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Sample records for floating matrix tablets

  1. Formulation and evaluation of floating matrix tablet of stavudine

    PubMed Central

    Prajapati, Pankaj H; Nakum, Vijay V; Patel, Chhagan N

    2012-01-01

    Background/Aim: The purpose of the study was to prolong the gastric residence time of stavudine by designing its floating tablets and to study the influence of different polymers on its release rate. Materials and Methods: The floating mix matrix tablets of stavudine were prepared by melt granulation method. Beeswax was used as hydrophobic meltable material. Hydroxypropyl methylcellulose (HPMC), sodium bicarbonate, and ethyl cellulose were used as matrixing agent, gas generating agent, and floating enhancer, respectively. The prepared tablets were evaluated for physicochemical parameters such as hardness, weight variation, friability, floating properties (floating lag time, total floating time), drug content, stability study, and in vitro drug release. The drug- polymer interaction was studied by Differential Scanning Calorimetry (DSC) thermal analysis and Fourier transform infared (FT-IR). Results: The floating lag time of all the formulations was within the prescribed limit (<3 min). All the formulations showed good matrix integrity and retarded the release of drug for 12 h except the formulation F5.The concentration of beeswax (X1), HPMC K4M (X2), and ethyl cellulose (X3) were selected as independent variables and drug release values at 1 (Q1), at 6 (Q6) and at 12 h (Q12) as dependent variables. Formulation F7 was selected as an optimum formulation as it showed more similarity in dissolution profile with theoretical profile (similarity factor, f2 = 70.91). The dissolution of batch F7 can be described by zero-order kinetics (R2 =0.9936) with anomalous (non-Fickian) diffusion as the release mechanism (n=0.545). There was no difference observed in release profile after temperature sensitivity study at 40°C/75% relative humidity (RH) for 1 month. Conclusion: It can be concluded from this study that the combined mix matrix system containing hydrophobic and hydrophilic polymer minimized the burst release of drug from the tablet and achieved a drug release by zero-order kinetics, which is practically difficult with only hydrophilic matrix. PMID:23119237

  2. Design, Development and Optimization of S (-) Atenolol Floating Sustained Release Matrix Tablets Using Surface Response Methodology.

    PubMed

    Gunjal, P T; Shinde, M B; Gharge, V S; Pimple, S V; Gurjar, M K; Shah, M N

    2015-01-01

    The objective of this present investigation was to develop and formulate floating sustained release matrix tablets of s (-) atenolol, by using different polymer combinations and filler, to optimize by using surface response methodology for different drug release variables and to evaluate the drug release pattern of the optimized product. Floating sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: Hydroxypropyl methylcellulose, sodium bicarbonate as a gas generating agent, polyvinyl pyrrolidone as a binder and lactose monohydrate as filler. The 3(2) full factorial design was employed to investigate the effect of formulation variables on different properties of tablets applicable to floating lag time, buoyancy time, % drug release in 1 and 6 h (D1 h,D6 h) and time required to 90% drug release (t90%). Significance of result was analyzed using analysis of non variance and P < 0.05 was considered statistically significant. S (-) atenolol floating sustained release matrix tablets followed the Higuchi drug release kinetics that indicates the release of drug follows anomalous (non-Fickian) diffusion mechanism. The developed floating sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet. PMID:26798171

  3. Design, Development and Optimization of S (-) Atenolol Floating Sustained Release Matrix Tablets Using Surface Response Methodology

    PubMed Central

    Gunjal, P. T.; Shinde, M. B.; Gharge, V. S.; Pimple, S. V.; Gurjar, M. K.; Shah, M. N.

    2015-01-01

    The objective of this present investigation was to develop and formulate floating sustained release matrix tablets of s (-) atenolol, by using different polymer combinations and filler, to optimize by using surface response methodology for different drug release variables and to evaluate the drug release pattern of the optimized product. Floating sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: Hydroxypropyl methylcellulose, sodium bicarbonate as a gas generating agent, polyvinyl pyrrolidone as a binder and lactose monohydrate as filler. The 32 full factorial design was employed to investigate the effect of formulation variables on different properties of tablets applicable to floating lag time, buoyancy time, % drug release in 1 and 6 h (D1 h,D6 h) and time required to 90% drug release (t90%). Significance of result was analyzed using analysis of non variance and P < 0.05 was considered statistically significant. S (-) atenolol floating sustained release matrix tablets followed the Higuchi drug release kinetics that indicates the release of drug follows anomalous (non-Fickian) diffusion mechanism. The developed floating sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet. PMID:26798171

  4. Swellable floating tablet based on spray-dried casein nanoparticles: Near-infrared spectral characterization and floating matrix evaluation.

    PubMed

    Elzoghby, Ahmed O; Vranic, Branko Z; Samy, Wael M; Elgindy, Nazik A

    2015-08-01

    In this study, spray-dried alfuzosin hydrochloride (ALF)-loaded casein (CAS) nanoparticles were successfully used for the preparation of a swellable floating matrix via direct compression. The developed NIR calibration model was able to assess ALF and CAS levels in five different batches of drug-loaded nanoparticles. The calibration and prediction plots exhibited good linearity with correlation coefficients of more than 0.9. The standard error of calibration and cross-validation was less than 5% of the measured values, confirming the accuracy of the model. A linear relationship was obtained correlating the actual drug entrapped and the predicted values obtained from the NIR partial least squares regression model. The un-crosslinked tablet demonstrated a substantial weight gain (317% after 2h) and completely disintegrated after 3-4h whereas both 10 and 40% w/w genipin-crosslinked tablets showed lower weight gain (114 and 42% after 2h, respectively). A rapid floating of the tablets within 5-15min (compared to 45min for the marketed tablet) was observed, with maintained floating for 24h. Marketed and prepared tablets succeeded to prolong ALF release for 24h. The development of drug-loaded CAS nanoparticles using spray-drying represents a new alternative for the preparation of swellable floating tablets for prolonged drug release. PMID:26095913

  5. Sustained-release effervescent floating matrix tablets of baclofen: development, optimization and in vitro-in vivo evaluation in healthy human volunteers

    PubMed Central

    Gande, S

    2011-01-01

    Background and the purpose of the study Baclofen, a centrally acting skeletal muscle relaxant, is indicated in the long-term treatment of spasticity. It is difficult to formulate baclofen sustained release dosage forms because its absorption on arrival to colon (or even before) is low or nonexistent. In the present investigation efforts were made to improve the bioavailability of baclofen by increasing the residence time of the drug through sustained-release matrix tablet formulation via gastroretentive mechanism. Methods Tablets were prepared by wet granulation technique. The influence of gas generating and gel forming agents, amount of baclofen and total weight of tablet on physical properties, in vitro buoyancy, floating lag time, drug release, DSC, X-ray studies were investigated. The release mechanisms were explored and explained by applying zero order, first order, Higuchi and Korsmeyer equations. The selected formulations were subjected to stability study for the period of three months. Results For all formulations, kinetics of drug release from tablet followed Higuchi's square root of time kinetic treatment heralding diffusion as predominant mechanism of drug release. Formulations containing 20 mg and 40 mg (F-1 and F-7) showed similar release profiles. There was no significant change in the selected formulations, when subjected to accelerated stability conditions over a period of three months. X-ray imaging in six healthy human volunteers revealed a mean gastric retention period of 5.50±0.7 hrs for the selected formulation. Conclusion Stable, sustained release effervescent floating matrix tablets of baclofen could be prepared by wet granulation technique. PMID:22615658

  6. Preparation and evaluation of gastroretentive floating tablets of Silymarin.

    PubMed

    Garg, Rajeev; Gupta, Ghanshyam Das

    2009-06-01

    The present study performed by preparation and evaluation of floating tablets of Silymarin as model drug for prolongation of gastric residence time. Floating effervescent tablets were formulated by various materials like hydroxypropyl methylcellulose (HPMC) K 4M, K 15M, psyllium husk, swelling agent as crospovidone and microcrystalline cellulose and gas generating agent like sodium bicarbonate and citric acid and evaluated for floating properties, swelling characteristics and in vitro drug release studies. Floating noneffervescent tablets were prepared by polypropylene foam powder and different matrix forming polymers like HPMC K 4M, Carbopol 934P, xanthan gum and sodium alginate. In vitro drug release studies were performed and drug release kinetics evaluated using the linear regression method was found to follow both the Higuchi and the Korsemeyer and Peppas equation. The drug release mechanism was found fickian type in most of the formulations. The developed floating tablets of Silymarin may be used in clinic for prolonged drug release for at least 24 h, thereby improving the bioavailability and patient compliance. PMID:19483331

  7. Formulation and evaluation of effervescent floating tablets of tizanidine hydrochloride.

    PubMed

    Someshwar, Komuravelly; Chithaluru, Kalyani; Ramarao, Tadikonda; Kumar, K K Kalyan

    2011-06-01

    Tizanidine hydrochloride is an orally administered prokinetic agent that facilitates or restores motility through-out the length of the gastrointestinal tract. The objective of the present investigation was to develop effervescent floating matrix tablets of tizanidine hydrochloride for prolongation of gastric residence time in order to overcome its low bioavailability (34-40 %) and short biological half life (4.2 h). Tablets were prepared by the direct compression method, using different viscosity grades of hydroxypropyl methylcellulose (HPMC K4M, K15M and K100M). Tablets were evaluated for various physical parameters and floating properties. Further, tablets were studied for in vitro drug release characteristics in 12 hours. Drug release from effervescent floating matrix tablets was sustained over 12 h with buoyant properties. DSC study revealed that there is no drug excipient interaction. Based on the release kinetics, all formulations best fitted the Higuchi, first-order model and non-Fickian as the mechanism of drug release. Optimized formulation (F9) was selected based on the similarity factor (f2) (74.2), dissolution efficiency at 2, 6 and 8 h, and t50 (5.4 h) and was used in radiographic studies by incorporating BaSO4. In vivo X-ray studies in human volunteers showed that the mean gastric residence time was 6.2 ± 0.2 h. PMID:21684848

  8. Effect of formulation parameters on the drug release and floating properties of gastric floating two-layer tablets with acetylsalicylic acid.

    PubMed

    Hasçiçek, Canan; Yüksel-Tilkan, Günseli; Türkmen, Berna; Ozdemir, Nurten

    2011-09-01

    Floating dosage forms of acetylsalicylic acid, used for its antithrombotic effect, were developed to prolong gastric residence time and increase bioavailability. In the two-layer tablet formulation, hydroxypropyl methylcellulose (HPMC) of high viscosity and an effervescent mixture of citric acid and sodium bicarbonate formed the floating layer. The release layer contained the drug, direct tableting agent and different types of matrix-forming polymers such as HPMC of low viscosity, sodium carboxymethylcellulose and chitosan. Tablets were prepared using a direct compression technique. The effect of formulation variables on physicochemical and floating properties and the drug release from tablets were investigated. Floating ability was dependent on the amount of effervescent agent and gel-forming polymer of the floating layer. Drug release was prolonged to 8 hours by changing the type and viscosity of the matrix-forming polymer in the drug-loading layer and all formulations showed a diffusion release mechanisms. PMID:21945909

  9. Comparative evaluation of single and bilayered lamotrigine floating tablets

    PubMed Central

    Lakshmi, PK; Sridhar, M; Shruthi, B

    2013-01-01

    Aim: The purpose of this study was to prepare lamotrigine (LM) bilayered and single layered floating tablets and to compare their release profiles. Materials and Methods: LM floating tablets were prepared by direct compression method. Drug, hydroxy propyl methyl cellulose K4M, lactose monohydrate and polyvinylpyrrolidone K30 constitute controlled release layer components and floating layer components includes polymers and sodium bicarbonate. The prepared tablets were evaluated for physicochemical parameters such as hardness, friability, weight variation, thickness, floating lag time (FLT), floating time, in vitro buoyancy study, in vitro release studies. The drug-polymer interaction was studied by fourier transform infrared and differential scanning calorimetry. Results and Discussion: The FLT of all the formulations were within the prescribed limits (<3 min). When ethyl cellulose was used as floating layer component, tablets showed good buoyancy effect but eroded within 6-8 h. Hence it was replaced with hydroxypropyl cellulose -M hydrophilic polymer, which showed good FLT and floating duration for 16 h. Formulation LFC4 was found to be optimized with dissolution profile of zero order kinetics showing fickian diffusion. A comparative study of bilayered and single layered tablets of LM showed a highest similarity factor of 83.03, difference factor of 2.74 and t-test (P < 0.05) indicates that there is no significant difference between them. Conclusion: Though bilayered tablet possess many advantages, single layered tablet would be economical, cost-effective and reproducible for large scale production in the industry. However, the results of present study demonstrated that the in vitro development of bilayered gastro retentive floating tablets with controlled drug release profile for LM is feasible. PMID:24167788

  10. Preparation and evaluation of floating tablets of pregabalin.

    PubMed

    Kanwar, Navjot; Kumar, Rakesh; Sarwal, Amita; Sinha, V R

    2016-04-01

    Floating tablets of pregabalin were prepared using different concentrations of the gums (xanthan gum and guar gum), Carbopol 974P NF and HPMC K100. Optimized formulations were studied for physical tests, floating time, swelling behavior, in vitro release studies and stability studies. In vitro drug release was higher for tablet batches containing guar and xanthan gum as compared to the batches containing Carbopol 974P NF. Tablet batches were subjected to stability studies and evaluated by different parameters (drug release, drug content, FTIR and DSC studies). The optimized tablet batch was selected for in vivo pharmacodynamic studies (PTZ induced seizures). The results obtained showed that the onset of jerks and clonus were delayed and extensor phase was abolished with time in treated groups. A significant difference (p > 0.05) was observed in control and treated group behavior indicating an excellent activity of the formulation for a longer period (>12 h). PMID:26146770

  11. Formulation and evaluation of different floating tablets containing metronidazole to target stomach.

    PubMed

    Loh, Zhiao C; Elkordy, Amal A

    2015-01-01

    The purpose of this study is to formulate and develop tablets dosage form containing Metronidazole which has swelling and floating properties as a gastroretentive controlled-release drug delivery system to improve drug bioavailability. Fifteen different formulations of effervescence-forming floating systems were designed using HPMC K15M, xanthan gum, co-povidone, Eudragit® RL PO, pluronic® F-127 and/or polypropylene foam powder as swelling agents and sodium bicarbonate with/ without citric acid as gas-forming agents at different compositions. Six out of these 15 formulations which have satisfactory tablet floating behaviour were further studied with the incorporation of Metronidazole. The tablets were evaluated based on tablet physicochemical properties, floating behaviour, swelling ability and drug dissolution studies which were carried out using 0.1M HCl at 37°C for 8 hours. Furthermore, evaluation of the powder mixtures using Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscope (SEM) were investigated. Most of the tablets show good physicochemical properties except for F11 which contains pluronic® F-127 as its release-retarding matrix-forming polymer. Other formulations show high swelling capacity, ability to float for at least 8 hours in vitro and have sustained drug release characteristics. Data obtained indicated that F3 which contains HPMC (12.5%w/w), xanthan gum (25%w/w), co-povidone (12.5%w/w) and sodium bicarbonate (31.7%w/w) is a suitable formulation with short floating lag time, good floating behaviour and sustained drug release for at least 8 hours in vitro with a zero order kinetic. Combinations of HPMC K15M and xanthan gum as swelling agents show synergistic effect in retarding drug release and are suitable in providing the most sustained drug release system. PMID:25924732

  12. Design and evaluation of gastroretentive levofloxacin floating mini-tablets-in-capsule system for eradication of Helicobacter pylori.

    PubMed

    El-Zahaby, Sally A; Kassem, Abeer A; El-Kamel, Amal H

    2014-12-01

    Gastroretentive levofloxacin (LVF) floating mini-tablets for the eradication of Helicobacter pylori (H. pylori) were prepared using the matrix forming polymer hydroxypropyl methylcellulose (HPMC K100M), alone or with Carbopol 940P in different ratios by wet granulation technique. Buoyancy of mini-tablets was achieved by an addition of an effervescent mixture consisting of sodium bicarbonate and anhydrous citric acid to some formulations. The prepared mini-tablets were evaluated for weight variation, thickness, friability, hardness, drug content, in vitro buoyancy, water uptake and in vitro release. The optimized formula was subjected to further studies: FT-IR, DSC analysis and in vivo examination in healthy volunteers. The prepared mini-tablets exhibited satisfactory physicochemical characteristics. Incorporation of gas-generating agent improved the floating parameters. HPMC K100M mini-tablet formulation (F1) offered the best controlled drug release (>8 h) along with floating lag time <1 s and total floating time >24 h. The obtained DSC thermograms and FT-IR charts indicated that there is no positive evidence for the interaction between LVF and ingredients of the optimized formula. The in vivo test confirmed the success of the optimized formula F1 in being retained in the stomach of the volunteers for more than 4 h. LVF floating mini-tablets based on HPMC K100M is a promising formulation for eradication of H. pylori. PMID:25561871

  13. Design and evaluation of gastroretentive levofloxacin floating mini-tablets-in-capsule system for eradication of Helicobacter pylori

    PubMed Central

    El-Zahaby, Sally A.; Kassem, Abeer A.; El-Kamel, Amal H.

    2014-01-01

    Gastroretentive levofloxacin (LVF) floating mini-tablets for the eradication of Helicobacter pylori (H. pylori) were prepared using the matrix forming polymer hydroxypropyl methylcellulose (HPMC K100M), alone or with Carbopol 940P in different ratios by wet granulation technique. Buoyancy of mini-tablets was achieved by an addition of an effervescent mixture consisting of sodium bicarbonate and anhydrous citric acid to some formulations. The prepared mini-tablets were evaluated for weight variation, thickness, friability, hardness, drug content, in vitro buoyancy, water uptake and in vitro release. The optimized formula was subjected to further studies: FT-IR, DSC analysis and in vivo examination in healthy volunteers. The prepared mini-tablets exhibited satisfactory physicochemical characteristics. Incorporation of gas-generating agent improved the floating parameters. HPMC K100M mini-tablet formulation (F1) offered the best controlled drug release (>8 h) along with floating lag time <1 s and total floating time >24 h. The obtained DSC thermograms and FT-IR charts indicated that there is no positive evidence for the interaction between LVF and ingredients of the optimized formula. The in vivo test confirmed the success of the optimized formula F1 in being retained in the stomach of the volunteers for more than 4 h. LVF floating mini-tablets based on HPMC K100M is a promising formulation for eradication of H. pylori. PMID:25561871

  14. Development and in vivo floating behavior of verapamil HCl intragastric floating tablets.

    PubMed

    Patel, Anand; Modasiya, Moin; Shah, Dushyant; Patel, Vishnu

    2009-01-01

    A novel gastro retentive controlled release drug delivery system of verapamil HCl was formulated in an effort to increase the gastric retention time of the dosage form and to control drug release. Hydroxypropylmethylcellulose (HPMC), carbopol, and xanthan gum were incorporated for gel-forming properties. Buoyancy was achieved by adding an effervescent mixture of sodium bicarbonate and anhydrous citric acid. In vitro drug release studies were performed, and drug release kinetics was evaluated using the linear regression method. The optimized intragastric floating tablet composed of 3:2 of HPMC K4M to xanthan gum exhibited 95.39% drug release in 24 h in vitro, while the buoyancy lag time was 36.2 s, and the intragastric floating tablet remained buoyant for >24 h. Zero-order and non-Fickian release transport was confirmed as the drug release mechanism from the optimized formulation (F7). X-ray studies showed that total buoyancy time was able to delay the gastric emptying of verapamil HCl intragastric floating tablet in mongrel dogs for more than 4 h. Optimized intragastric floating tablet showed no significant change in physical appearance, drug content, total buoyancy time, or in vitro dissolution pattern after storage at 40 degrees C/75% relative humidity for 3 months. PMID:19296224

  15. Design and evaluation of effervescent floating tablets based on hydroxyethyl cellulose and sodium alginate using pentoxifylline as a model drug

    PubMed Central

    Rahim, Safwan Abdel; Carter, Paul A; Elkordy, Amal Ali

    2015-01-01

    The aim of this work was to design and evaluate effervescent floating gastro-retentive drug delivery matrix tablets with sustained-release behavior using a binary mixture of hydroxyethyl cellulose and sodium alginate. Pentoxifylline was used as a highly water-soluble, short half-life model drug with a high density. The floating capacity, swelling, and drug release behaviors of drug-loaded matrix tablets were evaluated in 0.1 N HCl (pH 1.2) at 37°C±0.5°C. Release data were analyzed by fitting the power law model of Korsmeyer–Peppas. The effect of different formulation variables was investigated, such as wet granulation, sodium bicarbonate gas-forming agent level, and tablet hardness properties. Statistical analysis was applied by paired sample t-test and one-way analysis of variance depending on the type of data to determine significant effect of different parameters. All prepared tablets through wet granulation showed acceptable physicochemical properties and their drug release profiles followed non-Fickian diffusion. They could float on the surface of dissolution medium and sustain drug release over 24 hours. Tablets prepared with 20% w/w sodium bicarbonate at 50–54 N hardness were promising with respect to their floating lag time, floating duration, swelling ability, and sustained drug release profile. PMID:25848220

  16. Design and evaluation of effervescent floating tablets based on hydroxyethyl cellulose and sodium alginate using pentoxifylline as a model drug.

    PubMed

    Rahim, Safwan Abdel; Carter, Paul A; Elkordy, Amal Ali

    2015-01-01

    The aim of this work was to design and evaluate effervescent floating gastro-retentive drug delivery matrix tablets with sustained-release behavior using a binary mixture of hydroxyethyl cellulose and sodium alginate. Pentoxifylline was used as a highly water-soluble, short half-life model drug with a high density. The floating capacity, swelling, and drug release behaviors of drug-loaded matrix tablets were evaluated in 0.1 N HCl (pH 1.2) at 37°C±0.5°C. Release data were analyzed by fitting the power law model of Korsmeyer-Peppas. The effect of different formulation variables was investigated, such as wet granulation, sodium bicarbonate gas-forming agent level, and tablet hardness properties. Statistical analysis was applied by paired sample t-test and one-way analysis of variance depending on the type of data to determine significant effect of different parameters. All prepared tablets through wet granulation showed acceptable physicochemical properties and their drug release profiles followed non-Fickian diffusion. They could float on the surface of dissolution medium and sustain drug release over 24 hours. Tablets prepared with 20% w/w sodium bicarbonate at 50-54 N hardness were promising with respect to their floating lag time, floating duration, swelling ability, and sustained drug release profile. PMID:25848220

  17. Preparation and evaluation of dual-mode floating gastroretentive tablets containing itraconazole.

    PubMed

    Kim, Ju-Young; Rhee, Yun-Seok; Park, Chun-Woong; Ha, Jung-Myung; Park, Eun-Seok

    2014-11-01

    The aims of the present study were to prepare new dual-mode floating gastroretentive tablets (DF-GRT) containing itraconazole (ITR) and to evaluate influence of the dosage forms on pharmacokinetic parameters of ITR. The solubility of ITR was enhanced around 200 times (from 1.54 to 248.38 µg/mL) by preparing solid dispersion (SD) with hydroxypropylmethyl cellulose. Buoyancy of DF-GRT containing ITR-SD was established by both camphor sublimation and gas generation. Camphor sublimation decreased density of DF-GRT by making pores in tablet matrix, which led to elimination of lag time for floating. Carbon dioxide generated by sodium bicarbonate and citric acid helped to maintain buoyancy of DF-GRT. Therefore DF-GRT floated on the medium without lag time until disintegrated entirely during in vitro release study. They released 89.11% of the drug at 2 h. Residual camphor was <0.5 wt% after sublimation. The pharmacokinetics of DF-GRT was evaluated in six miniature pigs and compared to immediate release tablets (IRT). Mean AUC ratio of GRT/IRT was 1.36 but there was no statistical difference between AUC values. However delayed tmax, increased MRT and equivalent Cmax of DF-GRT supposed it could be a promising tool for gastroretentive drug delivery system containing ITR. PMID:24245857

  18. [Modern polymers in matrix tablets technology].

    PubMed

    Zimmer, Łukasz; Kasperek, Regina; Poleszak, Ewa

    2014-01-01

    Matrix tablets are the most popular method of oral drug administration, and polymeric materials have been used broadly in matrix formulations to modify and modulate drug release rate. The main goal of the system is to extend drug release profiles to maintain a constant in vivo plasma drug concentration and a consistent pharmacological effect. Polymeric matrix tablets offer a great potential as oral controlled drug delivery systems. Cellulose derivatives, like hydroxypropyl methylcellulose (HPMC) are often used as matrix formers. However, also other types of polymers can be used for this purpose including: Kollidon SR, acrylic acid polymers such as Eudragits and Carbopols. Nevertheless, polymers of natural origin like: carragens, chitosan and alginates widely used in the food and cosmetics industry are now coming to the fore of pharmaceutical research and are used in matrix tablets technology. Modern polymers allow to obtain matrix tablets by 3D printing, which enables to develop new formulation types. In this paper, the polymers used in matrix tablets technology and examples of their applications were described. PMID:25739125

  19. Solid dispersions in the development of a nimodipine floating tablet formulation and optimization by artificial neural networks and genetic programming.

    PubMed

    Barmpalexis, Panagiotis; Kachrimanis, Kyriakos; Georgarakis, Emanouil

    2011-01-01

    The present study investigates the use of nimodipine-polyethylene glycol solid dispersions for the development of effervescent controlled release floating tablet formulations. The physical state of the dispersed nimodipine in the polymer matrix was characterized by differential scanning calorimetry, powder X-ray diffraction, FT-IR spectroscopy and polarized light microscopy, and the mixture proportions of polyethylene glycol (PEG), polyvinyl-pyrrolidone (PVP), hydroxypropylmethylcellulose (HPMC), effervescent agents (EFF) and nimodipine were optimized in relation to drug release (% release at 60 min, and time at which the 90% of the drug was dissolved) and floating properties (tablet's floating strength and duration), employing a 25-run D-optimal mixture design combined with artificial neural networks (ANNs) and genetic programming (GP). It was found that nimodipine exists as mod I microcrystals in the solid dispersions and is stable for at least a three-month period. The tablets showed good floating properties and controlled release profiles, with drug release proceeding via the concomitant operation of swelling and erosion of the polymer matrix. ANNs and GP both proved to be efficient tools in the optimization of the tablet formulation, and the global optimum formulation suggested by the GP equations consisted of PEG=9%, PVP=30%, HPMC=36%, EFF=11%, nimodipine=14%. PMID:20934511

  20. Design and evaluation of floating multi-layer coated tablets based on gas formation.

    PubMed

    Sungthongjeen, Srisagul; Sriamornsak, Pornsak; Puttipipatkhachorn, Satit

    2008-05-01

    Floating multi-layer coated tablets were designed based on gas formation. The system consists of a drug-containing core tablet coated with a protective layer (hydroxypropyl methylcellulose), a gas forming layer (sodium bicarbonate) and a gas-entrapped membrane, respectively. The mechanical properties of acrylic polymers (Eudragit RL 30D, RS 30D, NE 30D) and ethylcellulose were characterized by the puncture test in order to screen a suitable film for the system. Eudragit RL 30D was chosen as a gas-entrapped membrane due to its high flexibility and high water permeability. The obtained tablets enabled to float due to the CO2-gas formation and the gas entrapment by polymeric membrane. The effect of formulation variables on floating properties and drug release was investigated. The floating tablets using direct-compressed cores had shorter time to float and faster drug release than those using wet-granulated cores. The increased amount of a gas forming agent did not affect time to float but increased the drug release from the floating tablets while increasing coating level of gas-entrapped membrane increased time to float and slightly retarded drug release. Good floating properties and sustained drug release were achieved. These floating tablets seem to be a promising gastroretentive drug delivery system. PMID:17967527

  1. Innovative intragastric ascaridole floating tablets: Development, optimization, and in vitro-in vivo evaluation.

    PubMed

    Zhao, Qiang; Gao, Baoan; Ma, Lulu; Lian, Jianhao; Deng, Li; Chen, Jianming

    2015-12-30

    Gastro-floating tablets of ascaridole, a volatile oil were developed to prolong the gastric residence time and thereby, enhance local therapeutic efficacy. The tablets were optimized and prepared by direct compression techniques using hydroxypropylmethylcellulose (HPMC K15M) and polyethylene oxide (PEO WSRN-750) as hydrophilic matrices and calcium carbonate (CaCO3) as a gas-generating agent. In vitro evaluation of the prepared tablets was performed by determining the hardness, friability, content uniformity, and weight variation. In addition, floating lag time, total floating time, and drug release behavior were evaluated. Finally, optimized tablets were subjected to stability and in vivo gamma scintigraphy studies. Results showed that the formulated tablets were white, smooth, and flat in appearance and met the Chinese Pharmacopoeia (ChP) criteria for weight variation, drug content, and friability. The tablets had satisfactory buoyancy and sustained drug release profile that followed non-Fickian kinetics. In vivo gamma scintigraphy suggests that the floating tablet did not adhere to the stomach mucous but were retained in the stomach for extended periods of 5.80±0.50h following administration, indicating that gastro retentive time of ascaridole tablets increased owing to the floating principle. PMID:26453784

  2. Influence of different types of low substituted hydroxypropyl cellulose on tableting, disintegration, and floating behaviour of floating drug delivery systems

    PubMed Central

    Diós, Péter; Pernecker, Tivadar; Nagy, Sándor; Pál, Szilárd; Dévay, Attila

    2014-01-01

    The object of the present study is to evaluate the effect of application of low-substituted hydroxypropyl cellulose (L-HPC) 11 and B1 as excipients promoting floating in gastroretentive tablets. Directly compressed tablets were formed based on experimental design. Face-centred central composite design was applied with two factors and 3 levels, where amount of sodium alginate (X1) and L-HPC (X2) were the numerical factors. Applied types of L-HPCs and their 1:1 mixture were included in a categorical factor (X3). Studied parameters were floating lag time, floating time, floating force, swelling behaviour of tablets and dissolution of paracetamol, which was used as a model active substance. Due to their physical character, L-HPCs had different water uptake and flowability. Lower flowability and lower water uptake was observed after 60 min at L-HPC 11 compared to L-HPC B1. Shorter floating times were detected at L-HPC 11 and L-HPC mixtures with 0.5% content of sodium alginate, whereas alginate was the only significant factor. Evaluating results of drug release and swelling studies on floating tablets revealed correlation, which can serve to help to understand the mechanism of action of L-HPCs in the field development of gastroretentive dosage forms. PMID:26702261

  3. Formulation and in-vitro evaluation of floating bilayer tablet of lisinopril maleate and metoprolol tartrate.

    PubMed

    Ijaz, Hira; Qureshi, Junaid; Danish, Zeeshan; Zaman, Muhammad; Abdel-Daim, Mohamed; Hanif, Muhammad; Waheed, Imran; Mohammad, Imran Shair

    2015-11-01

    The purpose of this study was to introduce the technology for the development of rate-controlled oral drug delivery system to overcome various physiological problems. Several approaches are being used for the purpose of increasing the gastric retentive time, including floating drug delivery system. Gastric floating lisinopril maleate and metoprolol tartrate bilayer tablets were formulated by direct compression method using the sodium starch glycolate, crosscarmellose sodium for IR layer. Eudragit L100, pectin, acacia as sustained release polymers in different ratios for SR metoprolol tartrate layer and sodium bicarbonate, citric acid as gas generating agents for the floating extended release layer. The floating bilayer tablets of lisinopril maleate and metoprolol tartrate were designed to overcome the various problems associated with conventional oral dosage form. Floating tablets were evaluated for floating lag time, drug contents and in-vitro dissolution profile and different kinetic release models were applied. It was clear that the different ratios of polymers affected the drug release and floating time. L2 and M4 showed good drug release profile and floating behavior. The linear regression and model fitting showed that all formulation followed Higuchi model of drug release model except M4 that followed zero order kinetic. From the study it is evident that a promising controlled release by floating bilyer tablets of lisinopril maleate and metoprolol tartrate can be developed successfully. PMID:26639495

  4. Development and Evaluation of Gastroretentive Floating Tablets of an Antihypertensive Drug Using Hydrogenated Cottonseed Oil

    PubMed Central

    Pawar, Harshal Ashok; Gharat, Pooja Ramchandra; Dhavale, Rachana Vivek; Joshi, Pooja Rasiklal; Rakshit, Pushpita Pankajkumar

    2013-01-01

    The aim of the present work was to develop a gastroretentive floating tablet of Atenolol and investigate the effects of both hydrophilic and hydrophobic retardant on in vitro release. Atenolol is an antihypertensive drug with an oral bioavailability of only 50% because of its poor absorption from lower gastrointestinal tract. The floating tablets of Atenolol were prepared to increase the gastric retention, to extend the drug release, and to improve the bioavailability of the drug. The floating tablets were formulated using hydrophilic polymers as Hydroxy propyl methyl cellulose (HPMC K4M and HPMC K15M), hydrophobic retardant as a hydrogenated cottonseed oil (HCSO), and sodium bicarbonate as a gas generating agent to reduce floating lag time. The formulated tablets were evaluated for the quality control tests such as weight variation, hardness, friability, swelling index, floating lag time, and total floating time. The in vitro release study of the tablets was performed in 0.1 N HCl as a dissolution media. The results of the present study clearly indicates the promising potential of Atenolol floating system as an alternative to the conventional dosage and other sustained release formulations. The study also revealed the effectiveness of HCSO as retardant in combination with HPMC. PMID:24455312

  5. Formulation development, optimization, and evaluation of sustained release tablet of valacyclovir hydrochloride by combined approach of floating and swelling for better gastric retention.

    PubMed

    Upadhyay, Pratik; Nayak, Kunal; Patel, Kaushika; Patel, Jaymin; Shah, Shreeraj; Deshpande, Jayant

    2014-12-01

    The present study is intended to enhance gastric retention of sustained release tablet of valacyclovir hydrochloride by combined approach of floating and swelling. The tablets are prepared by direct compression method. Polyethylene oxide (Polyox WSR 303) is selected as the swelling matrix agent. Sodium starch glycolate (SSG) is used as swelling enhancer, and sodium bicarbonate is used as an effervescent agent for floating. A 3(2) full factorial design is applied to systematically optimize the formulation. The concentration of Polyox WSR 303 (X 1) and concentration of SSG (X 2) are selected as independent variables. The percentage drug release at 12 h, floating lag time, and maximum percentage swelling are selected as dependent variables. Formulations are evaluated for hardness, friability, floating lag time, total floating time, percentage swelling, in vitro drug release, and in vivo floating study. The results indicated that X 1 and X 2 significantly affected the drug release properties, floating lag times, and maximum percentage swelling. Release rate decreases as the concentration of Polyox increased. Regression analysis and numerical optimization are performed to identify the best formulation. Formulation F5 prepared with Polyox WSR 303 (15 %) and SSG (10 %) is found to be the best formulation. F5 followed zero-order release mechanism. Swelling and floating gastroretentive tablets of valacyclovir HCl are successfully formulated with controlled delivery to stomach with an aim of increasing the mean residence time in the upper part of GIT where the drug has its absorption window. PMID:25787207

  6. Formulation and In Vitro, In Vivo Evaluation of Effervescent Floating Sustained-Release Imatinib Mesylate Tablet

    PubMed Central

    Kadivar, Ali; Kamalidehghan, Behnam; Javar, Hamid Akbari; Davoudi, Ehsan Taghizadeh; Zaharuddin, Nurul Dhania; Sabeti, Bahareh; Chung, Lip Yong; Noordin, Mohamed Ibrahim

    2015-01-01

    Introduction Imatinib mesylate is an antineoplastic agent which has high absorption in the upper part of the gastrointestinal tract (GIT). Conventional imatinib mesylate (Gleevec) tablets produce rapid and relatively high peak blood levels and requires frequent administration to keep the plasma drug level at an effective range. This might cause side effects, reduced effectiveness and poor therapeutic management. Therefore, floating sustained-release Imatinib tablets were developed to allow the tablets to be released in the upper part of the GIT and overcome the inadequacy of conventional tablets. Methodology Floating sustained-release Imatinib mesylate tablets were prepared using the wet granulation method. Tablets were formulated using Hydroxypropyl Methylcellulose (HPMC K4M), with Sodium alginate (SA) and Carbomer 934P (CP) as release-retarding polymers, sodium bicarbonate (NaHCO3) as the effervescent agent and lactose as a filler. Floating behavior, in vitro drug release, and swelling index studies were conducted. Initial and total drug release duration was compared with a commercial tablet (Gleevec) in 0.1 N HCl (pH 1.2) at 37 ± 0.5°C for 24 hours. Tablets were then evaluated for various physical parameters, including weight variation, thickness, hardness, friability, and drug content. Consequently, 6 months of physical stability studies and in vitro gastro-retentive studies were conducted. Results and Discussion Statistical data analysis revealed that tablets containing a composition of 14.67% w/w HPMC K4M, 10.67%, w/w Na alginate, 1.33%, w/w Carbomer 934P and 9.33%, w/w NaHCO3 produced the most favorable formulation to develop 24-hour sustained-release tablets with optimum floating behavior and satisfactory physicochemical characteristics. Furthermore, in vitro release study revealed that the formulated SR tablet had significantly lower Cmax and higher Tmax compared to the conventional tablet (Gleevec). Thus, formulated SR tablets preserved persistent concentration of plasma up to 24 hours. Conclusion In conclusion, in order to suggest a better drug delivery system with constant favorable release, resulting in optimized absorption and less side effects, formulated CP-HPMC-SA based imatinib mesylate floating sustained-release tablets can be a promising candidate for cancer chemotherapy. PMID:26035710

  7. Impact of anti-tacking agents on properties of gas-entrapped membrane and effervescent floating tablets.

    PubMed

    Kriangkrai, Worawut; Puttipipatkhachorn, Satit; Sriamornsak, Pornsak; Pongjanyakul, Thaned; Sungthongjeen, Srisagul

    2014-12-01

    Tackiness caused by the gas-entrapped membrane (Eudragit(®)RL 30D) was usually observed during storage of the effervescent floating tablets, leading to failure in floatation and sustained release. In this work, common anti-tacking agents (glyceryl monostearate (GMS) and talc) were used to solve this tackiness problem. The impact of anti-tacking agent on the properties of free films and corresponding floating tablets was investigated. GMS was more effective than talc in reducing tackiness of the film. Addition and increasing amount of anti-tacking agents lowered the film mechanical strength, but the coating films were still strong and flexible enough to resist the generated gas pressure inside the floating tablet. Wettability and water vapor permeability of the film decreased with increasing level of anti-tacking agents as a result of their hydrophobicity. No interaction between anti-tacking agents and polymer was observed as confirmed by Fourier transform infrared spectroscopy, powder X-ray diffractometry, and differential scanning calorimetry studies. Increasing amount of anti-tacking agents decreased time to float and tended to retard drug release of the floating tablets. Floating properties and drug release were also influenced by type of anti-tacking agents. The obtained floating tablets still possessed good floating properties and controlled drug release even though anti-tacking agent had some effects. The results demonstrated that the tackiness problem of the floating tablets could be solved by incorporating anti-tacking agent into the gas-entrapped membrane. PMID:24927669

  8. A modified emulsion gelation technique to improve buoyancy of hydrogel tablets for floating drug delivery systems.

    PubMed

    Yom-Tov, Ortal; Seliktar, Dror; Bianco-Peled, Havazelet

    2015-10-01

    The use of buoyant or floating hydrogel tablets is of particular interest in the sustained release of drugs to the stomach. They have an ability to slow the release rates of drugs by prolonging their absorption window in the upper part of the gastrointestinal (GI) tract. In this study we synthesized bioactive hydrogels that have sustainable release rates for drugs in the stomach based on a hydrogel preparation technique that employs emulsifying surfactants. The emulsion gelation technique, which encapsulates oil droplets within the hydrogels during crosslinking, was used to decrease their specific gravity in aqueous environments, resulting in floating drug release depots. Properties such as swelling, buoyancy, density and drug release were manipulated by changing the polymer concentrations, surfactant percentages and the oil:polymer ratios. The relationship between these properties and the hydrogel's floating lag time was documented. The potential for this material to be used as a floating drug delivery system was demonstrated. PMID:26117764

  9. Theophylline loaded gastroretentive floating tablets based on hydrophilic polymers: preparation and in vitro evaluation.

