biosynthesis of trans-nootkatol and (+)-nootkatone in Pichia pastoris. In the current study, we aimed at enhancing CYP-mediated (+)-valencene hydroxylation by over-expressing target genes identified through transcriptome analysis in P. pastoris. Strikingly, over-expression of the DNA repair and recombination gene RAD52 had a distinctly positive effect on trans-nootkatol formation. Combining RAD52 over-expression with optimization of whole-cell biotransformation conditions, i.e. optimized media composition and cultivation at higher pH value, enhanced trans-nootkatol production 5-fold compared to the initial strain and condition. These engineering approaches appear to be generally applicable for enhanced hydroxylation of hydrophobic compounds in P. pastoris as confirmed here for two additional membrane-attached CYPs, namely the limonene-3-hydroxylase from Mentha piperita and the human CYP2D6. PMID:26898115

  3. Promising Tools in Prostate Cancer Research: Selective Non-Steroidal Cytochrome P450 17A1 Inhibitors

    PubMed Central

    Bonomo, Silvia; Hansen, Cecilie H.; Petrunak, Elyse M.; Scott, Emily E.; Styrishave, Bjarne; Jørgensen, Flemming Steen; Olsen, Lars

    2016-01-01

    Cytochrome P450 17A1 (CYP17A1) is an important target in the treatment of prostate cancer because it produces androgens required for tumour growth. The FDA has approved only one CYP17A1 inhibitor, abiraterone, which contains a steroidal scaffold similar to the endogenous CYP17A1 substrates. Abiraterone is structurally similar to the substrates of other cytochrome P450 enzymes involved in steroidogenesis, and interference can pose a liability in terms of side effects. Using non-steroidal scaffolds is expected to enable the design of compounds that interact more selectively with CYP17A1. Therefore, we combined a structure-based virtual screening approach with density functional theory (DFT) calculations to suggest non-steroidal compounds selective for CYP17A1. In vitro assays demonstrated that two such compounds selectively inhibited CYP17A1 17α-hydroxylase and 17,20-lyase activities with IC50 values in the nanomolar range, without affinity for the major drug-metabolizing CYP2D6 and CYP3A4 enzymes and CYP21A2, with the latter result confirmed in human H295R cells. PMID:27406023

  4. Meclizine metabolism and pharmacokinetics: formulation on its absorption.

    PubMed

    Wang, Zhijun; Lee, Benjamin; Pearce, Daniel; Qian, Shuai; Wang, Yanfeng; Zhang, Qizhi; Chow, Moses S S

    2012-09-01

    Meclizine, an antihistamine, has been widely used for prophylactic treatment and management of motion sickness. However, the onset of action of meclizine was about 1 hour for the treatment of motion sickness and vertigo. A new suspension formulation of meclizine (MOS) was developed with the intention to achieve a rapid effect. To investigate the pharmacokinetics of the new MOS formulation versus the marketed meclizine oral tablet (MOT), a phase 1 pharmacokinetic study was performed in 20 healthy volunteers. In addition, an in vitro metabolic study using human hepatic microsome and recombinant CYP enzyme was also performed to determine the metabolic pathway in the human body. The plasma concentration of MOS appeared more rapidly in comparison to the MOT. The geometric mean ratios (90% confidence interval) of AUC(0-24) and AUC(0-∞) indicated no significant difference in bioavailability between the 2 formulations. CYP2D6 was found to be the dominant enzyme for metabolism of meclizine, and its genetic polymorphism could contribute to the large interindividual variability. In view of the similar bioavailability with a much shorter peak time of the plasma meclizine concentration from the MOS formulation, this new formulation is expected to produce a much quicker onset of action when used for the management of motion sickness. PMID:21903894

  5. The AmpliChip CYP450 test: principles, challenges, and future clinical utility in digestive disease.

    PubMed

    Juran, Brian D; Egan, Laurence J; Lazaridis, Konstantinos N

    2006-07-01

    Understanding genetically encoded inherited differences in drug metabolism and targets (ie, receptors, transporters) offers the promise of minimizing adverse drug reactions and improving therapies. Among the enzymes involved in drug metabolism, the cytochromes P450 (CYP450) hold a central position. In fact, CYP450 are involved in the biotransformation of most drugs used in clinical practice. Recent advances in the development of DNA-based diagnostics, coupled with a better understanding of genetic polymorphisms in influencing pharmacologic responses, have provided the foundation for novel in vitro tests that may predict side effects and/or therapeutic responses. The AmpliChip CYP450 test was developed as a clinical test to evaluate an individual's metabolic capacity for certain drugs by identifying polymorphisms of 2 CYP450 enzymes (ie, CYP2D6 and CYP2D19). Even though the AmpliChip CYP450 has been approved by the US Food and Drug Administration, its practical clinical utility has not yet been determined, and there is a paucity of data related to gastrointestinal and liver diseases. An understanding of the principles and opportunities provided by this new category of diagnostic test is key before planning the necessary studies to evaluate the usefulness of AmpliChip CYP450 in gastroenterologic clinical practice. PMID:16797246

  6. In vivo prediction of CYP-mediated metabolic interaction potential of formononetin and biochanin A using in vitro human and rat CYP450 inhibition data.

    PubMed

    Arora, Sumit; Taneja, Isha; Challagundla, Muralikrishna; Raju, Kanumuri Siva Rama; Singh, Sheelendra Pratap; Wahajuddin, Muhammad

    2015-11-19

    Formononetin (FMN) and Biochanin A (BCA) are the principal isoflavones present in commercially available extracts of red clover that are widely been consumed for various health benefits. We investigated the in vitro effects of FMN and BCA on catalytic activity of human/rat cytochrome P450 enzymes to assess the drug interaction potential of red clover. IC50 and Ki values of FMN and BCA for CYPs were determined in human/rat liver microsomes. FMN and BCA showed concentration-dependent inhibition of CYP1A2 activity with IC50 values of 13.42 and 24.98μM in human liver microsomes and 38.57 and 11.86μM in rat liver microsomes, respectively. The mode of inhibition of human CYP1A2 by FMN was found to be competitive with apparent Ki value of 10.13±1.96μM. FMN also inhibited human CYP2D6. BCA exerted moderately inhibitory effects on human CYP2C9. The predicted in vivo inhibition for CYP1A2 was insignificant (R value <1.1) at hepatic level while at intestinal level, it was significant (R value >11). The inhibitory effects on other CYPs were found to be minimal. Red clover may be considered safe to be consumed along with co-prescribed medications; however, precaution must be taken while co-administering it with CYP1A2 substrates. PMID:26278343

  7. Bioactivation and bioinactivation of drugs and drug metabolites: Relevance to adverse drug reactions.

    PubMed

    Park, B K; Pirmohamed, M; Tingle, M D; Madden, S; Kitteringham, N R

    1994-08-01

    Adverse drug reactions that cannot be predicted from the pharmacological properties of the drug and which are not easily reproduced in laboratory animals are a major complication of drug therapy. It is necessary to investigate the mechanisms of such reactions in order to (1) define structural features within a given drug molecule which are responsible for causing toxicity and (2) to identify those individuals who are particularly sensitive to a given drug reaction. In theory, drug toxicity may arise by direct toxicity, genotoxicity or immune-mediated toxicity caused by either parent drug or chemical. In this respect chemically reactive metabolites are of particular importance and the balance between bioactivation and bioinactivation pathways of drug metabolism will be a critical factor in both the type and extent of toxicity. We have therefore developed in vitro techniques that incorporate human cells for the detection and characterization of stable, chemically reactive and cytotoxic metabolites. In such experiments bioactivation (by CYP1A, CYP2D6, CYP3A, etc.) can be investigated by use of a liver bank, while lymphocytes provide accessible human cells, which can be obtained from both patients and volunteers, genotyped and/or phenotyped for particular drug-metabolizing enzymes (eg. glutathione transferase mu). The relevance of in vitro experiments to drug toxicity observed in humans will be illustrated by reference to studies with anticonvulsants and antimalarials. PMID:20692973

  8. Design, synthesis, and biological evaluation of a novel series of peripheral-selective noradrenaline reuptake inhibitors-Part 2.