    PubMed

    Khan, Ferdous; Ibn Razzak, Shaikhul Millat; Khan, Ziaur Rahman; Azad, Mohammad Abul Kalam; Chowdhury, Jakir Ahmed; Reza, Selim

    2009-04-01

    This investigation describes the preparation and in vitro evaluation of gastroretentive floating tablet of theophylline. Two hydrophilic cellulose derivatives, Methocel K100M and Methocel K15MCR were evaluated for their gel forming and release controlling properties. Sodium bicarbonate and citric acid were incorporated as gas generating agents. The effects of soluble components (sodium bicarbonate and citric acid), gel forming agents and amount variation of theophylline on drug release profile and floating properties were investigated. Tablets were prepared by direct compression technique. Formulations were evaluated for in vitro buoyancy and drug release study was evaluated for eight hours using USP XXII paddle-type dissolution apparatus using 0.1N HCl as dissolution medium. The release mechanisms were explored and explained with zero order, first order, Higuchi and Korsmeyer equations. The release rate, extent and mechanisms were found to be governed by polymer and floating agent content. The content of active ingredient was also a vital factor in controlling drug release pattern. It was found that polymer content and amount of floating agent significantly affected the mean dissolution time, percentage drug release after 8 hours, release rate constant and diffusion exponent. PMID:19339225

  10. Development, characterization and permeability assessment based on caco-2 monolayers of self-microemulsifying floating tablets of tetrahydrocurcumin.

    PubMed

    Sermkaew, Namfa; Wiwattanawongsa, Kamonthip; Ketjinda, Wichan; Wiwattanapatapee, Ruedeekorn

    2013-03-01

    Novel self-microemulsifying floating tablets were developed to enhance the dissolution and oral absorption of the poorly water-soluble tetrahydrocurcumin (THC). Their physicochemical properties and THC permeability across Caco-2 cell monolayers were assessed. The self-microemulsifying liquid containing THC was adsorbed onto colloidal silicon dioxide, mixed with HPMC, gas-generating agents (sodium bicarbonate and tartaric acid), lactose and silicified-microcrystalline cellulose and transformed into tablets by direct compression. The use of different types/concentrations of HPMC and sodium bicarbonate in tablet formulations had different effects on the floating characteristics and in vitro THC release. The optimum tablet formulation (F2) provided a short floating lag time (∼23 s) together with a prolonged buoyancy (>12 h). About 72% of THC was released in 12 h with an emulsion droplet size in aqueous media of 33.9±1.0 nm while that of a self-microemulsifying liquid was 29.9±0.3 nm. The tablet formulation was stable under intermediate and accelerated storage conditions for up to 6 months. The THC released from the self-microemulsifying liquid and tablet formulations provided an approximately three- to fivefold greater permeability across the Caco-2 cell monolayers than the unformulated THC and indicated an enhanced absorption of THC by the formulations. The self-microemulsifying floating tablet could provide a dosage form with the potential to improve the oral bioavailability of THC and other hydrophobic compounds. PMID:23319299

  11. Optimization and evaluation of clarithromycin floating tablets using experimental mixture design.

    PubMed

    Uğurlu, Timucin; Karaçiçek, Uğur; Rayaman, Erkan

    2014-01-01

    The purpose of the study was to prepare and evaluate clarithromycin (CLA) floating tablets using experimental mixture design for treatment of Helicobacter pylori provided by prolonged gastric residence time and controlled plasma level. Ten different formulations were generated based on different molecular weight of hypromellose (HPMC K100, K4M, K15M) by using simplex lattice design (a sub-class of mixture design) with Minitab 16 software. Sodium bicarbonate and anhydrous citric acid were used as gas generating agents. Tablets were prepared by wet granulation technique. All of the process variables were fixed. Results of cumulative drug release at 8th h (CDR 8th) were statistically analyzed to get optimized formulation (OF). Optimized formulation, which gave floating lag time lower than 15 s and total floating time more than 10 h, was analyzed and compared with target for CDR 8th (80%). A good agreement was shown between predicted and actual values of CDR 8th with a variation lower than 1%. The activity of clarithromycin contained optimizedformula against H. pylori were quantified using well diffusion agar assay. Diameters of inhibition zones vs. log10 clarithromycin concentrations were plotted in order to obtain a standard curve and clarithromycin activity. PMID:25272652

  12. CONTROLLED RELEASE USING STARCH AS A FLOATING DOSAGE MATRIX

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Starch-based polymeric materials were tested using model drug compounds to determine the feasibility of using starch as an oral floating dosage matrix. Oral controlled release systems require increased bio-availability, predictable release rates, and site-specific delivery. Starch and model drug c...

  13. Gamma scintigraphic study of the hydrodynamically balanced matrix tablets of Metformin HCl in rabbits

    PubMed Central

    Razavi, Mahboubeh; Karimian, Hamed; Yeong, Chai Hong; Sarji, Sazilah Ahmad; Chung, Lip Yong; Nyamathulla, Shaik; Noordin, Mohamed Ibrahim

    2015-01-01

    The purpose of this study is to evaluate the in vitro and in vivo performance of gastro-retentive matrix tablets having Metformin HCl as model drug and combination of natural polymers. A total of 16 formulations were prepared by a wet granulation method using xanthan, tamarind seed powder, tamarind kernel powder and salep as the gel-forming agents and sodium bicarbonate as a gas-forming agent. All the formulations were evaluated for compendial and non-compendial tests and in vitro study was carried out on a USP-II dissolution apparatus at a paddle speed of 50 rpm. MOX2 formulation, composed of salep and xanthan in the ratio of 4:1 with 96.9% release, was considered as the optimum formulation with more than 90% release in 12 hours and short floating lag time. In vivo study was carried out using gamma scintigraphy in New Zealand White rabbits, optimized formulation was incorporated with 10 mg of 153Sm for labeling MOX2 formulation. The radioactive samarium oxide was used as the marker to trace transit of the tablets in the gastrointestinal tract. The in vivo data also supported retention of MOX2 formulation in the gastric region for 12 hours and were different from the control formulation without a gas and gel forming agent. It was concluded that the prepared floating gastro-retentive matrix tablets had a sustained-release effect in vitro and in vivo, gamma scintigraphy played an important role in locating the oral transit and the drug-release pattern. PMID:26124637

  14. Gamma scintigraphic study of the hydrodynamically balanced matrix tablets of Metformin HCl in rabbits.

    PubMed

    Razavi, Mahboubeh; Karimian, Hamed; Yeong, Chai Hong; Sarji, Sazilah Ahmad; Chung, Lip Yong; Nyamathulla, Shaik; Noordin, Mohamed Ibrahim

    2015-01-01

    The purpose of this study is to evaluate the in vitro and in vivo performance of gastro-retentive matrix tablets having Metformin HCl as model drug and combination of natural polymers. A total of 16 formulations were prepared by a wet granulation method using xanthan, tamarind seed powder, tamarind kernel powder and salep as the gel-forming agents and sodium bicarbonate as a gas-forming agent. All the formulations were evaluated for compendial and non-compendial tests and in vitro study was carried out on a USP-II dissolution apparatus at a paddle speed of 50 rpm. MOX2 formulation, composed of salep and xanthan in the ratio of 4:1 with 96.9% release, was considered as the optimum formulation with more than 90% release in 12 hours and short floating lag time. In vivo study was carried out using gamma scintigraphy in New Zealand White rabbits, optimized formulation was incorporated with 10 mg of (153)Sm for labeling MOX2 formulation. The radioactive samarium oxide was used as the marker to trace transit of the tablets in the gastrointestinal tract. The in vivo data also supported retention of MOX2 formulation in the gastric region for 12 hours and were different from the control formulation without a gas and gel forming agent. It was concluded that the prepared floating gastro-retentive matrix tablets had a sustained-release effect in vitro and in vivo, gamma scintigraphy played an important role in locating the oral transit and the drug-release pattern. PMID:26124637

  15. Floating tablets for controlled release of ofloxacin via compression coating of hydroxypropyl cellulose combined with effervescent agent.

    PubMed

    Qi, Xiaole; Chen, Haiyan; Rui, Yao; Yang, Fengjiao; Ma, Ning; Wu, Zhenghong

    2015-07-15

    To prolong the residence time of dosage forms within gastrointestinal trace until all drug released at desired rate was one of the real challenges for oral controlled-release drug delivery system. Herein, we developed a fine floating tablet via compression coating of hydrophilic polymer (hydroxypropyl cellulose) combined with effervescent agent (sodium bicarbonate) to achieve simultaneous control of release rate and location of ofloxacin. Sodium alginate was also added in the coating layer to regulate the drug release rate. The effects of the weight ratio of drug and the viscosity of HPC on the release profile were investigated. The optimized formulations were found to immediately float within 30s and remain lastingly buoyant over a period of 12 h in simulated gastric fluid (SGF, pH 1.2) without pepsin, indicating a satisfactory floating and zero-order drug release profile. In addition, the oral bioavailability experiment in New Zealand rabbits showed that, the relative bioavailability of the ofloxacin after administrated of floating tablets was 172.19%, compared to marketed common release tablets TaiLiBiTuo(®). These results demonstrated that those controlled-released floating tables would be a promising gastro-retentive delivery system for drugs acting in stomach. PMID:25956047

  16. Evaluation of roll compaction as a preparation method for hydroxypropyl cellulose-based matrix tablets

    PubMed Central

    Jeon, Imjak; Gilli, Tiziana; Betz, Gabriele

    2011-01-01

    Roll compaction was applied for the preparation of hydroxypropyl cellulose (HPC)-based sustained-release matrix tablets. Matrix tablets made via roll compaction exhibited higher dosage uniformity and faster drug release than direct-compacted tablets. HPC viscosity grade, roll pressure, and milling speed affected tablet properties significantly. Roll compaction seems to be an adequate granulation method for the preparation of HPC-based matrix tablets due to the simplicity of the process, less handling difficulty from HPC tackiness as well as easier particle size targeting. Selecting the optimum ratio of plastic excipients and the particle size of starting materials can however be critical issues in this method. PMID:21687348

  17. Hydrogel polysaccharides of tamarind and xanthan to formulate hydrodynamically balanced matrix tablets of famotidine.

    PubMed

    Razavi, Mahboubeh; Nyamathulla, Shaik; Karimian, Hamed; Moghadamtousi, Soheil Zorofchian; Noordin, Mohamed Ibrahim

    2014-01-01

    The gastroretentive dosage form of famotidine was modified using tamarind seed powders to prolong the gastric retention time. Tamarind seeds were used in two different forms having different swelling and gelling properties: with husk (TSP) or without husk (TKP). TKP (TKP1 to TKP 6) and TSP (TSP1 to TSP 6) series were prepared using tamarind powder:xanthan in the ratios of 5:0, 4:1, 3:2, 2:3, 1:4, 0:5, respectively. The matrix tablets were prepared by the wet granulation method and evaluated for pharmacopoeial requirements. TKP2 was the optimum formulation as it had a short floating lag time (FLT<30 s) and more than 98.5% drug release in 12 h. The dissolution data were fitted to popular mathematical models to assess the mechanism of drug release, and the optimum formulation showed a predominant first order release and diffusion mechanism. It was concluded that the TKP2 prepared using tamarind kernel powder:xanthan (4:1) was the optimum formulation with shortest floating lag time and more than 90% release in the determined period of time. PMID:25197930

  18. Gastroretentive Matrix Tablets of Boswellia Oleogum Resin: Preparation, Optimization, In Vitro Evaluation, and Cytoprotective Effect on Indomethacin-Induced Gastric Ulcer in Rabbits.

    PubMed

    Yusif, Rehab Mohammad; Abu Hashim, Irhan Ibrahim; Mohamed, Elham Abdelmonem; Badria, Farid Abd-Elreheim

    2016-04-01

    Currently available anti-ulcer drugs suffer from serious side effects which limited their uses and prompted the need to search for a safe and efficient new anti-ulcer agent. Boswellia gum resin (BR) emerged as a safe, efficient, natural, and economic potential cytoprotective agent. Thus, it is of medical importance to develop gastroretentive (GR) formulations of BR to enhance its bioavailability and anti-ulcer efficacy. Early attempts involved the use of organic solvents and non-applicability to large-scale production. In this study, different tablet formulations were prepared by simple direct compression combining floating and bioadhesion mechanisms employing hydroxypropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (SCMC), pectin (PC), and/or carbopol (CP) as bioadhesive polymers and sodium bicarbonate (SB) as a gas former. The prepared tablets were subjected for assessment of swelling, floating, bioadhesion, and drug release in 0.1 N HCl. The optimized GR formulation was examined for its protective effect on the gastric ulcer induced by indomethacin in albino rabbits compared with lactose tablets. The obtained results disclosed that swelling, floating, bioadhesion, and drug release of the GR tablets of BR depend mainly on the nature of the matrix and the ratio of polymer combinations. Moreover, a combination of SCMC-CP in a ratio of 2:1 (SCP21) exhibited desirable floating, bioadhesion, swelling, and extended drug release. Also, a 6-h pretreatment with SCP21 tablets decreased the severity of inflammation and number of bleeding spots among ulcer-induced rabbits in comparison to those treated with lactose tablets. PMID:26092303

  19. The effect of geometric shape on the release properties of metronidazole from lipid matrix tablets.

    PubMed

    Gke, Evren H; Ozyazici, Mine; Ertan, Gokhan

    2009-08-01

    In this study, the lipophilic matrix tablets of metronidazole were prepared with Cutina HR (hydrogenated castor oil), stearic acid, Compritol ATO 888 (glyceryl behenate) and Precirol ATO 5 (glycerol palmitostearate) in two different shapes; cylinder and hexagonal. Our first aim was to investigate the influence of the lipid excipients and geometric shape on the release behavior of metronidazole, and the second aim was to investigate the influence of tablet surface area/volume (SA/V) ratio on drug release from controlled release matrix tablets. In vitro release test was performed using a standard USP dissolution apparatus I. Hardness, surface/volume ratio and friability were determined. The hexagonal tablets were harder than the cylinder tablets. Stearic acid showed the highest release rates for both geometric shapes reflecting the highest surface area and the lowest SA/V ratio. According to power law analysis, the diffusion mechanism was expressed as a Fickian diffusion for all lipid matrix tablets. The square root of time relationship was operative for all tablets. Higuchi kinetic constants obtained with hexagonal tablets were higher than the cylinder tablets. As the type of lipid matrix, the geometric shape of the tablets was also effective on the diffusion and release kinetics. From the present study, it was shown that surface area and volume ratio may be used as parameters for the evaluation of the drug release profile. PMID:20055089

  20. Development and evaluation of hydrophilic colloid matrix of famotidine tablets.

    PubMed

    Shoaib, Muhammad Harris; Al Sabah Siddiqi, Saniah; Yousuf, Rabia Ismail; Zaheer, Kamran; Hanif, Muhammad; Rehana, Saeed; Jabeen, Sabahat

    2010-06-01

    The objective of the present study was to develop a once-daily sustained-release (SR) matrix tablet of famotidine. Nine different formulations (F1-F9) were prepared by direct compression method using Avicel PH101 as filler/binder in the range of 41-27% in F1-F3, 18-22% in F4-F7, and 16-18% in F8-F9 and hydroxypropyl methylcellulose (4,000 cps) as hydrophilic matrix was used in F1-F3 from 19% to 30%, around 40% in F4-F7, and 42-45% in F8-F9. Talc and Aerosil were added in the ratio of 0.7-1.2%. The tablets were subjected to various physical parameters including weight variation test, hardness, thickness, diameter, friability, and in vitro release studies. Assay was also performed according to the USP 30 NF 25 procedure. The results of the physical parameters and assay were found to be within the acceptable range. In vitro dissolution results indicated that formulation F4-F7, having around 40% of rate control polymer, produced a SR pattern throughout 24 h. F1-F3 showed drug release at a faster rate, while F8-F9 released much slower, i.e., <80% in 24 h. Model-dependent and model-independent methods were used for data analysis and the best results were observed for F4 in zero order (r(2) = 0.984) and F6 in Korsmeyer and Higuchi (r(2) = 0.992 and 0.988). The parameter n indicated anomalous diffusion, while beta in Weibull showed a parabolic curve with higher initial slope. The f(2) similarity test was performed taking F4 as a reference formulation. Only the F5-F7 formulations were similar to the reference formulation F4. The mean dissolution time was around 10 h for the successful formulation. PMID:20422332

  1. Effect of carboxymethylation on rheological and drug release characteristics of locust bean gum matrix tablets.

    PubMed

    Chakravorty, Amrita; Barman, Gouranga; Mukherjee, Sudipta; Sa, Biswanath

    2016-06-25

    This study was undertaken to investigate correlation between the carboxymethylation-induced rheological changes and drug release characteristics of locust bean gum (LBG) matrix tablets. LBG was derivatized to carboxymethyl LBG (CMLBG) and characterized by (13)C NMR, FTIR and elemental analyses. Rheological studies revealed that LBG, in contact with water, produced a strong elastic gel which swelled less due to lower penetration of water resulting in slower drug release. On the other hand, CMLBG formed a viscous polymer solution through which higher influx of water resulted in rapid swelling of the matrix and faster drug release. Although the release from a particular matrix was dependent on drugs' solubilities, CMLBG matrix tablet produced faster release of all the drugs than LBG matrix tablets. In conclusion, rheological study appeared to be an useful tool to predict release of drugs from polysaccharide matrix tablets. PMID:27083792

  2. Investigation and Evaluation of an in Situ Interpolymer Complex of Carbopol with Polyvinylpyrrolidone as a Matrix for Gastroretentive Tablets of Ranitidine Hydrochloride.

    PubMed

    Yusif, Rehab Mohammad; Abu Hashim, Irhan Ibrahim; Mohamed, Elham Abdelmonem; El Rakhawy, Mohamed Magdy

    2016-01-01

    Carbopol (CP) is a biocompatible bioadhesive polymer used as a matrix for gastroretentive (GR) tablets, however, its rapid hydration shortens its bioadhesion and floating when incorporated in effervescent formulae. The interpolymer complexation of CP with polyvinylpyrrolidone (PVP) significantly reduced the excessive hydration of CP, prolonging floating and maintaining the mucoadhesiveness. In early attempts, a lengthy process was followed to prepare such an interpolymer complex. In this study, an in situ interpolymer complexation between CP and two grades of PVP (K25 and K90) in 0.1 N HCl was investigated and characterized by Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Hence, directly compressed GR tablets of different combinations of PVP and CP with sodium bicarbonate (SB) as an effervescent agent were examined for prolonged gastroretention and sustained release of ranitidine hydrochloride (RHCl) as a model drug. Tablets were evaluated for in vitro buoyancy, bioadhesiveness, swelling, and drug release in 0.1 N HCl. All GR tablets containing PVP-CP combinations achieved more prolonged floating (>24 h) than CP tablets (5.2 h). Their bioadhesiveness, swelling, and drug release were dependent on the PVP molecular weight and its ratio to CP. Drug release profiles of all formulae followed non-Fickian diffusion. Formula containing the PVP K90-CP combination at a respective ratio of 1 : 3 (P90C13) was a promising system, exhibiting good floating and bioadhesive properties as well as sustained drug release. Abdominal X-ray imaging of P90C13 formula, loaded with barium sulfate, in six healthy volunteers showed a mean gastric retention period of 6.8±0.3 h. PMID:26726743

  3. Floating elementary osmotic pump tablet (FEOPT) for controlled delivery of diethylcarbamazine citrate: a water-soluble drug.

    PubMed

    Khan, Zulfequar Ahamad; Tripathi, Rahul; Mishra, Brahmeshwar

    2011-12-01

    The present work investigates the feasibility of the design of a novel floating elementary osmotic pump tablet (FEOPT) to prolong the gastric residence of a highly water-soluble drug. Diethylcarbamazine citrate (DEC) was chosen as a model drug. The FEOPT consisted of an osmotic core (DEC, mannitol, and hydrophilic polymers) coated with a semipermeable layer (cellulose acetate) and a gas-generating gelling layer (sodium bicarbonate, hydrophilic polymers) followed by a polymeric film (Eudragit RL 30D). The effect of formulation variables such as concentration of polymers, types of diluent, and coat thickness of semipermeable membrane was evaluated in terms of physical parameters, floating lag time, duration of floatation, and in vitro drug release. The Fourier transform infrared and X-ray diffraction analysis were carried out to study the physicochemical changes in the drug excipients powder blend. The integrity of the orifice and polymeric film layer was confirmed from scanning electron microscopy image. All the developed FEOPT showed floating lag time of less than 8 min and floating duration of 24 h. A zero-order drug release could be attained for DEC. The formulations were found to be stable up to 3 months of stability testing at 40°C/75% relative humidity. PMID:21969244

  4. Development of injection moulded matrix tablets based on mixtures of ethylcellulose and low-substituted hydroxypropylcellulose.

    PubMed

    Quinten, Thomas; Gonnissen, Yves; Adriaens, Els; De Beer, Thomas; Cnudde, Veerle; Masschaele, Bert; Van Hoorebeke, Luc; Siepmann, Juergen; Remon, Jean Paul; Vervaet, Chris

    2009-06-28

    The objective of this study was to produce sustained-release matrix tablets by means of injection moulding and to evaluate the influence of matrix composition, process temperature and viscosity grade of ethylcellulose on processability and drug release by means of a statistical design. The matrix tablets were physico-chemically characterized and the drug release mechanism and kinetics were studied. Formulations containing metoprolol tartrate (30%, model drug), ethylcellulose with dibutylsebacate (matrix former and plasticizer) and L-HPC were extruded and subsequently injection moulded into tablets (375mg, 10mm diameter, convex-shaped) at different temperatures (110, 120 and 130 degrees C). Dissolution tests were performed and tablets were characterized by means of DSC, X-ray powder diffraction studies, X-ray tomography, porosity and hardness. Tablets containing 30% metoprolol and 70% ethylcellulose (EC 4cps) showed an incomplete drug release within 24h (<50%). Formulations containing L-HPC and EC in a ratio of 20/50 and 27.5/42.5 resulted in nearly zero-order drug release, while the drug release rate was not constant when 35% L-HPC was included. Processing of these formulations was possible at all temperatures, but at higher processing temperatures the drug release rate decreased and tablet hardness increased. Higher viscosity grades of EC resulted in a faster drug release and a higher tablet hardness. The statistical design confirmed a significant influence of the EC and L-HPC concentration on drug release, while the processing temperature and EC viscosity grade did not affect drug release. Tablet porosity was low (<5%), independent of the formulation and process conditions. DSC and XRD demonstrated the formation of a solid dispersion. The hydration front in the tablets during dissolution was visualized by dynamic X-ray tomography, this technique also revealed an anisotropic pore structure through the tablet. PMID:19491007

  5. Lyophilized mucoadhesive-dendrimer enclosed matrix tablet for extended oral delivery of albendazole.

    PubMed

    Mansuri, Shakir; Kesharwani, Prashant; Tekade, Rakesh Kumar; Jain, Narendra Kumar

    2016-05-01

    Dendrimers are multifunctional carriers widely employed for delivering drugs in a variety of disease conditions including HIV/AIDS and cancer. Albendazole (ABZ) is a commonly used anthelmintic drug in human as well as veterinary medicine. In this investigation, ABZ was formulated as a "muco-dendrimer" based sustained released tablet. The mucoadhesive complex was synthesized by anchoring chitosan to fifth generation PPI dendrimer (Muco-PPI) and characterized by UV, FTIR, (1)H NMR spectroscopy and electron microscopy. ABZ was entrapped inside Muco-PPI followed by lyophilization and tableting as matrix tablet. A half-life (t1/2) of 8.06±0.15, 8.17±0.47, 11.04±0.73, 11.49±0.92, 12.52±1.04 and 16.9±1.18h was noted for ABZ (free drug), conventional ABZ tablet (F1), conventional ABZ matrix tablet (F2), PPI-ABZ complex, PPI-ABZ matrix tablet (F3) and Muco-PPI-ABZ matrix tablet (F4), respectively. Thus the novel mucoadhesive-PPI based formulation of ABZ (F4) increased the t1/2 of ABZ significantly by almost twofold as compared to the administration of free drug. The in vivo drug release data showed that the Muco-PPI based formulations have a significantly higher Cmax (2.40±0.02μg/mL) compared with orally administered free ABZ (0.19±0.07μg/mL) as well as conventional tablet (0.20±0.05μg/mL). In addition, the Muco-PPI-ABZ matrix tablet displayed increased mean residence time (MRT) and is therefore a potential candidate to appreciably improve the pharmacokinetic profile of ABZ. PMID:26563727

  6. Albizia procera gum as an excipient for oral controlled release matrix tablet.

    PubMed

    Pachuau, Lalduhsanga; Mazumder, Bhaskar

    2012-09-01

    The purpose of this research was to develop and evaluate controlled release matrix tablets of paracetamol based on natural gum exudates of Albizia procera. Procera gum was characterized of its properties like compressibility index, angle of repose, viscosity and moisture content. The interaction between the gum and paracetamol was also studied through differential scanning calorimetry (DSC) and FTIR spectroscopy. Matrix tablets were then prepared by wet granulation method with different concentrations of procera gum and hydroxypropyl methylcellulose (HPMC) and evaluated for their physical properties like weight variation, hardness, friability and content uniformity. Dissolution study was conducted to characterize release mechanism from the matrix system and data were fitted to various kinetic models. The mechanism of drug release from both types of matrix tablets was found to be anomalous type. Results from various evaluations suggested that A. procera gum could be used as drug release retardant in controlled release matrix systems. PMID:24751043

  7. Retard implantation tablets on a matrix base with Eudragit as a structural substance.

    PubMed

    Korsatko, W

    1982-04-01

    A model for prolonged availability of low concentrated drugs was successfully tested by using 7-hydroxyethyltheophylline and Eudragit RS 100 as matrix to form implant-tablets. Those tablets have the same size, same weight, same hardness, but a different concentration of the model substance and are coated with liquid Eudragit RS 100. Statistical evaluation of the different liberation rates led to a drawing of a diagram whereby a desired drug liberation up to 6 d can easily be obtained by choosing a certain drug concentration of the tablet. PMID:7100251

  8. Formulation and evaluation of once daily minocycline hydrochloride extended release matrix tablets.

    PubMed

    Keny, R V; Mankame, S A; Lourenco, C F

    2009-05-01

    The present study was aimed to develop once daily extended release matrix tablets of minocycline hydrochloride, using hydroxypropylmethylcellulose either alone or in combination with ethyl cellulose as the matrix material in different proportions. The formulated tablets were also compared with a marketed product. The results of the dissolution study indicate that formulations FC-IV, FC-V and FC-VI showed maximum drug release upto 24 h, whereas the marketed product was found to extend the release only up to 14 h. Incase of formulations containing combination of hydroxypropylmethylcellulose and ethyl cellulose (FC-I to FC-IX), the release of the drug was found to be dependent on the relative proportions of hydroxypropylmethylcellulose and ethyl cellulose used in the tablet matrix. Mathematical treatment of the in vitro drug release data suggests that, all the formulations best fitted into first order release kinetics. Drug release from the matrix occurred by combination of two mechanisms, diffusion of drug from tablet matrix and erosion of tablet surface, which was reflected from Higuchi's model and Erosion plot. PMID:20490297

  9. Formulation and Evaluation of Once Daily Minocycline Hydrochloride Extended Release Matrix Tablets

    PubMed Central

    Keny, R. V.; Mankame, S. A.; Lourenco, C. F.

    2009-01-01

    The present study was aimed to develop once daily extended release matrix tablets of minocycline hydrochloride, using hydroxypropylmethylcellulose either alone or in combination with ethyl cellulose as the matrix material in different proportions. The formulated tablets were also compared with a marketed product. The results of the dissolution study indicate that formulations FC-IV, FC-V and FC-VI showed maximum drug release upto 24 h, whereas the marketed product was found to extend the release only up to 14 h. Incase of formulations containing combination of hydroxypropylmethylcellulose and ethyl cellulose (FC-I to FC-IX), the release of the drug was found to be dependent on the relative proportions of hydroxypropylmethylcellulose and ethyl cellulose used in the tablet matrix. Mathematical treatment of the in vitro drug release data suggests that, all the formulations best fitted into first order release kinetics. Drug release from the matrix occurred by combination of two mechanisms, diffusion of drug from tablet matrix and erosion of tablet surface, which was reflected from Higuchi's model and Erosion plot. PMID:20490297

  10. Modulation of Venlafaxine Hydrochloride Release from Press Coated Matrix Tablet

    PubMed Central

    Gohel, M. C.; Soni, C. D.; Nagori, S. A.; Sarvaiya, K. G.

    2008-01-01

    The aim of present study was to prepare novel modified release press coated tablets of venlafaxine hydrochloride. Hydroxypropylmethylcellulose K4M and hydroxypropylmethylcellulose K100M were used as release modifier in core and coat, respectively. A 32 full factorial design was adopted in the optimization study. The drug to polymer ratio in core and coat were chosen as independent variables. The drug release in the first hour and drug release rate between 1 and 12 h were chosen as dependent variables. The tablets were characterized for dimension analysis, crushing strength, friability and in vitro drug release. A check point batch, containing 1:2.6 and 1:5.4 drug to polymer in core and coat respectively, was prepared. The tablets of check point batch were subjected to in vitro drug release in dissolution media with pH 5, 7.2 and distilled water. The kinetics of drug release was best explained by Korsmeyer and Peppas model (anomalous non-Fickian diffusion). The systematic formulation approach enabled us to develop modified release venlafaxine hydrochloride tablets. PMID:20046735

  11. pH-independent sustained release matrix tablet containing doxazosin mesylate: effect of citric acid.

    PubMed

    Cha, Kwang-Ho; Tran, Thanh-Huyen; Kim, Min-Soo; Kim, Jeong-Soo; Park, Hee Jun; Park, Junsung; Cho, Wonkyung; Hwang, Sung-Joo

    2010-12-01

    The aim of this study was to develop a pH-independent sustained release matrix tablets of doxazosin mesylate. The matrix tablets were prepared by direct compression technique using polyethylene oxide, sodium alginate and citric acid as a pH modifier. Formulations were evaluated for an in vitro drug release study, erosion study, and the microenvironmental pH was studied using the pH indicator methyl red. For formulations without citric acid, the extent and rate of drug release in simulated gastric fluid were much higher than those in simulated intestinal fluid. By adding the citric acid, the drug release rate in simulated intestinal fluid was increased, and microenvironmental pH values within the tablets were maintained at low pH during drug release. Furthermore, drug release from the matrix tablet containing 20% w/w citric acid was comparable to that from a commercial product, Cardura® XL, and a pH-independent release could be achieved. Therefore, the incorporation of citric acid as a pH modifier to Polyethylene oxide-sodium alginate matrix tablets effectively produced pH-independent doxazosin mesylate release profiles. PMID:21191766

  12. The Role of Oral Controlled Release Matrix Tablets in Drug Delivery Systems

    PubMed Central

    Nokhodchi, Ali; Raja, Shaista; Patel, Pryia; Asare-Addo, Kofi

    2012-01-01

    Formulations that are able to control the release of drug have become an integral part of the pharmaceutical industry. In particular oral drug delivery has been the focus of pharmaceutical research for many years. This type of drug delivery has been at the centre of research due to its many benefits over conventional dosage. The focus of this review is on matrix tablets due to their widely use and simplicity of the formulation. This includes the discussion of various types of matrix tablets and factors affecting the drug release from these formulations. The mechanism of drug release from HPMC matrices is also discussed. PMID:23678458

  13. Design and development of polyethylene oxide based matrix tablets for verapamil hydrochloride.

    PubMed

    Vidyadhara, S; Sasidhar, R L C; Nagaraju, R

    2013-03-01

    In the present investigation an attempt has been made to increase therapeutic efficacy, reduced frequency of administration and improved patient compliance by developing controlled release matrix tablets of verapamil hydrochloride. Verapamil hydrochloride was formulated as oral controlled release matrix tablets by using the polyethylene oxides (Polyox WSR 303). The aim of this study was to investigate the influence of polymer level and type of fillers namely lactose (soluble filler), swellable filler (starch 1500), microcrystalline cellulose and dibasic calcium phosphate (insoluble fillers) on the release rate and mechanism of release for verapamil hydrochloride from matrix tablets prepared by direct compression process. Higher polymeric content in the matrix decreased the release rate of drug. On the other hand, replacement of lactose with anhydrous dibasic calcium phosphate and microcrystalline cellulose has significantly retarded the release rate of verapamil hydrochloride. Biopharmaceutical evaluation of satisfactory formulations were also carried out on New Zealand rabbits and parameters such as maximum plasma concentration, time to reach peak plasma concentration, area under the plasma concentration time curve(0-t) and area under first moment curve(0-t) were determined. In vivo pharmacokinetic study proves that the verapamil hydrochloride from matrix tablets showed prolonged release and were be able to sustain the therapeutic effect up to 24 h. PMID:24019567

  14. Use of Response Surface Methodology in the Formulation and Optimization of Bisoprolol Fumarate Matrix Tablets for Sustained Drug Release

    PubMed Central

    Malakar, Jadupati; Nayak, Amit Kumar; Goswami, Soumita

    2012-01-01

    The aim of this investigation was to develop and optimize bisoprolol fumarate matrix tablets for sustained release application by response surface methodology based on 23 factorial design. The effects of the amounts of calcium alginate, HPMC K4M, and Carbopol 943 in bisoprolol fumarate matrix tablets on the properties of bisoprolol fumarate sustained release matrix tablets like drug release and hardness were analyzed and optimized. The observed responses were coincided well with the predicted values by the experimental design. The optimized bisoprolol fumarate matrix tablets showed prolonged sustained release of bisoprolol fumarate over 6 hours. These matrix tablets followed the first-order model with anomalous (non-Fickian) diffusion mechanism. PMID:23378933

  15. Effect of Kollidon® SR on the release of Albuterol Sulphate from matrix tablets.

    PubMed

    Sakr, Walid; Alanazi, Fars; Sakr, Adel

    2011-01-01

    The objective of this study was to evaluate Kollidon SR for the development of extended release Albuterol Sulphate matrix tablets in comparison with other polymers as Hydroxypropylmethylcellulose K15M, Carbopol 71G NF, and Eudragit L100-55. The mechanical properties of the tablets were improved as concentration of Kollidon SR or other polymers increased. It was found that Kollidon SR 30% (w/w) and HPMC 30% (w/w) tablets have f 2 similarity factor of 83.5 in their Albuterol Sulphate dissolution profile. The marketed product was found to release 99.7% of drug content within 8 h, while Kollidon SR and HPMC tablets with 30% (w/w) polymer concentration level released 92.7% and 92.9% respectively of drug content within 8 h. Kollidon SR has a unique character of maintaining tablets geometric shape until the end of dissolution test, this is mainly due to the water insoluble content, polyvinyl acetate, forming 80% (w/w) of Kollidon SR, while the remaining content 20% (w/w) is the water soluble, polyvinylpyrrolidone, responsible for pore formation causing a diffusion controlled release. Drug release from all previous formulations is best described to be controlled by more than one kinetic mechanism of release. In conclusion, Kollidon SR and HPMC and Carbopol were found to be potential candidates for the development of extended release of Albuterol Sulphate tablets. PMID:24115901

  16. EXPANDED STARCH AS A FLOATING DOSAGE MATRIX FOR THE CONTROLLED RELEASE OF MODEL DRUG COMPOUNDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Starch-based materials were tested using model drug compounds to determine the feasibility of using starch as an oral floating dosage matrix. Oral controlled release systems require increased bio-availability, predictable release rates, and site-specific delivery. Starch and model drugs were compo...

  17. In vitro characterization and release study of Ambroxol hydrochloride matrix tablets prepared by direct compression.

    PubMed

    Abd-Elbary, A; Haider, M; Sayed, S

    2012-01-01

    A series of either hydrophilic or hydrophobic polymers were used to prepare controlled release Ambroxol hydrochloride (AMX) matrix tablets by direct compression. Both the compatibility and flow properties of AMX/polymer mixtures were investigated. The effect of the amount and type of polymer on the physical properties and in vitro drug release was studied and compared to commercially available Ambroxol(®) SR capsules. A kinetic study of the release profile of AMX from the prepared matrix tablets was performed. All excipients used in the study were compatible with the model drug. AMX/drug mixtures containing sodium alginate (NA) and hydroxypropylmethyl cellulose (HPMC) showed better flow properties than other polymers used in the study. The in vitro drug release studies showed that matrix tablets formulae containing 10% HPMC (S7) or a combination of 30% NA and 5% HPMC (Ah) exhibited a higher ability to control the release of AMX. The kinetic study revealed that a diffusion controlled mechanism prevailed except when carbopol was used. Formula Ah followed a non-fickian diffusion mechanism similar to Ambroxol(®) SR capsules. Both formulae S7 and Ah could be considered as potential candidates for formulation of AMX controlled release matrix tablets. PMID:21428699

  18. Influence of formulation technique on acrylate methacrylate copolymer modified paracetamol matrix tablets.

    PubMed

    Cash-Torunarigha, Omonyemen Edoise; Eichie, Florence Egbomonjiade; Arhewoh, Matthew Ikhuoria

    2015-03-01

    This work was designed to evaluate the influence of various methods such as dry granulation (DG), wet granulation (using the polymer in an ethanolic solution (WGO) or aqueous dispersion (WGA) and solid dispersion (SD) techniques, on properties of paracetamol matrix tablets prepared using varying concentrations of acrylate methacrylate copolymer. Tablet properties were investigated using official and unofficial standards. Drug dissolution profile assessed at pH 1.2 was studied spectrophotometrically at λ(max) of 245 nm. With the use of various kinetic models, the release mechanism of the drug was analyzed. The parameters, maximum amount of drug release (m(∞)) at time t(∞) were obtained, m(∞) was ≥ 91.36 %, while t(∞) was ≥ 4.5 h. The release rate constant (k) for DG tablets was 15.61 h(sup>-1(/sup>, while, WGO, WGA and SD tablets were 12.90, 11.03 and 10.75 h(-1) respectively. The matrix tablets, which exhibited marked retardation in drug release displayed a Higuchi square root of time model (R(2) > 0.98). The mechanism through which the drug was released was governed by Fickian diffusion release (n values < 0.5). The performance of the drug was affected by the formulation technique in the order of SD > WGO > WGA > DG. PMID:25730787

  19. Matrix-mini-tablets of lornoxicam for targeting early morning peak symptoms of rheumatoid arthritis

    PubMed Central

    Mohd, Abdul Hadi; Raghavendra Rao, Nidagurthi Guggilla; Avanapu, Srinivasa Rao

    2014-01-01

    Objective(s): The aim of present research was to develop matrix-mini-tablets of lornoxicam filled in capsule for targeting early morning peak symptoms of rheumatoid arthritis. Materials and Methods: Matrix-mini-tablets of lornoxicam were prepared by direct compression method using microsomal enzyme dependent and pH-sensitive polymers which were further filled into an empty HPMC capsule. To assess the compatibility, FT-IR and DSC studies for pure drug, polymers and their physical mixture were performed. The formulated batches were subjected to physicochemical studies, estimation of drug content, in vitro drug release, drug release kinetics, and stability studies. Results: When FTIR and DSC studies were performed it was found that there was no interaction between lornoxicam and polymers which used. All the physicochemical properties of prepared matrix-mini-tablets were found to be in normal limits. The percentage of drug content was found to be 99.60±0.07%. Our optimized matrix mini-tablets-filled-capsule formulation F30 released lornoxicam after a lag time of 5.02±0.92 hr, 95.48±0.65 % at the end of 8 hr and 99.90±0.83 % at the end of 12 hr. Stability was also found for this formulation as per the guidelines of International Conference on Harmonisation of Technical Requirements of Pharmaceuticals for Human Use. Conclusion: A novel colon targeted delivery system of lornoxicam was successfully developed by filling matrix-mini-tablets into an empty HPMC capsule shell for targeting early morning peak symptoms of rheumatoid arthritis. PMID:24967065

  20. Solid Dispersion Matrix Tablet Comprising Indomethacin-PEG-HPMC Fabricated with Fusion and Mold Technique

    PubMed Central

    Mesnukul, A.; Yodkhum, K.; Phaechamud, T.