    PubMed

    Yukawa, Tomoya; Fujimori, Ikuo; Kamei, Taku; Nakada, Yoshihisa; Sakauchi, Nobuki; Yamada, Masami; Ohba, Yusuke; Ueno, Hiroyuki; Takiguchi, Maiko; Kuno, Masako; Kamo, Izumi; Nakagawa, Hideyuki; Fujioka, Yasushi; Igari, Tomoko; Ishichi, Yuji; Tsukamoto, Tetsuya

    2016-07-15

    Peripherally selective inhibition of noradrenaline reuptake is a novel mechanism for the treatment of stress urinary incontinence to overcome adverse effects associated with central action. Herein, we describe our medicinal chemistry approach to discover peripheral-selective noradrenaline reuptake inhibitors to avert the risk of P-gp-mediated DDI at the blood-brain barrier. We observed that steric shielding of the hydrogen-bond acceptors and donors (HBA and HBD) of compound 1 reduced the multidrug resistance protein 1 (MDR1) efflux ratio; however, the resulting compound 6, a methoxyacetamide derivative, was mainly metabolized by CYP2D6 and CYP2C19 in the in vitro phenotyping study, implying the risk of PK variability based on the genetic polymorphism of the CYPs. Replacement of the hydrogen atom with a deuterium atom in a strategic, metabolically hot spot led to compound 13, which was mainly metabolized by CYP3A4. To our knowledge, this study represents the first report of the effect of deuterium replacement for a major metabolic enzyme. The compound 13, N-{[(6S,7R)-7-(4-chloro-3-fluorophenyl)-1,4-oxazepan-6-yl]methyl}-2-[(2H(3))methyloxy]acetamide hydrochloride, which exhibited peripheral NET selective inhibition at tested doses in rats, increased urethral resistance in a dose-dependent manner. PMID:27255177

  9. Codeine Ultra-rapid Metabolizers: Age Appears to be a Key Factor in Adverse Effects of Codeine.

    PubMed

    Heintze, K; Fuchs, W

    2015-12-01

    Codeine is widely used as an analgesic drug. Taking into account the high consumption of codeine, only few fatal adverse events have been published. A number of reports, where neonates and children showed serious or fatal adverse reactions, led to a restriction of the use of codeine in this patient group. Therefore, we reviewed the safety of codeine in adults. PubMed was systematically searched for clinical studies and case reports, with a special focus on CYP2D6, the enzyme that converts codeine to morphine and exhibits genetic polymorphism.181 cases were identified in adults in conjunction with serious or lethal effects of codeine. In the vast majority of cases, codeine was used in combination with other drugs by drug-dependent individuals or with a suicidal intent. Only 2 cases were found where ultra-rapid metabolizers experienced severe non-lethal adverse events. This is far less than would be predicted from the number of cases reported in children. The discrepancy may be explained by developmental changes in the disposition of codeine.The strategy of regulatory authorities to restrict access to codeine for infants and young children, the apparent highest risk group, has a factual and pharmacological rationale. By the same standards, there is no need for restrictions for adult use of codeine. PMID:25585351

  10. Reductive amination-assisted quantitation of tamoxifen and its metabolites by liquid phase chromatography tandem mass spectrometry.

    PubMed

    Liang, Shih-Shin; Wang, Tsu-Nai; Chiu, Chien-Chih; Kuo, Po-Lin; Huang, Mei-Fang; Liu, Meng-Chieh; Tsai, Eing-Mei

    2016-02-19

    Tamoxifen, a hormonal therapy drug against estrogen receptor-positive breast cancer, can be metabolized by cytochrome P450 enzymes such as CYP3A4 and CYP3A5, and converted to N-desmethyltamoxifen, which is subsequently, metabolized by CYP2D6 and inverted to form 4-hydroxy-N-desmethyltamoxifen (endoxifen). Conventional mass spectrometry (MS) analyses of tamoxifen and its metabolites require isotopic internal standards (ISs). In this study, endoxifen and N-desmethyltamoxifen amine groups were modified by reductive amination with formaldehyde-D2 to produce new metabolite molecules. Both endoxifen and N-desmethyltamoxifen generated their corresponding D2-methyl modified analogs. This method is expected to simplify MS detection and overcome the difficulty in selecting adequate ISs when tamoxifen metabolites are analyzed by absolute quantification. It identified tamoxifen, D2-methyl modified endoxifen, and D2-methyl modified N-desmethyltamoxifen with a linearity ranging from 2 to 5000 ng/mL with correlation coefficient (R(2)) values of 0.9868, 0.9849, and 0.9880, respectively. Furthermore, this reductive amination-based method may enhance the signal intensities of D2-methyl modified N-desmethyltamoxifen and endoxifen, thus facilitating the MS detection. PMID:26814364

  11. Inhibitory effect of salvianolate on human cytochrome P450 3A4 in vitro involving a noncompetitive manner

    PubMed Central

    Qin, Chong-Zhen; Ren, Xian; Zhou, Hong-Hao; Mao, Xiao-Yuan; Liu, Zhao-Qian

    2015-01-01

    Salvianolic acid B (Sal B), which is purified from Danshen, is a popular herb extract. Sal B has anti-oxidative, anti-inflammatory, anti-hypoxic, anti-arteriosclerotic and anti-apoptotic properties. This substance can also ameliorate brain injury or neurodegenerative diseases. The listed drug Salvianolate, which contains a substantial amount of Sal B, has been used for the treatment of coronary heart disease. Our present work aimed to evaluate the inhibitory effect of salvianolate on seven cytochrome P450 isoforms (CYP450), namely, CYP1A2, CYP2A6, CYP2E1, CYP2C9, CYP2C19, CYP2D6 and CYP3A4, in human liver microsomes (HLMs) and recombinant enzymes through high-performance liquid chromatography (HPLC) assay. Salvianolate have a potent inhibitory effect on CYP3A4 activity with IC50 values of 1.438 (HLMs) and 3.582 (recombinant cDNA-expressed CYP3A4) mg/L, respectively. Salvianolate strongly dose, but not time-dependently decreased CYP3A4 activity in HLMs. The typical Lineweaver-Burk plots showed that Salvianolate inhibited CYP3A4 activity noncompetitively, with a Ki value of 2.27 mg/L in HLMs. Other CYP450 isoforms are not markedly affected by Salvianolate. These findings indicate that salvianolate may be involved in potential drug interactions when co-administrated with CYP3A4 substrates. PMID:26629047

  12. Interaction between dose and susceptibility to environmental cancer: a short review.

    PubMed Central

    Hietanen, E; Husgafvel-Pursiainen, K; Vainio, H

    1997-01-01

    Increased risk of environmentally induced cancer is associated with various types of exposures and host factors, including differences in carcinogen metabolism. Since many carcinogenic compounds require metabolic activation to enable them to react with cellular macromolecules, individual features of carcinogen metabolism may play an essential role in the development of environmental cancer. In this context, cigarette smoking has often been the main type of carcinogenic exposure examined in human studies. Increasing attention has recently been paid to the dose level at which individual susceptibility may be observed. Present studies on increased risk of smoking-related lung cancer associated with phenotypic or genotypic variation of the genes encoding for CYP1A1 or CYP2D6 enzymes are summarized. Similarly, higher risks of lung or bladder cancer seen at various levels of smoking in association with polymorphism of the glutathione S-transferase gene GSTM1 or NAT1 and NAT2 genes involved in N-acetylation are reviewed. Finally, the influence of CYP2E1, GSTM1, or the combined at-risk genotype on the risk of hepatocellular carcinoma in smokers is briefly discussed. PMID:9255556

  13. Clinical Utility of Combinatorial Pharmacogenomics-Guided Antidepressant Therapy: Evidence from Three Clinical Studies.

    PubMed

    Altar, C Anthony; Carhart, Joseph; Allen, Josiah D; Hall-Flavin, Daniel; Winner, Joel; Dechairo, Bryan

    2015-10-01

    DNA of 258 patients with treatment-resistant depression was collected in three 8-10 week, two-arm, prospective clinical trials. Forty-four allelic variations were measured in genes for the cytochrome P450 (CYP) enzymes CYP2D6, CYPC19, and CYP1A2, the serotonin transporter (SLC6A4), and the 5-HT2A receptor (HTR2A). The combinatorial pharmacogenomic (CPGx™) GeneSight test results were provided to clinicians to support medication changes from baseline (guided arm), or they were provided at the end of each study to clinicians of unguided patients who were treated as usual (TAU). TAU subjects who at baseline were prescribed medications genetically discordant for them showed only a 12% symptom improvement, far less than the 32.5% or 28.5% improvements of the TAU subjects on yellow-category ('use with caution'; p = 0.002) or green-category medications ('use as recommended'; p = 0.02), respectively. The odds of a clinical response were increased 2.3-fold among all GeneSight-guided compared to all TAU subjects (p = 0.004), and overall, the guided group had a 53% greater improvement in depressive symptoms (p = 0.0002), a 1.7-fold relative improvement in response (p = 0.01), and a number needed to treat for one clinical response above that seen in the TAU group of 6.07. PMID:27606312

  14. Safety and side effect profile of fluoxetine.

    PubMed

    Wernicke, Joachim F

    2004-09-01

    Fluoxetine was the first selective serotonin re-uptake inhibitor to be widely available for treatment of depression and numerous other neuropsychiatric disorders. Its attributes have been described in numerous scientific papers, and it has been the subject of a considerable volume of lay press. Fluoxetine is generally safe and well-tolerated. Common adverse events reported with the recommended dose of 20 mg/day are referable to the gastrointestinal system and the nervous system. The approved dose range is up to 80 mg/day, and when higher doses are used, adverse events are more common. The long half-life of fluoxetine and its active metabolite essentially preclude a withdrawal phenomenon. It is an inhibitor of cytochrome P450 (CYP) 2D6 and other CYP enzymes, which increases the potential for drug interactions. However, most of these are not clinically important. The purpose of this review is to provide an overview of some of the most important information related to safety and side effects of this drug. PMID:15335304