    2009-01-01

    The purpose of this study is to fabricate the polyethylene glycol matrix tablet by mold technique. Indomethacin and hydroxypropylmethylcellulose were used as model drug and polymer, respectively, in PEG matrix system. The physical and drug release characteristics of developed matrix tablet were studied. This inert carrier system comprising 7:3 polyethylene glycol 4000: polyethylene glycol 400 could effectively enhance the solubility of indomethacin and an addition of hydroxypropylmethylcellulose could sustain the drug release. Scanning electron microscope photomicrograph indicated the drug diffusion outward through the porous network of this developed matrix tablet into the dissolution fluid. Least square fitting the experimental dissolution data to the mathematical expressions (power law, first-order, Higuchi's and zero-order) indicated the drug release kinetics primarily as Fickian diffusion. Both the enhancement of drug dissolution and the prolongation of the drug release could be achieved for aqueous insoluble drug such as, indomethacin, by using polyethylene glycol-hydroxypropylmethylcellulose matrix system prepared with melting and mold technique. PMID:20502547

  1. Single and dual drug release patterns from shellac wax-lutrol matrix tablets fabricated with fusion and molding techniques.

    PubMed

    Phaechamud, T; Choncheewa, C

    2015-01-01

    The objective of this investigation was to prepare the shellac wax matrix tablets by fusion and molding technique incorporated with Lutrol in different ratios to modify the hydrophobicity of matrix tablet. The matrix tablets with single drug were loaded either with propranolol hydrochloride or hydrochlorothiazide as hydrophilic and hydrophobic model drugs, and a dual drug formula was also prepared. The single and dual drug release patterns were studied in a dissolution apparatus using distilled water as medium. Propranolol hydrochloride released from matrix was easier than hydrochlorothiazide. Drug release from shellac wax matrix could be enhanced by incorporation of Lutrol. However retardation of drug release from some matrix tablets was evident for the systems that could form dispersion in the dissolution medium. The gel network from high content of Lutrol was hexagonal which was a dense and more compact structure than the other structures found when low amounts of Lutrol were present in the formula. Therefore, the formulae with high content of Lutrol could prolong drug release more efficiently than those containing low content of Lutrol. Hence shellac wax matrix could modulate the drug release with the addition of Lutrol. Sustainable dual drug release was also obtained from these developed matrix tablets. Thus shellac wax-Lutrol component could be used as a potential matrix tablet prepared with fusion and molding technique with excellent controlled drug release. PMID:25767320

  2. Single and Dual Drug Release Patterns from Shellac Wax-Lutrol Matrix Tablets Fabricated with Fusion and Molding Techniques

    PubMed Central

    Phaechamud, T.; Choncheewa, C.

    2015-01-01

    The objective of this investigation was to prepare the shellac wax matrix tablets by fusion and molding technique incorporated with Lutrol in different ratios to modify the hydrophobicity of matrix tablet. The matrix tablets with single drug were loaded either with propranolol hydrochloride or hydrochlorothiazide as hydrophilic and hydrophobic model drugs, and a dual drug formula was also prepared. The single and dual drug release patterns were studied in a dissolution apparatus using distilled water as medium. Propranolol hydrochloride released from matrix was easier than hydrochlorothiazide. Drug release from shellac wax matrix could be enhanced by incorporation of Lutrol. However retardation of drug release from some matrix tablets was evident for the systems that could form dispersion in the dissolution medium. The gel network from high content of Lutrol was hexagonal which was a dense and more compact structure than the other structures found when low amounts of Lutrol were present in the formula. Therefore, the formulae with high content of Lutrol could prolong drug release more efficiently than those containing low content of Lutrol. Hence shellac wax matrix could modulate the drug release with the addition of Lutrol. Sustainable dual drug release was also obtained from these developed matrix tablets. Thus shellac wax-Lutrol component could be used as a potential matrix tablet prepared with fusion and molding technique with excellent controlled drug release. PMID:25767320

  3. Gamma scintigraphic evaluation of floating gastroretentive tablets of metformin HCl using a combination of three natural polymers in rabbits.

    PubMed

    Razavi, Mahboubeh; Karimian, Hamed; Yeong, Chai Hong; Chung, Lip Yong; Nyamathulla, Shaik; Noordin, Mohamed Ibrahim

    2015-01-01

    The present research was aimed at formulating a metformin HCl sustained-release formulation from a combination of polymers, using the wet granulation technique. A total of 16 formulations (F1-F16) were produced using different combinations of the gel-forming polymers: tamarind kernel powder, salep (palmate tubers of Orchis morio), and xanthan. Post-compression studies showed that there were no interactions between the active drug and the polymers. Results of in vitro drug-release studies indicated that the F10 formulation which contained 5 mg of tamarind kernel powder, 33.33 mg of xanthan, and 61.67 mg of salep could sustain a 95% release in 12 hours. The results also showed that F2 had a 55% similarity factor with the commercial formulation (C-ER), and the release kinetics were explained with zero order and Higuchi models. The in vivo study was performed in New Zealand White rabbits by gamma scintigraphy; the F10 formulation was radiolabeled using samarium (III) oxide ((153)Sm2O3) to trace transit of the tablets in the gastrointestinal tract. The in vivo data supported the retention of F10 formulation in the gastric region for 12 hours. In conclusion, the use of a combination of polymers in this study helped to develop an optimal gastroretentive drug-delivery system with improved bioavailability, swelling, and floating characteristics. PMID:26273196

  4. Gamma scintigraphic evaluation of floating gastroretentive tablets of metformin HCl using a combination of three natural polymers in rabbits

    PubMed Central

    Razavi, Mahboubeh; Karimian, Hamed; Yeong, Chai Hong; Chung, Lip Yong; Nyamathulla, Shaik; Noordin, Mohamed Ibrahim

    2015-01-01

    The present research was aimed at formulating a metformin HCl sustained-release formulation from a combination of polymers, using the wet granulation technique. A total of 16 formulations (F1–F16) were produced using different combinations of the gel-forming polymers: tamarind kernel powder, salep (palmate tubers of Orchis morio), and xanthan. Post-compression studies showed that there were no interactions between the active drug and the polymers. Results of in vitro drug-release studies indicated that the F10 formulation which contained 5 mg of tamarind kernel powder, 33.33 mg of xanthan, and 61.67 mg of salep could sustain a 95% release in 12 hours. The results also showed that F2 had a 55% similarity factor with the commercial formulation (C-ER), and the release kinetics were explained with zero order and Higuchi models. The in vivo study was performed in New Zealand White rabbits by gamma scintigraphy; the F10 formulation was radiolabeled using samarium (III) oxide (153Sm2O3) to trace transit of the tablets in the gastrointestinal tract. The in vivo data supported the retention of F10 formulation in the gastric region for 12 hours. In conclusion, the use of a combination of polymers in this study helped to develop an optimal gastroretentive drug-delivery system with improved bioavailability, swelling, and floating characteristics. PMID:26273196

  5. Preparation and characterization of Compritol 888 ATO matrix tablets for the sustained release of diclofenac sodium.

    PubMed

    Roberts, Matthew; Pulcini, Lia; Mostafa, Shabbir; Cuppok-Rosiaux, Yvonne; Marchaud, Delphine

    2015-06-01

    The preparation of lipophilic matrix tablets for the sustained release of water soluble drugs via direct compression is not always feasible due to poor flow and rapid drug release. The aim was to evaluate the potential for developing sustained-release diclofenac sodium tablets, using Compritol® 888 ATO as a lipid matrix, by a wet granulation technique. The effects of wet granulation method (planetary mixer and fluid-bed) and liquid binder type (HPMC Metolose® 603, 606 or 615) on weight uniformity, tensile strength and release rates were investigated. The influence of compression force and speed during tablet manufacture under simulated rotary press production conditions were also evaluated. Rapid release of diclofenac sodium from directly compressed matrices was observed. A wet granulation technique using different HPMC binders produced free-flowing granules and matrices which released diclofenac sodium in a sustained manner over several hours. When the formulation comprising the lowest viscosity grade HPMC (Metolose® 603) was further evaluated using a laboratory scale fluid-bed system, consistently sized granules with good flowability and matrices with good weight uniformity and tensile strengths were produced. Release rates were consistent over a range of compression speeds and forces indicating the suitability of the formulation for production on a rotary tablet press. PMID:24354893

  6. Formulation and in vitro release studies of pegylated mucin based matrix tablets.

    PubMed

    Eraga, Sylvester Okhuelegbe; Arhewoh, Matthew Ikhuoria; Iwuagwu, Magnus Amara; Ukponahiusi, Oyenmwen Enoma

    2015-01-01

    The effects of polymer concentration on the flow properties of granules and in-vitro release profiles from matrix tablets of three model drugs formulated from pegylated mucin base was investigated. Mucin was extracted from the African giant snail and in combination with PEG was used to produce a copolymer matrix base, which was mixed with the model drugs using wet granulation method. The granules and tablets were evaluated according to official and unofficial requirements. Results showed best flow with Acetylsalicylic acid (ASA) and Chloroquine Phosphate (CQ) granules with Hausner ratio of 1.04-1.2, Carr's index of 4.2-17.5% and angle of repose between 19°-26°. The tablets met B.P specifications with respect to tablet weights, friability and drug content. The release profiles showed faster release of the drug with high content of PEG and a slower release with high concentration of mucin. Pegylated mucin base will find useful application in the development of a wide range of formulations. PMID:25553689

  7. Evaluation of injection moulding as a pharmaceutical technology to produce matrix tablets.

    PubMed

    Quinten, Thomas; De Beer, Thomas; Vervaet, Chris; Remon, Jean Paul

    2009-01-01

    The aim of this study was to develop sustained-release matrix tablets by means of injection moulding and to evaluate the influence of process temperature, matrix composition (EC and HPMC concentration) and viscosity grade of ethylcellulose (EC) and hydroxypropylmethylcellulose (HPMC) on processability and drug release. The drug release data were analyzed to get insight in the release kinetics and mechanism. Formulations containing metoprolol tartrate (30%, model drug), EC with dibutyl sebacate (matrix former and plasticizer) and hydrophilic polymer HPMC were extruded and subsequently injection moulded into tablets (375 mg, 10 mm diameter, convex-shaped) at temperatures ranging from 110 to 140 degrees C. Tablets containing 30% metoprolol and 70% ethylcellulose (EC 4mPa s) showed an incomplete drug release within 24 h (<50%). Increasing production temperatures resulted in a lower drug release rate. Substituting part of the EC fraction by HPMC (HPMC/EC-ratio: 20/50 and 35/35) resulted in faster and constant drug release rates. Formulations containing 50% HPMC had a complete and first-order drug release profile with drug release controlled via the combination of diffusion and swelling/erosion. Faster drug release rates were observed for higher viscosity grades of EC (Mw>20 mPa s) and HPMC (4000 and 10,000 mPa s). Tablet porosity was low (<4%). Differential scanning calorimetry (DSC) and X-ray powder diffraction studies (X-RD) showed that solid dispersions were formed during processing. Using thermogravimetrical analysis (TGA) and gel-permeation chromatography no degradation of drug and matrix polymer was observed. The surface morphology was investigated with the aid of scanning electron microscopy (SEM) showing an influence of the process temperature. Raman spectroscopy demonstrated that the drug is distributed in the entire matrix, however, some drug clusters were identified. PMID:18511248

  8. Modulation of drug release kinetics of shellac-based matrix tablets by in-situ polymerization through annealing process.

    PubMed

    Limmatvapirat, Sontaya; Limmatvapirat, Chutima; Puttipipatkhachorn, Satit; Nunthanid, Jurairat; Luangtana-anan, Manee; Sriamornsak, Pornsak

    2008-08-01

    A new oral-controlled release matrix tablet based on shellac polymer was designed and developed, using metronidazole (MZ) as a model drug. The shellac-based matrix tablets were prepared by wet granulation using different amounts of shellac and lactose. The effect of annealing temperature and pH of medium on drug release from matrix tablets was investigated. The increased amount of shellac and increased annealing temperature significantly affected the physical properties (i.e., tablet hardness and tablet disintegration) and MZ release from the matrix tablets. The in-situ polymerization played a major role on the changes in shellac properties during annealing process. Though the shellac did not dissolve in acid medium, the MZ release in 0.1N HCl was faster than in pH 7.3 buffer, resulting from a higher solubility of MZ in acid medium. The modulation of MZ release kinetics from shellac-based matrix tablets could be accomplished by varying the amount of shellac or annealing temperature. The release kinetics was shifted from relaxation-controlled release to diffusion-controlled release when the amount of shellac or the annealing temperature was increased. PMID:18362064

  9. Hydration, erosion, and release behavior of guar-based hydrophilic matrix tablets containing total alkaloids of Sophora alopecuroides.

    PubMed

    Zhao, Wenchang; Song, Lijun; Deng, Hongzhu; Yao, Hui

    2009-05-01

    It is a challenge to deliver water-soluble drug based on hydrophilic matrix to colon because of swelling and erosion of polysaccharides in contact with media. In our study, guar-based hydrophilic matrix tablets containing water-soluble total alkaloids of Sophora alopecuroides prepared by wet granulation technique were evaluated. A novel method was established to investigate the changes of swelling and volume for guar-based tablets in undynamic state, which generally showed a rapid swelling and volume change in the first 9 h, then the hydrated speed slowed down. On the other hand, the influence of different pH of the media on water uptake and erosion of various guar-based formulations in dynamic state indicated that the hydrated constants in simulated gastric fluid (SGF) was higher than that in SIF, which followed varied mechanism of water penetration by fitting Davidson and Peppas model. The extent of erosion was between 22.4 and 32.6% in SIF within 360 min. In vitro sophoridine release studies in successive different mimicking media showed that the guar matrix tablets released 13.5-25.6% of sophoridine in the first 6 h; therefore it was necessary to develop the bilayer matrix tablet by direct-compressing coating 100 mg guar granula on core tablet. The initial release of coated tablet was retarded and the bilayer matrix tablet was suitable for colon target. PMID:19040179

  10. Comparative release profile of sustained release matrix tablets of verapamil HCl

    PubMed Central

    Mathur, Vikas; Nagpal, Kalpana; Singh, Shailendra Kumar; Mishra, Dina Nath

    2013-01-01

    Introduction: Verapamil hydrochloride (VH) is a calcium channel blocking agent used in the treatment of hypertension, cardiac arrhythmia and angina pectoris. The short half-life and high frequency of administration of VH makes it a suitable candidate for designing sustained drug delivery system. The aim of the present investigation was to develop a sustained release matrix tablet of verapamil hydrochloride (VH) using ethyl cellulose, methyl cellulose, Eudragit RS 100, hydroxypropyl methylcellulose and carboxymethyl cellulose and to evaluate the drug release kinetics. Materials and Methods: In order to achieve the required sustained release profile, the tablets were prepared by a wet granulation method using avicel PH 101 and magnesium stearate as binder and lubricant, respectively. Results: The formulated tablets were characterized for pre-compression and post-compression parameters and they were in the acceptable limits. The drug release data obtained after an in vitro dissolution study was fitted to various release kinetic models in order to evaluate the release mechanism and kinetics. The criterion for selecting the best fit model was linearity (coefficient of correlation). Drug release mechanism was found to follow a complex mixture of diffusion, swelling and erosion. Furthermore, to minimize the initial burst drug release, batches were coated by using Eudragit RS100 polymer. After coating the tablets, a better release profile of the formulated tablets was expected and the release rate of the drug was compared with the marketed SR tablet of VH. Conclusion: The dosage form holds the potential to control the release rate of drug and extend the duration of action of a drug. PMID:23799207

  11. A comprehensive in vitro and in vivo evaluation of thiolated matrix tablets as a gastroretentive delivery system.

    PubMed

    Senyigit, Zeynep Ay; Vetter, Anja; Guneri, Tamer; Bernkop-Schnürch, Andreas

    2011-08-01

    The aim of this study was to investigate the potential of thiolated matrix tablets for gastroretentive delivery systems. Poly(acrylic acid)-cysteine (PAA-Cys) and chitosan-4-thiobuthylamidine (chitosan-TBA) were evaluated as anionic and cationic thiolated polymers and riboflavin was used as a model drug. Tablets were prepared by direct compression and each formulation was characterized in terms of disintegration, swelling, mucoadhesion, and drug release properties. Thereafter, the gastric residence times of tablets were determined with in vivo study in rats. The resulting PAA-Cys and chitosan-TBA conjugates displayed 172.80 ± 30.33 and 371.11 ± 72.74 µmol free thiol groups, respectively. Disintegration studies demonstrated the stability of thiolated tablets up to 24 h, whereas tablets prepared with unmodified PAA and chitosan disintegrated within a time period of 1 h. Mucoadhesion studies showed that mucoadhesion work of PAA-Cys and chitosan-TBA tablets were 1.341- and 2.139-times higher than unmodified ones. The mucoadhesion times of PAA, PAA-Cys, chitosan, and chitosan-TBA tablets were 1.5 ± 0.5, 21 ± 1, 1 ± 0.5, 17 ± 1 h, respectively. These results confirm the theory that thiol groups react with mucin glycoproteins and form covalent bonds to the mucus layer. Release studies indicated that a controlled release was provided with thiolated tablets up to 24 h. These promising in vitro results of thiolated tablets were proved with in vivo studies. The thiolated tablets showed a gastroretention time up to 6 h, whereas unmodified tablets completely disintegrated within 1 h in rat stomach. Consequently, the study suggests that thiolated matrix tablets might be promising formulations for gastroretentive delivery systems. PMID:21463156

  12. Formulation and evaluation of cephalexin extended release matrix tablets using 3 factorial design.

    PubMed

    Jishnu, V; Prabhakaran, R; Gilhotra, Rm

    2011-10-01

    The aim of the present investigation was to prepare extended release film coated matrix tablets of cephalexin using binary mixture of two grades of hydrophilic polymer, hydroxypropyl methyl cellulose (HPMC), by direct compression method. Results of the preliminary trials indicated that the polymers used have significant release retarding effect on the formulation. To study the effect of concentration of polymers on drug release from matrix tablets, 3(2) full factorial design was applied. The concentration of HPMC K15M and HPMC 15cps were used as independent variables, while percentage drug release was selected as dependent variable. The dissolution data were fitted into zero-order, first-order, Higuchi and Korsemeyer-Peppas models to identify the pharmacokinetics and mechanism of drug release. Comparative study of dissolution profile of final batch F3 with market preparation (Sporidex AF 375) was done by similarity factor (f(2)) determination and it was concluded that final formulation F3 (10% HPMC K15M, 17.5% HPMC 15cps) shows good similarity with the market product. The results of the accelerated stability study of final formulation F3 for 1 month revealed that storage conditions were not found to have made any significant changes in final formulation F3. The release of cephalexin was prolonged for 6 h by using polymer combinations of HPMC and a twice daily matrix tablet was formulated. PMID:22224031

  13. Formulation and evaluation of controlled release matrix mucoadhesive tablets of domperidone using Salvia plebeian gum

    PubMed Central

    Arora, Gurpreet; Malik, Karan; Singh, Inderbir; Arora, Sandeep; Rana, Vikas

    2011-01-01

    The aim of study was to prepare controlled release matrix mucoadhesive tablets of domperidone using Salvia plebeian gum as natural polymer. Tablets were formulated by direct compression technology employing the natural polymer in different concentrations (5, 10, 15 and 20% w/w). The prepared batches were evaluated for drug assay, diameter, thickness, hardness and tensile strength, swelling index, mucoadhesive strength (using texture analyzer) and subjected to in vitro drug release studies. Real-time stability studies were also conducted on prepared batches. In vitro drug release data were fitted in various release kinetic models for studying the mechanism of drug release. Tensile strength was found to increase from 0.808 ± 0.098 to 1.527 ± 0.10 mN/cm2 and mucoadhesive strength increased from 13.673 ± 1.542 to 40.378 ± 2.345 N, with an increase in the polymer concentration from 5 to 20% (A1 to A4). Swelling index was reported to increase with both increase in the concentration of gum and the time duration. The in vitro drug release decreased from 97.76 to 83.4% (A1 to A4) with the increase in polymer concentration. The drug release from the matrix tablets was found to follow zero-order and Higuchi models, indicating the matrix-forming potential of natural polymer. The value of n was found to be between 0.5221 and 0.8992, indicating the involvement of more than one drug release mechanism from the formulation and possibly the combination of both diffusion and erosion. These research findings clearly indicate the potential of S. plebeian gum to be used as binder, release retardant and mucoadhesive natural material in tablet formulations. PMID:22171313

  14. Elucidation of release characteristics of highly soluble drug trimetazidine hydrochloride from chitosan-carrageenan matrix tablets.

    PubMed

    Li, Liang; Wang, Linlin; Shao, Yang; Tian, Ye; Li, Conghao; Li, Ying; Mao, Shirui

    2013-08-01

    The aim of this study was to better understand the underlying drug release characteristics from matrix tablets based on the combination of chitosan (CS) and different types of carrageenans [kappa (κ)-CG, iota (ι)-CG, and lambda (λ)-CG]. Highly soluble trimetazidine hydrochloride (TH) was used as a model drug. First, characteristics of drug release from different formulations were investigated, and then in situ complexation capacity of CG with TH and CS was studied by differential scanning calorimetry and Fourier transform infrared spectroscopy. Erosion and swelling of matrix were also characterized to better understand the drug-release mechanisms. Effects of pH and ionic strength on drug release were also studied. It was found that not only ι-CG and λ-CG could reduce the burst release of TH by the effect of TH-CG interaction, CS-ι-CG- and CS-λ-CG-based polyelectrolyte film could further modify the controlled-release behavior, but not CS-κ-CG. High pH and high ionic strength resulted in faster drug release from CS-κ-CG- and CS-ι-CG-based matrix, but drug release from CS-λ-CG-based matrix was less sensitive to pH and ionic strength. In conclusion, CS-λ-CG-based matrix tablets are quite promising as controlled-release drug carrier based on multiple mechanisms. PMID:23754467

  15. Direct analysis of pharmaceutical tablet formulations using Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging.

    PubMed

    Earnshaw, Caroline J; Carolan, Vikki A; Richards, Don S; Clench, Malcolm R

    2010-06-15

    Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (MALDI MSI) has been used to directly analyse a range of tablets in order to assess the homogeneity of the active drug compound throughout the excipients contained within the tablets studied. The information gained from the imaging experiments can be used to improve and gain a greater understanding of the manufacturing process; such knowledge will enable improvements in finished product quality to make safer and more efficacious tablet formulations. Commercially available and prescription tablet formulations have been analysed, including aspirin, paracetamol, sildenafil citrate (Viagra(R)) and a batch of tablets in development (tablet X: placebo; 1 mg; 3 mg and 6 mg). MALDI MSI provides semi-quantitative information that is related to ion abundance, therefore Principal Component Analysis (PCA), a multivariate analysis technique, has been used to differentiate between tablets containing different amounts of active drug ingredient. Aspects of sample preparation have also been investigated with regard to tablet shape and texture. The results obtained indicate that MALDI MSI can be used effectively to analyse the spatial distribution of the active pharmaceutical component (API) in pharmaceutical tablet formulations. PMID:20486264

  16. Drug release characteristics from chitosan-alginate matrix tablets based on the theory of self-assembled film.

    PubMed

    Li, Liang; Wang, Linlin; Shao, Yang; Ni, Rui; Zhang, Tingting; Mao, Shirui

    2013-06-25

    The aim of this study was to better understand the underlying drug release characteristics from chitosan-alginate matrix tablets containing different types of drugs. Theophylline, paracetamol, metformin hydrochloride and trimetazidine hydrochloride were used as model drugs exhibiting significantly different solubilities (12, 16, 346 and >1000 mg/ml at 37 °C in water). A novel concept raised was that drugs were released from chitosan-alginate matrix tablets based on the theory of a self-assembled film-controlled release system. The film was only formed on the surface of tablets in gastrointestinal environment and originated from chitosan-alginate polyelectrolyte complex, confirmed by differential scanning calorimetry characterization. The formed film could decrease the rate of polymer swelling to a degree, also greatly limit the erosion of tablets. Drugs were all released through diffusion in the hydrated matrix and polymer relaxation, irrespective of the drug solubility. The effects of polymer level and initial drug loading on release depended on drug properties. Drug release was influenced by the change of pH. In contrast, the impact of ionic strength of the release medium within the physiological range was negligible. Importantly, hydrodynamic conditions showed a key factor determining the superiority of the self-assembled film in controlling drug release compared with conventional matrix tablets. The new insight into chitosan-alginate matrix tablets can help to broaden the application of this type of dosage forms. PMID:23624081

  17. Statistical Optimization of Sustained Release Venlafaxine HCI Wax Matrix Tablet.

    PubMed

    Bhalekar, M R; Madgulkar, A R; Sheladiya, D D; Kshirsagar, S J; Wable, N D; Desale, S S

    2008-01-01

    The purpose of this research was to prepare a sustained release drug delivery system of venlafaxine hydrochloride by using a wax matrix system. The effects of bees wax and carnauba wax on drug release profile was investigated. A 3(2) full factorial design was applied to systemically optimize the drug release profile. Amounts of carnauba wax (X(1)) and bees wax (X(2)) were selected as independent variables and release after 12 h and time required for 50% (t(50)) drug release were selected as dependent variables. A mathematical model was generated for each response parameter. Both waxes retarded release after 12 h and increases the t(50) but bees wax showed significant influence. The drug release pattern for all the formulation combinations was found to be approaching Peppas kinetic model. Suitable combination of two waxes provided fairly good regulated release profile. The response surfaces and contour plots for each response parameter are presented for further interpretation of the results. The optimum formulations were chosen and their predicted results found to be in close agreement with experimental findings. PMID:20046773

  18. Statistical Optimization of Sustained Release Venlafaxine HCI Wax Matrix Tablet

    PubMed Central

    Bhalekar, M. R.; Madgulkar, A. R.; Sheladiya, D. D.; Kshirsagar, S. J.; Wable, N. D.; Desale, S. S.

    2008-01-01

    The purpose of this research was to prepare a sustained release drug delivery system of venlafaxine hydrochloride by using a wax matrix system. The effects of bees wax and carnauba wax on drug release profile was investigated. A 32 full factorial design was applied to systemically optimize the drug release profile. Amounts of carnauba wax (X1) and bees wax (X2) were selected as independent variables and release after 12 h and time required for 50% (t50) drug release were selected as dependent variables. A mathematical model was generated for each response parameter. Both waxes retarded release after 12 h and increases the t50 but bees wax showed significant influence. The drug release pattern for all the formulation combinations was found to be approaching Peppas kinetic model. Suitable combination of two waxes provided fairly good regulated release profile. The response surfaces and contour plots for each response parameter are presented for further interpretation of the results. The optimum formulations were chosen and their predicted results found to be in close agreement with experimental findings. PMID:20046773

  19. Drug release-modulating mechanism of hydrophilic hydroxypropylmethylcellulose matrix tablets: distribution of atoms and carrier and texture analysis.

    PubMed

    Park, Jun-Bom; Lim, Jisung; Kang, Chin-Yang; Lee, Beom-Jin

    2013-12-01

    Although release profiles of drug from hydrophilic matrices have been well recognized, the visual distribution of hydroxypropylmethylcellulose (HPMC) and atoms inside of internal structures of hydrophilic HPMC matrices has not been characterized. In this paper, drug release mechanism from HPMC matrix tablet was investigated based on the release behaviors of HPMC, physical properties of gelled HPMC tablet and atomic distributions of formulation components using diverse instruments. A matrix tablet consisting of hydroxypropyl methylcellulose (HPMC 6, 4,000 and 100,000 mPa·s), chlorpheniramine maleate (CPM) as a model and fumed silicon dioxide (Aerosil(®) 200) was prepared via direct compression. The distribution of atoms and HPMC imaging were characterized using scanning electron microscope (SEM)/ energy-dispersive X-ray spectroscopy (EDX), and near-infrared (NIR) analysis, respectively as a function of time. A texture analyzer was also used to characterize the thickness and maintenance of gel layer of HPMC matrix tablet. The HPMC matrix tablets showed Higuchi release kinetics with no lag time against the square root of time. High viscosity grades of HPMC gave retarded release rate because of the greater swelling and gel thickness as characterized by texture analyzer. According to the NIR imaging, low-viscosity-grade HPMC (6 mPa·s) quickly leached out onto the surface of the tablet, while the high-viscosity-grade HPMC (4000 mPa·s) formed much thicker gel layer around the tablet and maintained longer via slow erosion, resulting in retarded drug release. The atomic distribution of the drug (chlorine, carbon, oxygen), HPMC (carbon, oxygen) and silicon dioxide (silica, oxygen) and NIR imaging of HPMC corresponded with the dissolution behaviors of drug as a function of time. The use of imaging and texture analyses could be applicable to explain the release- modulating mechanism of hydrophilic HPMC matrix tablets. PMID:23855499

  20. Statistical optimization of a novel excipient (CMEC) based gastro retentive floating tablets of propranolol HCl and it's in vivo buoyancy characterization in healthy human volunteers.

    PubMed

    Meka, Venkata Srikanth; Nali, Sreenivasa Rao; Songa, Ambedkar Sunil; Battu, Janaki Ram; Kolapalli, Venkata Ramana Murthy

    2012-01-01

    The objective of the present investigation is to formulate gastro retentive floating drug delivery systems (GRFDDS) of propranolol HCl by central composite design and to study the effect of formulation variables on floating lag time, D1hr (% drug release at 1 hr) and t90 (time required to release 90% of the drug). 3 factor central composite design was employed for the development of GRFDDS containing novel semi synthetic polymer carboxymethyl ethyl cellulose (CMEC) as a release retarding polymer. CMEC, sodium bicarbonate and Povidone concentrations were included as independent variables. The tablets were prepared by direct compression method and were evaluated for in vitro buoyancy and dissolution studies. From the polynomial model fitting statistical analysis, it was confirmed that the response floating lag time and D1hr is suggested to quadratic model and t90 is suggested to linear model. All the statistical formulations followed first order rate kinetics with non-Fickian diffusion mechanism. The desirability function was used to optimize the response variables, each having a different target, and the observed responses were highly agreed with experimental values. Statistically optimized formulation was characterized by FTIR and DSC studies and found no interactions between drug and polymer. The results demonstrate the feasibility of the model in the development of GRFDDS containing a propranolol HCl. Statistically optimized formulation was evaluated for in vivo buoyancy studies in healthy humans for both fed and fasted states. From the results, it was concluded that gastric residence time of the floating tablets were enhanced at fed stage but not in fasted state. PMID:23351981

  1. Statistical optimization of a novel excipient (CMEC) based gastro retentive floating tablets of propranolol HCl and it’s in vivo buoyancy characterization in healthy human volunteers

    PubMed Central

    2012-01-01

    The objective of the present investigation is to formulate gastro retentive floating drug delivery systems (GRFDDS) of propranolol HCl by central composite design and to study the effect of formulation variables on floating lag time, D1hr (% drug release at 1 hr) and t90 (time required to release 90% of the drug). 3 factor central composite design was employed for the development of GRFDDS containing novel semi synthetic polymer carboxymethyl ethyl cellulose (CMEC) as a release retarding polymer. CMEC, sodium bicarbonate and Povidone concentrations were included as independent variables. The tablets were prepared by direct compression method and were evaluated for in vitro buoyancy and dissolution studies. From the polynomial model fitting statistical analysis, it was confirmed that the response floating lag time and D1hr is suggested to quadratic model and t90 is suggested to linear model. All the statistical formulations followed first order rate kinetics with non-Fickian diffusion mechanism. The desirability function was used to optimize the response variables, each having a different target, and the observed responses were highly agreed with experimental values. Statistically optimized formulation was characterized by FTIR and DSC studies and found no interactions between drug and polymer. The results demonstrate the feasibility of the model in the development of GRFDDS containing a propranolol HCl. Statistically optimized formulation was evaluated for in vivo buoyancy studies in healthy humans for both fed and fasted states. From the results, it was concluded that gastric residence time of the floating tablets were enhanced at fed stage but not in fasted state. PMID:23351981

  2. Floating Node Method and Virtual Crack Closure Technique for Modeling Matrix Cracking-Delamination Interaction

    NASA Technical Reports Server (NTRS)

    DeCarvalho, N. V.; Chen, B. Y.; Pinho, S. T.; Baiz, P. M.; Ratcliffe, J. G.; Tay, T. E.

    2013-01-01

    A novel approach is proposed for high-fidelity modeling of progressive damage and failure in composite materials that combines the Floating Node Method (FNM) and the Virtual Crack Closure Technique (VCCT) to represent multiple interacting failure mechanisms in a mesh-independent fashion. In this study, the approach is applied to the modeling of delamination migration in cross-ply tape laminates. Delamination, matrix cracking, and migration are all modeled using fracture mechanics based failure and migration criteria. The methodology proposed shows very good qualitative and quantitative agreement with experiments.

  3. Floating Node Method and Virtual Crack Closure Technique for Modeling Matrix Cracking-Delamination Migration

    NASA Technical Reports Server (NTRS)

    DeCarvalho, Nelson V.; Chen, B. Y.; Pinho, Silvestre T.; Baiz, P. M.; Ratcliffe, James G.; Tay, T. E.

    2013-01-01

    A novel approach is proposed for high-fidelity modeling of progressive damage and failure in composite materials that combines the Floating Node Method (FNM) and the Virtual Crack Closure Technique (VCCT) to represent multiple interacting failure mechanisms in a mesh-independent fashion. In this study, the approach is applied to the modeling of delamination migration in cross-ply tape laminates. Delamination, matrix cracking, and migration are all modeled using fracture mechanics based failure and migration criteria. The methodology proposed shows very good qualitative and quantitative agreement with experiments.

  4. Sustained-release matrix tablets of metformin hydrochloride in combination with triacetyl-beta-cyclodextrin.

    PubMed

    Corti, Giovanna; Cirri, Marzia; Maestrelli, Francesca; Mennini, Natascia; Mura, Paola

    2008-02-01

    The low bioavailability and short half-life of metformin hydrochloride (MH) make the development of sustained-release forms desirable. However, drug absorption is limited to the upper gastrointestinal (GI) tract, thus requiring suitable delivery systems providing complete release during stomach-to-jejunum transit. This study was undertaken to develop a MH sustained-release formulation in compliance with these requirements. The strategy proposed is based on direct-compressed matrix tablets consisting of a combination of MH with the hydrophobic triacetyl-beta-cyclodextrin (TAbetaCD), dispersed in a polymeric material. Different polymers were tested as excipients, i.e. hydroxypropylmethylcellulose, xanthan gum, chitosan, ethylcellulose, Eudragit L100-55, and Precirol. Compatibility among the formulation components was assessed by DSC analysis. All the tablets were examined for drug release pattern in simulated gastric and jejunal fluids used in sequence to mimic the GI transit. Release studies demonstrated that blends of a hydrophobic swelling polymer (hydroxypropylmethylcellulose or chitosan) with a pH-dependent one (Eudragit L100-55) were more useful than single polymers in controlling drug release. Moreover, the main role played by the MH-TAbetaCD system preparation method (i.e. grinding or spray-drying) in determining the behaviour of the final formulation was evidenced. In fact, for a given matrix-tablet composition, different sustained-release effects were obtained by varying the relative amounts of MH-TAbetaCD as ground or spray-dried product. In particular, the 1:1 (w/w) blend of such systems, dispersed in a Eudragit-chitosan polymeric matrix, fully achieved the prefixed goal, giving about 30% released drug after 2h at gastric pH, and overcoming 90% released drug within the subsequent 3h in jejunal fluid. PMID:17616379

  5. Citric acid monohydrate as a release-modifying agent in melt extruded matrix tablets.

    PubMed

    Schilling, Sandra U; Bruce, Caroline D; Shah, Navnit H; Malick, A Waseem; McGinity, James W

    2008-09-01

    Incomplete drug release and particle size-dependent dissolution performance can compromise the quality of controlled release matrix systems. The objective of the current study was to investigate the ability of citric acid monohydrate (CA MH) to enhance the release of diltiazem hydrochloride from melt extruded Eudragit RS PO tablets and to eliminate drug particle size effects. Preformulation studies demonstrated the thermal stability of all components, drug insolubility in the polymer but miscibility with the CA MH. Tablets with either constant polymer levels or constant drug-to-polymer ratios and containing different drug particle size fractions and increasing amounts of CA MH were manufactured by melt extrusion and characterized by dissolution testing, powder X-ray diffraction and scanning electron microscopy. The addition of CA MH to the formulation promoted the thermal processibility and matrix integrity by plasticization of the polymer. The drug release from systems with constant drug-to-polymer ratio was significantly increased when CA MH was added as a result of enhanced pore formation. Particle size effects were eliminated when large amounts of CA MH were used due to the loss of drug crystallinity. Matrix tablets with CA MH furthermore showed a faster and more complete drug release compared to systems with drug only or alternative pore formers (sucrose, NaCl, or PEG 3350). The enhanced drug release was attributed to the amorphous character of the soluble components, improved drug dispersion in the plasticized polymer along with increased polymer permeability. In summary, CA MH promoted the miscibility between the drug and Eudragit RS PO during hot-melt extrusion, resulting in the extrusion of an amorphous system with improved dissolution characteristics. PMID:18582547

  6. Introduction of Sustained Release Opipramol Dihydrochloride Matrix Tablets as a New Approach in the Treatment of Depressive Disorders

    PubMed Central

    Gönüllü, Ümit; Üner, Melike; Yener, Gülgün; Altınkurt, Turan

    2006-01-01

    Opipramol 2-HCl (OP) is used for therapy of general somatoform and anxiety disorders. Conventional tablets in the market contain 50 mg OP to be used once or up to three times a day in effective treatment of depression in mild. In case of serious depressive disorders, OP may be administired up to 300 mg a day. Decrease in frequency of high dose administration via sustained drug release would reduce incidence of symptoms of intoxication in long-term use of OP. With this aim, OP matrix tablets containing 100 mg were prepared by direct compression method to be used once a day to provide patient compliance and constant blood level, consequently to decrease side effects. Two concentrations of polymers (10% and 20%): hydroxypropylcellulose (HPC) and hydroxypropyl methylcellulose (HPMC), sodium alginate (NaAlg), xanthan gum (XG) and Carbopol®941 (C941) were used in preparation of matrix tablets. Drug release study were performed in distilled water, pH1.2 HCl buffer and pH7.4 phosphate buffer solutions according to the Method II in USP 29. Two commercial tablets containing 50 mg OP available in Turkish market were used for comparison. Kinetic models of release patterns from tablets were evaluated. Drug release was displayed slower to faster pattern in order of formulations containing C941, HPMC and HPC. Drug release was significantly faster in tablets of 10% polymers than those of 20%. NaAlg and XG were insufficient to sustain drug release. The most sustaining drug release effect at the lowest polymer concentration was obtained with C941. Drug release from matrix tablets containing 10% C941 was determined as 58.2%, 52.4 and 57.0% in related dissolution mediums above after 8 hours, respectively. However, HPMC and HPC sustained drug release at 20% concentration. As a result, Carbopol® 941, HPMC and HPC can be suggested as suitable to prepare matrix tablets of OP. PMID:23675002

  7. Development of a simple analytical methodology for determination of glucosamine release from modified release matrix tablets.