  15. Geneva cocktail for cytochrome p450 and P-glycoprotein activity assessment using dried blood spots.

    PubMed

    Bosilkovska, M; Samer, C F; Déglon, J; Rebsamen, M; Staub, C; Dayer, P; Walder, B; Desmeules, J A; Daali, Y

    2014-09-01

    The suitability of the capillary dried blood spot (DBS) sampling method was assessed for simultaneous phenotyping of cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp) using a cocktail approach. Ten volunteers received an oral cocktail capsule containing low doses of the probes bupropion (CYP2B6), flurbiprofen (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), midazolam (CYP3A), and fexofenadine (P-gp) with coffee/Coke (CYP1A2) on four occasions. They received the cocktail alone (session 1), and with the CYP inhibitors fluvoxamine and voriconazole (session 2) and quinidine (session 3). In session 4, subjects received the cocktail after a 7-day pretreatment with the inducer rifampicin. The concentrations of probes/metabolites were determined in DBS and plasma using a single liquid chromatography-tandem mass spectrometry method. The pharmacokinetic profiles of the drugs were comparable in DBS and plasma. Important modulation of CYP and P-gp activities was observed in the presence of inhibitors and the inducer. Minimally invasive one- and three-point (at 2, 3, and 6 h) DBS-sampling methods were found to reliably reflect CYP and P-gp activities at each session. PMID:24722393

  16. Augmentative effects of fluvoxamine on duloxetine plasma levels in depressed patients.

    PubMed

    Paulzen, M; Finkelmeyer, A; Grözinger, M

    2011-11-01

    Duloxetine is a potent and selective inhibitor of serotonin and norepinephrine reuptake with weak activity on dopamine reuptake. Enzymes involved in duloxetine metabolism are cytochrome P450 isoenzymes (CYP) CYP1A2 and to a lesser extent CYP2D6 whereas the selective serotonin reuptake inhibitor Fluvoxamine is known to be a potent inhibitor of CYP1A2. Changes in plasma levels of duloxetine revealing pharmacokinetic interactions with fluvoxamine, clinical effects and adverse effects of adding fluvoxamine in thirteen patients with a steady-state duloxetine treatment by intraindividual comparisons were analyzed in this retrospective survey. Patients had been treated with duloxetine under steady-state conditions until fluvoxamine was added. Plasma duloxetine levels were measured at steady state of different daily doses due to lacking experience with the combination of DLX and FLX. Adding 25 mg of fluvoxamine (FLX) per day to a steady-state treatment with 30 mg of duloxetine (DLX) in 8 patients led to an average increase of duloxetine plasma levels that was 3-fold with a magnitude of 50-506%. Our findings indicate that duloxetine plasma levels can be enhanced by a potent CYP1A2 inhibition by FLX and that DLX, even in higher plasma levels, seems to be well tolerated. The use of combined treatments, however, underscores the importance of understanding pharmacokinetic interactions. PMID:21979923

  17. High-throughput screening of inhibitory effects of Bo-yang-hwan-o-tang on human cytochrome P450 isoforms in vitro using UPLC/MS/MS.

    PubMed

    Lee, Miran; Park, Jeonghyeon; Lim, Mi-sun; Seong, Sook Jin; Lee, Joomi; Seo, Jeong Ju; Park, Yong-Ki; Lee, Hae Won; Yoon, Young-Ran

    2012-01-01

    Bo-yang-hwan-o-tang (BHT) is an oriental herbal medicine for treating brain disorders such as cerebral ischemia. The objective of this study was to develop an economically feasible and time-saving high-throughput screening method to monitor the potential inhibitory effects of BHT on human cytochrome P450 (CYP) enzymes in vitro. Two cocktail sets were used for incubation of human liver microsomes: Cocktail A: 6 probe substrates for CYP1A2, CYP2A6, CYP2C8, CYP2C19, CYP2D6, CYP3A4; Cocktail B: 3 for CYP2B6, CYP2C9, CYP2E1. The concentrations of the substrate metabolites were simultaneously analyzed using UPLC/MS/MS. The BHT extract had almost negligible inhibitory effects on the nine human CYP isoforms tested, with the half-maximal inhibitory concentration value ranged from 3624.99 to 45412.44 μg/ml. The results suggest that BHT extract has no inhibitory effects on CYP isoforms within the clinically recommended dosage range. We conclude that BHT might be free of drug-herb interactions when co-administered with other medicines. However, more in vivo human studies are needed to confirm these results. The high-throughput screening method can be a useful tool for drug discovery and for understanding drug interactions. PMID:23232241

  18. Drug interactions with vortioxetine, a new multimodal antidepressant.

    PubMed

    Spina, Edoardo; Santoro, Vincenza

    2015-01-01

    This article summarized the available knowledge on clinically relevant drug interactions of vortioxetine, a new antidepressant with a “multimodal” serotonergic mechanism of action, recently approved for the treatment of major depressive disorder. Although information is still limited and mainly based on studies performed in healthy volunteers, vortioxetine appears to have a favorable drug interaction profile. Concerning the potential for pharmacokinetic drug interactions, vortioxetine has little to no effect on various cytochrome P450 (CYP) isoforms and therefore is not expected to markedly affect plasma concentrations of other medications metabolized by these enzymes. This is a major advantage when compared to other antidepressants which are known to inhibit the activity of one or more CYP isoforms. On the other hand, dosage adjustments may be required when vortioxetine is coadministered with strong CYP2D6 inhibitors or broad-spectrum CYP inducers. Vortioxetine carries a relatively low risk for pharmacodynamic drug interactions, at least as compared to first-generation antidepressants. Like other antidepressants enhancing serotonergic activity, vortioxetine is associated with a potential risk of serotonin syndrome when used in combination with other serotonergic agents. Based on all available clinical data, vortioxetine has no increased risk of serotonin syndrome when used without other serotoninergic agents and at therapeutic doses. PMID:26489070

  19. Novel Cytochrome P450 Reaction Phenotyping for Low-Clearance Compounds Using the Hepatocyte Relay Method.

    PubMed

    Yang, Xin; Atkinson, Karen; Di, Li

    2016-03-01

    A novel cytochrome P450 (P450) reaction phenotyping method for low-clearance compounds has been developed for eight P450 enzymes (CYP1A2, 2B6, 2D6, 2C8, 2C9, 2C19, 3A, and 3A4) and pan-cytochrome using the hepatocyte relay approach. Selective mechanism-based inhibitors were used to inactivate the individual P450 enzymes during preincubation, and inactivators were removed from the incubation before adding substrates to minimize reversible inhibition and maximize inhibitor specificity. The inhibitors were quite selective for specific P450 isoforms using the following inhibitor concentrations and preincubation times: furafylline (1 µM, 15 minutes) for CYP1A2, phencyclidine (20 µM, 15 minutes) for 2B6, paroxetine (1.8 µM, 15 minutes) for CYP2D6, gemfibrozil glucuronide (100 µM, 30 minutes) for 2C8, tienilic acid (15 µM, 30 minutes) for 2C9, esomeprazole (8 µM, 15 minutes) for 2C19, troleandomycin (25 µM, 15 minutes) for 3A4/5, CYP3cide (2 µM, 15 minutes) for 3A4, and 1-aminobenzotriazole (1 mM, 30 minutes) supplemented with tienilic acid (15 µM, 30 minutes) for pan-cytochrome. The inhibitors were successfully applied to the hepatocyte relay method in a 48-well format for P450 reaction phenotyping of low-clearance compounds. This novel method provides a new approach for determining the fraction metabolized of low-turnover compounds that are otherwise challenging with the traditional methods, such as chemical inhibitors with human liver microsomes and hepatocytes or human recombinant P450 enzymes. PMID:26700955

  20. Enzyme Kinetics.

    ERIC Educational Resources Information Center

    Moe, Owen; Cornelius, Richard

    1988-01-01

    Conveys an appreciation of enzyme kinetic analysis by using a practical and intuitive approach. Discusses enzyme assays, kinetic models and rate laws, the kinetic constants (V, velocity, and Km, Michaels constant), evaluation of V and Km from experimental data, and enzyme inhibition. (CW)

  1. Enzyme Informatics

    PubMed Central

    Alderson, Rosanna G.; Ferrari, Luna De; Mavridis, Lazaros; McDonagh, James L.; Mitchell, John B. O.; Nath, Neetika

    2012-01-01

    Over the last 50 years, sequencing, structural biology and bioinformatics have completely revolutionised biomolecular science, with millions of sequences and tens of thousands of three dimensional structures becoming available. The bioinformatics of enzymes is well served by, mostly free, online databases. BRENDA describes the chemistry, substrate specificity, kinetics, preparation and biological sources of enzymes, while KEGG is valuable for understanding enzymes and metabolic pathways. EzCatDB, SFLD and MACiE are key repositories for data on the chemical mechanisms by which enzymes operate. At the current rate of genome sequencing and manual annotation, human curation will never finish the functional annotation of the ever-expanding list of known enzymes. Hence there is an increasing need for automated annotation, though it is not yet widespread for enzyme data. In contrast, functional ontologies such as the Gene Ontology already profit from automation. Despite our growing understanding of enzyme structure and dynamics, we are only beginning to be able to design novel enzymes. One can now begin to trace the functional evolution of enzymes using phylogenetics. The ability of enzymes to perform secondary functions, albeit relatively inefficiently, gives clues as to how enzyme function evolves. Substrate promiscuity in enzymes is one example of imperfect specificity in protein-ligand interactions. Similarly, most drugs bind to more than one protein target. This may sometimes result in helpful polypharmacology as a drug modulates plural targets, but also often leads to adverse side-effects. Many cheminformatics approaches can be used to model the interactions between druglike molecules and proteins in silico. We can even use quantum chemical techniques like DFT and QM/MM to compute the structural and energetic course of enzyme catalysed chemical reaction mechanisms, including a full description of bond making and breaking. PMID:23116471

  2. Enzymes, Industrial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Enzymes serve key roles in numerous biotechnology processes and products that are commonly encountered in the forms of food and beverages, cleaning supplies, clothing, paper products, transportation fuels, pharmaceuticals, and monitoring devices. Enzymes can display regio- and stereo-specificity, p...