    PubMed

    Wu, Yunqi; Hussain, Munir; Fassihi, Reza

    2005-06-15

    A simple spectrophotometric method for determination of glucosamine release from sustained release (SR) hydrophilic matrix tablet based on reaction with ninhydrin is developed, optimized and validated. The purple color (Ruhemann purple) resulted from the reaction was stabilized and measured at 570 nm. The method optimization was essential as many procedural parameters influenced the accuracy of determination including the ninhydrin concentration, reaction time, pH, reaction temperature, purple color stability period, and glucosamine/ninhydrin ratio. Glucosamine tablets (600 mg) with different hydrophilic polymers were formulated and manufactured on a rotary press. Dissolution studies were conducted (USP 26) using deionized water at 37+/-0.2 degrees C with paddle rotation of 50 rpm, and samples were removed manually at appropriate time intervals. Under given optimized reaction conditions that appeared to be critical, glucosamine was quantitatively analyzed and the calibration curve in the range of 0.202-2.020 mg (r=0.9999) was constructed. The recovery rate of the developed method was 97.8-101.7% (n=6). Reproducible dissolution profiles were achieved from the dissolution studies performed on different glucosamine tablets. The developed method is easy to use, accurate and highly cost-effective for routine studies relative to HPLC and other techniques. PMID:15925217

  8. Formulation and roentgenographic studies of naproxen-pectin-based matrix tablets for colon drug delivery.

    PubMed Central

    Rao, K. Purushotham; Prabhashankar, B.; Kumar, Ashok; Khan, Azeemuddin; Biradar, S. S.; Srishail, S. Patil; Satyanath, B.

    2003-01-01

    A study has been carried out to assess the potential use of pectin in combination with two added hydrocolloids, i.e., hydroxy-propyl-methyl cellulose and hydroxyethyl cellulose in varied concentrations and coated with ethyl cellulose and cellulose acetate phthalate. The results of in vitro drug release showed that the matrix tablets prepared with pectin, hydroxy ethyl cellulose (20 percent) when coated with ethyl cellulose and cellulose acetate phthalate were found to be 63.0 percent, 8.4 percent, and 4.5 percent, respectively, in after eight hours during drug release study period. These results were confirmed with the results of roentgenographic studies in nine healthy human volunteers to find the shape and integrity of the dosage form. The X-ray photographs revealed that the enteric-coated tablet was visible only up to 5.5 hours and at the end of eighth hour, the photograph has not shown any presence of tablet indicating the loss of shape and size by the microflora present in the colon region. So, the results of in vitro and roentgenographic studies revealed that pectin, hydroxy ethyl cellulose (20 percent) base coated with ethyl cellulose and cellulose acetate phthalate was found to be a promising carrier for naproxen to colon. PMID:15482652

  9. Prolonged release matrix tablet of pyridostigmine bromide: formulation and optimization using statistical methods.

    PubMed

    Bolourchian, Noushin; Rangchian, Maryam; Foroutan, Seyed Mohsen

    2012-07-01

    The aim of this study was to design and optimize a prolonged release matrix formulation of pyridostigmine bromide, an effective drug in myasthenia gravis and poisoning with nerve gas, using hydrophilic - hydrophobic polymers via D-optimal experimental design. HPMC and carnauba wax as retarding agents as well as tricalcium phosphate were used in matrix formulation and considered as independent variables. Tablets were prepared by wet granulation technique and the percentage of drug released at 1 (Y(1)), 4 (Y(2)) and 8 (Y(3)) hours were considered as dependent variables (responses) in this investigation. These experimental responses were best fitted for the cubic, cubic and linear models, respectively. The optimal formulation obtained in this study, consisted of 12.8 % HPMC, 24.4 % carnauba wax and 26.7 % tricalcium phosphate, had a suitable prolonged release behavior followed by Higuchi model in which observed and predicted values were very close. The study revealed that D-optimal design could facilitate the optimization of prolonged release matrix tablet containing pyridostigmine bromide. Accelerated stability studies confirmed that the optimized formulation remains unchanged after exposing in stability conditions for six months. PMID:22713949

  10. Formulation and Evaluation of Cefixime Trihydrate Matrix Tablets Using HPMC, Sodium CMC, Ethyl Cellulose

    PubMed Central

    Sirisolla, Janakidevi; Ramanamurthy, K. V.

    2015-01-01

    The objective of the present work is to design sustained release matrix tablets of cefixime trihydrate by incorporating drug in a matrix made up of release retardant polymers, which prolong drug release leading to minimization of the peak and valley effect in the plasma and provide patient convenience. The effect of combination of polymers on parameters like release pattern, release mechanism of the drug were studied. Total nine formulations each containing 200 mg of drug were prepared by direct compression method. The formulations F-1, F-2, F-3 were prepared with a 1:1 drug to polymer ratio using hydroxypropyl methylcellulose, carboxymethyl cellulose sodium and ethyl cellulose. F-4 was prepared with a 1:1 ratio of hydroxypropyl methylcellulose, carboxymethyl cellulose sodium, F-5 as prepared with a 1:1 ratio of hydroxypropyl methylcellulose and ethyl cellulose, F-6 was prepared with a 1:1 ratio of carboxymethyl cellulose sodium and ethyl cellulose, F-7, F-8, F-9 were prepared by using polymers hydroxypropyl methylcellulose, carboxymethyl cellulose sodium and ethyl cellulose in the ratios of 0.5:0.5:1, 0.5:1:0.5, and 1:0.5:0.5. Designed matrix tablets were evaluated for various pre-compression and post-compression parameters. Formulation F-5 showed 102.15 % release at the end of 12 h and it is selected as the best formulation. All Formulations followed zero order with non-Fickian diffusion method. PMID:26180278

  11. In vitro release of ketoprofen from hydrophilic matrix tablets containing cellulose polymer mixtures.

    PubMed

    Vueba, M L; Batista de Carvalho, L A E; Veiga, F; Sousa, J J; Pina, M E

    2013-11-01

    The effect of cellulose ether polymer mixtures, containing both hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose (HPMC K15M or K100M), on ketoprofen (KTP) release from matrix tablets was investigated. In order to evaluate the compatibility between the matrix components, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray powder diffraction (XRPD) experiments were performed. The results evidence the absence of significant intermolecular interactions that could eventually lead to an incompatibility between the drug and the different excipients. Formulations containing mixtures of polymers with both low and high viscosity grades were prepared by a direct compression method, by varying the polymer/polymer (w/w) ratio while keeping the drug amount incorporated in the solid dispersion constant (200 mg). The hardness values of different matrices were found within the range 113.8 to 154.9 N. HPLC analysis showed a drug content recovery between 99.3 and 102.1%, indicating that no KTP degradation occurred during the preparation process. All formulations attained a high hydration degree after the first hour, which is essential to allow the gel layer formation prior to tablet dissolution. Independent-model dissolution parameters such as t(10%) and t(50%) dissolution times, dissolution efficiency (DE), mean dissolution time (MDT), and area under curve (AUC) were calculated for all formulations. Zero-order, first-order, Higuchi, and Korsmeyer-Peppas kinetic models were employed to interpret the dissolution profiles: a predominantly Fickian diffusion release mechanism was obtained - with Korsmeyer-Peppas exponent values ranging from 0.216 to 0.555. The incorporation of HPC was thus found to play an essential role as a release modifier from HPMC containing tablets. PMID:23094867

  12. Influence of Organic Acids on Diltiazem HCl Release Kinetics from Hydroxypropyl Methyl Cellulose Matrix Tablets.

    PubMed

    Sateesha, Sb; Rajamma, Aj; Narode, Mk; Vyas, Bd

    2010-07-01

    The matrix tablets of diltiazem hydrochloride were prepared by direct compression using hydroxypropyl methyl cellulose (HPMC) and various amounts (2.5%, 5.0%, 10% and 20%) of citric acid, malic acid and succinic acid. The characterization of physical mixture of drug and organic acids was performed by Infra-red spectroscopy. An organic acid was incorporated to set up a system bringing about gradual release of this drug. The influence of organic acids on the release rate were described by the Peppas equation: M (t) /M(∞) = Kt (n) and Higuchi's equation: Q (t) = K(1)t(1/2). The addition of organic acids and the pH value of medium could notably influence the dissolution behavior and mechanism of drug-release from matrices. Increasing amounts of organic acid produced an increase in drug release rate, which showed a good linear relationship between contents of organic acid and drug accumulate release (%) in phosphate buffer, pH 7.4. The drug release increased significantly (P < 0.05) with use of succinic acid in tablet formulation. Increasing amounts of succinic acid above 10% produced decreasing values of n and increasing values of k, in a linear relationship, which indicated there was a burst release of drug from the matrix. Optimized formulations are found to be stable upon 3-month study. PMID:21042476

  13. Pharmaceutical applications of shellac: moisture-protective and taste-masking coatings and extended-release matrix tablets.

    PubMed

    Pearnchob, N; Siepmann, J; Bodmeier, R

    2003-09-01

    Shellac is a natural polymer, which is used as enteric coating material in pharmaceutical applications. The major objective of the present study was to investigate the potential of shellac for other purposes, namely to provide moisture-protective and taste-masking coatings as well as extended-release matrix tablets. The efficiency of shellac to achieve moisture protection and taste masking was compared with that of hydroxypropyl methylcellulose (HPMC), which is most frequently used for these purposes. Shellac-coated tablets showed lower water uptake rates than HPMC-coated systems at the same coating level. The stability of acetylsalicylic acid was higher in tablets coated with shellac compared with HPMC-coated systems, irrespective of the storage humidity. Therefore, lower shellac coating levels were required to achieve the same degree of drug protection. Shellac coatings effectively masked the unpleasant taste of acetaminophen tablets. Compared to HPMC, again lower coating levels were required to achieve similar effects. The resulting drug release in simulated gastric fluid was not significantly altered by the thin shellac coatings, which rapidly ruptured due to the swelling of the coated tablet core. In addition, shellac was found to be a suitable matrix former for extended-release tablets. The latter could be prepared by direct compression or via wet granulation using ethanolic or ammoniated aqueous shellac binder solutions. The resulting drug-release patterns could effectively be altered by varying different formulation and processing parameters. PMID:14570313

  14. Pectin/anhydrous dibasic calcium phosphate matrix tablets for in vitro controlled release of water-soluble drug.

    PubMed

    Mamani, Pseidy Luz; Ruiz-Caro, Roberto; Veiga, María Dolores

    2015-10-15

    Different pectin/anhydrous dibasic calcium phosphate (ADCP) matrix tablets have been developed in order to obtain controlled release of a water-soluble drug (theophylline). Swelling, buoyancy and dissolution studies have been carried out in different aqueous media (demineralized water, progressive pH medium, simulated gastric fluid, simulated intestinal fluid and simulated colonic fluid), to characterize the matrix tablets. When the pectin/ADCP ratio was ≥0.26 (P1, P2, P3 and P4 tablets) a continuous swelling and low theophylline dissolution rate from the matrices were observed. So, pectin gel forming feature predominated over the ADCP properties, yielding pH-independent drug release behavior from these matrices. On the contrary, pectin/ADCP ratios ≤0.11 (P5 and P6 tablets) allowed to achieve drug dissolution pH dependent. Consequently, the suitable selection of the pectin/ADCP ratio will allow to tailor matrix tablets for controlled release of water-soluble drugs in a specific manner in the gastrointestinal tract. PMID:26276258

  15. Design of pH-independent extended release matrix tablets of minocycline hydrochloride for the treatment of dementia.

    PubMed

    Cha, Kwang-Ho; Park, Junsung; Cho, Wonkyung; Gu, Dong-Geon; Jeong, Kihyang; Hwang, Sung-Joo

    2009-11-01

    The aim of this study was to develop a pH-independent extended release matrix tablet of minocycline HCl for the treatment of dementia. The matrix tablets were prepared by wet granulation technique using Eudragit L and S as release modifiers at different w/w ratios (1:0, 1:1 and 0:1) and PEO as a matrix former. In the case of the matrix tablet without any release modifiers, the drug release rate at pH 1.2 was much higher than that of pH 7.4. By adding the release modifier, the drug release rate at pH 7.4 increased close to that of pH 1.2 and the pH-independent release was obtained. In addition, it was shown that lubricants containing a divalent cation such as Mg stearate inhibited minocycline release in basic medium. Therefore, the incorporation of Eudragit L and S (1:1 ratio) as release modifiers and Na stearyl fumarate as a lubricant into PEO-based matrix tablets effectively produced pH-independent minocycline release profiles. PMID:20091273

  16. Formulation and Evaluation of a Novel Matrix-Type Orally Disintegrating Ibuprofen Tablet

    PubMed Central

    Tayebi, Hoda; Mortazavi, Seyed Alireza

    2011-01-01

    Orally disintegrating tablets (ODTs) are capable of turning quickly into a liquid dosage form in contact with the saliva, thus possessing the advantages of both the solid dosage forms particularly stability and liquid dosage forms specially ease of swallowing and pre-gastric absorption of drug. The aim of this study was to prepare a novel matrix-type buccal fast disintegrating ibuprofen tablet formulation using special polymers, water soluble excipients, super-disintegrants and quickly soluble granules. For this purpose different tablet formulations of ibuprofen were prepared. The amount of ibuprofen in each formulation was 100 mg. Eight groups of formulation were prepared (A-H series), accounting for a total number of 45 formulations. Formulations prepared were examined in terms of different physicochemical tests including powder/granule flowability, appearance, thickness, uniformity of weight, hardness, friability and disintegration time. Results of formulation F22a (in series F), was found to be acceptable, making it the chosen formulation for further studies. Then, by adding various flavorants and sweeteners to this formulation, complementary series of formulations, named G and H, were prepared. Following the comparison of their taste with each other through asking 10 volunteers, the most suitable formulation regarding the taste, being formulation F22s, was chosen as the ultimate formulation. This formulation had PVP, ibuprofen and croscarmellose as the intra-granular components and xylitol and saccharin as the extra-granular ingredients. Formulation F22s was found to be acceptable in terms of physicochemical tests conducted, showing quick disintegration within the buccal cavity, appropriate hardness and rather low friability. Hence formulation F22s was selected as the final formulation. PMID:24250378

  17. Formulation Development and Stability Studies of Norfloxacin Extended-Release Matrix Tablets

    PubMed Central

    Oliveira, Paulo Renato; Klein, Lilian; Sangoi, Maximiliano da Silva; Bernardi, Larissa Sakis; Silva, Marcos Antônio Segatto

    2013-01-01

    The aim of this research was to develop a new hydrophilic matrix system containing norfloxacin (NFX). Extended-release tablets are usually intended for once-a-day administration with benefits to the patient and lower discontinuation of the therapy. Formulations were developed with hydroxypropylmethylcellulose or poly(ethylene oxide) as hydrophilic polymers, with different molecular weights (MWs) and concentrations (20 and 30%). The tablets were found to be stable (6 months at 40 ± 2°C and 75 ± 5% relative humidity), and the film-coating process is recommended to avoid NFX photodegradation. The dissolution profiles demonstrated an extended-release of NFX for all developed formulations. Dissolution curves analyzed using the Korsmeyer exponential equation showed that drug release was controlled by both drug diffusion and polymer relaxation or erosion mechanisms. A more erosion controlled system was obtained for the formulations containing lower MW and amount of polymer. With the increase in both MW and amount of polymer in the formulation, the gel layer became stronger, and the dissolution was more drug-diffusion dependent. Formulations containing intermediate MW polymers or high concentration (30%) of low MW polymers demonstrated a combination of extended and complete in vitro drug release. This way, these formulations could provide an increased bioavailability in vivo. PMID:24083235

  18. Controlled release of dual drug-loaded hydroxypropyl methylcellulose matrix tablet using drug-containing polymeric coatings.

    PubMed

    Lee, B J; Ryu, S G; Cui, J H

    1999-10-15

    A dual drug-loaded hydroxypropylmethylcellulose (HPMC) matrix tablet simultaneously containing drug in inner tablet core and outer coated layer was formulated using drug-containing aqueous-based polymeric Eudragit RS30D dispersions. Effects of coating levels, drug loadings in outer layers, amount and type of five plasticizers and talc concentration on the release characteristics were evaluated on the characteristics in simulated gastric fluid for 2 h followed by a study in intestinal fluids. Melatonin (MT) was selected as a model drug. The surface morphology of dual drug-loaded HPMC tablets using scanning electron microscope (SEM) was smooth, showing the distinct coated layer with about 75-microm coating thickness at the 15% coating level. Unlike the uncoated and conventionally coated HPMC tablet, the dual drug-loaded HPMC matrix tablet gave a biphasic linear release, showing a zero-order for 4 h (first) followed by another zero-order release when fitted using linear regression (r(2) = 0.99). As the coating levels (15, 25%) increased, the release rate was further decreased. The biphasic release profiles of dual drug-loaded HPMC matrix tablet was unchanged except when 25% coating level containing 0.5% drug concentration was applied. As the drug concentration in polymeric coating dispersion increased (0.25-1.0%), the amount of drug released increased. The time for the first linear release was also advanced. However, the biphasic release pattern was not changed. The biphasic release profiles of dual drug-loaded HPMC matrix tablet were highly modified, depending on the amount and type of five plasticizers. Talc (10-30%) in coating dispersion as an anti-sticking material did not affect the release profiles. The current dual drug-loaded HPMC matrix tablet, showing biphasic release profiles may provide an alternative to deliver drugs with circadian rhythmic behaviors in the body but needs to be further validated in future in human studies. The dual drug-loaded coating method is also interesting for the modified release of poorly water-soluble drugs because solubilizers and other additives can be added in drug-containing polymeric coating dispersions. PMID:10528084

  19. Formulation and evaluation of ileo-colonic targeted matrix-mini-tablets of Naproxen for chronotherapeutic treatment of rheumatoid arthritis.

    PubMed

    Hadi, Mohd Abdul; Raghavendra Rao, N G; Srinivasa Rao, A

    2016-01-01

    In this present research work, the aim was to develop ileo-colonic targeted matrix-mini-tablets-filled capsule system of Naproxen for chronotherapeutic treatment of Rheumatoid Arthritis. So Matrix-mini-tablets of Naproxen were prepared using microsomal enzyme dependent and pH-sensitive polymers by direct compression method which were further filled into an empty HPMC capsule. The compatibility was assessed using FT-IR and DSC studies for pure drug, polymers and their physical mixtures. The prepared batches were subjected to physicochemical studies, drug content estimation, in-vitro drug release and stability studies. When FTIR and DSC studies were performed, it was found that there was no interaction between Naproxen and polymers used. The physicochemical properties of all the prepared matrix-mini-tablets batches were found to be in limits. The drug content percentage in the optimized formulation F18 was found to be 99.24 ± 0.10%. Our optimized matrix-mini-tablets-filled-capsule formulation F18 releases Naproxen after a lag time of 2.45 ± 0.97 h and 27.30 ± 0.86%, 92.59 ± 0.47%, 99.38 ± 0.69% at the end of 5, 8, 12 h respectively. This formulation was also found to be stable as per the guidelines of International Conference on Harmonisation of Technical Requirements of Pharmaceuticals for Human Use. Thus, a novel ileo-colonic targeted delivery system of Naproxen was successfully developed by filling matrix-mini-tablets into an empty HPMC capsule shell for targeting early morning peak symptoms of rheumatoid arthritis. PMID:26903770

  20. Formulation and evaluation of ileo-colonic targeted matrix-mini-tablets of Naproxen for chronotherapeutic treatment of rheumatoid arthritis

    PubMed Central

    Hadi, Mohd Abdul; Raghavendra Rao, N.G.; Srinivasa Rao, A.

    2015-01-01

    In this present research work, the aim was to develop ileo-colonic targeted matrix-mini-tablets-filled capsule system of Naproxen for chronotherapeutic treatment of Rheumatoid Arthritis. So Matrix-mini-tablets of Naproxen were prepared using microsomal enzyme dependent and pH-sensitive polymers by direct compression method which were further filled into an empty HPMC capsule. The compatibility was assessed using FT-IR and DSC studies for pure drug, polymers and their physical mixtures. The prepared batches were subjected to physicochemical studies, drug content estimation, in-vitro drug release and stability studies. When FTIR and DSC studies were performed, it was found that there was no interaction between Naproxen and polymers used. The physicochemical properties of all the prepared matrix-mini-tablets batches were found to be in limits. The drug content percentage in the optimized formulation F18 was found to be 99.24 ± 0.10%. Our optimized matrix-mini-tablets-filled-capsule formulation F18 releases Naproxen after a lag time of 2.45 ± 0.97 h and 27.30 ± 0.86%, 92.59 ± 0.47%, 99.38 ± 0.69% at the end of 5, 8, 12 h respectively. This formulation was also found to be stable as per the guidelines of International Conference on Harmonisation of Technical Requirements of Pharmaceuticals for Human Use. Thus, a novel ileo-colonic targeted delivery system of Naproxen was successfully developed by filling matrix-mini-tablets into an empty HPMC capsule shell for targeting early morning peak symptoms of rheumatoid arthritis. PMID:26903770

  1. Photoimages and the release characteristics of lipophilic matrix tablets containing highly water-soluble potassium citrate with high drug loadings.

    PubMed

    Cao, Qing-Ri; Kim, Tae-Wan; Lee, Beom-Jin

    2007-07-18

    Two types of the carnauba wax-based lipophilic matrix tablet using spray-dried granules (SDT) or directly compressible powdered mixtures (DCT) were prepared for sustained release. The model drug was a highly water-soluble potassium citrate and loaded about 74% of the total tablet weight. The SDT slowly eroded and disintegrated during the release study without showing sustained release when the hydrophilic excipients were added. In contrast, the DCT was more efficient for sustained release. The release rate decreased with increasing carnauba wax concentration. In particular, the sustained release rate was markedly pronounced when the lipophilic stearyl alcohol and stearic acid were combined with the carnauba wax. The surface of the intact DCT appeared to be smooth and rusty. The DCT rose to the surface from the bottom of the vessel during the release test, and numerous pores and cracks with no signs of disintegration were also observed after the release test. The release profile was dependent on the formulation composition and preparation method of the matrix tablet. Diffusion-controlled leaching through the channels of the pores and cracks of the lipophilic matrix tablet (DCT) is a key to the sustained release. PMID:17532156

  2. Synthesis and Characterization of Sodium Alginate Conjugate and Study of Effect of Conjugation on Drug Release from Matrix Tablet

    PubMed Central

    Satheeshababu, B. K.; Mohamed, I.

    2015-01-01

    The aim of the present research work to study the effect of conjugation of the polymer on drug release from the matrix tablets. Sodium alginate L-cysteine conjugate was achieved by covalent attachment of thiol group of L-cysteine with the primary amino group of sodium alginate through the amide bonds formed by primary amino groups of the sodium alginate and the carboxylic acid group of L-cysteine. The synthesised sodium alginate L-cysteine conjugate was characterised by determining of charring point, Fourier transmission-infrared and differential scanning calorimetric analysis. To study the effect of conjugation on drug release pattern, the matrix tablets were prepared using various proportions of sodium alginate and sodium alginate L-cysteine conjugate along with atorvastatin calcium as model drug. The wet granulation technique was adopted and prepared matrix tablets were evaluated for various physical parameters. The in vitro drug release study results suggested that tablet formulated in combination of sodium alginate and sodium alginate L-cysteine conjugate S4 showed 100% after 8 h drug release whereas formulated with only sodium alginate S0 released 40% in 8 h. PMID:26798173

  3. Synthesis and Characterization of Sodium Alginate Conjugate and Study of Effect of Conjugation on Drug Release from Matrix Tablet.

    PubMed

    Satheeshababu, B K; Mohamed, I

    2015-01-01

    The aim of the present research work to study the effect of conjugation of the polymer on drug release from the matrix tablets. Sodium alginate L-cysteine conjugate was achieved by covalent attachment of thiol group of L-cysteine with the primary amino group of sodium alginate through the amide bonds formed by primary amino groups of the sodium alginate and the carboxylic acid group of L-cysteine. The synthesised sodium alginate L-cysteine conjugate was characterised by determining of charring point, Fourier transmission-infrared and differential scanning calorimetric analysis. To study the effect of conjugation on drug release pattern, the matrix tablets were prepared using various proportions of sodium alginate and sodium alginate L-cysteine conjugate along with atorvastatin calcium as model drug. The wet granulation technique was adopted and prepared matrix tablets were evaluated for various physical parameters. The in vitro drug release study results suggested that tablet formulated in combination of sodium alginate and sodium alginate L-cysteine conjugate S4 showed 100% after 8 h drug release whereas formulated with only sodium alginate S0 released 40% in 8 h. PMID:26798173

  4. An innovative matrix controlling drug delivery produced by thermal treatment of DC tablets containing polycarbophil and ethylcellulose.

    PubMed

    Caviglioli, Gabriele; Baldassari, Sara; Cirrincione, Paola; Russo, Eleonora; Parodi, Brunella; Gatti, Paolo; Drava, Giuliana

    2013-12-15

    An innovative matrix, produced by thermal treatment on direct compression (DC) tablets containing polycarbophil (POL) and ethylcellulose (EC), identified as matrix forming polymers, and able to control the release of diltiazem hydrochloride, was developed. At pH 7.2, 72 ± 1.2% (w/w) of drug loaded was released in 25 h, mostly at constant rate. This swellable and unerodible matrix controls drug release by an anomalous transport mechanism. The modifications induced by the thermal treatment are irreversible and can be used to control and characterize the matrix. A 3-component constrained mixture design allowed the investigation of the experimental domain in which the matrix forms and the computation of a mathematical model that can be used to optimize the formulation properties. The release rate can be modulated (0.032-0.064% drug released/min) through the choice of suitable treatment conditions and tablet composition. The maximum amount of diltiazem hydrochloride released by zero-order kinetics, at the lowest release rate, occurs for POL:EC ratio in the range of 1:1-2:3 with 20-30% of diluent. The tablets are able to load up to 50% (w/w) of diltiazem hydrochloride without losing their properties. A stability study performed on a selected formulation containing DTZ showed stability for at least 2.7 years at RT conditions. PMID:24144954

  5. Insights into the mechanisms of chitosan-anionic polymers-based matrix tablets for extended drug release.

    PubMed

    Li, Liang; Wang, Linlin; Li, Jinfeng; Jiang, Shan; Wang, Yitong; Zhang, Xin; Ding, Jiaojiao; Yu, Tongya; Mao, Shirui

    2014-12-10

    The aim of this study was to investigate drug release mechanisms from physical mixtures of chitosan-anionic polymers-based matrix tablets and to obtain a comprehensive understanding about release characteristics. Six types of anionic polymers (i.e., Eudragit(®) L100, sodium alginate, carrageenan, carboxymethylcellulose sodium, carbomer and xanthan gum) and two model drugs (i.e., theophylline and metoprolol succinate) with varied solubility were chosen. Texture analyzer, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were applied to better understand drug release mechanisms. In vitro release experiments were conducted in a pH-changing medium to simulate the physiological condition of the gastrointestinal tract. Interestingly, a common phenomenon was observed in all the CS-anionic polymers-based matrix tablets investigated here, that is, the inner layer of the swollen tablets was coated by CS-anionic polymer polyelectrolyte complexes (PEC)-based film formed by self-assembly. Formation of the in situ self-assembled film was further confirmed by texture analysis, DSC, and FTIR. It was further identified that properties of the film were influenced by the characteristics of anionic polymers and the physiological conditions of the gastrointestinal tract. Moreover, this novel structure could alter swelling and erosion-based release mechanisms of the tablets. In addition, drug release characteristics from CS-anionic polymer systems depended on the properties of anionic polymers and the drug solubility. In conclusion, our studies may broaden current views on cationic polymer-anionic polymer-based oral matrix tablets for extended release. PMID:25290814

  6. Optimization and prediction of drug release from matrix tablets using response surface methodology and near infrared chemical imaging.

    PubMed

    Bagchi, Saumitra; Li, Weiyong; Plakogiannis, Fotios

    2012-01-01

    The purpose of this work was to understand the formulation effect on the drug release from a hydrophilic matrix tablet of niacin using a multivariate statistical technique and Near Infrared Chemical Imaging (NIR-CI). Tablets were composed of ethyl cellulose (EC) and polyethylene oxide (PEO) as release retarding polymers and lactose as the release modulator. D-optimal experimental design was composed of three formulation variables: the content of EC(X(1)), PEO (X(2)), and lactose (X(3)). Response surface methodology (RSM) and multiple response optimization utilizing the polynomial equation were used to predict the optimal formulation. Results showed that the interaction effect of lactose with the polymers PEO and EC and lactose by itself were the most influential factors on the drug release rate. While lactose enhances the drug release rate by forming pores it also promotes water penetration into the tablet core. This in turn helps the formation of the gel layer which acts as barrier to drug diffusion. NIR-CI showed that tablets with higher level of PEO swells at a faster rate and greater extent than formulations with higher level of EC. NIR-CI was thus found to be a very useful technique to predict the drug release rate from hydrophilic matrix systems. PMID:21222508

  7. Development and evaluation of natural gum-based extended release matrix tablets of two model drugs of different water solubilities by direct compression.

    PubMed

    Ofori-Kwakye, Kwabena; Mfoafo, Kwadwo Amanor; Kipo, Samuel Lugrie; Kuntworbe, Noble; Boakye-Gyasi, Mariam El

    2016-01-01

    The study was aimed at developing extended release matrix tablets of poorly water-soluble diclofenac sodium and highly water-soluble metformin hydrochloride by direct compression using cashew gum, xanthan gum and hydroxypropylmethylcellulose (HPMC) as release retardants. The suitability of light grade cashew gum as a direct compression excipient was studied using the SeDeM Diagram Expert System. Thirteen tablet formulations of diclofenac sodium (∼100 mg) and metformin hydrochloride (∼200 mg) were prepared with varying amounts of cashew gum, xanthan gum and HPMC by direct compression. The flow properties of blended powders and the uniformity of weight, crushing strength, friability, swelling index and drug content of compressed tablets were determined. In vitro drug release studies of the matrix tablets were conducted in phosphate buffer (diclofenac: pH 7.4; metformin: pH 6.8) and the kinetics of drug release was determined by fitting the release data to five kinetic models. Cashew gum was found to be suitable for direct compression, having a good compressibility index (ICG) value of 5.173. The diclofenac and metformin matrix tablets produced generally possessed fairly good physical properties. Tablet swelling and drug release in aqueous medium were dependent on the type and amount of release retarding polymer and the solubility of drug used. Extended release of diclofenac (∼24 h) and metformin (∼8-12 h) from the matrix tablets in aqueous medium was achieved using various blends of the polymers. Drug release from diclofenac tablets fitted zero order, first order or Higuchi model while release from metformin tablets followed Higuchi or Hixson-Crowell model. The mechanism of release of the two drugs was mostly through Fickian diffusion and anomalous non-Fickian diffusion. The study has demonstrated the potential of blended hydrophilic polymers in the design and optimization of extended release matrix tablets for soluble and poorly soluble drugs by direct compression. PMID:26903772

  8. Development and evaluation of natural gum-based extended release matrix tablets of two model drugs of different water solubilities by direct compression

    PubMed Central

    Ofori-Kwakye, Kwabena; Mfoafo, Kwadwo Amanor; Kipo, Samuel Lugrie; Kuntworbe, Noble; Boakye-Gyasi, Mariam El

    2015-01-01

    The study was aimed at developing extended release matrix tablets of poorly water-soluble diclofenac sodium and highly water-soluble metformin hydrochloride by direct compression using cashew gum, xanthan gum and hydroxypropylmethylcellulose (HPMC) as release retardants. The suitability of light grade cashew gum as a direct compression excipient was studied using the SeDeM Diagram Expert System. Thirteen tablet formulations of diclofenac sodium (∼100 mg) and metformin hydrochloride (∼200 mg) were prepared with varying amounts of cashew gum, xanthan gum and HPMC by direct compression. The flow properties of blended powders and the uniformity of weight, crushing strength, friability, swelling index and drug content of compressed tablets were determined. In vitro drug release studies of the matrix tablets were conducted in phosphate buffer (diclofenac: pH 7.4; metformin: pH 6.8) and the kinetics of drug release was determined by fitting the release data to five kinetic models. Cashew gum was found to be suitable for direct compression, having a good compressibility index (ICG) value of 5.173. The diclofenac and metformin matrix tablets produced generally possessed fairly good physical properties. Tablet swelling and drug release in aqueous medium were dependent on the type and amount of release retarding polymer and the solubility of drug used. Extended release of diclofenac (∼24 h) and metformin (∼8–12 h) from the matrix tablets in aqueous medium was achieved using various blends of the polymers. Drug release from diclofenac tablets fitted zero order, first order or Higuchi model while release from metformin tablets followed Higuchi or Hixson-Crowell model. The mechanism of release of the two drugs was mostly through Fickian diffusion and anomalous non-Fickian diffusion. The study has demonstrated the potential of blended hydrophilic polymers in the design and optimization of extended release matrix tablets for soluble and poorly soluble drugs by direct compression. PMID:26903772

  9. Effect of Quaternary Ammonium Carboxymethylchitosan on Release Rate In-vitro of Aspirin Sustained-release Matrix Tablets

    PubMed Central

    Meng, Lingbin; Teng, Zhongqiu; Zheng, Nannan; Meng, Weiwei; Dai, Rongji; Deng, Yulin

    2013-01-01

    The aim of this study was to develop a derivative of chitosan as pharmaceutical excipient used in sustained-release matrix tablets of poorly soluble drugs. A water-soluble quaternary ammonium carboxymethylchitosan was synthesized by a two-step reaction with carboxymethylchitosan (CMCTS), decylalkyl dimethyl ammonium and epichlorohydrin. The elemental analysis showed that the target product with 10.27% of the maximum grafting degree was obtained. To assess the preliminary safety of this biopolymer, cell toxicity assay was employed. In order to further investigate quaternary ammonium carboxymethylchitosan application as pharmaceutical excipient, aspirin was chosen as model drug. The effect of quaternary ammonium CMCTS on aspirin release rate from sustained-release matrix tablets was examined by in-vitro dissolution experiments. The results showed that this biopolymer had a great potential in increasing the dissolution of poorly soluble drug. With the addition of CMCTS-CEDA, the final cumulative release rate of drug rose up to 90%. After 12 h, at the grade of 10, 20 and 50 cps, the drug release rate increased from 58.1 to 90.7%, from 64.1 to 93.9%, from 69.3 to 96.1%, respectively. At the same time, aspirin release rate from sustainedrelease model was found to be related to the amount of quaternary ammonium CMCTS employed. With the increase of CMCTS-CEDA content, the accumulated release rate increased from 69.1% to 86.7%. The mechanism of aspirin release from sustained-release matrix tablets was also preliminary studied to be Fick diffusion. These data demonstrated that the chitosan derivative has positive effect on drug release from sustained-release matrix tablets. PMID:24250627

  10. Formulation and in vitro evaluation of theophylline matrix tablets prepared by direct compression: Effect of polymer blends

    PubMed Central

    El-Bagory, Ibrahim; Barakat, Nahla; Ibrahim, Mohamed A.; El-Enazi, Fouza

    2011-01-01

    The deformation mechanism of pharmaceutical powders, used in formulating directly compressed matrix tablets, affects the characteristics of the formed tablets. Three polymers of different deformation mechanisms were tested for their impact on theophylline directly compressed tablets namely Kollidon SR (KL SR, plastic deformation), Ethylcellulose (EC, elastic deformation) and Carnauba wax (CW, brittle deformation) at different compression forces. However, tablets based mainly on KL SR, the plastically deformed polymer (TN1) exhibited the highest hardness values compared to the other formulae which are based on either blends of KL SR with CW, the very brittle deformed polymer. The upper detected force for TN formulae and the lower punch force were found to dependent mainly on the powder deformation. This difference is attributed to the work done during the compression phase as well as the work lost during the decompression phase. Furthermore, the release profiles of TN from formulae TN2 and TN4 that are based on the composition (2KL SR:1EC) and (1KL SR:2EC), respectively, were consistent with different deformation mechanisms of KL SR and EC and on the physicochemical properties like the water absorptive capacity of EC. Upon increasing the weight ratio of KL SR (TN2), the release rate was greatly retarded (39.4%, 37.1%, 35.0% and 33.6% released after 8 h at 5, 10, 15 and 20 kN. PMID:24115902

  11. Formulation of bi-layer matrix tablets of tramadol hydrochloride: Comparison of rate retarding ability of the incorporated hydrophilic polymers.