  3. Understanding Enzymes.

    ERIC Educational Resources Information Center

    Sinnott, M. L.

    1979-01-01

    Describes the way enzymes operate through reaction energetics, and explains that most of the catalytic power of enzymes lies in the strong noncovalent forces responsible for initial binding of substrate, which are only manifested at the transition state of the reaction. (Author/GA)

  4. Soil Enzymes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The functionality and resilience of natural and managed ecosystems mainly rely on the metabolic abilities of microbial communities, the main source of enzymes in soils. Enzyme mediated reactions are critical in the decomposition of organic matter, cycling of nutrients, and in the breakdown of herbic...

  5. Effects of gestational and overt diabetes on human placental cytochromes P450 and glutathione S-transferase.

    PubMed

    McRobie, D J; Glover, D D; Tracy, T S

    1998-04-01

    The placenta possesses the ability to metabolize a number of xenobiotics and endogenous compounds by processes similar to those seen in the liver. Animal and in vivo studies have observed that the presence of diabetes alters the expression of hepatic metabolizing enzymes (cytochrome P450 and glutathione S-transferase); however, it is unknown whether similar alterations occur in the human placenta. To evaluate whether diabetes has any effect of placental xenobiotic metabolizing activity, the catalytic activities of 7-ethoxyresorufin O-deethylation (EROD, CYP1A1), chlorzoxazone 6-hydroxylation (CYP2E1), dextromethorphan N-demethylation (CYP3A4), dextromethorphan O-demethylation (CYP2D6), and 1-chloro-2, 4-dinitrobenzene (CDNB) conjugation with glutathione (glutathione S-transferase, GST) from placentas of diet (class A1) and insulin-dependent (class A2) gestational diabetics and overt diabetics were compared with matched controls. EROD activity (CYP1A1) ranged from 0.29 to 2.67 pmol/min/mg protein. However, no differences were observed among overt or gestational diabetics and their respective matched controls. CDNB conjugation (GST) ranged from 0.275 to 1.65 units/min/mg protein. In contrast to that observed with CYP1A1, a small but statistically significant reduction in GST activity was noted in overt diabetics as compared with their matched controls and gestational diabetics. CYP2E1, 2D6, and 3A4 enzymatic activities were not detected in human placental tissue. GST protein was detectable in all tissues studied, but no CYP protein could be detected in any of the tissues. Thus, it seems that pregnant women with overt diabetes have reduced GST activity in the placenta, which could potentially result in the exposure of the fetus to harmful electrophiles. However, the full clinical significance of this finding remains to be elucidated. PMID:9531526

  6. Pharmacogenetics of Risperidone and Cardiovascular Risk in Children and Adolescents

    PubMed Central

    Dos Santos-Júnior, Amilton; Henriques, Taciane Barbosa; de Mello, Maricilda Palandi; Della Torre, Osmar Henrique; Paes, Lúcia Arisaka; Ferreira-Neto, Adriana Perez; Sewaybricker, Letícia Esposito; Fontana, Thiago Salum; Celeri, Eloisa Helena Rubello Valler; Guerra-Júnior, Gil; Dalgalarrondo, Paulo

    2016-01-01

    Objective. To identify the frequency of obesity and metabolic complications in child and adolescent users of risperidone. Potential associations with clinical parameters and SNPs of the HTR2C, DRD2, LEP, LEPR, MC4R, and CYP2D6 genes were analyzed. Methods. Samples from 120 risperidone users (8–20 years old) were collected and SNPs were analyzed, alongside assessment of chronological and bone ages, prescribed and weight-adjusted doses, use of other psychotropic drugs, waist circumference, BMI z-scores, blood pressure, HOMA-IR index, fasting levels of serum glucose, insulin, cholesterol, triglycerides, transaminases, and leptin. Results. Thirty-two (26.7%) patients were overweight and 5 (4.2%) obese. Hypertension was recorded in 8 patients (6.7%), metabolic syndrome in 6 (5%), and increased waist circumference in 20 (16.7%). The HOMA-IR was high for 22 patients (18.3%), while total cholesterol and triglycerides were high in 20 (16.7%) and 41 (34.2%) patients, respectively. SNP associations were found for LEP, HTR2C, and CYP2D6 with BMI; CYP2D6 with blood pressure, ALT, and HOMA-IR; HTR2C and LEPR with leptin levels; MC4R and DRD2 with HOMA-IR; HTR2C with WC; and LEP with ALT. Conclusions. Although not higher than in the general pediatric population, a high frequency of patients was overweight/obese, with abnormalities in metabolic parameters and some pharmacogenetic associations. PMID:26880915

  7. Population Pharmacokinetic Meta-Analysis of Vortioxetine in Healthy Individuals

    PubMed Central

    Areberg, Johan; Petersen, Kamilla B; Chen, Grace; Naik, Himanshu

    2014-01-01

    The objective was to describe the pharmacokinetics of vortioxetine and evaluate the effect of intrinsic and extrinsic factors in the healthy population. Data from 26 clinical pharmacology studies were pooled. A total of 21,758 vortioxetine quantifiable plasma concentrations were collected from 887 subjects with corresponding demography. The doses ranged from 2.5 to 75 mg (single dose) and 2.5–60 mg (multiple QD doses). The pharmacokinetics of vortioxetine was best characterised by a two-compartment model with first-order absorption, lag-time and linear elimination, with interindividual error terms for absorption rate constant, oral clearance and central volume of distribution. The population mean was 32.7 L/hr for oral clearance and 1.97·103 L for the central volume of distribution. The average elimination half-life was 65.8 hr. CYP2D6 inferred metabolic status (ultra, extensive, intermediate or poor metabolisers) and age on oral clearance and height on central volume of distribution were identified as statistically significant covariate–parameter relationships. For CYP2D6 poor metabolisers, CL/F was approximately 50% to that seen in CYP2D6 extensive metabolisers. The impact of height on V2/F and age on CL/F was low and not considered to be clinically relevant. The final model was found to be reliable, stable and predictive. A reliable, stable and predictive pharmacokinetic model was developed to characterise pharmacokinetics of vortioxetine in the healthy population. PMID:24766668

  8. Perception of the usefulness of drug/gene pairs and barriers for pharmacogenomics in Latin America.

    PubMed

    Quinones, Luis Abel; Lavanderos, Maria Alejandra; Cayun, Juan Pablo; Garcia-Martin, Elena; Agundez, Jose Augusto; Caceres, Dante Daniel; Roco, Angela Margarita; Morales, Jorge E; Herrera, Luisa; Encina, Gonzalo; Isaza, Carlos Alberto; Redal, Maria Ana; Larovere, Laura; Soria, Nestor Walter; Eslava-Schmalbach, Javier; Castaneda-Hernandez, Gilberto; Lopez-Cortes, Andres; Magno, Luiz Alexandre; Lopez, Marisol; Chiurillo, Miguel Angel; Rodeiro, Idania; Castro de Guerra, Dinorah; Teran, Enrique; Estevez-Carrizo, Francisco; Lares-Assef, Ismael

    2014-02-01

    Pharmacogenetics and Pharmacogenomics areas are currently emerging fields focused to manage pharmacotherapy that may prevent undertreatment while avoiding associated drug toxicity in patients. Large international differences in the awareness and in the use of pharmacogenomic testing are presumed, but not well assessed to date. In the present study we review the awareness of Latin American scientific community about pharmacogenomic testing and the perceived barriers for their clinical application. In order to that, we have compiled information from 9 countries of the region using a structured survey which is compared with surveys previously performed in USA and Spain. The most relevant group of barriers was related to the need for clear guidelines for the use of pharmacogenomics in clinical practice, followed by insufficient awareness about pharmacogenomics among clinicians and the absence of regulatory institutions that facilitate the use of pharmacogenetic tests. The higher ranked pairs were TPMT/thioguanine, TPMT/azathioprine, CYP2C9/warfarin, UGT1A1/irinotecan, CYP2D6/amitriptiline, CYP2C19/citalopram and CYP2D6/clozapine. The lower ranked pairs were SLCO1B1/simvastatin, CYP2D6/metoprolol and GP6D/chloroquine. Compared with USA and Spanish surveys, 25 pairs were of lower importance for Latin American respondents. Only CYP2C19/esomeprazole, CYP2C19/omeprazole, CYP2C19/celecoxib and G6PD/dapsone were ranked higher or similarly to the USA and Spanish surveys. Integration of pharmacogenomics in clinical practice needs training of healthcare professionals and citizens, but in addition legal and regulatory guidelines and safeguards will be needed. We propose that the approach offered by pharmacogenomics should be incorporated into the decision-making plans in Latin America. PMID:24524664