    PubMed

    Arif, Hasanul; Al-Masum, Abdullah; Sharmin, Florida; Reza, Selim; Sm Islam, Sm Ashraful

    2015-05-01

    Bi-layer tablets of tramadol hydrochloride were prepared by direct compression technique. Each tablet contains an instant release layer with a sustained release layer. The instant release layer was found to release the initial dose immediately within minutes. The instant release layer was combined with sustained release matrix made of varying quantity of Methocel K4M, Methocel K15MCR and Carbomer 974P. Bi-layer tablets were evaluated for various physical tests including weight variation, thickness and diameter, hardness and percent friability. Drug release from bi-layer tablet was studied in acidic medium and buffer medium for two and six hours respectively. Sustained release of tramadol hydrochloride was observed with a controlled fashion that was characteristic to the type and extent of polymer used. % Drug release from eight-hour dissolution study was fitted with several kinetic models. Mean dissolution time (MDT) and fractional dissolution values (T25%, T50% and T80%) were also calculated as well, to compare the retarding ability of the polymers. Methocel K15MCR was found to be the most effective in rate retardation of freely water-soluble tramadol hydrochloride compared to Methocel K4M and Capbomer 974P, when incorporated at equal ratio in the formulation. PMID:26004717

  12. Formulation and in vitro evaluation of theophylline matrix tablets prepared by direct compression: Effect of polymer blends.

    PubMed

    El-Bagory, Ibrahim; Barakat, Nahla; Ibrahim, Mohamed A; El-Enazi, Fouza

    2012-07-01

    The deformation mechanism of pharmaceutical powders, used in formulating directly compressed matrix tablets, affects the characteristics of the formed tablets. Three polymers of different deformation mechanisms were tested for their impact on theophylline directly compressed tablets namely Kollidon SR (KL SR, plastic deformation), Ethylcellulose (EC, elastic deformation) and Carnauba wax (CW, brittle deformation) at different compression forces. However, tablets based mainly on KL SR, the plastically deformed polymer (TN1) exhibited the highest hardness values compared to the other formulae which are based on either blends of KL SR with CW, the very brittle deformed polymer. The upper detected force for TN formulae and the lower punch force were found to dependent mainly on the powder deformation. This difference is attributed to the work done during the compression phase as well as the work lost during the decompression phase. Furthermore, the release profiles of TN from formulae TN2 and TN4 that are based on the composition (2KL SR:1EC) and (1KL SR:2EC), respectively, were consistent with different deformation mechanisms of KL SR and EC and on the physicochemical properties like the water absorptive capacity of EC. Upon increasing the weight ratio of KL SR (TN2), the release rate was greatly retarded (39.4%, 37.1%, 35.0% and 33.6% released after 8 h at 5, 10, 15 and 20 kN. PMID:24115902

  13. Surface-Deacetylated Chitin Nano-Fiber/Hyaluronic Acid Composites as Potential Antioxidative Compounds for Use in Extended-Release Matrix Tablets

    PubMed Central

    Anraku, Makoto; Tabuchi, Ryo; Ifuku, Shinsuke; Ishiguro, Takako; Iohara, Daisuke; Hirayama, Fumitoshi

    2015-01-01

    In this study, we examined a possible use of a surface-deacetylated chitin nano-fiber (SDCH-NF) and hyaluronic acid (HA) interpolymer complex (IPC) tablet as a potential antioxidative compound in extended-release matrix tablets. The antioxidant properties of untreated chitin (UCH), SDCH-NF, and HA were examined using N-centered radicals derived from 1,1′-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). SDCH-NF and HA had acceptable scavenging abilities and were relatively efficient radical scavengers, but UCH was much less effective. The results suggest that SDCH-NF and HA could serve as scavengers of compounds related to the development of oxidative stress. An SDCH-NF/HA IPC tablet was prepared and evaluated as an extended-release tablet matrix using famotidine (FMT) as a model drug. The release of FMT from the IPC tablet (DCF-NF:HA = 1:1) was slower than that from a SDCH-NF only tablet. Turbidity measurements and X-ray diffraction (XRD) data also indicated that the optimum complexation ratio for IPC between SDCH-NF/HA is 1/1, resulting in a good relationship between turbidity or XRD of the complex and the release ratio of FMT. These results suggest that an SDCH-NF/HA tablet has the potential for use in an extended-release IPC tablet with a high antioxidant activity. PMID:26501272

  14. Influence of pH modifiers and HPMC viscosity grades on nicotine-magnesium aluminum silicate complex-loaded buccal matrix tablets.

    PubMed

    Pongjanyakul, Thaned; Kanjanabat, Sopaphan

    2012-06-01

    Hydroxypropyl methylcellulose (HPMC) tablets containing nicotine-magnesium aluminum silicate (NCT-MAS) complex particles and pH modifiers, namely, sodium chloride, citric acid, and magnesium hydroxide, were prepared using the direct compression method. The effects of HPMC viscosity grades and pH modifiers on NCT release and permeation of the matrix tablets were examined. The results showed that the higher the viscosity grade of HPMC that was used in the tablets, the lower was the unidirectional NCT release rate found. The unidirectional NCT permeation was not affected by the viscosity grade of HPMC because the NCT diffusion through the mucosal membrane was the rate-limiting step of the permeation. Incorporation of magnesium hydroxide could retard NCT release, whereas the enhancement of unidirectional NCT release was found in the tablets containing citric acid. Citric acid could inhibit NCT permeation due to the formation of protonated NCT in the swollen tablets at an acidic pH. Conversely, the NCT permeation rate increased with the use of magnesium hydroxide as a result of the neutral NCT that formed at a basic microenvironmental pH. The swollen HPMC tablets, with or without pH modifiers, gave sufficient adhesion to the mucosal membrane. Furthermore, the addition of magnesium hydroxide to the matrix tablets was the major factor in controlling buccal delivery of NCT. This study suggests that the NCT-MAS complex-loaded HPMC tablets, which contained magnesium hydroxide, are potential buccal delivery systems of NCT. PMID:22552930

  15. Formulation and Evaluation of Cephalexin Extended-release Matrix Tablets Using Hydroxy Propyl Methyl Cellulose as Rate-controlling Polymer.

    PubMed

    Vijay, J; Sahadevan, Jt; Prabhakaran, R; Gilhotra, R Mehra

    2012-01-01

    The present investigation reports the design and evaluation of six-hour extended release film-coated matrix tablets of cephalexin using different grades of hydrophilic polymer hydroxypropylmethylcellulose (HPMC) employing direct compression method. The preformulation studies performed included the physical compatibility studies, Differential Scanning Calorimetry analysis, drug characterization using Fourier Transform Infra Red spectroscopic analysis and particle size analysis using sieve method. The tablets were evaluated for weight variation, hardness, thickness and friability. Results of the studies indicate that the polymers used have significant release-retarding effect on the formulation. The dissolution profile comparison of the prepared batches P1 to P8 and market preparation (Sporidex AF 375) was done by using Food and Drug Administration-recommended similarity factor (f(2)) determination. The formulation P8 (10% HPMC K4M, 15% HPMC 15cps) with a similarity factor (f(2)) of 77.75 was selected as the optimized formulae for scale-up batches. The dissolution data of the best formulation P8 was fitted into zero order, first order, Higuchi and Korsemeyer-Peppas models to identify the pharmacokinetics and mechanism of drug release. The results of the accelerated stability study of best formulation P8 for three months revealed that storage conditions were not found to have made any significant changes in final formulation F3. The release of cephalexin was prolonged for 6 h by using polymer combinations of HPMC and a twice daily matrix tablet was formulated. PMID:22523453

  16. Preparation and evaluation of sustained-release matrix tablets based on metoprolol and an acrylic carrier using injection moulding.

    PubMed

    Quinten, T; Andrews, G P; De Beer, T; Saerens, L; Bouquet, W; Jones, D S; Hornsby, P; Remon, J P; Vervaet, C

    2012-12-01

    Sustained-release matrix tablets based on Eudragit RL and RS were manufactured by injection moulding. The influence of process temperature; matrix composition; drug load, plasticizer level; and salt form of metoprolol: tartrate (MPT), fumarate (MPF) and succinate (MPS) on ease of processing and drug release were evaluated. Formulations composed of 70/30% Eudragit RL/MPT showed the fastest drug release, substituting part of Eudragit RL by RS resulted in slower drug release, all following first-order release kinetics. Drug load only affected drug release of matrices composed of Eudragit RS: a higher MPT concentration yielded faster release rates. Adding triethyl citrate enhanced the processability, but was detrimental to long-term stability. The process temperature and plasticizer level had no effect on drug release, whereas metoprolol salt form significantly influenced release properties. The moulded tablets had a low porosity and a smooth surface morphology. A plasticizing effect of MPT, MPS and MPF on Eudragit RS and Eudragit RL was observed via DSC and DMA. Solubility parameter assessment, thermal analysis and X-ray diffraction demonstrated the formation of a solid solution immediately after production, in which H-bonds were formed between metoprolol and Eudragit as evidenced by near-infrared spectroscopy. However, high drug loadings of MPS and MPF showed a tendency to recrystallise during storage. The in vivo performance of injection-moulded tablets was strongly dependent upon drug loading. PMID:22965662

  17. Film-coated matrix mini-tablets for the extended release of a water-soluble drug.

    PubMed

    Mohamed, Faiezah A A; Roberts, Matthew; Seton, Linda; Ford, James L; Levina, Marina; Rajabi-Siahboomi, Ali R

    2015-04-01

    Extended release (ER) of water-soluble drugs from hydroxypropylmethylcellulose (HPMC) matrix mini-tablets (mini-matrices) is difficult to achieve due to the large surface area to volume ratio of the mini matrices. Therefore, the aims of this study were to control the release of a water-soluble drug (theophylline) from mini-matrices by applying ER ethylcellulose film coating (Surelease®), and to assess the effects of Surelease®:pore former (Opadry®) ratio and coating load on release rates. Mini-matrices containing 40%w/w HPMC K100M CR were coated with 100:0, 85:15, 80:20, 75:25 or 70:30 Surelease®:Opadry® to different coating weight gains (6-20%). Non-matrix mini-tablets were also produced and coated with 80:20 Surelease®:Opadry® to different coating weight gains. At low coating weight gains, nonmatrix mini-tablets released the entire drug within 0.5 h, while at high coating weight gains only a very small amount (<5%) of drug was released after 12 h. The gel formation of HPMC prevented disintegration of mini-matrices at low coating weight gains but contributed to rupture of the film even at high coating weight gains. As a result, drug release from mini-matrices was slower than that from nonmatrix mini-tablets at low coating weight gains, yet faster at high coating weight gains. An increase in the lag time of drug release from mini-matrices was observed as the concentration of Opadry® reduced or the coating weight gain increased. This study has demonstrated the possibility of extending the release of a water-soluble drug from HPMC mini-matrices by applying ER film coating with appropriate levels of pore former and coating weight gains to tailor the release rate. PMID:24564797

  18. Sucrose stearate-enriched lipid matrix tablets of etodolac: modulation of drug release, diffusional modeling and structure elucidation studies.

    PubMed

    Abd-Elbary, Ahmed; Tadros, Mina Ibrahim; Alaa-Eldin, Ahmed Adel

    2013-06-01

    Etodolac is a non-steroidal anti-inflammatory drug having an elimination half-life of 7 h; oral doses are given every 6-8 h. The aim of current work was the development of controlled-release etodolac lipid matrix tablets. The variables influencing design of these tablets (L1-L28) by the hot fusion method were investigated including; (1) lipid type (stearic acid, cetyl alcohol, cetostearyl alcohol, Imwitor 900K, Precirol ATO 5 and Compritol ATO 888), (2) drug/lipid ratio (1:0.25 and 1:0.50, respectively), (3) filler type (lactose, Avicel PH101 and their physical mixtures; 2:1, 1:1, and 1:2, respectively), (4) surfactant's HLB (5 and 11), and (5) drug/surfactant ratio (20:1 and 10:1, respectively). Statistical analysis and kinetic modeling of drug release data were evaluated. The inner matrix of the tablet was visualized via scanning electron microscopy (SEM). An inverse correlation was observed between the drug/lipid ratio and the drug release rate. Precirol- and Compritol-containing formulae showed more retarded drug release rates. Lactose/Avicel physical mixture (1:1) was considered as a filler of choice where it minimized the burst effect observed with Avicel-free formulae. The higher surfactant's HLB, the higher drug release rate. The similarity factor (f(2)) between the drug release profiles revealed similarity within the investigated drug/surfactant ratios. Sucrose stearate D1805-based matrix (L21) succeeded in delivering more than 90% of etodolac over 12 h, following anomalous (non-Fickian) controlled-release kinetics. SEM micrographs confirmed pore formation, within the latter matrix, upon contact with dissolution medium. PMID:23572253

  19. Quality by Design approach to understand the physicochemical phenomena involved in controlled release of captopril SR matrix tablets.

    PubMed

    Saur, J; Milln, D; Su-Negre, J M; Colom, H; Tic, J R; Miarro, M; Prez-Lozano, P; Garca-Montoya, E

    2014-12-30

    The aim of this study is to obtain swelling controlled release matrix tablets of captopril using the Quality by Design methodology (ICH Q8) and to know the transport mechanisms involved in captopril release. To obtain the area of knowledge, the design of experiments studying the effect of two components (HPMC K15M and ethylcellulose) at different levels has been applied, with the captopril dissolution profile as the product's most important critical quality attribute (CQA). Different dissolution profiles have been obtained with the design of experiments performed, which is a key factor in the development of controlled release matrix tablets. Kinetic analysis according to the equations of Higuchi and Korsmeyer-Peppas demonstrates that the release mechanism is a mechanism of erosion when the whole percentage of the polymer is ethylcellulose, and a diffusion mechanism when the whole percentage of the polymer is HPMC K15M. The physico-chemical characteristics of the gel layer determine the release rate of captopril. The thickness of the gel layer, the porosity which is formed in the matrix upon contact with water, pore size, the swelling rate, the erosion rate of the matrix, and the physico-chemical characteristics of captopril, are factors related to the kinetic equations described and that allow us to predict the release mechanism of captopril. A new relationship of the kinetic equations governing the in vitro behavior with the physical characteristics of the gel layer of the different formulations has been established. This study shows that the size of water-filled pores and the degree of crosslinking between the chains of HPMC K15M of the matrix are related to the exponent n of the Korsmeyer-Peppas equation and the type of transport of the captopril from within the matrix to the dissolution medium, that is, if the transport is only through water-filled pores, or if a combination of diffusion occurs through water-filled pores with a transport through continuous polymeric networks. PMID:25445523

  20. Roller compaction of hydrophilic extended release tablets-combined effects of processing variables and drug/matrix former particle size.

    PubMed

    Heiman, Johanna; Tajarobi, Farhad; Gururajan, Bindhumadhavan; Juppo, Anne; Abrahmsén-Alami, Susanna

    2015-04-01

    The present study shows that roller compaction (RC) can successfully be used as a granulation method to prepare hydroxypropyl methylcellulose (HPMC)-based extended release matrix tablets containing a high drug load, both for materials deforming mainly by fragmentation (paracetamol) as for those having mainly plastic deformation (ibuprofen). The combined effect of RC process variables and composition on the manufacturability of HPMC tablets was investigated. Standard wet granulation grade HPMC was compared with a larger particle size direct compressible HPMC grade. Higher roll pressure was found to result in larger paracetamol granules and narrower granule particle size distributions, especially for formulations containing smaller size HPMC. However, for ibuprofen, no clear effect of roll pressure was observed. High roll pressure also resulted in denser ribbon and less bypass fines during RC. Loss of compactibility was observed for granules compared to powder blends, which was found to be related to differences in granule porosity and morphology. Using the large-sized HPMC grade did in some cases result in lower tensile strength tablets but had the advantage to improve the powder flow into the roller compactor. This work also indicates that when the HPMC level lies near the percolation threshold, significant changes can occur in the drug release rate due to changes in other factors (raw material characteristics and processing). PMID:25273028

  1. Ballistic Impact Behavior of Nacre-Like Laminated Composites Consisting of B4C Tablets and Polyurea Matrix

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Snipes, J. S.; Ramaswami, S.

    2016-03-01

    A nacre-like composite armor consisting of B4C tablets and polyurea matrix is modeled, and its ballistic impact behavior and penetration resistance (under a normal and a 15°-oblique impact by a solid right circular cylindrical projectile) were analyzed using a series of transient, nonlinear dynamic, finite-element analyses. Nacre is a biological material constituting the innermost layer of the shells of gastropods and bivalves. It consists of polygonal tablets of aragonite, tessellated to form individual layers and having the adjacent layers as well as the tablets within a layer bonded by a biopolymer. Due to its highly complex hierarchical microstructure, nacre possesses an outstanding combination of mechanical properties, the properties which are far superior to the ones that are predicted using the homogenization techniques such as the rule of mixtures. The results of the transient nonlinear dynamic analysis pertaining to the ballistic impact response and the penetration resistance of the modeled nacre-like armor are compared with their counterparts for the B4C single-block armor having an identical areal density. Furthermore, the effect of various nacre microstructural features (e.g., surface profiling, micron-scale asperities, mineral bridges between the overlapping tablets lying in adjacent layers) on the ballistic penetration resistance of the nacre-like composite armor is investigated in order to identify an optimal nacre-like composite-armor architecture having the largest penetration resistance. The results obtained clearly show that a nacre-like armor possesses a superior penetration resistance relative to its monolithic counterpart, and that the nacre microstructural features considered play a critical role in the armor penetration resistance.

  2. Ballistic Impact Behavior of Nacre-Like Laminated Composites Consisting of B4C Tablets and Polyurea Matrix

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Snipes, J. S.; Ramaswami, S.

    2016-02-01

    A nacre-like composite armor consisting of B4C tablets and polyurea matrix is modeled, and its ballistic impact behavior and penetration resistance (under a normal and a 15°-oblique impact by a solid right circular cylindrical projectile) were analyzed using a series of transient, nonlinear dynamic, finite-element analyses. Nacre is a biological material constituting the innermost layer of the shells of gastropods and bivalves. It consists of polygonal tablets of aragonite, tessellated to form individual layers and having the adjacent layers as well as the tablets within a layer bonded by a biopolymer. Due to its highly complex hierarchical microstructure, nacre possesses an outstanding combination of mechanical properties, the properties which are far superior to the ones that are predicted using the homogenization techniques such as the rule of mixtures. The results of the transient nonlinear dynamic analysis pertaining to the ballistic impact response and the penetration resistance of the modeled nacre-like armor are compared with their counterparts for the B4C single-block armor having an identical areal density. Furthermore, the effect of various nacre microstructural features (e.g., surface profiling, micron-scale asperities, mineral bridges between the overlapping tablets lying in adjacent layers) on the ballistic penetration resistance of the nacre-like composite armor is investigated in order to identify an optimal nacre-like composite-armor architecture having the largest penetration resistance. The results obtained clearly show that a nacre-like armor possesses a superior penetration resistance relative to its monolithic counterpart, and that the nacre microstructural features considered play a critical role in the armor penetration resistance.

  3. A unified multicomponent stress-diffusion model of drug release from non-biodegradable polymeric matrix tablets.

    PubMed

    Salehi, Ali; Zhao, Jin; Cabelka, Tim D; Larson, Ronald G

    2016-02-28

    We propose a new transport model of drug release from hydrophilic polymeric matrices, based on Stefan-Maxwell flux laws for multicomponent transport. Polymer stress is incorporated in the total mixing free energy, which contributes directly to the diffusion driving force while leading to time-dependent boundary conditions at the tablet interface. Given that hydrated matrix tablets are dense multicomponent systems, extended Stefan-Maxwell (ESM) flux laws are adopted to ensure consistency with the Onsager reciprocity principle and the Gibbs-Duhem thermodynamic constraint. The ESM flux law for any given component takes into account the friction exerted by all other species and is invariant with respect to reference velocity, thus satisfying Galilean translational invariance. Our model demonstrates that penetrant-induced plasticization of polymer chains partially or even entirely offsets the steady decline of chemical potential gradients at the tablet-medium interface that drive drug release. Utilizing a Flory-Huggins thermodynamic model, a modified form of the upper convected Maxwell constitutive equation for polymer stress and a Fujita-type dependence of mutual diffusivities on composition, depending on parameters, Fickian, anomalous or case II drug transport arises naturally from the model, which are characterized by quasi-power-law release profiles with exponents ranging from 0.5 to 1, respectively. A necessary requirement for non-Fickian release in our model is that the matrix stress relaxation time is comparable to the time scale for water diffusion. Mutual diffusivities and their composition dependence are the most decisive factors in controlling drug release characteristics in our model. Regression of the experimental polymer dissolution and drug release profiles in a system of Theophylline/cellulose (K15M) demonstrate that API-water mutual diffusivity in the presence of excipient cannot generally be taken as a constant. PMID:26763374

  4. Drug Release Kinetics and Front Movement in Matrix Tablets Containing Diltiazem or Metoprolol/λ-Carrageenan Complexes

    PubMed Central

    Bonferoni, Maria Cristina; Colombo, Paolo; Zanelotti, Laura; Caramella, Carla

    2014-01-01

    In this work we investigated the moving boundaries and the associated drug release kinetics in matrix tablets prepared with two complexes between λ-carrageenan and two soluble model drugs, namely, diltiazem HCl and metoprolol tartrate aiming at clarifying the role played by drug/polymer interaction on the water uptake, swelling, drug dissolution, and drug release performance of the matrix. The two studied complexes released the drug with different mechanism indicating two different drug/polymer interaction strengths. The comparison between the drug release behaviour of the complexes and the relevant physical mixtures indicates that diltiazem gave rise to a less soluble and more stable complex with carrageenan than metoprolol. The less stable metoprolol complex afforded an erodible matrix, whereas the stronger interaction between diltiazem and carrageenan resulted in a poorly soluble, slowly dissolving matrix. It was concluded that the different stability of the studied complexes affords two distinct drug delivery systems: in the case of MTP, the dissociation of the complex, as a consequence of the interaction with water, affords a classical soluble matrix type delivery system; in the case of DTZ, the dissolving/diffusing species is the complex itself because of the very strong interaction between the drug and the polymer. PMID:25045689

  5. Synthesis, characterization and evaluation of methacrylamide grafted gellan as sustained release tablet matrix.

    PubMed

    Nandi, Gouranga; Patra, Poushali; Priyadarshini, Rosy; Kaity, Santanu; Ghosh, Lakshmi Kanta

    2015-01-01

    In the present study, the microwave induced synthesis of polymethacrylamide-grafted-gellan gum (PMaa-g-GG) was carried out by free radical initiation using cerric (IV) ammonium nitrate (CAN) as redox initiator. Concentrations of methacrylamide (Maa), CAN and microwave irradiation time were taken as variable synthetic parameters. The modified polysaccharide obtained from different synthetic conditions was then characterized by FTIR, CHN analysis, DSC and powder X-ray diffraction. The yield and extent of grafting were assessed by determining percentage grafting, percentage grafting efficiency, percentage conversion and these were correlated with elemental analysis. The acute oral toxicity study of modified polysaccharide was performed as per OECD guideline. Histological comparison of different organs between control and test animal showed no significant difference. Sustained release tablets of diclofenac sodium (DS) were prepared with modified gellan. In vitro dissolution study showed the tablets were capable of releasing the drug over a period of 8 h. PMID:25316428

  6. Quantifying the release of lactose from polymer matrix tablets with an amperometric biosensor utilizing cellobiose dehydrogenase.

    PubMed

    Knöös, Patrik; Schulz, Christopher; Piculell, Lennart; Ludwig, Roland; Gorton, Lo; Wahlgren, Marie

    2014-07-01

    The release of lactose (hydrophilic) from polymer tablets made with hydrophobically modified poly(acrylic acid) (HMPAA) have been studied and compared to the release of ibuprofen, a hydrophobic active substance. Lactose is one of the most used excipients for tablets, but lactose release has not been widely studied. One reason could be a lack of good analytical tools. A novel biosensor with cellobiose dehydrogenase (CDH) was used to detect the lactose release, which has a polydiallyldimethylammonium chloride (PDADMAC) layer that increases the response. A sample treatment using polyethylenimine (PEI) was developed to eliminate possible denaturants. The developed methodology provided a good approach to detect and quantify the released lactose. The release was studied with or without the presence of a model amphiphilic substance, sodium dodecyl sulphate (SDS), in the release medium. Ibuprofen showed very different release rates in the different media, which was attributed to hydrophobic interactions between the drug, the HMPAA and the SDS in the release medium. The release of hydrophilic lactose, which did not associate to any of the other components, was rapid and showed only minor differences. The new methodology provides a useful tool to further evaluate tablet formulations by a relatively simple set of experiments. PMID:24726632

  7. Preparation and comparative evaluation of sustained release metoclopramide hydrochloride matrix tablets.

    PubMed

    Abdel-Rahman, Sayed I; Mahrous, Gamal M; El-Badry, Mahmoud

    2009-10-01

    Metoclopramide hydrochloride (MCP) is commonly used for the management of gastrointestinal disorders. Frequent administration and the undesired side effects (extra pyramidal symptoms) of the drug on the central nervous system due to the fluctuations of its plasma concentrations may lead to patient incompliance, and hence, improper therapy. Therefore, the present work will be devoted to formulate the drug in sustained release formulations. MCP was incorporated in 12 formulae containing different polymers and/or different polymer ratios. These polymers were hydroxypropylmethyl cellulose (HPMC), carboxymethylcellulose (CMC) and ethyl cellulose (EC). Sodium starch glycolate (SSG) was added to some formulae in different amounts in order to soften and/or disintegrate the tablets. Both direct compression and granulation techniques were used to prepare the tablets. The physical properties were found to be satisfactory for all the formulae. The dissolution profiles of the tablets were constructed using the change-over method. The drug release involved a combination of both diffusion and polymer-chain relaxation mechanisms. The time required to release 50% of MCP ranged from 1.2 to more than 8 h. Direct compression and dry granulation techniques produced sufficient sustaining of the drug release. However, the pellets made by wet granulation released MCP in about 2 h, i.e., pelletization spheronization technique was not effective in sustaining the drug. PMID:23960711

  8. RELEASE AND MUCOADHESION PROPERTIES OF DICLOFENAC MATRIX TABLETS FROM NATURAL AND SYNTHETIC POLYMER BLENDS.

    PubMed

    Odeniyi, Michael A; Khan, Nasir H; Peh, Kok K

    2015-01-01

    The delayed release and mucoadhesive properties of Cedrela gum and hydroxypropylmethylcellulose blend in diclofenac sodium tablet formulations were evaluated. Tablets were prepared by direct compression and the crushing strength and detachment force were found to increase from 74.49 ± 1.22 to 147.25 ± 2.57 N and 0.302 ± 0.36 to 1.141 ± 0.05 N from low to high level of polymers, respectively. The release kinetics followed Korsmeyer-Peppas release and the n varied between 0.834 and 1.273, indicating that the release mechanism shifts from Fickian to super case I (anomalous release). The drug release profile fits a pulsatile-release pattern characterized by a lag time followed by a more or less rapid and complete drug release. The Cedrela gum-hydroxypropylmethylcelluse blend tablets delayed diclofenac release for 2 h and sustained the release for 12 h. The polymer blend delayed drug release in the 0.1 M HCl simulating gastric environment and subsequent release pH 6.8 phosphate buffer. PMID:26642664

  9. Formulation development and optimization of sustained release matrix tablet of Itopride HCl by response surface methodology and its evaluation of release kinetics

    PubMed Central

    Bose, Anirbandeep; Wong, Tin Wui; Singh, Navjot

    2012-01-01

    The objective of this present investigation was to develop and formulate sustained release (SR) matrix tablets of Itopride HCl, by using different polymer combinations and fillers, to optimize by Central Composite Design response surface methodology for different drug release variables and to evaluate drug release pattern of the optimized product. Sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and polyvinyl pyrolidine (pvp) and lactose as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was further subjected to scanning electron microscopy to reveal its release pattern. The in vitro study revealed that combining of HPMC K100M (24.65 MG) with pvp(20 mg)and use of LACTOSE as filler sustained the action more than 12 h. The developed sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet. PMID:23960836

  10. Evaluation of Influence of Various Polymers on Dissolution and Phase Behavior of Carbamazepine-Succinic Acid Cocrystal in Matrix Tablets

    PubMed Central

    Ullah, Majeed; Ullah, Hanif; Murtaza, Ghulam; Mahmood, Qaisar; Hussain, Izhar

    2015-01-01

    The aim of current study was to explore the influence of three commonly used polymers, that is, cellulosics and noncellulosics, for example, Methocel K4M, Kollidon VA/64, and Soluplus, on the phase disproportionation and drug release profile of carbamazepine-succinic acid (CBZ-SUC) cocrystal at varying drug to polymer ratios (1 : 1 to 1 : 0.25) in matrix tablets. The polymorphic phase disproportionation during in-depth dissolution studies of CBZ-SUC cocrystals and its crystalline properties were scrutinized by X-ray powder diffractrometry and Raman spectroscopy. The percent drug release from HPMC formulations (CSH) showed inverse relation with the concentration of polymer; that is, drug release increased with decrease in polymer concentration. On contrary, direct relation was observed between percent drug release and polymer concentrations of Kollidon VA 64/Soluplus (CSK, CSS). At similar polymer concentration, drug release from pure carbamazepine was slightly lower with HPMC formulations than that of cocrystal; however, opposite trend in release rate was observed with Kollidon VA/64 and Soluplus. The significant increase in dissolution rate of cocrystal occurred with Kollidon VA/64 and Soluplus at higher polymer concentration. Moreover, no phase change took place in Methocel and Kollidon formulations. No tablet residue was left for Soluplus formulation so the impact of polymer on cocrystal integrity cannot be predicted. PMID:26380301

  11. Formulation development and evaluation of Diltiazem HCl sustained release matrix tablets using HPMC K4M and K100M.

    PubMed

    Qazi, Faaiza; Shoaib, Muhammad Harris; Yousuf, Rabia Ismail; Qazi, Tanveer Mustafa; Mehmood, Zafar Alam; Hasan, S M Farid

    2013-07-01

    The aim of this study was to develop a sustained release hydrophilic matrix tablet of Diltiazem HCl and evaluates the effect of formulation variables (e.g. lubricant, binder, polymer content and viscosity grades of HPMC) on drug release. Twelve different formulations (F1-F12) were prepared by direct compression. The results of the physical parameters and assay were found to be within the acceptable range. Rate of drug release was found to be slow as the fraction of the polymer was increased from 20-50%. The drug release rate from tablets containing K4M was effectively controlled by increasing the talc concentration, whereas the burst effect was reduced by increasing binder content. The drug release was higher with K4M as compare to K100M. Model-dependent and independent methods were used for data analysis and the best results were observed for K4M in Higuchi (R(2)=0.9903-0.9962) and K100M in Baker and Lonsdale (R(2)=0.9779-0.9941). The release mechanism of all formulations was non-Fickian. F7 (50% K4M, 2% talc, 10% Avicel PH101) and F11 (40% K100M) were very close to targeted release profile. F12 (50% K100M) exhibited highest degree of swelling and lowest erosion. The f1 and f2 test were performed taking F11 as a reference formulation. PMID:23811439

  12. Influence of admixed citric acid and physiological variables on the vinpocetine release from sodium alginate compressed matrix tablets.

    PubMed

    Nie, Shufang; Wu, Jie; Liu, Hui; Pan, Weisan; Liu, Yanli

    2011-08-01

    In this study, the controlled release matrix tablets of vinpocetine were prepared by direct compression using sodium alginate (SAL) as hydrophilic polymer and different amounts of citric acid as hydrosoluble acidic excipient to set up a system bringing about zero-order release of this drug in distilled water containing 0.5% sodium dodecyl sulfate. At the critical content of admixed citric acid (60 mg/tab.), the lowest drug-release rate was observed. In order to explain the effect of this critical content on drug-release rate from SAL matrices, investigation of the possibility of interaction of citric acid with SAL was performed using differential scanning calorimetric analysis and infrared analysis, which confirmed the existence of direct citric acid-SAL interaction when these two excipients came in contact with water. A zero-order drug-release system could be obtained by regulating the ratio of citric acid-to-SAL and the capacity of this system in controlling drug-release rate depended on the extent of interaction between citric acid and SAL. It is worth noticing that pH and the ionic strength of the dissolution medium were found to exert an influence on the drug-release performance of SAL tablets. PMID:21417613

  13. Sustained release of acetaminophen from heterogeneous matrix tablets: influence of polymer ratio, polymer loading, and co-active on drug release.

    PubMed

    Ebube, N K; Hikal, A H; Wyandt, C M; Beer, D C; Miller, L G; Jones, A B

    1997-05-01

    The aim of this research was to investigate the effect of pseudoephedrine (PE), polymer ratio, and polymer loading on the release of acetaminophen (APAP) from hydroxypropyl methyl cellulose (HPMC)/polyvinylpyrrolidone (PVP) matrices. Granules formulated with APAP or both APAP and PE, and various blends of HPMC and PVP were compressed into tablets at varying compression forces ranging from 2000 to 6000 Ib. In vitro drug release from the matrix tablets was determined and the results correlated with those of tablet water uptake and erosion studies. Drug release from the formulations containing both APAP and PE was slower than those containing only APAP (P < 0.05, F = 3.10). Drug release from tablets formulated with APAP only showed an initial burst at pH 1.16 or 7.45, and at high total polymer loading (> or = 9.6%). Formulations containing both APAP and PE showed slower drug release at pH 1.16 than at pH 7.45. At pH 1.16, a decline in the percentage of APAP released occurred after 18 hours. This was due to the hydrolysis of APAP to p-aminophenol. The drug dissolution data showed good fit to the Korsmeyer and Peppas model, and the values of the release exponents ranged from 0.20 to 0.62, indicating a complex drug release pattern. Tablet erosion studies indicated that the amount of APAP released was linearly related to the percentage of tablet weight loss. The kinetics of tablet water uptake was consistent with a diffusion and stress relaxation controlled mechanism. Overall, the results of this study indicated that PE, as a co-active in the formulation, modified the matrix, and hence retarded APAP release. PMID:9552442

  14. A canine biorelevant dissolution method for predicting in vivo performance of orally administered sustained release matrix tablets.

    PubMed

    Walsh, Paul L; Bothe, Jameson R; Bhardwaj, Sunny; Hu, Mengwei; Nofsinger, Rebecca; Xia, Binfeng; Persak, Steven; Pennington, Justin; Bak, Annette

    2016-05-01

    Preclinical species are a crucial component of drug development, but critical differences in physiology and anatomy need to be taken into account when attempting to extrapolate to humans or between species. The same is true when trying to develop oral formulations for preclinical species, especially unconventional formulations, such as sustained release tablets. During the evaluation of such specialized dosage forms, dissolution can be a critical in vitro tool used to rank-order formulations and ultimately choose the desired release rate. Here, the development of a canine biorelevant dissolution method for the prediction of the in vivo performance of sustained release matrix tablets in beagle dogs is described. The method accounts for differences in physiology between humans and dogs such as gastrointestinal fluid composition, gastric emptying forces, and gastric residence time. The most critical dissolution method parameters were found to be the paddle speed used to simulate the gastric emptying forces as well as the time spent in simulated gastric fluid. The resulting differences in method conditions are further explored through in silico models of the hydrodynamic forces applied to a dosage form. Two case studies are reported showing that the method was able to obtain excellent in vitro-in vivo relationships (slopes ranging from 1.08-1.01) which are significantly (p < 0.01-0.05) improved compared to human biorelevant dissolution used to predict in vivo performance in humans (slopes ∼1.5-1.75). The quality of the method's predictive ability allows for it to help drive the development of matrix sustained release formulations intended for preclinical studies. PMID:26339722

  15. The effect of polymer properties on direct compression and drug release from water-insoluble controlled release matrix tablets.

    PubMed

    Grund, Julia; Koerber, Martin; Walther, Mathias; Bodmeier, Roland

    2014-07-20

    The objective of this study was to identify and evaluate key polymer properties affecting direct compression and drug release from water-insoluble matrices. Commonly used polymers, such as Kollidon() SR, Eudragit() RS and ethyl cellulose, were characterized, formulated into tablets and compared with regard to their properties in dry and wet state. A similar site percolation threshold of 65% v/v was found for all polymers in dry state. Key parameters influencing polymer compactibility were the surface properties and the glass transition temperature (T(g)), affecting polymer elasticity and particle size-dependent binding. The important properties observed in dry state also governed matrix characteristics and therefore drug release in wet state. A low T(g) (Kollidon() SRmatrix integrity (Eudragit() RSmatrix systems. PMID:24746409

  16. Effect of different polymers and their combinations on the release of metoclopramide HCl from sustained-release hydrophilic matrix tablets.

    PubMed

    Savaşer, Ayhan; Taş, Çetin; Bayrak, Ziya; Özkan, Cansel Köse; Özkan, Yalçın

    2013-01-01

    Metoclopramide HCl (MTC) is commonly used for the management of gastrointestinal disorders. It has a short biological half-life and is usually administered four times daily to maintain effective concentrations throughout the day. The aim of this study is to develop sustained-release hydrophilic matrix tablet formulations of drug to achieve reproducible and predictable release rates, extended duration of activity, decreased toxicity, reduction of required dose, optimized therapy, and improved patient compliance. Hydroxypropylmethyl cellulose (HPMC), carboxymethylcellulose sodium (NaCMC), chitosan and Carbopol 981 were incorporated in the matrix system separately or in combinations as release controlling factor by direct compression technique. Compatibility among the formulation components was assessed by DSC and FTIR analysis. MTC release from matrix was evaluated by using the US Pharmacopeia dissolution apparatus II. All formulations met the criteria of pharmacopeial requirements. Dissolution studies show that polymer type and concentration are important parameters on drug release. Chitosan, carbopol and NaCMC formulations exhibited pH-dependent drug release profile whereas HPMC did not. All the formulations containing 1:1 ratio of HPMC and chitosan exhibited desired drug release showing that all active substance releases progressively in a period of whole dissolution time and therefore it can be regarded as worthy of consideration for the manufacture of sustained-release MTC product. PMID:22881478

  17. Regulating drug release behavior and kinetics from matrix tablets based on fine particle-sized ethyl cellulose ether derivatives: an in vitro and in vivo evaluation.