  9. Coding-noncoding gene expression in intrahepatic cholangiocarcinoma.

    PubMed

    Wang, Jianguo; Xie, Haiyang; Ling, Qi; Lu, Di; Lv, Zhen; Zhuang, Runzhou; Liu, Zhikun; Wei, Xuyong; Zhou, Lin; Xu, Xiao; Zheng, Shusen

    2016-02-01

    Recent studies have shown that long noncoding RNAs (lncRNAs) play crucial roles in human cancers. However, the function of lncRNAs and their downstream mechanisms are largely unknown in the molecular pathogenesis of intrahepatic cholangiocarcinoma (ICC). In the present study, we performed transcriptomic profiling of ICC and paired adjacent noncancerous tissues (N) by using lncRNA and messenger RNA (mRNA) microarrays. Quantitative real-time polymerase chain reaction was used to validate the microarray results. We tested for correlations between the expression levels of lncRNAs and target genes. Clinicopathologic characteristics and overall survival were compared using the t test and the Kaplan-Meier method, respectively. A total of 2773 lncRNAs were significantly upregulated in ICC tissues compared with the noncancerous tissues, whereas 2392 lncRNAs were downregulated. Bioinformatic analysis indicated that most of the genes were involved in carcinogenesis, hepatic system diseases, and signal transductions. Positive correlations were found between 4 lncRNA-mRNA pairs (RNA43085 and SULF1, RNA47504 and KDM8, RNA58630 and PCSK6, and RNA40057 and CYP2D6). When the clinicopathologic characteristics were accounted for, the cumulative overall survival rate was found to be associated with low expression levels of CYP2D6 (P = 0.005) and PCSK6 (P = 0.038). Patients with high expression levels of CYP2D6 and RNA40057 had a better prognosis (P = 0.014). Our results suggested that the lncRNA expression profiling in ICC tissues is profoundly different from that in noncancerous tissues. Thus, lncRNA may be a potential diagnostic and prognostic biomarker for ICC. Furthermore, the combined assessment of lncRNA and mRNA expressions might predict the survival of patients with ICC. PMID:26297049

  10. [Effect of Fuzheng Huayu recipe on CYP450 isozymes in normal and liver fibrosis rats].

    PubMed

    Zheng, Tian-hui; Liu, Wei; Li, Shu-ping; Yang, Tao; Wang, Chang-hong; Liu, Cheng-hai

    2015-03-01

    To study the effect of Fuzheng Huayu recipe (FZHY) on five types of isozymes of cytochrome P450 (CYP450) of normal and liver fibrosis rats by using the cocktail probe method. Dimethylnitrosamine ( DMN) was injected to induce the liver fibrosis model. After the tail vein injection with Cocktail probe solutions prepared with five CYP450s probe substrates (phenacetin-CYP1A2, omeprazole-CYP2C9, tolbutamide-CYP2C19, dextromethorphan-CYP2D6, midazolam-CYP3A4), the plasma concentrations of the five probe substrates were determined by LC-MS/MS, and the pharmacokinetic parameters were calculated by PK solutions 2. After the oral administration with FZHY, normal rats given phenacetin, omeprazole, tolbutamide and dextromethorphan showed increase in AUC(0-t) and decrease in CL to varying degrees, indicating that FZHY obviously inhibited the activities of CYP1A2, CYP2C9, CYP2C19 and CYP2D6 in normal rats, but with no obvious effect on the activity of CYP3A4. After the oral administration with FZHY, liver fibrosis rats treated with CYP2C9 showed the significant increase in AUC(0-t) and significant decrease in Vd, hut with no obvious changes in the pharmacokinetic parameters of other four types of prove substances, suggesting that FZHY could significantly inhibit the activity of CYP2C9 in rats but had no effect on the activities of CYP1A2, CYP2C19, CYP2D6 and CYP3A4. The changes in the activity of CYP450 isozymes in liver fibrosis rats may be the reason for FZHY's different effects on CYP450 isozymes in normal and liver fibrosis rats. PMID:26226765

  11. Frequencies of Functional Polymorphisms in Three Pharmacokinetic Genes of Clinical Interest within the Admixed Puerto Rican Population

    PubMed Central

    Orengo-Mercado, Carmelo; Nieves, Bianca; López, Lizbeth; Vallés-Ortiz, Nabila; Renta, Jessicca Y.; Santiago-Borrero, Pedro J.; Cadilla, Carmen L.; Duconge, Jorge

    2013-01-01

    Objective This cross-sectional study was aimed at determining the allele frequencies for the CYP2C19*2, CYP2C19*3, CYP2D6*10 and PON1 (rs662) polymorphisms in the Puerto Rican population. The CYP2C19, CYP2D6 and PON1 genes are known to be associated with functional changes in drug metabolism and activation. Individuals carrying the aforementioned polymorphisms are at a higher risk of suffering from drug-induced adverse events and/ or unresponsiveness from a variety of drugs that includes antidepressants, atypical antipsychotics and antiplatelet compounds. Information on the frequency of these polymorphisms is more commonly found on homogeneous populations, but is scarce in highly heterogeneous populations like Hispanics, as in the case of Puerto Ricans. Method Genotyping was carried out in 100 genomic DNA samples from dried blood spots supplied by the Puerto Rican Newborn Screening program using Taqman® Genotyping Assays. Results The Minor Allele Frequencies (MAF) obtained were 9% for CYP2C19*2 and CYP2D6*10, 50% for PON1 (rs662), while the CYP2C19*3 variant was not detected in our study. Furthermore, Hardy Weinberg equilibrium analysis was assessed as well as a comparison between Puerto Rico and other reference populations using a Z-test for proportions. Conclusion The observed allele and genotype frequencies on these relevant pharmacogenes in Puerto Ricans were more closely related to those early reported in two other reference populations of Americans (Mexicans and Colombians). PMID:24040574

  12. Population pharmacokinetic meta-analysis of vortioxetine in healthy individuals.

    PubMed

    Areberg, Johan; Petersen, Kamilla B; Chen, Grace; Naik, Himanshu

    2014-12-01

    The objective was to describe the pharmacokinetics of vortioxetine and evaluate the effect of intrinsic and extrinsic factors in the healthy population. Data from 26 clinical pharmacology studies were pooled. A total of 21,758 vortioxetine quantifiable plasma concentrations were collected from 887 subjects with corresponding demography. The doses ranged from 2.5 to 75 mg (single dose) and 2.5-60 mg (multiple QD doses). The pharmacokinetics of vortioxetine was best characterised by a two-compartment model with first-order absorption, lag-time and linear elimination, with interindividual error terms for absorption rate constant, oral clearance and central volume of distribution. The population mean was 32.7 L/hr for oral clearance and 1.97∙10(3)  L for the central volume of distribution. The average elimination half-life was 65.8 hr. CYP2D6 inferred metabolic status (ultra, extensive, intermediate or poor metabolisers) and age on oral clearance and height on central volume of distribution were identified as statistically significant covariate-parameter relationships. For CYP2D6 poor metabolisers, CL/F was approximately 50% to that seen in CYP2D6 extensive metabolisers. The impact of height on V2/F and age on CL/F was low and not considered to be clinically relevant. The final model was found to be reliable, stable and predictive. A reliable, stable and predictive pharmacokinetic model was developed to characterise pharmacokinetics of vortioxetine in the healthy population. PMID:24766668

  13. Biotransformation and pharmacokinetics of ethylmorphine after a single oral dose.

    PubMed Central

    Aasmundstad, T A; Xu, B Q; Johansson, I; Ripel, A; Bjørneboe, A; Christophersen, A S; Bodd, E; Mørland, J