    PubMed

    Shah, Kifayat Ullah; Khan, Gul Majid

    2012-01-01

    The design and fabrication of sustained/controlled release dosage forms, employing new excipients capable of extending/controlling the release of drugs from the dosage forms over prolonged periods, has worked well in achieving optimally enhanced therapeutic levels of the drugs. In this sense, the objective of this study was to investigate the suitability of selected cellulose ether derivatives for use in direct compression (DC) and as efficient drug release controlling agents. Controlled release matrix tablets of ciprofloxacin were prepared at different drug-to-polymer (D : P) ratios by direct compression using a fine particle sized ethylcellulose ether derivative (ETHOCEL Standard Premium 7FP) as rate controlling polymer. The tablets obtained were evaluated for various physico-chemical characteristics and in-vitro drug release studies were conducted in phosphate buffer (pH 7.4) using PharmaTest dissolution apparatus at constant temperature of 37 °C ± 0.1. Similarity factor f(2) was employed to the release profiles of test formulations and were compared with marketed ciprofloxacin conventional tablets. Drug release mechanism and the kinetics involved were investigated by fitting the release profile data to various kinetic models. It was found that with increasing the proportion of ethylcellulose ether derivative in the matrix, the drug release was significantly extended up to 24 hours. The tablets exhibited zero order or nearly zero order drug transport mechanism. In vivo drug release performance of the developed controlled release tablets and reference conventional tablets containing ciprofloxacin were determined in rabbit serum according to randomized two-way crossover study design using High Performance Liquid Chromatography. Several bioavailability parameters of both the test tablets and conventional tablets including C(max⁡), T(max⁡) and AUC(0-t) were compared which showed an optimized C(max⁡) and T(max⁡) (P < 0.05). A good correlation was obtained between in vitro drug release and in vivo drug absorption with correlation value (R(2) = 0.934). Relative bioavailability was found to be 93%. Reproducibility of manufacturing process and accelerated stability of the developed tablets were performed in stability chamber at 40 ± 2°C and 75 ± 5% relative humidity for a period of 6 months and were found to be stable throughout the stability period. PMID:22649325

  18. Modified guar gum matrix tablet for controlled release of diltiazem hydrochloride.

    PubMed

    Toti, Udaya S; Aminabhavi, Tejraj M

    2004-03-24

    Polyacrylamide-grafted-guar gum (pAAm-g-GG) was prepared by taking three different ratios of guar gum to acrylamide (1:2, 1:3.5 and 1:5). Amide groups of these grafted copolymers were converted into carboxylic functional groups. Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry were used to characterize copolymers. Tablets were prepared by incorporating an antihypertensive drug viz., diltiazem hydrochloride. In-vitro drug release was carried out in simulated gastric and intestinal conditions. Effect of drug loading on release kinetics was evaluated. Release continued up to 8 and 12 h, respectively, for pAAm-g-GG and hydrolyzed pAAm-g-GG copolymers. Nature of drug transport through the polymer matrices was studied by comparing with Higuchi, Hixson-Crowell and Kopcha equations. Drug release was found to be dissolution-controlled in case of unhydrolyzed copolymer. With hydrolyzed copolymers, drug release was swelling-controlled initially (i.e., in 0.1 N HCl), but at later stage, it became dissolution-controlled in pH 7.4. Hydrolyzed pAAm-g-GG matrices are pH sensitive and can be used for intestinal drug delivery. PMID:15023467

  19. Sustained-release and swelling characteristics of xanthan gum/ethylcellulose-based injection moulded matrix tablets: in vitro and in vivo evaluation.

    PubMed

    Quinten, T; De Beer, T; Onofre, F O; Mendez-Montealvo, G; Wang, Y J; Remon, J P; Vervaet, C

    2011-07-01

    Sustained-release matrix tablets were developed by injection moulding using metoprolol tartrate (MPT) and ethylcellulose (EC) as sustained-release agent. Dibutyl sebacate was selected as plasticiser. The influence of matrix composition, plasticiser concentration, and drug load on drug release was evaluated. The influence of plasticiser addition was assessed on processability and drug release: Dibutyl sebacate was added to a dichloromethane/EC solution and subsequently spray-dried, or was mixed as a liquid with EC powder. Hydrated tablets were evaluated by frequency sweep and creep rheological tests to correlate the results with drug release. Xanthan gum (XG) was added to the formulation because drug release was too slow (<50%, 24 h) from EC/MPT matrices (70%/30%, w/w). Increasing XG concentrations provided faster MPT release rates characterised by zero-order release kinetics, no burst release was observed. Lower plasticiser concentrations and higher drug loads increased drug release substantially. The plasticiser addition method did not affect drug release. Matrix composition, drug load, and plasticiser level affected the rheological properties of the swollen matrix tablets. X-ray diffraction demonstrated the formation of solid dispersions. Formulations composed of XG/EC (ratio 1:1.5) and 30% (w/w) MPT had a low relative bioavailability compared with the commercial product Lopressor®, which significantly improved at higher MPT concentration (50%, w/w). PMID:21254067

  20. Sustained-release and swelling characteristics of xanthan gum/ethylcellulose-based injection moulded matrix tablets: in vitro and in vivo evaluation.

    TOXLINE Toxicology Bibliographic Information

    Quinten T; De Beer T; Onofre FO; Mendez-Montealvo G; Wang YJ; Remon JP; Vervaet C

    2011-07-01

    Sustained-release matrix tablets were developed by injection moulding using metoprolol tartrate (MPT) and ethylcellulose (EC) as sustained-release agent. Dibutyl sebacate was selected as plasticiser. The influence of matrix composition, plasticiser concentration, and drug load on drug release was evaluated. The influence of plasticiser addition was assessed on processability and drug release: Dibutyl sebacate was added to a dichloromethane/EC solution and subsequently spray-dried, or was mixed as a liquid with EC powder. Hydrated tablets were evaluated by frequency sweep and creep rheological tests to correlate the results with drug release. Xanthan gum (XG) was added to the formulation because drug release was too slow (<50%, 24 h) from EC/MPT matrices (70%/30%, w/w). Increasing XG concentrations provided faster MPT release rates characterised by zero-order release kinetics, no burst release was observed. Lower plasticiser concentrations and higher drug loads increased drug release substantially. The plasticiser addition method did not affect drug release. Matrix composition, drug load, and plasticiser level affected the rheological properties of the swollen matrix tablets. X-ray diffraction demonstrated the formation of solid dispersions. Formulations composed of XG/EC (ratio 1:1.5) and 30% (w/w) MPT had a low relative bioavailability compared with the commercial product Lopressor®, which significantly improved at higher MPT concentration (50%, w/w).

  1. [Preparation of preoral sustained-release preparations with a base of biodegradable polymers. 3. Preparation of matrix tablets with a base of poly-3-hydroxybutyric acid].

    PubMed

    Mank, R; Kala, H; Richter, M; Babel, W; Sattler, K

    1989-08-01

    Poly-3-hydroxybutyric acid belongs to the biological polymers, which are produced by bacterials. The determination of the grain size, moisture content, flowability and the parameters for the direct compression was performed in regard of their use as auxillary substance for the preparation of solid sustained release dosage forms. The production of the matrix tablets was performed on the basis of a factorial design. The content of substance, an addition of Heweten 12 and the compression power served as factors. Caffeine was used as model drug. The in vitro release values show, that all three factors have an influence of the drug release. Optimized matrix tablets were produced on the basis of this result. PMID:2594825

  2. Controlled release matrix tablets of glipizide: Influence of different grades of ethocel and Co-excipient on drug release.

    PubMed

    Mehsud, Saif Ullah; Khan, Gul Majid; Hussain, Abid; Akram, Muhammad; Akhlaq, Muhammad; Khan, Kamran Ahmad; Shakoor, Abdul

    2016-05-01

    The aim of the current study was to formulate and evaluate glipizide controlled release matrix tablets by means of different grades of polymer Ethoceland different co-excipients in order to evaluate their effect on drug release profiles during in vitro dissolution studies. Type II diabetes mellitus is usually treated with Glipizide. Glipizide belongs to sulfonylurea group. Gastric disturbance and severe hypoglycemia has been observed after taking glipizide orally. To overcome these problems, controlled release matrices were developed using different grades of ethyl cellulose polymer with a drug-polymer ratio of 1:3by the direct compression method. The effect on drug release of partial replacement of lactose by different co-excipients, HPMC K100M, starch and CMC, were also studied. Diameter, thickness, hardness, friability, weight variations, drug contents of formulations were tested, these properties were within prescribed limits. Co-excipients and polymer containing formulations were compared to the without co-excipients and polymer containing formulations with respect to their release profile. After a 24-hour release study, ethyl cellulose polymer containing formulation exhibited prolonged release for 5-16 hours; however the polymer Ethocel (R) standard FP 7 Premium without co-excipient containing formulation exhibited controlled release for 24 hours. Incompatibility was investigated between drugs, co-excipient DSC and polymer study was performed and any type of interaction was not found. Different kinetic models were used to study the release mechanism. An enhanced release rate was observed in case of excipients containing formulations. PMID:27166548

  3. An in vitro evaluation of fenugreek mucilage as a potential excipient for oral controlled-release matrix tablet.

    PubMed

    Nokhodchi, Ali; Nazemiyeh, Hossein; Khodaparast, Afagh; Sorkh-Shahan, Tarifeh; Valizadeh, Hadi; Ford, J L

    2008-03-01

    A polysaccharide mucilage derived from the seeds of fenugreek, Trigonella foenum-graceum L (family Fabaceae) was investigated for use in matrix formulations containing propranolol hydrochloride. Methocel hypomellose K4M was used as a standard controlled release polymer for comparison purposes. In this study the effect of lactose on the release behaviour of propranolol hydrochloride from matrices formulated to contain the fenugreek mucilage also was investigated. An increase in concentration of the mucilage in matrices resulted in a reduction in the release rate of propranolol hydrochloride comparable to that observed with hypomellose matrices. The rate of release of propranolol hydrochloride from fenugreek mucilage matrices was mainly controlled by the drug:mucilage ratio. However, the mechanism of release from matrices containing drug:mucilage ratios of 1:1, 1:1.25, 1:1.5, and 1:2 remained the same. The kinetics of release, utilising the release exponent n, showed that the values of n were between 0.46-0.57 indicating that the release from fenugreek mucilage matrices was predominantly by diffusion. The presence of lactose in matrices containing mucilage increased the release rate of propranolol hydrochloride. This is due to a reduction in tortuoisity and increased pore size of channels caused by lactose through which propranolol diffuses and therefore diffusion of water into the tablet is facilitated. PMID:18363148

  4. The Relationship Between the Evolution of an Internal Structure and Drug Dissolution from Controlled-Release Matrix Tablets.

    PubMed

    Kulinowski, Piotr; Hudy, Wiktor; Mendyk, Aleksander; Juszczyk, Ewelina; Węglarz, Władysław P; Jachowicz, Renata; Dorożyński, Przemysław

    2016-06-01

    In the last decade, imaging has been introduced as a supplementary method to the dissolution tests, but a direct relationship of dissolution and imaging data has been almost completely overlooked. The purpose of this study was to assess the feasibility of relating magnetic resonance imaging (MRI) and dissolution data to elucidate dissolution profile features (i.e., kinetics, kinetics changes, and variability). Commercial, hydroxypropylmethyl cellulose-based quetiapine fumarate controlled-release matrix tablets were studied using the following two methods: (i) MRI inside the USP4 apparatus with subsequent machine learning-based image segmentation and (ii) dissolution testing with piecewise dissolution modeling. Obtained data were analyzed together using statistical data processing methods, including multiple linear regression. As a result, in this case, zeroth order release was found to be a consequence of internal structure evolution (interplay between region's areas-e.g., linear relationship between interface and core), which eventually resulted in core disappearance. Dry core disappearance had an impact on (i) changes in dissolution kinetics (from zeroth order to nonlinear) and (ii) an increase in variability of drug dissolution results. It can be concluded that it is feasible to parameterize changes in micro/meso morphology of hydrated, controlled release, swellable matrices using MRI to establish a causal relationship between the changes in morphology and drug dissolution. Presented results open new perspectives in practical application of combined MRI/dissolution to controlled-release drug products. PMID:26335419

  5. Formulation and evaluation of gastroretentive controlled release tablets of alfuzosin hydrochloride.

    PubMed

    Rudraswamy-Math, Nijaguni Revansiddayya; Gupta, Vankdari Rama-Mohan

    2015-11-01

    Alfuzosin hydrochloride is a novel drug used in the treatment of urinary incontinency. The purpose of this research was to develop controlled release floating matrix formulations of Alfuzosin HCl. Floating matrix tablets of Alfuzosin HCl were prepared using hydroxypropyl methylcellulose (HPMC), Polyethylene oxide (PEO), Carbopol 971P NF polymer (Direct compressible) and Blend of Polyvinyl Acetate and Povidone 30 (80:19:1(0.8% sodium laury sulfate and 0.2% silica)). Combination of citric acid and sodium bicarbonate were also used as gas forming agent. Matrix formulations were prepared by direct compression method and evaluated for floating, in vitro drug release profile and swelling characteristics. The mechanism of drug release was found to follow non-Fickian or anomalous type. The data obtained from the invitro release studies demonstrated that the floating matrix tablets containing HPMC 100K CR (controlled-release) and carbopol along with sodium CMC were found to sustain the release of drug over a period of 12 hours. Formulations containing 25% PEO 303WSR was also capable of sustaining delivery the release of Alfuzosin HCl. PMID:26639508

  6. Eudragit() RS PO/RL PO as rate-controlling matrix-formers via roller compaction: Influence of formulation and process variables on functional attributes of granules and tablets.

    PubMed

    Dave, Vivek S; Fahmy, Raafat M; Bensley, Dennis; Hoag, Stephen W

    2012-10-01

    The influence of plasticizer level, roll pressure and sintering temperature was investigated on the granule properties, tablet breaking force and theophylline release from tablets. Nine formulations using theophylline as a model drug, Eudragit() RL PO, Eudragit() RS PO, or both as a matrix former and triethyl citrate (TEC) as a plasticizer were prepared. The formulations were roller compacted and the granules obtained were evaluated for particle size distribution and flowability. These granules were compacted into tablets at a compression force of 7?kN. The tablets were thermally treated at different temperatures (50 and 75C) for 5?h and were evaluated for breaking force and dissolution. Increase in roll pressure and TEC levels resulted in a progressive increase in the mean particle size of the granules. The flowability of the granules also improved with increasing roll pressures and TEC levels. Tablet breaking force increased with an increase in TEC levels and sintering temperatures. But these effects were significant only at the highest level of plasticizer and sintering temperature respectively. For the tablets containing Eudragit() RS PO, theophylline release decreased proportionately with increase in TEC levels and sintering temperatures. Tablets containing either Eudragit() RL PO or a mixture of RS PO and RL PO failed to impart an extended-release property to the tablets at the studied variables i.e. roll pressure, TEC levels and sintering temperature. It was clearly demonstrated that with suitable optimization of these parameters, the release-rate of a water soluble drug from the matrix tablets prepared via roller compaction can be finely controlled. PMID:22257339

  7. Chronotherapeutic drug delivery of Tamarind gum, Chitosan and Okra gum controlled release colon targeted directly compressed Propranolol HCl matrix tablets and in-vitro evaluation.

    PubMed

    Newton, A M J; Indana, V L; Kumar, Jatinder

    2015-08-01

    The main objective of this investigation is to develop a chronotherapeutic drug delivery of various natural polymers based colon targeted drug delivery systems to treat early morning sign in BP. The polymers such as Tamarind gum, Okra gum and Chitosan were used in the formulation design. A model drug Propranolol HCl was incorporated in the formulation in order to assess the controlled release and time dependent release potential of various natural polymers. A novel polymer Tamarind gum was extracted and used as a prime polymer in this study to prove the superiority of this polymer over other leading natural polymer. Propranolol HCl was used as a model drug which undergoes hepatic metabolism and witnesses the poor bioavailability. The matrix tablets of Propranolol HCl were prepared by direct compression. The tablets were evaluated for various quality control parameters and found to be within the limits. Carbopol 940 was used as an auxiliary polymer to modify the drug release and physicochemical characteristics of the tablets. The in vitro release studies were performed in 0.1N HCl for 1.5h, followed by pH 6.8 phosphate buffer for 2h and pH 7.4 phosphate buffer till maximum amount of drug release. The in vitro release profile of the formulations were fitted with various pharmacokinetic mathematical models and analyzed for release profile. The formulations prepared with Tamarind gum prolonged the release for an extended period of time compared to other polymer based formulation and showed an excellent compression characteristic. PMID:25936283

  8. Study the effect of formulation variables on drug release from hydrophilic matrix tablets of milnacipran and prediction of in-vivo plasma profile.

    PubMed

    Singhvi, Gautam; Shah, Abhishek; Yadav, Nilesh; Saha, Ranendra N

    2014-09-01

    The objective of this study was to design oral controlled release (CR) matrix tablets of Milnacipran using hydroxypropyl methylcellulose (HPMC) as the retardant polymer and to study the effect of various formulation factors such as polymer proportion, polymer viscosity, compression force and also the pH of dissolution medium on the in-vitro release of drug. Two viscosity grade of HPMC (15 K and 100 K) were used in the proportion of 50, 100, 150 and 200 mg per CR tablet. In-vitro release rate was characterized using various model dependent approaches and model independent dissolution parameters [T50% and T80% dissolution time, mean dissolution time (MDT), mean residence time (MRT), dissolution efficiency (DE)]. The statistical analysis was performed on all the model independent approaches using student t test and ANOVA. Results were found that as polymer concentration (50 mg to 200 mg) and viscosity (15 K to 100 K) increases, the MDT, MRT, T50% and T80% extended significantly. Drug release rate was found to be significantly different at different hardness. In-vivo human plasma concentration--time profile was predicted from in-vitro release data using convolution method. Predicted human pharmacokinetic parameters shows that the design CR formulation has capability to sustained the plasma drug level of milnacipran. PMID:23931031

  9. The Effects of Lactose, Microcrystalline Cellulose and Dicalcium Phosphate on Swelling and Erosion of Compressed HPMC Matrix Tablets: Texture Analyzer.

    PubMed

    Namdeo Tukaram, Bendgude; Vidaya Rajagopalan, Iyer; Sushi Ikumar Shartchandra, Poddar

    2010-01-01

    This paper reviews the use of texture analysis in studying the performance of hydrophilic matrices of highly soluble drugs and different types of excipients (i.e. water-soluble, water-insoluble and swellable, and water insoluble and non-swellable). Tablets were prepared by direct compression, and their swelling and erosion in presence of these different excipients were assessed with the help of volumetric, gravimetric, morphological, and rheological studies. Dissolution test was performed using USP 26 apparatus 2 modified by insertion of a sieve to prevent sticking of the tablets to the bottom of the vessel and allow them to swell 3-dimensionally. Loading 15% of the highly soluble drug in formulations containing 65% lactose showed the most pronounced swelling and erosion and the best sustained drug release, compared to matrices containing microcrystalline cellulose and dicalcium phosphate. The correlation between front movement, mass erosion and solute transport in relation to excipient type on progression of probe displacement and total work was examined throughout texture analysis studies. The formulation containing the soluble excipient lactose showed better swelling and erosion properties compared to formulations containing the swellable and insoluble excipients. In conclusion, it could be said that based on the distinct conventional dosage forms insertion of particular excipients in hydrophilic controlled release tablets containing water soluble drug, the finger print information of drug release profile could be obtained. To study the release profile from hydroxy propyl methyl cellulose K 15M matrices with different types of excpients, diltiazem hydrochloride was used as a model soluble drug. PMID:24381599

  10. Parmacokinetic evaluation of ibuprofen controlled release matrix tablets using hydrophilic Eudragit® polymer and co-excipients.

    PubMed

    Bakhsh, Sattar; Khan, Gul Majid; Menaa, Farid; Khan, Barkat Ali

    2015-09-01

    The present study was conducted to formulate controlled release dosage forms containing Ibuprofen with Eudragit® S 100 polymer. The tablets were formulated at three different ratios with the polymer to investigate the effect of different concentrations of polymer on in vitro drug release patterns/kinetics and in vivo absorption/pharmacokinetics. Pre-formulation studies were conducted including bulk density, tapped density, compressibility index, Hausner ratio and angle of repose. In vitro studies were conducted using phosphate buffer (pH 7.4) as dissolution medium. In vivo performance was evaluated using albino rabbits. Physico-chemical characteristics (i.e. dimensional tests, weight variation, hardness, friability and drug content determination) fell in the USP acceptable limits. The compressibility index was found to range between 12.02 ± 0.01% and 18.66 ± 0.03%, the Hausner ratio varied between 1.02 ± 0.01 and 1.19 ± 0.10 and the angle of repose ranged from 15.19 ± 0.01 to 24.52 ± 0.10, all indicating better flow properties than the bulk-reference standard. Both bulk and tapped densities also fell in the USP acceptable range. Ibuprofen market tablets showed Tmax of 2.1 ± 0.4h, which was significantly (P-value <0.05) lower compared to that of the reference standard (i.e. 4.09 ± 1.3h). Ibuprofen test formulation has a half-life (t1/2) of 16.9 ± 2.5h, which was significantly (P-value<0.001) higher compared to that of the reference standard (i.e. 9.23 ± 2.9h). Eudragit® S 100 polymers can be used efficiently to develop directly compressed prolonged release tablets. PMID:26408874

  11. Increased bioavailability of primaquine using poly(ethylene oxide) matrix extended-release tablets administered to beagle dogs

    PubMed Central

    Bertol, C D; Oliveira, P R; Kuminek, G; Rauber, G S; Stulzer, H K; Silva, M A S

    2011-01-01

    Primaquine (PQ) is used for the radical cure of Plasmodium vivax malaria and can cause serious side effects in some individuals. The development of an extended-release dosage with poly(ethylene oxide) as a hydrophilic polymer has been investigated to improve drug efficacy and tolerability. The aim of this study was to evaluate in vivo a new extended-release formulation of PQ (60 mg). The formulation was administered to beagle dogs and plasma PQ concentrations were compared to a conventional immediate-release formulation of PQ (60 mg). The evaluation was carried out using a validated high-performance liquid chromatography method using solid-phase extraction. Total PQ exposure in beagle dogs was 2.2 times higher (area under curve of 12?193 versus 5678 ng h/ml) and the elimination half-life of PQ was a 19-fold greater (12.95 hours versus 0.68 hours) with the extended-release tablets compared with the immediate-release tablets. These findings suggest that the extended-release formulation of PQ merits further evaluation for the treatment of P. vivax malaria and/or chemoprophylaxis. PMID:22185941

  12. Novel Strategy to Fabricate Floating Drug Delivery System Based on Sublimation Technique.

    PubMed

    Huanbutta, Kampanart; Limmatvapirat, Sontaya; Sungthongjeen, Srisagul; Sriamornsak, Pornsak

    2016-06-01

    The present study aims to develop floating drug delivery system by sublimation of ammonium carbonate (AMC). The core tablets contain a model drug, hydrochlorothiazide, and various levels (i.e., 0-50% w/w) of AMC. The tablets were then coated with different amounts of the polyacrylate polymers (i.e., Eudragit® RL100, Eudragit® RS100, and the mixture of Eudragit® RL100 and Eudragit® RS100 at 1:1 ratio). The coated tablets were kept at ambient temperature (25°C) or cured at 70°C for 12 h before further investigation. The floating and drug release behaviors of the tablets were performed in simulated gastric fluid USP without pepsin at 37°C. The results showed that high amount of AMC induced the floating of the tablets. The coated tablets containing 40 and 50% AMC floated longer than 8 h with a time-to-float of about 3 min. The sublimation of AMC from the core tablets decreased the density of system, causing floating of the tablets. The tablets coated with Eudragit® RL100 floated at a faster rate than those of Eudragit® RS100. Even the coating level of polymer did not influence the time-to-float and floating time of coated tablets containing the same amount of AMC, the drug release from the tablets coated with higher coating level of polymer showed slower drug release. The results suggested that the sublimation technique using AMC is promising for the development of floating drug delivery system. PMID:26314245

  13. Effect of hydrophilic natural gums in formulation of oral-controlled release matrix tablets of propranolol hydrochloride.

    PubMed

    Rajesh, K S; Venkataraju, M P; Gowda, D V

    2009-04-01

    In order to develop a controlled delivery of highly water-soluble propranolol hydrochloride (PPHCl) using hydrophilic natural gums (xanthan gum [X] and locust bean gum [LBG]) as cost-effective, nontoxic, easily available. The granules of PPHCl were prepared by wet granulation method using a different ratios drug: gum ratios of X, LBG and XLBG(X and LBG in 1:1 ratios). To increase the flowability and compressibility of the granules, and to prevent its adhesion to punch and die, magnesium stearate and talc were added to the granules in 1:2 ratios before punching. The tablet was analysed to determine hardness, friability, % assay and invitro release study was carried out. The release of PPHCl from a gelatinous swollen mass, which controls the diffusion of drug molecules through the polymeric material into aqueous medium. The XLBG matrice shows precise controlled release than the X and LBG matrice because of burst effect and fast release in case of X and LBG matrice respectively and there was no chemical interaction between drug and polymer in XLBG formulation as confirmed by FTIR studies. First pass effect of PPHCl can be avoided by these formulations. Matrices with XLBG show zero-order release via swelling, diffusion and relaxation mechanism. The XLBG matrice leads to more precise result than X and LBG alone by the utilization of synergistic interaction between two biopolymers and uniformity in the hydration layer in dissolution media. However, according to the similarity factor (f(2)) XLBG3 were the most similar formulations to Lol-SR as the reference standard. PMID:19339235

  14. Design and Optimization of Floating Drug Delivery System of Acyclovir

    PubMed Central

    Kharia, A. A.; Hiremath, S. N.; Singhai, A. K.; Omray, L. K.; Jain, S. K.

    2010-01-01

    The purpose of the present work was to design and optimize floating drug delivery systems of acyclovir using psyllium husk and hydroxypropylmethylcellulose K4M as the polymers and sodium bicarbonate as a gas generating agent. The tablets were prepared by wet granulation method. A 32 full factorial design was used for optimization of drug release profile. The amount of psyllium husk (X1) and hydroxypropylmethylcellulose K4M (X2) were selected as independent variables. The times required for 50% (t50%) and 70% (t70%) drug dissolution were selected as dependent variables. All the designed nine batches of formulations were evaluated for hardness, friability, weight variation, drug content uniformity, swelling index, in vitro buoyancy, and in vitro drug release profile. All formulations had floating lag time below 3 min and constantly floated on dissolution medium for more than 24 h. Validity of the developed polynomial equation was verified by designing two check point formulations (C1 and C2). The closeness of predicted and observed values for t50% and t70% indicates validity of derived equations for the dependent variables. These studies indicated that the proper balance between psyllium husk and hydroxypropylmethylcellulose K4M can produce a drug dissolution profile similar to the predicted dissolution profile. The optimized formulations followed Higuchi's kinetics while the drug release mechanism was found to be anomalous type, controlled by diffusion through the swollen matrix. PMID:21694992

  15. Development and in vitro characterization of floating sustained-release drug delivery systems of polyphenols.

    PubMed

    Rosenzweig, Ohad; Lavy, Eran; Gati, Irith; Kohen, Ron; Friedman, Michael

    2013-01-01

    The aim of this study was to develop and characterize floating stomach-retentive matrix tablets that will deliver polyphenols in a controlled release manner. The tablets were prepared by direct compression. A number of polymers were examined and egg albumin was chosen in light of a better performance in terms of floating behavior and decomposition time. Dissolution studies for three representative polyphenols loaded into a number of formulations were performed using the "f₂" factor in order to compare release profiles of different polyphenols and formulations. The release data showed a good fit into the power law equation and zero-order kinetics has been determined for some of the systems. Erosion and textural analysis studies revealed that higher concentration of egg albumin results in a higher gel strength that is less susceptible to erosion, potentially leading to a prolonged delivery time of drug. The ability of egg albumin-based tablets to resist high mechanical forces was also determined, while comparison to cellulose-derived polymers revealed that the latter have a much lower ability to resist the same forces. The developed delivery system has the potential to increase the efficacy of the therapy for various pathological stomach conditions and to improve patient compliance. PMID:23730744

  16. Preparation and in vitro characterization of a non-effervescent floating drug delivery system for poorly soluble drug, glipizide.

    PubMed

    Meka, Venkata Srikanth; Pillai, Shreeni; Dharmalingham, Senthil Rajan; Sheshala, Ravi; Gorajana, Adinarayana

    2015-01-01

    The aim of the present study was to formulate a non-effervescent floating drug delivery system of glipizide, a poorly water soluble drug. The solubility of glipizide was initially enhanced using a solid dispersion (SD) strategy with the help of hydrophilic carriers such as poloxamer, cyclodextrin, and povidone. The optimized core material/SD was further formulated into non-effervescent floating tablets (NEFT) by using matrix ballooning inducers, such as crospovidone and release retarding agents including HPMC and PEO. Poloxamer-based solid dispersions prepared by a solvent evaporation technique showed the highest dissolution rate (1 : 10 drug to carrier ratio) compared with all other dispersions. NEFT were evaluated for all physico-chemical properties including in vitro buoyancy, dissolution, and release rate. All of the tablets were found to be within pharmacopoeial limits and all of the formulations exhibited good floating behavior. The formulations (F2 and F3) were optimized based on their 12 h drug retardation with continuous buoyancy. The optimized formulations were characterized using FTIR and DSC and no drug and excipient interaction was found. In-vitro buoyancy and dissolution studies showed that non-effervescent floating drug delivery systems provide a promising method of achieving prolonged gastric retention time and improved bioavailability of glipizide. PMID:25850215

  17. An investigation into the erosion behaviour of a high drug-load (85%) particulate system designed for an extended-release matrix tablet. Analysis of erosion kinetics in conjunction with variations in lubrication, porosity and compaction rate.

    PubMed

    Dürig, T; Venkatesh, G M; Fassihi, R

    1999-10-01

    The effects of the amounts of lubricants (magnesium stearate 0-5% and talc 0-3%) and changes in compaction rate and tablet porosity on the mechanism of drug release from high drug-load controlled-release theophylline tablets have been examined. Drug release was satisfactorily described by a surface-erosion model that takes into account the geometry of the tablet, differential radial and axial erosion rates, and the initial burst effect (r2 > 0.99 for all formulations). The axial and radial erosion rate constants were inversely proportional to the amount of magnesium stearate in the formulation (P < 0.0001). The most dramatic reductions in erosion rate occurred between 0 and 1% magnesium stearate content. For magnesium stearate concentrations > or =2.5% the ratio of radial to axial erosion rate constants was essentially constant at 3 (approx.); however, for formulations with magnesium stearate < or =1% the ratio tended toward unity. Reducing matrix porosity over the range 26 to 14% resulted in reduced erosion rates. However, a threshold of 17% (approx.) porosity was identified below which further reductions in porosity resulted in only incremental changes in release rates. The rate of erosion and drug release was insensitive to changes in machine speed over the range 20 to 100 rev min(-1). For highly loaded matrix tablets containing sparingly soluble drugs, such as theophylline, magnesium stearate at appropriate levels can modulate the erosion rate constants and act as an effective release-controlling excipient. Drug-release profiles are predictable and relatively robust in terms of changes in compaction rate and applied force routinely encountered in large-scale tablet manufacturing. PMID:10579678

  18. On floats and float tests

    NASA Technical Reports Server (NTRS)

    Seewald, Friedrich

    1931-01-01

    The principal source of information on float resistance is the model test. In view of the insuperable difficulties opposing any attempt at theoretical treatment of the resistance problem, particularly at attitudes which tend toward satisfactory take-off, such as the transitory stage to planing, the towing test is and will remain the primary method for some time.

  19. Formulation and Evaluation of Fixed-Dose Combination of Bilayer Gastroretentive Matrix Tablet Containing Atorvastatin as Fast-Release and Atenolol as Sustained-Release

    PubMed Central

    Dey, Sanjay; Chattopadhyay, Sankha; Mazumder, Bhaskar

    2014-01-01

    The objective of the present study was to develop bilayer tablets of atorvastatin and atenolol that are characterized by initial fast-release of atorvastatin in the stomach and comply with the release requirements of sustained-release of atenolol. An amorphous, solvent evaporation inclusion complex of atorvastatin with ?-cyclodextrin, present in 1?:?3 (drug/cyclodextrin) molar ratio, was employed in the fast-release layer to enhance the dissolution of atorvastatin. Xanthan gum and guar gum were integrated in the sustained-release layer. Bilayer tablets composed of sustained-release layer (10% w/w of xanthan gum and guar gum) and fast-release layer [1?:?3 (drug/cyclodextrin)] showed the desired release profile. The atorvastatin contained in the fast-release layer showed an initial fast-release of more than 60% of its drug content within 2?h, followed by sustained release of the atenolol for a period of 12?h. The pharmacokinetic study illustrated that the fast absorption and increased oral bioavailability of atorvastatin as well as therapeutic concentration of atenolol in blood were made available through adoption of formulation strategy of bilayer tablets. It can be concluded that the bilayer tablets of atorvastatin and atenolol can be successfully employed for the treatment of hypertension and hypercholesterolemia together through oral administration of single tablet. PMID:24527446

  20. Development and Optimization of Gastro-Retentive Controlled-Release Tablet of Calcium-Disodium Edentate and its In Vivo Gamma Scintigraphic Evaluation.

    PubMed

    Kumar, Neeraj; Soni, Sandeep; Singh, Thakuri; Kumar, Amit; Ahmad, Farhan Jalees; Bhatnagar, Aseem; Mittal, Gaurav

    2015-12-01

    Medical management of heavy metal toxicity, including radioactive ones, is a cause for concern because of their increased use in energy production, healthcare, and mining. Though chelating agents like EDTA and DTPA in parenteral form are available, no suitable oral formulation is there that can trap ingested heavy metal toxicants in the stomach itself, preventing their systemic absorption. The objective of the present study was to develop and optimize gastro-retentive controlled-release tablets of calcium-disodium edentate (Ca-Na2EDTA). Gastro-retentive tablet of Ca-Na2EDTA was prepared by direct compression method. Thirteen tablet formulations were designed using HPMC-K4M, sodium chloride, and carbopol-934 along with effervescing agents sodium bicarbonate and citric acid. Tablet swelling ability, in vitro buoyancy, and drug dissolution studies were conducted in 0.1 N HCl at 37 ± 0.5°C. Ca-Na2EDTA was radiolabeled with technetium-99m for scintigraphy-based in vivo evaluation. Formula F8 (Ca-Na2EDTA 200 mg, carbopol 100 mg, avicel 55 mg, citric acid 30 mg, NaHCO3 70 mg, NaCl 100 mg, and HPMC 95 mg) was found to be optimum in terms of excellent floating properties and sustained drug release. F8 fitted best for Korsmeyer-Peppas equation with an R (2) value of 0.993. Gamma scintigraphy in humans showed mean gastric retention period of 6 h. Stability studies carried out in accordance with ICH guidelines and analyzed at time intervals of 0, 1, 2, 4, and 6 months have indicated insignificant difference in tablet hardness, drug content, total floating duration, or matrix integrity of the optimized formulation. Gastro-retentive, controlled-release tablet of Ca-Na2EDTA was successfully developed using effervescent technique as a potential oral antidote for neutralizing ingested heavy metal toxicity. PMID:25771737

  1. Ionotropic Cross-linked Carbo-protein Micro Matrix System: An Approach for Improvement of Drug Release, Compaction and Tableting behavior of Losartan Potassium.

    PubMed

    Khandai, Madhusmruti; Chakraborty, Santanu; Ghosh, Ashoke Kumar

    2015-01-01

    The aim of the present research work is to develop carbo-protein polymeric complex based sustain release microspheres of losartan potassium and investigate the ability of this dosage form to improve the flowability, compressibility and tableting properties of losartan potassium. The influence of silk sericin, alginate and its blend on various physicochemical parameters and in vitro drug release pattern were studied to optimize the concentration of polymeric blend required for 12 h. sustain release. Optimized batch was subjected to different flowability, compressibility and tableting properties studies to observe the effects of carbo-protein microspheres on flow properties. Results indicated that the concentration of sericin was found to be the main influential factor for prolonged drug release. Different micromeritic studies revealed that the poor flowability and compressibility properties of pure losartan potassium were significantly improved by this algino-sericin microspheric dosage form. Research findings also revealed that plasticity, die filling behavior and tableting properties of the pure drug were significantly improved by this microsphere formulation. So these prospective results concluded that carbo-protein polymeric microspheres helps to sustain the drug release for prolong hours as well as improve the flowability, compressibility and tableting properties of losartan potassium. PMID:25760869

  2. Formulation and development of pH-independent/dependent sustained release matrix tablets of ondansetron HCl by a continuous twin-screw melt granulation process.

    PubMed

    Patil, Hemlata; Tiwari, Roshan V; Upadhye, Sampada B; Vladyka, Ronald S; Repka, Michael A

    2015-12-30

    The objective of the present study was to develop pH-independent/dependent sustained release (SR) tablets of ondansetron HCl dihydrate (OND), a selective 5-HT3 receptor antagonist that is used for prevention of nausea and vomiting caused by chemotherapy, radiotherapy and postoperative treatment. The challenge with the OND API is its pH-dependent solubility and relatively short elimination half-life. Therefore, investigations were made to solve these problems in the current study. Formulations were prepared using stearic acid as a binding agent via a melt granulation process in a twin-screw extruder. The micro-environmental pH of the tablet was manipulated by the addition of fumaric acid to enhance the solubility and release of OND from the tablet. The in vitro release study demonstrated sustained release for 24h with 90% of drug release in formulations using stearic acid in combination with ethyl cellulose, whereas 100% drug release in 8h for stearic acid-hydroxypropylcellulose matrices. The formulation release kinetics was correlated to the Higuchi diffusion model and a non-Fickian drug release mechanism. The results of the present study demonstrated for the first time the pH dependent release from hydrophilic-lipid matrices as well as pH independent release from hydrophobic-lipid matrices for OND SR tablets manufactured by means of a continuous melt granulation technique utilizing a twin-screw extruder. PMID:25863118

  3. Preformulation studies and optimization of sodium alginate based floating drug delivery system for eradication of Helicobacter pylori.

    PubMed

    Diós, Péter; Nagy, Sándor; Pál, Szilárd; Pernecker, Tivadar; Kocsis, Béla; Budán, Ferenc; Horváth, Ildikó; Szigeti, Krisztián; Bölcskei, Kata; Máthé, Domokos; Dévay, Attila

    2015-10-01

    The aim of this study was to design a local, floating, mucoadhesive drug delivery system containing metronidazole for Helicobacter pylori eradication. Face-centered central composite design (with three factors, in three levels) was used for evaluation and optimization of in vitro floating and dissolution studies. Sodium alginate (X1), low substituted hydroxypropyl cellulose (L-HPC B1, X2) and sodium bicarbonate (X3) concentrations were the independent variables in the development of effervescent floating tablets. All tablets showed acceptable physicochemical properties. Statistical analysis revealed that tablets with 5.00% sodium alginate, 38.63% L-HPC B1 and 8.45% sodium bicarbonate content showed promising in vitro floating and dissolution properties for further examinations. Optimized floating tablets expressed remarkable floating force. Their in vitro dissolution studies were compared with two commercially available non-floating metronidazole products and then microbiologically detected dissolution, ex vivo detachment force, rheological mucoadhesion studies and compatibility studies were carried out. Remarkable similarity (f1, f2) between in vitro spectrophotometrically and microbiologically detected dissolutions was found. Studies revealed significant ex vivo mucoadhesion of optimized tablets, which was considerably increased by L-HPC. In vivo X-ray CT studies of optimized tablets showed 8h gastroretention in rats represented by an animation prepared by special CT technique. PMID:26247118

  4. Floating Point Control Library

    Energy Science and Technology Software Center (ESTSC)

    2007-08-02

    Floating Point Control is a Library that allows for the manipulation of floating point unit exception masking funtions control exceptions in both the Streaming "Single Instruction, Multiple Data" Extension 2 (SSE2) unit and the floating point unit simultaneously. FPC also provides macros to set floating point rounding and precision control.

  5. Tablet Use within Medicine

    ERIC Educational Resources Information Center

    Hogue, Rebecca J.

    2013-01-01

    This paper discusses the scholarly literature related to tablet computer use in medicine. Forty-four research-based articles were examined for emerging categories and themes. The most studied uses for tablet computers include: patients using tablets to complete diagnostic survey instruments, medical professionals using tablet computers to view…

  6. On the Correlation of Effective Terahertz Refractive Index and Average Surface Roughness of Pharmaceutical Tablets

    NASA Astrophysics Data System (ADS)

    Chakraborty, Mousumi; Bawuah, Prince; Tan, Nicholas; Ervasti, Tuomas; Pääkkönen, Pertti; Zeitler, J. Axel; Ketolainen, Jarkko; Peiponen, Kai-Erik

    2016-03-01

    In this paper, we have studied terahertz (THz) pulse time delay of porous pharmaceutical microcrystalline compacts and also pharmaceutical tablets that contain indomethacin (painkiller) as an active pharmaceutical ingredient (API) and microcrystalline cellulose as the matrix of the tablet. The porosity of a pharmaceutical tablet is important because it affects the release of drug substance. In addition, surface roughness of the tablet has much importance regarding dissolution of the tablet and hence the rate of drug release. Here, we show, using a training set of tablets containing API and with a priori known tablet's quality parameters, that the effective refractive index (obtained from THz time delay data) of such porous tablets correlates with the average surface roughness of a tablet. Hence, THz pulse time delay measurement in the transmission mode provides information on both porosity and the average surface roughness of a compact. This is demonstrated for two different sets of pharmaceutical tablets having different porosity and average surface roughness values.

  7. Investigating the in vitro drug release kinetics from controlled release diclofenac potassium-ethocel matrix tablets and the influence of co-excipients on drug release patterns.

    PubMed

    Shah, Shefaat Ullah; Shah, Kifayat Ullah; Rehman, Asimur; Khan, Gul Majid

    2011-04-01

    The objective of the study was to formulate and evaluate controlled release polymeric tablets of Diclofenac Potassium for the release rate, release patterns and the mechanism involved in the release process of the drug. Formulations with different types and grades of Ethyl Cellulose Ether derivatives in several drug-to-polymer ratios (D:P) were compressed into tablets using the direct compression method. In vitro drug release studies were performed in phosphate buffer (pH 7.4) as dissolution medium by using USP Method-1 (Rotating Basket Method). Similarity factor f2 and dissimilarity factor f1 were applied for checking the similarities and dissimilarities of the release profiles of different formulations. For the determination of the release mechanism and drug release kinetics various mathematical/kinetic models were employed. It was found that all of the Ethocel polymers could significantly slow down the drug release rate with Ethocel FP polymers being the most efficient, especially at D:P ratios of 10:03 which lead towards the achievement of zero or near zero order release kinetics. PMID:21454168

  8. WindWaveFloat

    SciTech Connect

    Weinstein, Alla

    2011-11-01

    Presentation from the 2011 Water Peer Review includes in which principal investigator Alla Weinstein discusses project progress in development of a floating offshore wind structure - the WindFloat - and incorporation therin of a Spherical Wave Energy Device.

  9. Terahertz Technology: A Boon to Tablet Analysis

    PubMed Central

    Wagh, M. P.; Sonawane, Y. H.; Joshi, O. U.

    2009-01-01

    The terahertz gap has a frequency ranges from ∼0.3 THz to ∼10 THz in the electromagnetic spectrum which is in between microwave and infrared. The terahertz radiations are invisible to naked eye. In comparison with x-ray they are intrinsically safe, non-destructive and non-invasive. Terahertz spectroscopy enables 3D imaging of structures and materials, and the measurement of the unique spectral fingerprints of chemical and physical forms. Terahertz radiations are produced by a dendrimer based high power terahertz source and spectroscopy technologies. It resolves many of the questions left unanswered by complementary techniques, such as optical imaging, Raman and infrared spectra. In the pharmaceutical industries it enables nondestructive, internal, chemical analysis of tablets, capsules, and other dosage forms. Tablet coatings are a major factor in drug bioavailability. Therefore tablet coatings integrity and uniformity are of crucial importance to quality. Terahertz imaging gives an unparalleled certainty about the integrity of tablet coatings and the matrix performance of tablet cores. This article demonstrates the potential of terahertz pulse imaging for the analysis of tablet coating thickness by illustrating the technique on tablets. PMID:20490288

  10. The Design of Floats

    NASA Technical Reports Server (NTRS)

    Sottorf, W

    1938-01-01

    Following a summary of the multiplicity of domestic and foreign floats and a brief enumeration of the requirements of floats, the essential form parameters and their effect on the qualities of floats are detailed. On this basis a standard float design is developed which in model families with varying length/beam ratio and angle of dead rise is analyzed by an experimental method which permits its best utilization on any airplane.

  11. Determining the polymer threshold amount for achieving robust drug release from HPMC and HPC matrix tablets containing a high-dose BCS class I model drug: in vitro and in vivo studies.

    PubMed

    Klančar, Uroš; Baumgartner, Saša; Legen, Igor; Smrdel, Polona; Kampuš, Nataša Jeraj; Krajcar, Dejan; Markun, Boštjan; Kočevar, Klemen

    2015-04-01

    It is challenging to achieve mechanically robust drug-release profiles from hydrophilic matrices containing a high dose of a drug with good solubility. However, a mechanically robust drug release over prolonged period of time can be achieved, especially if the viscosity and amount of the polymer is sufficiently high, above the "threshold values." The goal of this research was to determine the hydroxypropyl cellulose (HPC) and hydroxypropyl methylcellulose (HPMC) polymer threshold amount that would enable robust drug release from matrix tablets containing a high dose of levetiracetam as a class I model drug according to the Biopharmaceutical Classification System (BCS). For this purpose, formulations containing HPC or HPMC of similar viscosity range, but in different amounts, were prepared. Based on the dissolution results, two final formulations were selected for additional in vitro and in vivo evaluation to confirm the robustness and to show bioequivalence. Tablets were exposed to various stress conditions in vitro with the use of different mechanically stress-inducing dissolution methods. The in vitro results were compared with in vivo results obtained from fasted and fed bioequivalence studies. Under both conditions, the formulations were bioequivalent and food had a negligible influence on the pharmacokinetic parameters C max and area under the curve (AUC). It was concluded that the drug release from both selected formulations is mechanically robust and that HPC and HPMC polymers with intrinsic viscosities above 9 dL/g and in quantities above 30% enable good mechanical resistance, which ensures bioequivalence. In addition, HPC matrices were found to be more mechanically robust compared to HPMC. PMID:25331194

  12. An understanding of modified release matrix tablets behavior during drug dissolution as the key for prediction of pharmaceutical product performance - case study of multimodal characterization of quetiapine fumarate tablets.

    PubMed

    Kulinowski, Piotr; Woyna-Orlewicz, Krzysztof; Rappen, Gerd-Martin; Haznar-Garbacz, Dorota; Węglarz, Władysław P; Dorożyński, Przemysław P

    2015-04-30

    Motivation for the study was the lack of dedicated and effective research and development (R&D) in vitro methods for oral, generic, modified release formulations. The purpose of the research was to assess multimodal in vitro methodology for further bioequivalence study risk minimization. Principal results of the study are as follows: (i) Pharmaceutically equivalent quetiapine fumarate extended release dosage form of Seroquel XR was developed using a quality by design/design of experiment (QbD/DoE) paradigm. (ii) The developed formulation was then compared with originator using X-ray microtomography, magnetic resonance imaging and texture analysis. Despite similarity in terms of compendial dissolution test, developed and original dosage forms differed in micro/meso structure and consequently in mechanical properties. (iii) These differences were found to be the key factors of failure of biorelevant dissolution test using the stress dissolution apparatus. Major conclusions are as follows: (i) Imaging methods allow to assess internal features of the hydrating extended release matrix and together with the stress dissolution test allow to rationalize the design of generic formulations at the in vitro level. (ii) Technological impact on formulation properties e.g., on pore formation in hydrating matrices cannot be overlooked when designing modified release dosage forms. PMID:25701626

  13. Accuracy of tablet splitting.

    PubMed

    McDevitt, J T; Gurst, A H; Chen, Y

    1998-01-01

    We attempted to determine the accuracy of manually splitting hydrochlorothiazide tablets. Ninety-four healthy volunteers each split ten 25-mg hydrochlorothiazide tablets, which were then weighed using an analytical balance. Demographics, grip and pinch strength, digit circumference, and tablet-splitting experience were documented. Subjects were also surveyed regarding their willingness to pay a premium for commercially available, lower-dose tablets. Of 1752 manually split tablet portions, 41.3% deviated from ideal weight by more than 10% and 12.4% deviated by more than 20%. Gender, age, education, and tablet-splitting experience were not predictive of variability. Most subjects (96.8%) stated a preference for commercially produced, lower-dose tablets, and 77.2% were willing to pay more for them. For drugs with steep dose-response curves or narrow therapeutic windows, the differences we recorded could be clinically relevant. PMID:9469693

  14. Float Zone Workshop

    NASA Technical Reports Server (NTRS)

    Naumann, R. J.

    1980-01-01

    A summary of the Analytical Float Zone Experiment System (AFZES) concept is presented. The types of experiments considered for such a facility are discussed. Reports from various industrial producers and users of float zone material are presented. Special emphasis is placed on state-of-the-art developments in low gravity manufacturing and their applications to space processing.

  15. "Floating shoulder" injuries.

    PubMed

    Heng, Kenneth

    2016-12-01

    "Floating shoulder" is a rare injury complex resulting from high-energy blunt force trauma to the shoulder, resulting in scapulothoracic dissociation. It is commonly associated with catastrophic neurovascular injury. Two cases of motorcyclists with floating shoulder injuries are described. PMID:26961729

  16. Positive seal float collar

    SciTech Connect

    Bolding, B.H.

    1981-09-01

    A device for insuring a positive fluid seal between a float collar valving element and valve seat therein is disclosed. The device comprises a rubberlike tension strap or compression steel spring positioned within the float collar valve assembly for urging the valving element against the upper valve seat. Fluid pressure from above the valve assembly will overcome the force exerted on the valving element by the urging device and permit fluid to flow in a downwardly direction through the float collar valve assembly. However, when this fluid pressure above the float collar is reduced, the urging device overcomes the force exerted thereby and again urges the valving element in positive sealing engagement with the upper valve seat to preclude flow of fluid in an upperwardly direction back through the float collar valve assembly.

  17. Floating emitter solar cell

    NASA Technical Reports Server (NTRS)

    Chih, Sah (Inventor); Cheng, Li-Jen (Inventor)

    1987-01-01

    A front surface contact floating emitter solar cell transistor is provided in a semiconductor body (n-type), in which floating emitter sections (p-type) are diffused or implanted in the front surface. Between the emitter sections, a further section is diffused or implanted in the front surface, but isolated from the floating emitter sections, for use either as a base contact to the n-type semiconductor body, in which case the section is doped n+, or as a collector for the adjacent emitter sections.

  18. Calcification prevention tablets

    NASA Technical Reports Server (NTRS)

    Lindsay, Geoffrey A.; Hasting, Michael A.; Gustavson, Michael A.

    1991-01-01

    Citric acid tablets, which slowly release citric acid when flushed with water, are under development by the Navy for calcification prevention. The citric acid dissolves calcium carbonate deposits and chelates the calcium. For use in urinals, a dispenser is not required because the tablets are non-toxic and safe to handle. The tablets are placed in the bottom of the urinal, and are consumed in several hundred flushes (the release rate can be tailored by adjusting the formulation). All of the ingredients are environmentally biodegradable. Mass production of the tablets on commercial tableting machines was demonstrated. The tablets are inexpensive (about 75 cents apiece). Incidences of clogged pipes and urinals were greatly decreased in long term shipboard tests. The corrosion rate of sewage collection pipe (90/10 Cu/Ni) in citric acid solution in the laboratory is several mils per year at conditions typically found in traps under the urinals. The only shipboard corrosion seen to date is of the yellow brass urinal tail pieces. While this is acceptable, the search for a nontoxic corrosion inhibitor is underway. The shelf life of the tablets is at least one year if stored at 50 percent relative humidity, and longer if stored in sealed plastic buckets.

  19. Floating Magnet Demonstration.

    ERIC Educational Resources Information Center

    Wake, Masayoshi

    1990-01-01

    A room-temperature demonstration of a floating magnet using a high-temperature superconductor is described. The setup and operation of the apparatus are described. The technical details of the effect are discussed. (CW)

  20. Float-in powerhouses

    SciTech Connect

    Makela, G.A.

    1983-06-01

    The nation's inland waterway system affords a means of transporting large objects limited only by channel depth, size of locks and bridge clearances. The concept of prefabricating standardized, hydroelectric powerhouses at shipyards, transporting them along the inland waterways and installing them at navigation dams without powerhouses was examined for the McClellan-Kerr Arkansas River Navigation system. It was found that construction costs for the float-in design was very close to those of conventional sitebuilt design. Experience at Greenup Dam on the Ohio River where a float-in powerhouse has been installed indicated that construction time could be reduced if the float-in design was used. This time saving, use of standardized designs and construction of the float-in module at a shipyard may offer advantages that should be examined in more detailed when the power potential of the nation's low navigation dams is assessed.

  1. Micromechanisms with floating pivot

    DOEpatents

    Garcia, Ernest J.

    2001-03-06

    A new class of tilting micromechanical mechanisms have been developed. These new mechanisms use floating pivot structures to relieve some of the problems encountered in the use of solid flexible pivots.

  2. Stabilized floating platforms

    DOEpatents

    Thomas, David G.

    1976-01-01

    The subject invention is directed to a floating platform for supporting nuclear reactors and the like at selected offshore sites. The platform is provided with a stabilizer mechanism which significantly reduces the effects of wave action upon the platform and which comprises a pair of relatively small floats attached by rigid booms to the platform at locations spaced therefrom for reducing wave pitch, acceleration, and the resonance period of the wave.

  3. Design and in vitro evaluation of effervescent gastric floating drug delivery systems of propanolol HCl.

    PubMed

    Meka, Venkata Srikanth; Songa, Ambedkar Sunil; Nali, Sreenivasa Rao; Battu, Janaki Ram; Kolapalli, Venkata Ramana Murthy

    2012-03-01

    Abstract. The purpose of this research was to develop and evaluate effervescent gastric floating tablets of propranolol HCl. The oral delivery of antihypertensive propranolol HCl was facilitated by preparing an effervescent floating dosage form which could increase its absorption in the stomach by increasing the drug's gastric residence time. In the present work, effervescent floating tablets were prepared with a hydrophilic carrier such as polyethylene oxide (PEO WSR N 60K and PEO WSR 303) as a release retarding agent and sodium bicarbonate as a gas generating agent. The prepared tablets were evaluated for all their physicochemical properties, in vitro buoyancy, drug release and rate order kinetics. From the results, P9 was selected as an optimized formulation based on their 12 h drug release, minimal floating lag time and maximum total floating time. The optimized formulation followed first order rate kinetics with erosion mechanism. The optimized formulation was characterized with FTIR studies and no interaction between the drug and the polymers were observed. PMID:22524109

  4. Development of press-coated, floating-pulsatile drug delivery of lisinopril.

    PubMed

    Jagdale, Swati C; Suryawanshi, Vishnu M; Pandya, Sudhir V; Kuchekar, Bhanudas S; Chabukswar, Aniruddha R

    2014-06-01

    Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor, primarily used for the treatment of hypertension, congestive heart failure, and heart attack. It belongs to BCS class III having a half-life of 12 hrs and 25% bioavailability. The purpose of the present work was to develop a press-coated, floating-pulsatile drug delivery system. The core tablet was formulated using the super-disintegrants crosprovidone and croscarmellose sodium. A press-coated tablet (barrier layer) contained the polymer carrageenan, xanthan gum, HPMC K4M, and HPMC K15M. The buoyant layer was optimized with HPMC K100M, sodium bicarbonate, and citric acid. The tablets were evaluated for physical characteristics, floating lag time, swelling index, FTIR, DSC, and in vitro and in vivo behavior. The 5% superdisintgrant showed good results. The FTIR and DSC study predicted no chemical interactions between the drug and excipients. The formulation containing xanthan gum showed drug retaining abilities, but failed to float. The tablet containing HPMC K15M showed a high swelling index. The lag time for the tablet coated with 200 mg carrageenan was 3±0.1 hrs with 99.99±1.5% drug release; with 140 mg HPMC K4M, the lag time was 3±0.1 hrs with 99.71±1.2% drug release; and with 120 mg HPMC K15M, the lag time was 3±0.2 hrs with 99.98±1.7% drug release. The release mechanism of the tablet followed the Korsmeyer-Peppas equation and a first-order release pattern. Floating and lag time behavior have shown good in vitro and in vivo correlations. PMID:24959410

  5. Development of Press-Coated, Floating-Pulsatile Drug Delivery of Lisinopril

    PubMed Central

    Jagdale, Swati C.; Suryawanshi, Vishnu M.; Pandya, Sudhir V.; Kuchekar, Bhanudas S.; Chabukswar, Aniruddha R.

    2014-01-01

    Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor, primarily used for the treatment of hypertension, congestive heart failure, and heart attack. It belongs to BCS class III having a half-life of 12 hrs and 25% bioavailability. The purpose of the present work was to develop a press-coated, floating-pulsatile drug delivery system. The core tablet was formulated using the super-disintegrants crosprovidone and croscarmellose sodium. A press-coated tablet (barrier layer) contained the polymer carrageenan, xanthan gum, HPMC K4M, and HPMC K15M. The buoyant layer was optimized with HPMC K100M, sodium bicarbonate, and citric acid. The tablets were evaluated for physical characteristics, floating lag time, swelling index, FTIR, DSC, and in vitro and in vivo behavior. The 5% superdisintgrant showed good results. The FTIR and DSC study predicted no chemical interactions between the drug and excipients. The formulation containing xanthan gum showed drug retaining abilities, but failed to float. The tablet containing HPMC K15M showed a high swelling index. The lag time for the tablet coated with 200 mg carrageenan was 3±0.1 hrs with 99.99±1.5% drug release; with 140 mg HPMC K4M, the lag time was 3±0.1 hrs with 99.71±1.2% drug release; and with 120 mg HPMC K15M, the lag time was 3±0.2 hrs with 99.98±1.7% drug release. The release mechanism of the tablet followed the Korsmeyer-Peppas equation and a first-order release pattern. Floating and lag time behavior have shown good in vitro and in vivo correlations. PMID:24959410

  6. Novel chitosan-magnesium aluminum silicate nanocomposite film coatings for modified-release tablets.

    PubMed

    Khunawattanakul, Wanwisa; Puttipipatkhachorn, Satit; Rades, Thomas; Pongjanyakul, Thaned

    2011-04-01

    Chitosan (CS), a positively charged polysaccharide, and magnesium aluminum silicate (MAS), a negatively charged clay with silicate layers, can electrostatically interact to form nanocomposite films. In this study, CS-MAS nanocomposite films were evaluated for use in tablet film coating. Effects of CS-MAS ratio and coating level on water uptake and drug release from the coated tablets were investigated. Surface and film matrix morphology of the coated film and the effect of enzymes in the simulated gastro-intestinal fluid on drug release were also examined. The results demonstrated that the CS-MAS coated tablets had a rough surface and a layered matrix film, whereas a smooth surface and dense matrix film on the CS coated tablets was found. However, the CS-MAS coated tablets provided fewer film defects than the CS coated tablets. Nanocomposite formation between CS and MAS could retard swelling and erosion of CS in the composite films in acidic medium. The higher MAS ratio of the CS-MAS coated tablets gave lower water uptake and slower drug release when compared with the CS coated tablets. Moreover, the CS-MAS films on the tablets presented good stability towards enzymatic degradation in simulated intestinal fluid. The release of drug from the CS-MAS coated tablets could be modulated by varying CS-MAS ratios and coating levels. Additionally, drug solubility also influenced drug release characteristics of the CS-MAS coated tablets. These findings suggest that the CS-MAS nanocomposites displays a strong potential for use in tablet film coating intended for modifying drug release from tablets. PMID:21291977

  7. Floating nut retention system

    NASA Technical Reports Server (NTRS)

    Charles, J. F.; Theakston, H. A. (Inventor)

    1980-01-01

    A floating nut retention system includes a nut with a central aperture. An inner retainer plate has an opening which is fixedly aligned with the nut aperture. An outer retainer member is formed of a base plate having an opening and a surface adjacent to a surface of the inner retainer plate. The outer retainer member includes a securing mechanism for retaining the inner retainer plate adjacent to the outer retainer member. The securing mechanism enables the inner retainer plate to float with respect to the outer retainer number, while simultaneously forming a bearing surface for inner retainer plate.

  8. Improved bioavailability through floating microspheres of lovastatin

    PubMed Central

    Kumar, S.; Nagpal, K; Singh, SK.; Mishra, DN.

    2011-01-01

    Background and the purpose of the study Lovastatin is an antihyperlipidemic agent which has low bioavailability due to the extensive first pass metabolism. It was sought to increase gastric retention of lovastatin by development of a sustained release gastroretentive drug delivery system leading to reduced fluctuation in the plasma concentration and improved bioavailability. Mehods Floating microspheres were prepared by emulsion solvent diffusion technique, using various polymers and their blends. The in vitro performance was evaluated for drug-polymer compatibility, percent yield, particle size, drug entrapment efficiency, in vitro onset and duration of floatation, in vitro drug release as well as in vivo determination of serum cholesterol level. Results The mean particle size of microspheres was observed to be between 6.9 to 9.5 m and the maximum particle size was around 50 m. In vivo studies of the selected batches indicated lower level of serum cholesterol compared to the marketed tablet at the same dose but was not significant. Major conclusion The data obtained in this study suggested that a microparticulate floating dosage form of lovastatin can be successfully designed to yield controlled delivery with improved therapeutic efficacy. PMID:22615640

  9. Granule size distribution of tablets.

    PubMed

    Virtanen, Satu; Antikainen, Osmo; Räikkönen, Heikki; Yliruusi, Jouko

    2010-04-01

    The purpose of this study was to determine the variation in the granule size distribution in a die of an eccentric tableting machine. Theophylline anhydrate and alpha-lactose monohydrate were granulated with an aqueous solution of polyvinylpyrrolidone, using an instrumented fluid bed granulator. The granules were tabletted, using an instrumented eccentric tableting machine. Punch forces were recorded and tablets were collected in order during the tableting process. Powder samples, which had the same mass as the tablets, were also collected from the die for particle size determination. The particle size distribution was measured, using a spatial filtering technique. In addition, the segregation of microcrystalline cellulose pellets during tableting was analyzed. The particle size distribution changed dramatically during the tableting process, due to a segregation phenomenon. PMID:19780134

  10. Desktop 3D printing of controlled release pharmaceutical bilayer tablets.

    PubMed

    Khaled, Shaban A; Burley, Jonathan C; Alexander, Morgan R; Roberts, Clive J

    2014-01-30

    Three dimensional (3D) printing was used as a novel medicine formulation technique for production of viable tablets capable of satisfying regulatory tests and matching the release of standard commercial tablets. Hydroxypropyl methylcellulose (HPMC 2208) (Methocel™ K100M Premium) and poly(acrylic acid) (PAA) (Carbopol(®) 974P NF) were used as a hydrophilic matrix for a sustained release (SR) layer. Hypromellose(®) (HPMC 2910) was used as a binder while microcrystalline cellulose (MCC) (Pharmacel(®) 102) and sodium starch glycolate (SSG) (Primojel(®)) were used as disintegrants for an immediate release (IR) layer. Commercial guaifenesin bi-layer tablets (GBT) were used as a model drug (Mucinex(®)) for this study. There was a favourable comparison of release of the active guaifenesin from the printed hydrophilic matrix compared with the commercially available GBT. The printed formulations were also evaluated for physical and mechanical properties such as weight variation, friability, hardness and thickness as a comparison to the commercial tablet and were within acceptable range as defined by the international standards stated in the United States Pharmacopoeia (USP). All formulations (standard tablets and 3D printed tablets) showed Korsmeyer-Peppas n values between 0.27 and 0.44 which indicates Fickian diffusion drug release through a hydrated HPMC gel layer. PMID:24280018

  11. Tabletability Modulation Through Surface Engineering.

    PubMed

    Osei-Yeboah, Frederick; Sun, Changquan Calvin

    2015-08-01

    Poor powder tabletability is a common problem that challenges the successful development of high-quality tablet products. Using noncompressible microcrystalline cellulose beads, we demonstrate that surface coating is an effective strategy for modulating tabletability, almost at will, through judicious selection of coating material. This strategy has broad applicability as tabletability of such particles is dictated by the properties of the outermost layer coat regardless the nature of the core. PMID:26059496

  12. Floating Vegetation in Pantanal

    Mass of floating vegetation (embalsado)on Rio Negro river on the border between Paraguay and Bolivia. Located near RAMSAR site and Rio Negro National Park in the Pantanal ecoregion. This region, situated in the extreme northeastern corner of western Paraguay and extending south along the Paraguay ri...

  13. Floating Vegetation in Pantanal

    Mass of floating vegetation (embalsado) on Rio Negro river along the border between Paraguay and Bolivia. Located near RAMSAR site and Rio Negro National Park in the Pantanal ecoregion. This region, situated in the extreme northeastern corner of western Paraguay and extending south along the Paragua...

  14. Compound floating pivot micromechanisms

    DOEpatents

    Garcia, Ernest J.

    2001-04-24

    A new class of tilting micromechanical mechanisms have been developed. These new mechanisms use compound floating pivot structures to attain far greater tilt angles than are practical using other micromechanical techniques. The new mechanisms are also capable of bi-directional tilt about multiple axes.

  15. Tablet Splitting: A Risky Practice

    MedlinePlus

    ... helps to release the medicine slowly. Splitting these tablets destroys the coating, which means you might absorb the medicine too fast or not at all. What if You Still Want to Split a Tablet? FDA has approved drugs where tablet splitting is ...

  16. CES 2011: Tablet Crazy

    ERIC Educational Resources Information Center

    Rapp, David

    2011-01-01

    Ereaders are so last year. Tablets were the watchword at this year's annual Consumer Electronics Show (CES) in Las Vegas, January 6-9. This year, the show set new records, with some 2700 companies from around the world exhibiting at the multiple exhibition halls and 30,000 attendees gawking at the products. What did they see? There were still some…

  17. CES 2011: Tablet Crazy

    ERIC Educational Resources Information Center

    Rapp, David

    2011-01-01

    Ereaders are so last year. Tablets were the watchword at this year's annual Consumer Electronics Show (CES) in Las Vegas, January 6-9. This year, the show set new records, with some 2700 companies from around the world exhibiting at the multiple exhibition halls and 30,000 attendees gawking at the products. What did they see? There were still some

  18. Physical characterizations and sustained release profiling of gastroretentive drug delivery systems with improved floating and swelling capabilities.

    PubMed

    Chen, Ying-Chen; Ho, Hsiu-O; Lee, Tzu-Yu; Sheu, Ming-Thau

    2013-01-30

    The aim was to develop gastroretentive drug delivery systems (GRDDSs) by combining floating and swelling. GRDDS tablets formulated with hydroxyethylcellulose (HEC), chitosan (CS) and sodium bicarbonate (SB) for evaluating floating capacity (floating lag time and duration) and swelling characteristics. CS was used because it was swellable in acidic media and biocompatible. Losartan was incorporated into the optimized formulations for sustained release profiling. Results demonstrated that for those formulations at HEC:CS ratio of 5:5 containing CS, both the floating lag time and floating duration were optimal and reached the preferred swelling effect and sustain for 24h. Adding SB improved the floating capabilities for all ratios of HEC:CS, but reduced the swelling ability for those formulations containing a higher portion of low viscosity grade CS. Sustained release profiles for losartan in those formulations were achievable, using all viscosity grades of CS at all examined HEC:CS ratios; however, it is more adjustable at different HEC:CS ratios when using a lower viscosity grade of CS. Optimized GRDDS formulations for losartan composed of an equivalent ratio of HEC to CS with 20mg SB resulted in the tablets floating for more than 16 h and an adjustable sustained release profile. PMID:23237874

  19. Freely floating smectic films.

    PubMed

    May, Kathrin; Harth, Kirsten; Trittel, Torsten; Stannarius, Ralf

    2014-05-19

    We have investigated the dynamics of freely floating smectic bubbles using high-speed optical imaging. Bubbles in the size range from a few hundred micrometers to several centimeters were prepared from collapsing catenoids. They represent ideal model systems for the study of thin-film fluid dynamics under well-controlled conditions. Owing to the internal smectic layer structure, the bubbles combine features of both soap films and vesicles in their unique shape dynamics. From a strongly elongated initial shape after pinch-off, they relax towards the spherical equilibrium, first by a slow redistribution of the smectic layers, and finally by weak, damped shape oscillations. In addition, we describe the rupture of freely floating smectic bubbles, and the formation and stability of smectic filaments. PMID:24692347

  20. Preparation and in vitro characterization of non-effervescent floating drug delivery system of poorly soluble drug, carvedilol phosphate.

    PubMed

    Srikanth Meka, Venkata; Wee Liang, Vanitha A P Hong; Dharmalingham, Senthil Rajan; Sheshala, Ravi; Gorajana, Adinarayana

    2014-12-01

    The objective of the study was to enhance the solubility of carvedilol phosphate and to formulate it into non-effervescent floating tablets using swellable polymers. Solid dispersions (SD) of carvedilol were prepared with hydrophilic carriers such as polyvinylpyrrolidone and poloxamer to enhance solubility. Non-effervescent floating tablets were prepared with a combination of optimized solid dispersions and release retarding polymers/swellable polymers such as xanthan gum and polyethylene oxide. Tablets were evaluated for physicochemical properties such as hardness, thickness and buoyancy. SD prepared with the drug to poloxamer ratio of 1:4 by melt granulation showed a higher dissolution rate than all other dispersions. Formulations containing 40 mg of polyethylene oxide (C-P40) and 50 mg xanthan gum (C-X50) were found to be best, with the drug retardation up to 12 hours. Optimized formulations were characterized using FTIR and DSC and no drug and excipient interactions were detected. PMID:25531788

  1. Design and statistical optimization of an effervescent floating drug delivery system of theophylline using response surface methodology.

    PubMed

    Srikanth Meka, Venkata; Ee Li, Chew; Sheshala, Ravi

    2016-03-01

    The aim of this research was to formulate effervescent floating drug delivery systems of theophylline using different release retarding polymers such as ethyl cellulose, Eudragit® L100, xanthan gum and polyethylene oxide (PEO) N12K. Sodium bicarbonate was used as a gas generating agent. Direct compression was used to formulate floating tablets and the tablets were evaluated for their physicochemical and dissolution characteristics. PEO based formulations produced better drug release properties than other formulations. Hence, it was further optimized by central composite design. Further subjects of research were the effect of formulation variables on floating lag time and the percentage of drug released at the seventh hour (D7h). The optimum quantities of PEO and sodium bicarbonate, which had the highest desirability close to 1.0, were chosen as the statistically optimized formulation. No interaction was found between theophylline and PEO by Fourier Transformation Infrared spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) studies. PMID:26959542

  2. Gastroretentive pulsatile release tablets of lercanidipine HCl: development, statistical optimization, and in vitro and in vivo evaluation.

    PubMed

    Reddy, Gagganapalli Santhoshi; Nayak, Usha Yogendra; Deshpande, Praful Balavant; Mutalik, Srinivas

    2014-01-01

    The present study was aimed at the development of gastroretentive floating pulsatile release tablets (FPRTs) of lercanidipine HCl to enhance the bioavailability and treat early morning surge in blood pressure. Immediate release core tablets containing lercanidipine HCl were prepared and optimized core tablets were compression-coated using buoyant layer containing polyethylene oxide (PEO) WSR coagulant, sodium bicarbonate, and directly compressible lactose. FPRTs were evaluated for various in vitro physicochemical parameters, drug-excipient compatibility, buoyancy, swelling, and release studies. The optimized FPRTs were tested in vivo in New Zealand white rabbits for buoyancy and pharmacokinetics. DoE optimization of data revealed FPRTs containing PEO (20% w/w) with coat weight 480 mg were promising systems exhibiting good floating behavior and lag time in drug release. Abdominal X-ray imaging of rabbits after oral administration of the tablets, confirmed the floating behavior and lag time. A quadratic model was suggested for release at 7th and 12th h and a linear model was suggested for release lag time. The FPRT formulation improved pharmacokinetic parameters compared to immediate release tablet formulation in terms of extent of absorption in rabbits. As the formulation showed delay in drug release both in vitro and in vivo, nighttime administration could be beneficial to reduce the cardiovascular complications due to early morning surge in blood pressure. PMID:25525619

  3. Gastroretentive Pulsatile Release Tablets of Lercanidipine HCl: Development, Statistical Optimization, and In Vitro and In Vivo Evaluation

    PubMed Central

    Reddy, Gagganapalli Santhoshi; Nayak, Usha Yogendra; Deshpande, Praful Balavant; Mutalik, Srinivas

    2014-01-01

    The present study was aimed at the development of gastroretentive floating pulsatile release tablets (FPRTs) of lercanidipine HCl to enhance the bioavailability and treat early morning surge in blood pressure. Immediate release core tablets containing lercanidipine HCl were prepared and optimized core tablets were compression-coated using buoyant layer containing polyethylene oxide (PEO) WSR coagulant, sodium bicarbonate, and directly compressible lactose. FPRTs were evaluated for various in vitro physicochemical parameters, drug-excipient compatibility, buoyancy, swelling, and release studies. The optimized FPRTs were tested in vivo in New Zealand white rabbits for buoyancy and pharmacokinetics. DoE optimization of data revealed FPRTs containing PEO (20% w/w) with coat weight 480 mg were promising systems exhibiting good floating behavior and lag time in drug release. Abdominal X-ray imaging of rabbits after oral administration of the tablets, confirmed the floating behavior and lag time. A quadratic model was suggested for release at 7th and 12th h and a linear model was suggested for release lag time. The FPRT formulation improved pharmacokinetic parameters compared to immediate release tablet formulation in terms of extent of absorption in rabbits. As the formulation showed delay in drug release both in vitro and in vivo, nighttime administration could be beneficial to reduce the cardiovascular complications due to early morning surge in blood pressure. PMID:25525619

  4. The Floating Ball Paradox

    NASA Astrophysics Data System (ADS)

    Wente, Henry C.

    2008-11-01

    In capillary theory there are two kinds of surface tension. There is the surface tension at the interface between two immiscible fluids. Thomas Young [9] also allowed for there to be a surface tension associated with a liquid-solid interface. He proceeded to use a balance of forces argument to derive the well-known contact angle condition along a liquid-liquid-solid intersection. The validity of this argument has recently been called into question by R. Finn [6]. A floating ball experiment discussed in that paper leads to an apparent paradox. We address this issue.

  5. Influence of formulation factors on tablet formulations with liquid permeation enhancer using factorial design.

    PubMed

    Bejugam, Naveen K; Parish, Helen J; Shankar, Gita N

    2009-01-01

    For a drug with low bioavailability, a matrix tablet with liquid permeation enhancer (Labrasol) was formulated. Factorial design was used to evaluate the effect of three formulation factors: drug percentage, polymer type (Methocel K100M or Eudragit L 100-55), and tablet binder percentage (Plasdone S-630) on tablet characteristics. Tablets were prepared by direct compression and characterized. Compressibility index values ranged between 15.90% and 29.87% and tablet hardness values from 7.8 to 29.78 Kp. Eudragit-containing formulations had better compressibility index values with higher tablet hardness. Time for 75% of drug release (T75) was calculated, and formulations containing Eudragit L 100-55 had faster release rates than tablet formulations with Methocel K100M. Formulations with Methocel K100M fit well in the Higuchi model as indicated by their R2 values (>0.98). Among all the formulation factors studied, polymer type displayed the highest and statistically significant effect on compressibility index, tablet hardness, and dissolution rate. Statistical design helped in better understanding the effect of formulation factors on tablet characteristics important for designing formulations with desired characteristics. PMID:19957114

  6. Does It Sink or Float?

    ERIC Educational Resources Information Center

    McDonald, Judith Richards

    2012-01-01

    This activity is designed to teach prekindergarten to second grade students about the concept of sink or float through an inquiry activity. Students will use familiar objects to predict and test the properties of sink and float. Background information is offered to teachers to assist them with this activity. This lesson begins with an engaging…

  7. Does It Sink or Float?

    ERIC Educational Resources Information Center

    McDonald, Judith Richards

    2012-01-01

    This activity is designed to teach prekindergarten to second grade students about the concept of sink or float through an inquiry activity. Students will use familiar objects to predict and test the properties of sink and float. Background information is offered to teachers to assist them with this activity. This lesson begins with an engaging

  8. Tablet PCs: The Write Approach

    ERIC Educational Resources Information Center

    Milner, Jacob

    2006-01-01

    This article discusses the transforming effects of tablet PCs in the classroom. As 1-to-1 computing becomes the goal on K-12 campuses, school districts are turning to this newer, pen-based technology. Saint Mary's School's new Lenovo ThinkPad X41 tablet PCs had transformed the way Saint Mary's teachers did their jobs. Teachers created outlines for…

  9. Assessing Student Writing on Tablets

    ERIC Educational Resources Information Center

    Davis, Laurie Laughlin; Orr, Aline; Kong, Xiaojing; Lin, Chow-Hong

    2015-01-01

    There is increasing expectation that schools should be able to use tablets for a range of instructional and assessment purposes. This article considers the comparability of student writing on tablets and laptops to ensure that writing assessment is conducted in a way that is fair to all students. Data were collected from a sample of 826 students…

  10. Assessing Student Writing on Tablets

    ERIC Educational Resources Information Center

    Davis, Laurie Laughlin; Orr, Aline; Kong, Xiaojing; Lin, Chow-Hong

    2015-01-01

    There is increasing expectation that schools should be able to use tablets for a range of instructional and assessment purposes. This article considers the comparability of student writing on tablets and laptops to ensure that writing assessment is conducted in a way that is fair to all students. Data were collected from a sample of 826 students

  11. Review of bilayer tablet technology.

    PubMed

    Abebe, Admassu; Akseli, Ilgaz; Sprockel, Omar; Kottala, Niranjan; Cuitiño, Alberto M

    2014-01-30

    Therapeutic strategies based on oral delivery of bilayer (and multilayer) tablets are gaining more acceptance among brand and generic products due to a confluence of factors including advanced delivery strategies, patient compliance and combination therapy. Successful manufacturing of these ever more complex systems needs to overcome a series of challenges from formulation design to tablet press monitoring and control. This article provides an overview of the state-of-the-art of bilayer tablet technology, highlighting the main benefits of this type of oral dosage forms while providing a description of current challenges and advances toward improving manufacturing practices and product quality. Several aspects relevant to bilayer tablet manufacturing are addressed including material properties, lubrication, layer ordering, layer thickness, layer weight control, as well as first and final compression forces. A section is also devoted to bilayer tablet characterization that present additional complexities associated with interfaces between layers. The available features of the manufacturing equipment for bilayer tablet production are also described indicating the different strategies for sensing and controls offered by bilayer tablet press manufacturers. Finally, a roadmap for bilayer tablet manufacturing is advanced as a guideline to formulation design and selection of process parameters and equipment. PMID:24370841

  12. Dissolution testing of nitroglycerin tablets.

    PubMed

    Gaglia, C A; Lomner, J J; Leonard, B L; Chafetz, L

    1976-11-01

    The available types of dissolution testing apparatus for tablets and capsules are inapplicable to sublingual tablets, since these tablets are formulated to release their drug content within minutes in a small volume of fluid. A simple dissolution test method was developed for nitroglycerin tablets based on the reduction of nitroglycerin at a rotating platinum electrode, which provides reproducible stirring. The system provides instantaneous and continuous measurement of dissolved nitroglycerin in a small constant volume of buffered isotonic sodium chloride solution over a period of seconds to several minutes, when reduction is complete as shown by the current-time curve. Since the height of the curve is directly proportional to the amount of nitroglycerin in solution, the method also can be used to determine the drug content of individual tablets. PMID:825635

  13. Development and evaluation of orally disintegrating tablets (ODTs) containing Ibuprofen granules prepared by hot melt extrusion.