    1995-01-01

    1. The pharmacokinetics of ethylmorphine after administration of a single dose of the cough mixture Cosylan were investigated in 10 healthy subjects. 2. The median urinary recovery of ethylmorphine and measured metabolites was 77% over 48 h. The median tmax of unchanged ethylmorphine was 45 min, and the terminal elimination t1/2 was 2 h. Ethylmorphine-6-glucuronide was found to be the major metabolite. 3. Two subjects had significantly lower urinary recovery (0.48 h) of morphine and morphine-glucuronides than the remainder. Furthermore, these two had urinary metabolic ratios (MRO) and partial metabolic clearances (CLmO) for O-deethylation of ethylmorphine tentatively classifying them phenotypically as poor metabolisers of the debrisoquine/sparteine type. 4. Genotyping for cytochrome P450 (CYP) 2D6 alleles revealed five homozygote (wt/wt) and five heterozygote subjects. Two subjects phenotypically classified as poor metabolisers were genotypically CYP2D6A/wt and CYP2D6D/wt, respectively. 5. Serum and urine samples taken more than 8 and 24 h after administration of ethyl-morphine respectively, contained morphine and morphine-glucuronides, but no ethylmorphine, ethylmorphine-6-glucuronide or (serum only) norethylmorphine. Norethylmorphine could be detected after hydrolysis of urine samples in all subjects. The urinary recovery of the active metabolites morphine and morphine-6-glucuronide after administration of ethylmorphine varied by a factor of 9 between individuals. 6. The wide variation in recovery of morphine and morphine-glucuronides after oral administration of ethylmorphine could not be explained simply by a difference in CYP2D6 genotype. Constitutional variation in other enzymatic pathways involved in ethylmorphine metabolism is probably crucial. Ratios of morphine to parent drug cannot be used to distinguish the source of morphine after administration of ethylmorphine. Norethylmorphine should be included in urine assays for opiates in forensic toxicology

  14. Development of a cell viability assay to assess drug metabolite structure-toxicity relationships.

    PubMed

    Rana, Payal; Will, Yvonne; Nadanaciva, Sashi; Jones, Lyn H

    2016-08-15

    Many adverse drug reactions are caused by the cytochrome P450 (CYP)-dependent activation of drugs into reactive metabolites. In order to reduce attrition due to metabolism-induced toxicity and to improve the safety of drug candidates, we developed a simple cell viability assay by combining a bioactivation system (human CYP3A4, CYP2D6 and CYP2C9) with Hep3B cells. We screened a series of drugs to explore structural motifs that may be responsible for CYP450-dependent activation caused by reactive metabolite formation, which highlighted specific liabilities regarding certain phenols and anilines. PMID:27397500

  15. Alternative Sampling Strategies for Cytochrome P450 Phenotyping.

    PubMed

    De Kesel, Pieter M M; Lambert, Willy E; Stove, Christophe P

    2016-02-01

    Interindividual variability in the expression and function of drug metabolizing cytochrome P (CYP) 450 enzymes, determined by a combination of genetic, non-genetic and environmental parameters, is a major source of variable drug response. Phenotyping by administration of a selective enzyme substrate, followed by the determination of a specific phenotyping metric, is an appropriate approach to assess the in vivo activity of CYP450 enzymes as it takes into account all influencing factors. A phenotyping protocol should be as simple and convenient as possible. Typically, phenotyping metrics are determined in traditional matrices, such as blood, plasma or urine. Several sampling strategies have been proposed as an alternative for these traditional sampling techniques. In this review, we provide a comprehensive overview of available methods using dried blood spots (DBS), hair, oral fluid, exhaled breath and sweat for in vivo CYP450 phenotyping. We discuss the relation between phenotyping metrics measured in these samples and those in conventional matrices, along with the advantages and limitations of the alternative sampling techniques. Reliable phenotyping procedures for several clinically relevant CYP450 enzymes, including CYP1A2, CYP2C19 and CYP2D6, are currently available for oral fluid, breath or DBS, while additional studies are needed for other CYP450 isoforms, such as CYP3A4. The role of hair analysis for this purpose remains to be established. Being non- or minimally invasive, these sampling strategies provide convenient and patient-friendly alternatives for classical phenotyping procedures, which may contribute to the implementation of CYP450 phenotyping in clinical practice. PMID:26239501

  16. In vitro evaluation of cytochrome P450 induction and the inhibition potential of mitragynine, a stimulant alkaloid.

    PubMed

    Lim, Ee Lin; Seah, Tiong Chai; Koe, Xue Fen; Wahab, Habibah Abdul; Adenan, Mohd Ilham; Jamil, Mohd Fadzly Amar; Majid, Mohamed Isa Abdul; Tan, Mei Lan

    2013-03-01

    CYP450 enzymes are key determinants in drug toxicities, reduced pharmacological effect and adverse drug reactions. Mitragynine, an euphoric compound was evaluated for its effects on the expression of mRNAs encoding CYP1A2, CYP2D6 and CYP3A4 and protein expression and resultant enzymatic activity. The mRNA and protein expression of CYP450 isoforms were carried out using an optimized multiplex qRT-PCR assay and Western blot analysis. CYP1A2 and CYP3A4 enzyme activities were evaluated using P450-Glo™ assays. The effects of mitragynine on human CYP3A4 protein expression were determined using an optimized hCYP3A4-HepG2 cell-based assay. An in silico computational method to predict the binding conformation of mitragynine to the active site of the CYP3A4 enzyme was performed and further validated using in vitro CYP3A4 inhibition assays. Mitragynine was found to induce mRNA and protein expression of CYP1A2. For the highest concentration of 25 μM, induction of mRNA was approximately 70% that of the positive control and was consistent with the increased CYP1A2 enzymatic activity. Thus, mitragynine is a significant in vitro CYP1A2 inducer. However, it appeared to be a weak CYP3A4 inducer at the transcriptional level and a weak CYP3A4 enzyme inhibitor. It is therefore, unlikely to have any significant clinical effects on CYP3A4 activity. PMID:23274770

  17. Biopharmaceutical characterization, metabolism, and brain penetration of the triple reuptake inhibitor amitifadine.

    PubMed

    Bymaster, Frank P; Chao, Piyun; Schulze, Heidi; Tran, Pierre V; Marshall, Randall D

    2013-03-01

    Amitifadine (EB-1010, formerly DOV 21,947) is a serotonin-preferring triple reuptake inhibitor that is a drug candidate for major depressive disorder. We investigated several relevant biopharmaceutic and drug-like characteristics of amitifadine using in vitro methodology and additionally determined the in vivo brain to plasma ratio of the drug in rats. Amitifadine was highly plasma protein bound with over 99% of drug bound to human plasma proteins. Using Caco-2 cell lines, amitifadine was bidirectionally highly permeable and showed no evidence of active secretion. Amitifadine was metabolized slowly by human hepatocytes and the major metabolite was the lactam EB-10101. In vitro studies using human liver microsomes demonstrated that EB-10101 was formed by monoamine oxidase A (MAO-A) and a NADPHdependent enzyme, possibly a cytochrome P450 (CYP) isoform. Amitifadine was a moderate inhibitor of the human isoforms of the major drug metabolizing enzymes CYP2D6, CYP3A4, CYP2C9, and CYP2C19 (IC50 = 9 - 100 μM), but was a potent inhibitor of human CYP2B6 (IC50 = 1.8 μM). The brain to plasma ratio for amitifadine varied from 3.7 - 6.5 at various time points, indicating preferential partitioning into rat brain versus plasma. The low affinity for the major drug metabolizing CYP enzymes and metabolism by multiple pathways may reduce pharmacokinetic drug-drug interactions and effects of enzyme polymorphisms. Overall, these studies suggest that amitifadine has drug-like characteristics favorable for drug development. PMID:23826879

  18. Food Enzymes

    ERIC Educational Resources Information Center

    McBroom, Rachel; Oliver-Hoyo, Maria T.

    2007-01-01

    Many students view biology and chemistry as two unrelated, separate sciences; how these courses are generally taught in high schools may do little to change that impression. The study of enzymes provide a great opportunity for both biology and chemistry teachers to share with students the interdisciplinary nature of science. This article describes…

  19. Zinc Enzymes.

    ERIC Educational Resources Information Center

    Bertini, I.; And Others

    1985-01-01

    Discusses the role of zinc in various enzymes concerned with hydration, hydrolysis, and redox reactions. The binding of zinc to protein residues, properties of noncatalytic zinc(II) and catalytic zinc, and the reactions catalyzed by zinc are among the topics considered. (JN)

  20. Effects of OCT1 polymorphisms on the cellular uptake, plasma concentrations and efficacy of the 5-HT(3) antagonists tropisetron and ondansetron.

    PubMed

    Tzvetkov, M V; Saadatmand, A R; Bokelmann, K; Meineke, I; Kaiser, R; Brockmöller, J

    2012-02-01

    After uptake into liver cells, the antiemetic drugs tropisetron and ondansetron undergo metabolic inactivation by cytochrome P450 2D6 (CYP2D6). We investigated whether the hepatic organic cation transporter 1 (OCT1; SLC22A1) mediates cellular uptake and whether common OCT1 loss-of-function polymorphisms affect pharmacokinetics and efficacy of both drugs. Both tropisetron and ondansetron inhibited ASP(+) uptake in OCT1-overexpressing HEK293 cells. Overexpression of wild-type, but not OCT1 loss-of-function variants, significantly increased tropisetron uptake. Correspondingly, patients with two loss-of-function OCT1 alleles had higher tropisetron plasma concentrations (n=59, P<0.04) and higher clinical efficacy (n=91, P=0.009) compared with carriers of fully active OCT1. Overexpression of OCT1 did not increase ondansetron uptake. Nevertheless, OCT1 genotypes correlated with pharmacokinetics (n=45, P<0.05) and clinical efficacy (n=222, P<0.02) of ondansetron, the effect size of OCT1 genotypes on pharmacokinetics and efficacy was greater for tropisetron than for ondansetron. In conclusion, in addition to the known effects of CYP2D6, OCT1 deficiency may increase efficacy of tropisetron and potentially of ondansetron by limiting their hepatic uptake. PMID:20921968

  1. The Curious Case of Benzbromarone: Insight into Super-Inhibition of Cytochrome P450

    PubMed Central

    Parashar, Abhinav; Gade, Sudeep Kumar; Potnuru, Mahesh; Madhavan, Nandita; Manoj, Kelath Murali

    2014-01-01

    Cytochrome P450 (CYP) family of redox enzymes metabolize drugs and xenobiotics in liver microsomes. Isozyme CYP2C9 is reported to be inhibited by benzbromarone (BzBr) and this phenomenon was hitherto explained by classical active-site binding. Theoretically, it was impossible to envisage the experimentally derived sub-nM Ki for an inhibitor, when supra-nM enzyme and 10X KM substrate concentrations were employed. We set out to find a more plausible explanation for this highly intriguing “super-inhibition” phenomenon. In silico docking of various BzBr analogs with known crystal structure of CYP2C9 did not provide any evidence in support of active-site based inhibition hypothesis. Experiments tested the effects of BzBr and nine analogs on CYPs in reconstituted systems of lab-purified proteins, complex baculosomes & crude microsomal preparations. In certain setups, BzBr and its analogs could even enhance reactions, which cannot be explained by an active site hypothesis. Generally, it was seen that Ki became smaller by orders of magnitude, upon increasing the dilution order of BzBr analogs. Also, it was seen that BzBr could also inhibit other CYP isozymes like CYP3A4, CYP2D6 and CYP2E1. Further, amphipathic derivatives of vitamins C & E (scavengers of diffusible reactive oxygen species or DROS) effectively inhibited CYP2C9 reactions in different reaction setups. Therefore, the inhibition of CYP activity by BzBr analogs (which are also surface-active redox agents) is attributed to catalytic scavenging of DROS at phospholipid interface. The current work expands the scope of interpretations of inhibitions in redox enzymes and ushers in a new cellular biochemistry paradigm that small amounts of DROS may be obligatorily required in routine redox metabolism for constructive catalytic roles. PMID:24594849

  2. Drug metabolism and transport during pregnancy: how does drug disposition change during pregnancy and what are the mechanisms that cause such changes?

    PubMed

    Isoherranen, Nina; Thummel, Kenneth E

    2013-02-01

    There is increasing evidence that pregnancy alters the function of drug-metabolizing enzymes and drug transporters in a gestational-stage and tissue-specific manner. In vivo probe studies have shown that the activity of several hepatic cytochrome P450 enzymes, such as CYP2D6 and CYP3A4, is increased during pregnancy, whereas the activity of others, such as CYP1A2, is decreased. The activity of some renal transporters, including organic cation transporter and P-glycoprotein, also appears to be increased during pregnancy. Although much has been learned, significant gaps still exist in our understanding of the spectrum of drug metabolism and transport genes affected, gestational age-dependent changes in the activity of encoded drug metabolizing and transporting processes, and the mechanisms of pregnancy-induced alterations. In this issue of Drug Metabolism and Disposition, a series of articles is presented that address the predictability, mechanisms, and magnitude of changes in drug metabolism and transport processes during pregnancy. The articles highlight state-of-the-art approaches to studying mechanisms of changes in drug disposition during pregnancy, and illustrate the use and integration of data from in vitro models, animal studies, and human clinical studies. The findings presented show the complex inter-relationships between multiple regulators of drug metabolism and transport genes, such as estrogens, progesterone, and growth hormone, and their effects on enzyme and transporter expression in different tissues. The studies provide the impetus for a mechanism- and evidence-based approach to optimally managing drug therapies during pregnancy and improving treatment outcomes. PMID:23328895

  3. The effects of commercial preparations of herbal supplements commonly used by women on the biotransformation of fluorogenic substrates by human cytochromes P450.

    PubMed

    Ho, Shirley H Y; Singh, Mohini; Holloway, Alison C; Crankshaw, Denis J

    2011-07-01

    The study set out to determine the potential for commercially available preparations of black cohosh (Actaea racemosa), chaste tree berry (Vitex agnus-castus), crampbark (Viburnum opulus) and false unicorn (Chamaelirium luteum) to inhibit the major human drug metabolizing enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 as well as CYP1A1 which activates some carcinogens. In vitro microplate-based assays using cDNA-expressed CYP450 isoforms and fluorogenic substrates were used. Components of the commercial herbal preparations interfered with the assays and limited the concentration ranges that could be tested. Nevertheless, the fluorogenic assays were robust, reproducible and easy to perform and thus are still useful for initial screening for potential herb-drug interactions. None of the preparations affected CYPs 1A1 or 2C9 at the concentrations tested but all preparations inhibited some of the enzymes with potencies around 1 μg/mL. The three most potent interactions were: chaste tree berry and CYP2C19 (IC₅₀) 0.22 μg/mL); chaste tree berry and CYP3A4 (IC₅₀) 0.3 μg/mL); black cohosh and CYP2C19 (IC₅₀) 0.37 μg/mL,). Thus, the study successfully identified the potential for the commercial herbal preparations to inhibit human drug metabolizing enzymes. Whether this potential translates into clinically significant herb-drug interactions can only be confirmed by appropriate in vivo studies. PMID:21213356

  4. In Vitro and in Vivo Inhibitory Effects of Glycyrrhetinic Acid in Mice and Human Cytochrome P450 3A4

    PubMed Central

    Lv, Qiao-Li; Wang, Gui-Hua; Chen, Shu-Hui; Hu, Lei; Zhang, Xue; Ying, Guo; Qin, Chong-Zhen; Zhou, Hong-Hao

    2015-01-01

    Glycyrrhetinic acid (GA) has been used clinically in the treatment of patients with chronic hepatitis. This study evaluated the effect of GA on the activity of five P450(CYP450) cytochrome enzymes: CYP2A6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, in human liver microsomes (HLMs) and recombinant cDNA-expressed enzyme systems using a HPLC-MS/MS CYP-specific probe substrate assay. With midazolam as the probe substrate, GA greatly decreased CYP3A4 activity with IC50 values of 8.195 μM in HLMs and 7.498 μM in the recombinant cDNA-expressed CYP3A4 enzyme system, respectively. It significantly decreased CYP3A4 activity in a dose- but not time-dependent manner. Results from Lineweaver–Burk plots showed that GA could inhibit CYP3A4 activity competitively, with a Ki value of 1.57 μM in HLMs. Moreover, CYP2C9 and CYP2C19 could also be inhibited significantly by GA with IC50 of 42.89 and 40.26 μM in HLMs, respectively. Other CYP450 isoforms were not markedly affected by GA. The inhibition was also confirmed by an in vivo study of mice. In addition, it was observed that mRNA expressions of the Cyps2c and 3a family decreased significantly in the livers of mice treated with GA. In conclusion, this study indicates that GA may exert herb-drug interactions by competitively inhibiting CYP3A4. PMID:26712778

  5. Metabolism-mediated drug interaction potential of HS-23, a new herbal drug for the treatment of sepsis in human hepatocytes and liver microsomes.

    PubMed

    Jeong, Hyeon-Uk; Lee, Ji Young; Kwon, Soon-Sang; Kim, Ju Hyun; Kim, Young-Mok; Hong, Sung-Woon; Yeon, Sung Hum; Lee, Sun-Mee; Cho, Yong-Yeon; Lee, Hye Suk

    2015-02-01

    HS-23, an extract of the dried flower buds of Lonicera japonica, is a new botanical drug currently being evaluated in a phase I clinical study in Korea for the treatment of sepsis. The in vitro induction and inhibition potentials of HS-23 on the drug-metabolizing enzymes using human hepatocytes and liver microsomes were assessed to evaluate herb-drug interaction according to botanical drug guideline and drug interaction guidance of FDA. HS-23 slightly inhibited CYP2A6, CYP2B6, CYP2C9, CYP2C19, and CYP3A4 enzyme activities in human liver microsomes with IC50 values of 80.6, 160.7, 169.5, 85.4, and 76.6 μg/mL, respectively. HS-23 showed negligible inhibition of CYP1A2, CYP2C8, CYP2D6, UGT1A1, UGT1A4, UGT1A9, and UGT2B7 activities in human liver microsomes. Based on these results, HS-23 may not inhibit the metabolism of CYP2A6, CYP2B6, CYP2C9, CYP2C19, and CYP3A4-catalyzed drugs in humans. HS-23 did not affect the mRNA expression of CYP1A2, CYP2B6, and CYP3A4 after 48 h treatment at three concentrations (0.5, 5, and 50 μg/mL) in three independent human hepatocytes, indicating that HS-23 has no effect on herb-drug interactions that up- or down-regulate CYP1A2, CYP2B6, and CYP3A4. These results indicate that the administration of HS-23 in human may not cause clinically relevant inhibition and induction of these cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT) enzymes and HS-23 may be promising therapeutic agent for treatment of sepsis. PMID:25052959

  6. Primary enzyme quantitation

    DOEpatents

    Saunders, G.C.

    1982-03-04

    The disclosure relates to the quantitation of a primary enzyme concentration by utilizing a substrate for the primary enzyme labeled with a second enzyme which is an indicator enzyme. Enzyme catalysis of the substrate occurs and results in release of the indicator enzyme in an amount directly proportional to the amount of primary enzyme present. By quantifying the free indicator enzyme one determines the amount of primary enzyme present.

  7. The wild Egyptian artichoke as a promising functional food for the treatment of hepatitis C virus as revealed via UPLC-MS and clinical trials.

    PubMed

    Elsebai, Mahmoud Fahmi; Abass, Khaled; Hakkola, Jukka; Atawia, Ahmed Rezk; Farag, Mohamed A

    2016-07-13

    Infection by hepatitis C virus (HCV) and its subsequent complications are a major cause of mortality worldwide. The water extract of the wild Egyptian artichoke (WEA) (Cynara cardunculus L. var. sylvestris (Lam.) Fiori) leaves is a freely available herbal product that is used for treatment of HCV-infection complications such as jaundice and ascites. The purpose of this study was to evaluate whether WEA exhibits activity against HCV, identify bioactive chemicals in its extract and to tentatively examine the potential inhibitory interactions of WEA with human drug-metabolizing enzymes. The current pilot clinical trial revealed that the water extract of a WEA plant decreased the HCV viral load below the detection level in 12 out of 15 patients. Furthermore, the liver enzymes ALT and AST, as well as the level of bilirubin were normalized. The total WEA extract inhibited CYP2B6 (OH-BUP) and CYP2C19 (5-OH-OME) with high affinity, IC50 ∼ 20 μg ml(-1), while moderate inhibitory interactions were observed for CYP1A2, CYP2D6, CYP2E1 and CYP3A4. Results presented herein suggest that the WEA exhibits strong antiviral activity against HCV and may be useful for its treatment. Compared to the artichoke product "Hepar SL Forte(®)", WEA was found to be more enriched in sesquiterpenes versus the abundance of phenolic compounds, especially flavonoids in Hepar SL Forte(®) as revealed via UPLC-MS analysis coupled to chemometrics. PMID:27296047

  8. Literature Based Drug Interaction Prediction with Clinical Assessment Using Electronic Medical Records: Novel Myopathy Associated Drug Interactions

    PubMed Central

    Subhadarshini, Abhinita; Karnik, Shreyas D.; Li, Xiaochun; Hall, Stephen D.; Jin, Yan; Callaghan, J. Thomas; Overhage, Marcus J.; Flockhart, David A.; Strother, R. Matthew; Quinney, Sara K.; Li, Lang

    2012-01-01

    Drug-drug interactions (DDIs) are a common cause of adverse drug events. In this paper, we combined a literature discovery approach with analysis of a large electronic medical record database method to predict and evaluate novel DDIs. We predicted an initial set of 13197 potential DDIs based on substrates and inhibitors of cytochrome P450 (CYP) metabolism enzymes identified from published in vitro pharmacology experiments. Using a clinical repository of over 800,000 patients, we narrowed this theoretical set of DDIs to 3670 drug pairs actually taken by patients. Finally, we sought to identify novel combinations that synergistically increased the risk of myopathy. Five pairs were identified with their p-values less than 1E-06: loratadine and simvastatin (relative risk or RR = 1.69); loratadine and alprazolam (RR = 1.86); loratadine and duloxetine (RR = 1.94); loratadine and ropinirole (RR = 3.21); and promethazine and tegaserod (RR = 3.00). When taken together, each drug pair showed a significantly increased risk of myopathy when compared to the expected additive myopathy risk from taking either of the drugs alone. Based on additional literature data on in vitro drug metabolism and inhibition potency, loratadine and simvastatin and tegaserod and promethazine were predicted to have a strong DDI through the CYP3A4 and CYP2D6 enzymes, respectively. This new translational biomedical informatics approach supports not only detection of new clinically significant DDI signals, but also evaluation of their potential molecular mechanisms. PMID:22912565

  9. A pharmacogenetic study of docetaxel and thalidomide in patients with castration-resistant prostate cancer using the DMET genotyping platform.

    PubMed

    Deeken, J F; Cormier, T; Price, D K; Sissung, T M; Steinberg, S M; Tran, K; Liewehr, D J; Dahut, W L; Miao, X; Figg, W D

    2010-06-01

    The anticancer agent docetaxel shows significant inter-individual variation in its pharmacokinetic and toxicity profile. Thalidomide is an active anticancer agent and also shows wide pharmacological variation. Past pharmacogenetic research has not explained this variation. Patients with prostate cancer enrolled in a randomized phase II trial using docetaxel and thalidomide versus docetaxel alone were genotyped using the Affymetrix DMET 1.0 platform, which tests for 1256 genetic variations in 170 drug disposition genes. Genetic polymorphisms were analyzed for associations with clinical response and toxicity. In all, 10 single-nucleotide polymorphisms (SNPs) in three genes were potentially associated with response to therapy: peroxisome proliferator-activated receptor-delta (PPAR-delta), sulfotransferase family, cytosolic, 1C, member 2 (SULT1C2) and carbohydrate (chondroitin 6) sulfotransferase 3 (CHST3). In addition, 11 SNPs in eight genes were associated with toxicities to treatment: spastic paraplegia 7 (pure and complicated autosomal recessive) (SPG7), CHST3, cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6), N-acetyltransferase 2 (arylamine N-acetyltransferase) (NAT2), ATP-binding cassette, sub-family C (CFTR/MRP), member 6 (ABCC6), ATPase, Cu++ transporting, alpha polypeptide (ATP7A), cytochrome P450, family 4, subfamily B, polypeptide 1 (CYP4B1) and solute carrier family 10 (sodium/bile acid cotransporter family), member 2 (SLC10A2). Genotyping results between drug metabolizing enzymes and transporters (DMET) and direct sequencing showed >96% of concordance. These findings highlight the role that non-CYP450 metabolizing enzymes and transporters may have in the pharmacology of docetaxel and thalidomide. PMID:20038957

  10. Advantages of human hepatocyte-derived transformants expressing a series of human cytochrome p450 isoforms for genotoxicity examination.

    PubMed

    Hashizume, Tsuneo; Yoshitomi, Sumie; Asahi, Satoru; Uematsu, Rieko; Matsumura, Shigeo; Chatani, Fumio; Oda, Hiroaki

    2010-08-01

    Metabolites of chemicals can often be ultimate genotoxic species; thus, in vitro routine testing requires the use of rat liver S9. However, there is a question as to whether this represents an appropriate surrogate for human metabolism. We have previously demonstrated the usefulness of HepG2 transformants expressing major human cytochrome P450 (CYP) isoforms to assess the genotoxicity of metabolites. We further assessed the advantages of these transformants from the following three aspects. First, the sensitivity of these transformants was confirmed with micronucleus (MN) induction by 7,12-dimethylbenz[a]anthracene or ifosfamide in transformants expressing the corresponding CYP1A1 or CYP2B6 and CYP2C9, respectively. Second, by using these transformants, beta-endosulfan, a chemical for which the CYP isoforms contributing to its genotoxicity are unknown, was found to induce MN through the CYP3A4-mediated pathway. This result was confirmed by the facts that the decreased CYP3A4 activity using a inhibitor or short interfering RNA (siRNA) repressed MN induction by beta-endosulfan and that endosulfan sulfate, one of the metabolites produced by CYP3A4, induced MN in the transformants harboring an empty vector. Third, the interaction between phase I and II drug-metabolizing enzymes was demonstrated by MN induction with inhibitors of uridine diphosphate (UDP)-glucuronosyltransferases in tamoxifen-treated transformants harboring the corresponding CYP3A4 or with inhibitors of glutathione S-transferase in safrole-treated transformants harboring the corresponding CYP2D6, whereas neither tamoxifen nor safrole alone induced MN in any transformant. These advantages provide the benefits of newly established transformants for in vitro genotoxicity testing that reflects comprehensive metabolic pathways including not only human CYP isoforms but also the phase II enzymes. PMID:20507880

  11. Identification of in vitro metabolites of ethylphenidate by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

    PubMed

    Negreira, Noelia; Erratico, Claudio; van Nuijs, Alexander L N; Covaci, Adrian

    2016-01-01

    Ethylphenidate is a new potent synthetic psychoactive drug, structurally related to methylphenidate. Using human liver microsomes and cytosol, we have investigated for the first time the Phase-I and Phase-II in vitro metabolism of ethylphenidate. The structure of the metabolites was elucidated by hybrid quadrupole time-of-flight mass spectrometry. Overall, seven Phase-I, but no Phase-II metabolites were detected. Ethylphenidate underwent hydroxylation forming two primary mono-hydroxylated metabolites and, subsequently, dehydration and ring opening with an additional hydroxylation, forming secondary metabolites. The involvement of different human cytochrome P450 (CYP) enzymes in the formation of ethylphenidate metabolites was investigated using a panel of human recombinant CYPs (rCYPs). rCYP2C19 was the most active recombinant enzyme involved in the formation of all seven