    PubMed

    Gryczke, Andreas; Schminke, Silke; Maniruzzaman, Mohammed; Beck, Julien; Douroumis, Dennis

    2011-09-01

    In the current study Ibuprofen was embedded in a methacrylate copolymer (Eudragit® EPO) matrix to produce solid dispersions by hot-melt extrusion (HME) processing. The obtained granules were incorporated in orally disintegrating tablets (ODTs). The tablets were developed by varying the ratio of superdisintegrants such as sodium croscarmellose and crosslinked polyvinylpyrrolidone grades while a direct compression process was used to compress the ODTs under various compaction forces to optimize tablet robustness. The properties of the compressed tablets which included porosity, hardness, friability and dissolution profiles were further evaluated and compared with Nurofen® Meltlet ODTs. The taste and sensory evaluation in human volunteers demonstrated excellence in masking the bitter active and improved tablet palatability. PMID:21592751

  14. Floating Silicon Method

    SciTech Connect

    Kellerman, Peter

    2013-12-21

    The Floating Silicon Method (FSM) project at Applied Materials (formerly Varian Semiconductor Equipment Associates), has been funded, in part, by the DOE under a “Photovoltaic Supply Chain and Cross Cutting Technologies” grant (number DE-EE0000595) for the past four years. The original intent of the project was to develop the FSM process from concept to a commercially viable tool. This new manufacturing equipment would support the photovoltaic industry in following ways: eliminate kerf losses and the consumable costs associated with wafer sawing, allow optimal photovoltaic efficiency by producing high-quality silicon sheets, reduce the cost of assembling photovoltaic modules by creating large-area silicon cells which are free of micro-cracks, and would be a drop-in replacement in existing high efficiency cell production process thereby allowing rapid fan-out into the industry.

  15. Poking a floating sheet

    NASA Astrophysics Data System (ADS)

    Davidovitch, Benny; Huang, Jiangshui; Menon, Narayanan; Russell, Thomas P.; Vella, Dominic

    2014-03-01

    Poking of liquid surface leads to a simple deformation of the surface, whose characteristic scale is nothing but the capillary length. In contrast, the poking of a circular solid sheet floating on a liquid bath demonstrates a surprisingly complex phenomenology, with numerous distinct length scales that are determined by the capillary length as well as by the poking amplitude and the stretching modulus of the sheet. The fundamental physical mechanism that underlies this complex response is intimately related to the emergence of an highly anisotropic stress, whose radial component is tensile and its hoop component is asymptotically compression-free. In this talk I will discuss the various parameter regimes that describe this problem and will identify the characteristic patterns of the poked sheet in these regimes. Experimental results will be presented and compared to theoretical predictions.

  16. Application of design of experiment for floating drug delivery of tapentadol hydrochloride.

    PubMed

    Jagdale, Swati C; Patil, Somnath; Kuchekar, Bhanudas S

    2013-01-01

    The aim of the present study was to apply design of experiment (DOE) to optimize floating drug delivery of tapentadol hydrochloride. Tapentadol hydrochloride is a synthetic opioid used as a centrally acting analgesic and effective in both experimental and clinical pain. The half-life of the drug is about 4 hours and oral dose is 50 to 250 mg twice a day. For optimization 3(2) full factorial design was employed for formulation of tapentadol hydrochloride tablets. Sodium bicarbonate was incorporated as a gas-generating agent. Combination of polymers Xanthan gum and Locust bean gum was used to achieve controlled release effect. The concentration of polymers was considered as the independent variables and dependent variables were floating lag time and swelling index of the tablets. From the factorial batches, it was observed that formulation containing combination of 20% sodium bicarbonate and 10% citric acid shows optimum floating ability whereas the formulation containing 20% Xanthan gum and 28% Locust bean gum shows optimum sustained drug release pattern with adequate floating. PMID:23878616

  17. Floating into Deep Space

    NASA Astrophysics Data System (ADS)

    La Frenais, R.; Saraceno, T.; Powell, J.

    2014-04-01

    Is it possible for spaceflight to become more sustainable? Artist and architect Tomas Saraceno proposes a long-term artscience research project based on his initial work with solar balloons to join with the efforts of engineers such as John Powell, working on the Airship to Orbit experiments, which describe a three stage process of using airships to fly to a large suborbital "Dark Sky Station' then literally floating into orbit with additional electrical and chemical propulsion. (See: http://www.jpaerospace.com) In his artworks Tomás Saraceno proposes cell-like flying cities as possible architectonic living spaces in direct reference to Buckminster Fuller's Cloud Nine (circa 1960). The fantastic architectural utopia Cloud Nine consists of a freely floating sphere measuring one mile in diameter that offers living space to several autonomous communities encompassing thousands of inhabitants each. The notion of the cloud is essential to the artist's work. The cloud as metaphor stands for artistic intention, for the meaning of territory and border in today's (urban) society, and for exploring possibilities for the sustainable development of the human living environment. In Saraceno's work this environment is not limited to the earth, but is explicitly conceived to reach into outer space. (Biomimetic Constructions- On the works of Tomás Saraceno By Katharina Schlüter) Saraceno is also interested in human factors experiments using his existing constructions as analogue environments for living on Mars and is proposing carry out a series of workshops, experiments and solar balloon launces in White Sands desert in early 2016 in collaboration with the curator Dr Rob La Frenais, the Rubin Center at The University of Texas at El Paso and various scientific partners.

  18. Bioadhesive Mini-Tablets for Vaginal Drug Delivery

    PubMed Central

    Hiorth, Marianne; Nilsen, Susanne; Tho, Ingunn

    2014-01-01

    Different non-ionic cellulose ethers (methyl cellulose, MC; hydroxyethyl cellulose, HEC; hydroxypropyl cellulose, HPC; hydroxypropylmethyl cellulose, HPMC) and microcrystalline cellulose (MCC) were investigated as matrix formers for preparation of mini-tablets targeting vaginal drug delivery. Hexyl aminolevulinat hydrochloridum (HAL) was used as a model drug. The mini-tablets were characterized with respect to their mechanical strength, bioadhesion towards cow vaginal tissue in two independent tests (rotating cylinder test, detachment test using texture analyzer), and dissolution rate in two media mimicking the pH levels of fertile, healthy and post-menopausal women (vaginal fluid simulant pH 4.5, phosphate buffer pH 6.8). Mini-tablets with a matrix of either HPMC or HPC were found to possess adequate mechanical strength, superior bioadhesive behavior towards vaginal tissue, and pH independent controlled release of the model drug, suggesting that both systems would be suited for the treatment of women regardless of age, i.e., respective of their vaginal pH levels. Bioadhesive mini-tablets offer a potential for improved residence time in the vaginal cavity targeting contact with mucosal tissue and prolonged release of the drug. PMID:25166286

  19. NULL Convention Floating Point Multiplier

    PubMed Central

    Ramachandran, Seshasayanan

    2015-01-01

    Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation. PMID:25879069

  20. NULL convention floating point multiplier.

    PubMed

    Albert, Anitha Juliette; Ramachandran, Seshasayanan

    2015-01-01

    Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation. PMID:25879069

  1. Control development for floating wind

    NASA Astrophysics Data System (ADS)

    Savenije, Feike; Peeringa, Johan

    2014-06-01

    Control of a floating wind turbine has proven to be challenging, but essential for lowering the cost of floating wind energy. Topic of a recent joint R&D project by GustoMSC, MARIN and ECN, is the concept design and verification with coupled simulations and model tests of the GustoMSC Tri-Floater. Only using an integral design approach, including mooring and control design, a cost effective system can be obtained. In this project, ECN developed a general floating wind turbine control strategy and applied this in a case study to the GustoMSC Tri-Floater and the OC3Hywind spar, both equipped with the NREL 5MW RWT. The designed controller ensures stable operation, while maintaining proper speed and power regulation. The motions of the floating support are reduced and substantial load reduction has been achieved.

  2. Extra-strong "floating nut"

    NASA Technical Reports Server (NTRS)

    Charles, J. F.; Theakston, H.

    1979-01-01

    Increased bearing area withstands much higher torque than previous designs. Floating nut makes it possible to fasten parts on heavy-duty equipment, such as tractors and cranes, even though they can be reached for tightening from one side only.

  3. The Unified Floating Point Vector Coprocessor for Reconfigurable Hardware

    NASA Astrophysics Data System (ADS)

    Kathiara, Jainik

    There has been an increased interest recently in using embedded cores on FPGAs. Many of the applications that make use of these cores have floating point operations. Due to the complexity and expense of floating point hardware, these algorithms are usually converted to fixed point operations or implemented using floating-point emulation in software. As the technology advances, more and more homogeneous computational resources and fixed function embedded blocks are added to FPGAs and hence implementation of floating point hardware becomes a feasible option. In this research we have implemented a high performance, autonomous floating point vector Coprocessor (FPVC) that works independently within an embedded processor system. We have presented a unified approach to vector and scalar computation, using a single register file for both scalar operands and vector elements. The Hybrid vector/SIMD computational model of FPVC results in greater overall performance for most applications along with improved peak performance compared to other approaches. By parameterizing vector length and the number of vector lanes, we can design an application specific FPVC and take optimal advantage of the FPGA fabric. For this research we have also initiated designing a software library for various computational kernels, each of which adapts FPVC's configuration and provide maximal performance. The kernels implemented are from the area of linear algebra and include matrix multiplication and QR and Cholesky decomposition. We have demonstrated the operation of FPVC on a Xilinx Virtex 5 using the embedded PowerPC.

  4. Skylab floating ice experiment

    NASA Technical Reports Server (NTRS)

    Campbell, W. J. (Principal Investigator); Ramseier, R. O.; Weaver, R. J.; Weeks, W. F.

    1975-01-01

    The author has identified the following significant results. Coupling of the aircraft data with the ground truth observations proved to be highly successful with interesting results being obtained with IR and SLAR passive microwave techniques, and standard photography. Of particular interest were the results of the PMIS system which operated at 10.69 GHz with both vertical and horizontal polarizations. This was the first time that dual polarized images were obtained from floating ice. In both sea and lake ice, it was possible to distinguish a wide variety of thin ice types because of their large differences in brightness temperatures. It was found that the higher brightness temperature was invariably obtained in the vertically polarized mode, and as the age of the ice increases the brightness temperature increases in both polarizations. Associated with this change in age, the difference in temperature was observed as the different polarizations decreased. It appears that the horizontally polarized data is the most sensitive to variations in ice type for both fresh water and sea ice. The study also showed the great amount of information on ice surface roughness and deformation patterns that can be obtained from X-band SLAR observations.

  5. Impact on floating membranes

    NASA Astrophysics Data System (ADS)

    Vandenberghe, Nicolas; Duchemin, Laurent

    2016-05-01

    When impacted by a rigid body, a thin elastic membrane with negligible bending rigidity floating on a liquid pool deforms. Two axisymmetric waves radiating from the impact point propagate. First, a longitudinal wave front, associated with in-plane deformation of the membrane and traveling at constant speed, separates an outward stress-free domain from a stretched domain. Then, in the stretched domain a dispersive transverse wave travels at a speed that depends on the local stretching rate. The dynamics is found to be self-similar in time. Using this property, we show that the wave dynamics is similar to the capillary waves that propagate at a liquid-gas interface but with a surface tension coefficient that depends on impact speed. During wave propagation, we observe the development of a buckling instability that gives rise to radial wrinkles. We address the dynamics of this fluid-body system, including the rapid deceleration of an impactor of finite mass, an issue that may have applications in the domain of absorption of impact energy.

  6. Floating into Thin Air

    SciTech Connect

    Hazi, A U

    2007-02-06

    On May 18, 2005, a giant helium balloon carrying the High Energy Focusing Telescope (HEFT) sailed into the spring sky over the deserts of New Mexico. The spindly steel and aluminum gondola that houses the optics, detectors, and other components of the telescope floated for 25 hours after its launch from Fort Sumner, New Mexico. For 21 of those hours, the balloon was nearly 40 kilometers above Earth's surface--almost four times higher than the altitude routinely flown by commercial jet aircraft. In the upper reaches of Earth's atmosphere, HEFT searched the universe for x-ray sources from highly energetic objects such as binary stars, galaxy clusters, and supermassive black holes. Before landing in Arizona, the telescope observed and imaged a dozen scientific targets by capturing photons emitted from these objects in the high-energy (hard) x-ray range (above 10 kiloelectronvolts). Among these targets were the Crab synchrotron nebula, the black hole Cygnus X-1 (one of the brightest x-ray sources in the sky), and the blazar 3C454.3. The scientific data gathered from these targets are among the first focused hard x-ray images returned from high altitudes.

  7. Floating wind turbine system

    NASA Technical Reports Server (NTRS)

    Viterna, Larry A. (Inventor)

    2009-01-01

    A floating wind turbine system with a tower structure that includes at least one stability arm extending therefrom and that is anchored to the sea floor with a rotatable position retention device that facilitates deep water installations. Variable buoyancy for the wind turbine system is provided by buoyancy chambers that are integral to the tower itself as well as the stability arm. Pumps are included for adjusting the buoyancy as an aid in system transport, installation, repair and removal. The wind turbine rotor is located downwind of the tower structure to allow the wind turbine to follow the wind direction without an active yaw drive system. The support tower and stability arm structure is designed to balance tension in the tether with buoyancy, gravity and wind forces in such a way that the top of the support tower leans downwind, providing a large clearance between the support tower and the rotor blade tips. This large clearance facilitates the use of articulated rotor hubs to reduced damaging structural dynamic loads. Major components of the turbine can be assembled at the shore and transported to an offshore installation site.

  8. Electrically floating, near vertical incidence, skywave antenna

    DOEpatents

    Anderson, Allen A.; Kaser, Timothy G.; Tremblay, Paul A.; Mays, Belva L.

    2014-07-08

    An Electrically Floating, Near Vertical Incidence, Skywave (NVIS) Antenna comprising an antenna element, a floating ground element, and a grounding element. At least part of said floating ground element is positioned between said antenna element and said grounding element. The antenna is separated from the floating ground element and the grounding element by one or more electrical insulators. The floating ground element is separated from said antenna and said grounding element by one or more electrical insulators.

  9. Controlled release floating multiparticulates of metoprolol succinate by hot melt extrusion.

    PubMed

    Malode, Vilas N; Paradkar, Anant; Devarajan, Padma V

    2015-08-01

    We present hot melt extrusion (HME) for the design of floating multiparticulates. Metoprolol succinate was selected as the model drug. Our foremost objective was to optimize the components Eudragit(®) RS PO, polyethylene oxide (PEO) and hydroxypropyl methylcellulose (HPMC) to balance both buoyancy and controlled release. Gas generated by sodium bicarbonate in acidic medium was trapped in the polymer matrix to enable floating. Eudragit(®) RS PO and PEO with sodium bicarbonate resulted in multiparticulates which exhibited rapid flotation within 3 min but inadequate total floating time (TFT) of 3h. Addition of HPMC to the matrix did not affect floating lag time (FLT), moreover TFT increased to more than 12h with controlled release of metoprolol succinate. Floating multiparticulates exhibited t50% of 5.24h and t90% of 10.12h. XRD and DSC analysis revealed crystalline state of drug while FTIR suggested nonexistence of chemical interaction between the drug and the other excipients. The assay, FLT, TFT and the drug release of the multiparticulates were unchanged when stored at 40°C/75%RH for 3 months confirming stability. We present floating multiparticulates by HME which could be extrapolated to a range of other drugs. Our approach hence presents platform technology for floating multiparticulates. PMID:26142246

  10. Fresh look at floating shock fitting

    NASA Technical Reports Server (NTRS)

    Hartwich, PETER-M.

    1990-01-01

    A fast implicit upwind procedure for the two-dimensional Euler equations is described that allows accurate computations of shocked flows on nonadapted meshes. Away from shocks, the second-order accurate upwinding is based on the split-coefficient-matrix (SCM) method. In the presence of shocks, the difference stencils are modified using a floating shock fitting technique. Rapid convergence to steady-state solutions is attained with a diagonalized approximate factorization (AF) algorithm. Results are presented for Riemann's problem, for a regular shock reflection at an inviscid wall, for supersonic flow past a cylinder, and for a transonic airfoil. All computed shocks are ideally sharp and in excellent agreement with other numerical results or 'exact' solutions. Most importantly, this has been accomplished on unusually crude meshes without any attempt to align grid lines with shock fronts or to cluster grid lines around shocks.

  11. Formulation and evaluation of atenolol floating bioadhesive system using optimized polymer blends

    PubMed Central

    Siddam, Haritha; Kotla, Niranjan G.; Maddiboyina, Balaji; Singh, Sima; Sunnapu, Omprakash; Kumar, Anil; Sharma, Dinesh

    2016-01-01

    Introduction: Oral sustained release gastro retentive dosage forms offer several advantages for drugs having absorption from the upper gastrointestinal tract to improve the bioavailability of medications which have narrow absorption window. The aim of the study was to develop a floating bioadhesive drug delivery system exhibiting a unique combination of floatation and bioadhesion to prolong the residence in the stomach using atenolol as a model drug. Methods: Prior to compression, polymeric blend(s) were evaluated for flow properties. The tablets were prepared by direct compression method using bioadhesive polymer like Carbopol 934P and hydrophilic polymers like HPMC K4M, HPMC K15M, and HPMC K100M. The prepared tablets were evaluated for physical characteristics, bioadhesive strength, buoyancy lag time, swelling index and in vitro drug release studies. Results: The mean bioadhesive strength was found to be in the range of 16.2 to 52.1 gm. The optimized blend (F11) showed 92.3% drug releases after 24 hrs. Whilst, increase in concentration of carbopol 934P, bioadhesive strength and swelling index was increased with slow release. The n values of optimized formulations were found in the range of 0.631-0.719 indicating non-fickian anomalous type transport mechanism. Conclusion: The study aided in developing an ideal once-a-day gastro retentive floating drug delivery system with improved floating, swelling and bioadhesive characteristics with better bioavailability. PMID:27051631

  12. Development and optimization of press coated floating pulsatile drug delivery of sumatriptan succinate.

    PubMed

    Jagdale, Swati C; Pawar, Chandrakala R

    2014-01-01

    Floating pulsatile is combined approach designed according to circadian rhythm to deliver the drug at right time, in right quantity and at right site as per pathophysiological need of disease with prolong gastric residence and lag phase followed by burst release. As the migraine follows circadian rhythm in which headache is more painful at the awakening time, the dosage form should be given during night time to release drug when pain get worsen. Present work deals with formulation and optimization of floating pulsatile tablet of sumatriptan succinate. Core tablet containing crospovidone as superdisintegrant (10%) showed burst release. Lag time was maintained using swellable polymer as polyoxN12K and xanthum gum. 3(2) experimental design was carried out. Developed formulations were evaluated for physical characteristics, in vitro and in vivo study. Optimized batch F2 with concentration of polyox N12K (73.43%) and xanthum gum (26.56%) of total polymer weight showed floating lag time 15±2 sec, drug content 99.58±0.2 %, hardness 6±0.2 Kg/cm(2) and drug release 99.54±2% with pulsatile manner followed lag period of 7±0.1h. In vivo x-ray study confirms prolong gastric residence of system. Programmable pulsatile release has been achieved by formulation F2 which meet demand of chronotherapeutic objective of migraine. PMID:24893996

  13. Optimization Studies on Compression Coated Floating-Pulsatile Drug Delivery of Bisoprolol

    PubMed Central

    Jagdale, Swati C.; Bari, Nilesh A.; Kuchekar, Bhanudas S.; Chabukswar, Aniruddha R.

    2013-01-01

    The purpose of the present work was to design and optimize compression coated floating pulsatile drug delivery systems of bisoprolol. Floating pulsatile concept was applied to increase the gastric residence of the dosage form having lag phase followed by a burst release. The prepared system consisted of two parts: a core tablet containing the active ingredient and an erodible outer shell with gas generating agent. The rapid release core tablet (RRCT) was prepared by using superdisintegrants with active ingredient. Press coating of optimized RRCT was done by polymer. A 32 full factorial design was used for optimization. The amount of Polyox WSR205 and Polyox WSR N12K was selected as independent variables. Lag period, drug release, and swelling index were selected as dependent variables. Floating pulsatile release formulation (FPRT) F13 at level 0 (55 mg) for Polyox WSR205 and level +1 (65 mg) for Polyox WSR N12K showed lag time of 4 h with >90% drug release. The data were statistically analyzed using ANOVA, and P < 0.05 was statistically significant. Release kinetics of the optimized formulation best fitted the zero order model. In vivo study confirms burst effect at 4 h in indicating the optimization of the dosage form. PMID:24367788

  14. Application of ion exchange resin in floating drug delivery system.

    PubMed

    Upadhye, Abhijeet A; Ambike, Anshuman A; Mahadik, Kakasaheb R; Paradkar, Anant

    2008-10-01

    The purpose of this study was to explore the application of low-density ion exchange resin (IER) Tulsion(R) 344, for floating drug delivery system (FDDS), and study the effect of its particle size on rate of complexation, water uptake, drug release, and in situ complex formation. Batch method was used for the preparation of complexes, which were characterized by physical methods. Tablet containing resin with high degree of crosslinking showed buoyancy lag time (BLT) of 5-8 min. Decreasing the particle size of resin showed decrease in water uptake and drug release, with no significant effect on the rate of complexation and in situ complex formation for both preformed complexes (PCs) and physical mixtures (PMs). Thus, low-density and high degree of crosslinking of resin and water uptake may be the governing factor for controlling the initial release of tablet containing PMs but not in situ complex formation. However, further sustained release may be due to in situ complex formation. PMID:18777244

  15. Benznidazole Extended-Release Tablets for Improved Treatment of Chagas Disease: Preclinical Pharmacokinetic Study.

    PubMed

    Davanço, Marcelo Gomes; Campos, Michel Leandro; Rosa, Talita Atanazio; Padilha, Elias Carvalho; Alzate, Alejandro Henao; Rolim, Larissa Araújo; Rolim-Neto, Pedro José; Peccinini, Rosângela Gonçalves

    2016-04-01

    Benznidazole (BNZ) is the first-line drug for the treatment of Chagas disease. The drug is available in the form of immediate-release tablets for 100-mg (adult) and 12.5-mg (pediatric) doses. The drug is administered two or three times daily for 60 days. The high frequency of daily administrations and the long period of treatment are factors that significantly contribute to the abandonment of therapy, affecting therapeutic success. Accordingly, this study aimed to evaluate the preclinical pharmacokinetics of BNZ administered as extended-release tablets (200-mg dose) formulated with different types of polymers (hydroxypropyl methylcellulose K4M and K100M), compared to the tablets currently available. The studies were conducted with rabbits, and BNZ quantification was performed in plasma and urine by ultraperformance liquid chromatography methods previously validated. The bioavailability of BNZ was adequate in the administration of extended-release tablets; however, with the administration of the pediatric tablet, the bioavailability was lower than with other tablets, which showed that the clinical use of this formulation should be monitored. The pharmacokinetic parameters demonstrated that the extended-release tablets prolonged drug release from the pharmaceutical matrix and provided an increase in the maintenance of the drug concentrationin vivo, which would allow the frequency of administration to be reduced. Thus, a relative bioavailability study in humans will be planned for implementation of a new product for the treatment of Chagas disease. PMID:26883698

  16. Water-induced charge transport in tablets of microcrystalline cellulose of varying density: dielectric spectroscopy and transient current measurements

    NASA Astrophysics Data System (ADS)

    Nilsson, Martin; Alderborn, Göran; Strømme, Maria

    2003-12-01

    Room temperature dielectric frequency response data taken over 13 decades in frequency on microcrystalline cellulose (MCC) tablets of varying density are presented. The frequency response shows on three different processes: the first one is a high-frequency relaxation process whose magnitude increases and reaches a plateau as the tablet density increases. This process is associated with orientational motions of local chain segments via glycosidic bonds. The second relaxation process, related to the presence of water in the MCC matrix, is insensitive to changes in tablet density. At lower frequencies, dc-like imperfect charge transport dominates the dielectric spectrum. The dc conductivity was found to decrease with increasing tablet density and increase exponentially with increasing humidity. Transient current measurements indicated that two different ionic species, protons and OH - ions, lied behind the observed conductivity. At ambient humidity of 22%, only one in a billion of the water molecules present in the tablet matrix participated in long range dc conduction. The diffusion coefficient of the protons and OH - ions were found to be of the order of 10 -9 cm 2/s, which is the same as for small salt building ions in MCC. This shows that ionic drugs leaving a tablet matrix may diffuse in the same manner as the constituent ions of water and, thus, elucidates the necessity to understand the water transport properties of excipient materials to be able to tailor the drug release process from pharmaceutical tablets.

  17. 21 CFR 520.581 - Dichlorophene tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Specifications. Each tablet contains 1 gram of dichlorophene. (b) Sponsor. See 023851 in § 510.600(c) of this.... Dogs—(1) Amount. Single dose of 1 tablet (1 gram of dichlorophene) for each 10 pounds of body...

  18. 21 CFR 520.581 - Dichlorophene tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Specifications. Each tablet contains 1 gram of dichlorophene. (b) Sponsor. See 023851 in § 510.600(c) of this.... Dogs(1) Amount. Single dose of 1 tablet (1 gram of dichlorophene) for each 10 pounds of body weight....

  19. Crystal habit and tableting behavior.

    PubMed

    Rasenack, Norbert; Müller, Bernd W

    2002-09-01

    The tableting behavior of drugs can be affected by changes in the crystal habit. Different crystal habits of the common analgesic drugs ibuprofen and acetaminophen were prepared. Their tableting behavior was characterized. In the case of ibuprofen, a plate-shaped crystal was compared with the common needle-shaped form. In the case of acetaminophen, plate-shaped and prismatic crystals of two different particle sizes were prepared. The aim was to find a crystal form that is suitable for direct compression with only a low amount of excipients. This requires a substance that forms stable compacts at low punch forces, having a good flowability and only a low tendency to stick to the punches. In order to compare the tableting behavior of different substances, a comparative factor (T-factor) was calculated, based on typical parts of the punch force/displacement-profile and properties of the resulting compact. This method works with low amounts of substance and allows a rapid reproducible determination of the tableting behavior. The method was evaluated by characterizing different typical excipients normally used for the production of tablets. PMID:12204564

  20. Characterization of omega-3 tablets.

    PubMed

    Vestland, Tina Lien; Jacobsen, Øyvind; Sande, Sverre Arne; Myrset, Astrid Hilde; Klaveness, Jo

    2016-04-15

    Omega-3 nutraceuticals are extensively used as health supplements worldwide. Various administration forms for delivery of omega-3 are available. However, the niche omega-3 tablets have so far remained unexplored. In this work tablets containing 25-40% (w/w) omega-3 oil as triglycerides or ethyl esters were prepared utilizing a direct compaction grade powder with β-cyclodextrin as encapsulating agent. It was found that powders with up to 35% (w/w) triglyceride oil and 30% (w/w) ethyl ester oil, respectively, can be directly compressed into tablets of excellent quality. Physical properties of omega-3 containing powders and tablets are described. The powder X-ray diffractograms of the powders and crushed tablets show evidence of the formation of new crystalline phases not present in β-cyclodextrin. In addition, (1)H NMR data suggest that the ethyl esters form inclusion complexes with β-cyclodextrin. Compaction of other, commercially available, omega-3 powders was performed as a comparison and deemed unsuccessful. PMID:26616980

  1. Galileo's Telescopy and Jupiter's Tablet

    NASA Astrophysics Data System (ADS)

    Usher, P. D.

    2003-12-01

    A previous paper (BAAS 33:4, 1363, 2001) reported on the dramatic scene in Shakespeare's Cymbeline that features the descent of the deity Jupiter. The paper suggested that the four ghosts circling the sleeping Posthumus denote the four Galilean moons of Jupiter. The god Jupiter commands the ghosts to lay a tablet upon the prone Posthumus, but says that its value should not be overestimated. When Posthumus wakens he notices the tablet, which he calls a "book." Not only has the deity's "tablet" become the earthling's "book," but it appears that the book has covers which Posthumus evidently recognizes because without even opening the book he ascribes two further properties to it: rarity, and the very property that Jupiter had earlier attributed, viz. that one must not read too much into it. The mystery deepens when the Jovian gift undergoes a second metamorphosis, to "label." With the help of the OED, the potentially disparate terms "tablet," "book," and "label," may be explained by terms appropriate either to supernatural or worldly beings. "Tablet" may recognize the Mosaic artifact, whereas "book" and "label" are probably mundane references to Galileo's Sidereus Nuncius which appeared shortly before Cymbeline. The message of the Olympian god indicates therefore that the book is unique even as its contents have limited value. The first property celebrates the fact that Galileo's book is the first of its kind, and the second advises that all results except the discovery of Jupiter's moons have been reported earlier, in Hamlet.

  2. Detection of Floating Inputs in Logic Circuits

    NASA Technical Reports Server (NTRS)

    Cash, B.; Thornton, M. G.

    1984-01-01

    Simple modification of oscilloscope probe allows easy detection of floating inputs or tristate outputs in digital-IC's. Oscilloscope probe easily modified with 1/4 W resistor and switch for detecting floating inputs in CMOS logic circuits.

  3. 21 CFR 520.804 - Enalapril tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Enalapril tablets. 520.804 Section 520.804 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.804 Enalapril tablets. (a) Specifications. Each tablet contains either...

  4. Principles of Tablet Computing for Educators

    ERIC Educational Resources Information Center

    Katzan, Harry, Jr.

    2015-01-01

    In the study of modern technology for the 21st century, one of the most popular subjects is tablet computing. Tablet computers are now used in business, government, education, and the personal lives of practically everyone--at least, it seems that way. As of October 2013, Apple has sold 170 million iPads. The success of tablets is enormous and has…

  5. 21 CFR 520.455 - Clomipramine tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Clomipramine tablets. 520.455 Section 520.455 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.455 Clomipramine tablets. (a) Specifications. Each tablet contains 5,...

  6. 21 CFR 520.1510 - Nitenpyram tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... flavored milbemycin/lufenuron tablets as in paragraph (d)(1)(ii)(B) of this section shall be by or on the... tablets as in § 520.1288(c)(1) of this chapter or flavored milbemycin and lufenuron tablets as in §...

  7. 21 CFR 520.1510 - Nitenpyram tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... flavored milbemycin/lufenuron tablets as in paragraph (d)(1)(ii)(B) of this section shall be by or on the... tablets as in § 520.1288(c)(1) of this chapter or flavored milbemycin and lufenuron tablets as in §...

  8. 21 CFR 520.1510 - Nitenpyram tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... flavored milbemycin/lufenuron tablets as in paragraph (d)(1)(ii)(B) of this section shall be by or on the... tablets as in § 520.1288(c)(1) of this chapter or flavored milbemycin and lufenuron tablets as in §...

  9. 21 CFR 520.370 - Cefpodoxime tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Cefpodoxime tablets. 520.370 Section 520.370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.370 Cefpodoxime tablets. (a) Specifications. Each tablet...

  10. Mathematics Instruction and the Tablet PC

    ERIC Educational Resources Information Center

    Fister, K. Renee; McCarthy, Maeve L.

    2008-01-01

    The use of tablet PCs in teaching is a relatively new phenomenon. A cross between a notebook computer and a personal digital assistant (PDA), the tablet PC has all of the features of a notebook with the additional capability that the screen can also be used for input. Tablet PCs are usually equipped with a stylus that allows the user to write on…

  11. 21 CFR 520.1510 - Nitenpyram tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Nitenpyram tablets. 520.1510 Section 520.1510 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1510 Nitenpyram tablets. (a) Specifications. Each tablet contains 11.4 or 57 milligrams (mg) nitenpyram. (b) Sponsor. See No. 058198 in §...

  12. 21 CFR 520.1310 - Marbofloxacin tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Marbofloxacin tablets. 520.1310 Section 520.1310... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1310 Marbofloxacin tablets. (a) Specifications. Each tablet contains 25, 50, 100, or 200 milligrams (mg) marbofloxacin....

  13. 21 CFR 520.1510 - Nitenpyram tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Nitenpyram tablets. 520.1510 Section 520.1510 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1510 Nitenpyram tablets. (a) Specifications. Each tablet contains 11.4 or 57 milligrams (mg) nitenpyram. (b) Sponsor. See No. 058198 in §...

  14. Touch Screen Tablets and Emergent Literacy

    ERIC Educational Resources Information Center

    Neumann, Michelle M.; Neumann, David L.

    2014-01-01

    The use of touch screen tablets by young children is increasing in the home and in early childhood settings. The simple tactile interface and finger-based operating features of tablets may facilitate preschoolers' use of tablet application software and support their educational development in domains such as literacy. This article reviews…

  15. 21 CFR 520.1870 - Praziquantel tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Praziquantel tablets. 520.1870 Section 520.1870... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1870 Praziquantel tablets. (a) Specifications. Each tablet contains: (1) 34 milligrams (mg) praziquantel. (2) 11.5 or 23 mg praziquantel....

  16. 21 CFR 520.581 - Dichlorophene tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Dichlorophene tablets. 520.581 Section 520.581... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.581 Dichlorophene tablets. (a) Specifications. Each tablet contains 1 gram of dichlorophene. (b) Sponsor. See 023851 in § 510.600(c) of...

  17. 21 CFR 520.581 - Dichlorophene tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Dichlorophene tablets. 520.581 Section 520.581... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.581 Dichlorophene tablets. (a) Specifications. Each tablet contains 1 gram of dichlorophene. (b) Sponsor. See 023851 in § 510.600(c) of...

  18. 21 CFR 520.1451 - Moxidectin tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Moxidectin tablets. 520.1451 Section 520.1451 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1451 Moxidectin tablets. (a) Specifications. Each tablet contains 30, 68, or 136 micrograms of moxidectin. (b) Sponsor. See No. 000856...

  19. 21 CFR 520.370 - Cefpodoxime tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Cefpodoxime tablets. 520.370 Section 520.370 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.370 Cefpodoxime tablets. (a) Specifications. Each tablet contains cefpodoxime proxetil equivalent to 100 or 200 milligrams (mg)...

  20. 21 CFR 520.816 - Epsiprantel tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Epsiprantel tablets. 520.816 Section 520.816 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.816 Epsiprantel tablets. (a) Specifications. Each tablet contains either 12.5, 25, 50, or 100 milligrams of epsiprantel. (b) Sponsor. See...

  1. 21 CFR 520.312 - Carnidazole tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Carnidazole tablets. 520.312 Section 520.312 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.312 Carnidazole tablets. (a) Specifications. Each tablet contains 10 milligrams of carnidazole. (b) Sponsor. See 053923 in § 510.600(c)...

  2. 21 CFR 520.1900 - Primidone tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Primidone tablets. 520.1900 Section 520.1900 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1900 Primidone tablets. (a) Specifications. Each tablet contains 50 or 250 milligrams of primidone. (b) Sponsor. See No. 000010 in §...

  3. 21 CFR 520.1900 - Primidone tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Primidone tablets. 520.1900 Section 520.1900 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1900 Primidone tablets. (a) Specifications. Each tablet contains 50 or 250 milligrams of primidone. (b) Sponsor. See No. 000010 in §...

  4. 21 CFR 520.1310 - Marbofloxacin tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Marbofloxacin tablets. 520.1310 Section 520.1310... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1310 Marbofloxacin tablets. (a) Specifications. Each tablet contains 25, 50, 100, or 200 milligrams (mg) marbofloxacin....

  5. 21 CFR 520.816 - Epsiprantel tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Epsiprantel tablets. 520.816 Section 520.816 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.816 Epsiprantel tablets. (a) Specifications. Each tablet contains either 12.5, 25, 50, or 100 milligrams of epsiprantel. (b) Sponsor. See...

  6. Scaffolding Equals Success in Teaching Tablet PCs

    ERIC Educational Resources Information Center

    Dickerson, Jeremy; Williams, Scott; Browning, J. B.

    2009-01-01

    After many years of using the mouse and keyboard as the primary means of computer input, people are seeing a strong surge into a new generation of input technologies such as tablet PCs. As more professionals adopt tablet PCs for use in the workplace, there is a subsequent increased demand for tablet PC instruction in the classroom. Examples of…

  7. 21 CFR 520.812 - Enrofloxacin tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Enrofloxacin tablets. 520.812 Section 520.812 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.812 Enrofloxacin tablets. (a) Specifications. Each tablet contains...

  8. 21 CFR 520.1616 - Orbifloxacin tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Orbifloxacin tablets. 520.1616 Section 520.1616 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1616 Orbifloxacin tablets. (a) Specifications. Each tablet contains...

  9. 21 CFR 520.1616 - Orbifloxacin tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Orbifloxacin tablets. 520.1616 Section 520.1616 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1616 Orbifloxacin tablets. (a) Specifications. Each tablet contains...

  10. 21 CFR 520.1616 - Orbifloxacin tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Orbifloxacin tablets. 520.1616 Section 520.1616 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1616 Orbifloxacin tablets. (a) Specifications. Each tablet contains...

  11. 21 CFR 520.812 - Enrofloxacin tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Enrofloxacin tablets. 520.812 Section 520.812 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.812 Enrofloxacin tablets. (a) Specifications. Each tablet contains...

  12. 21 CFR 520.1616 - Orbifloxacin tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Orbifloxacin tablets. 520.1616 Section 520.1616 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1616 Orbifloxacin tablets. (a) Specifications. Each tablet contains...

  13. 21 CFR 520.812 - Enrofloxacin tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Enrofloxacin tablets. 520.812 Section 520.812 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.812 Enrofloxacin tablets. (a) Specifications. Each tablet contains...

  14. 21 CFR 520.812 - Enrofloxacin tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Enrofloxacin tablets. 520.812 Section 520.812 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.812 Enrofloxacin tablets. (a) Specifications. Each tablet contains...

  15. 21 CFR 520.804 - Enalapril tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Enalapril tablets. 520.804 Section 520.804 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.804 Enalapril tablets. (a) Specifications. Each tablet contains either...

  16. 21 CFR 520.1880 - Prednisolone tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Prednisolone tablets. 520.1880 Section 520.1880 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1880 Prednisolone tablets. (a) Specifications. Each tablet contains 5...

  17. 21 CFR 520.370 - Cefpodoxime tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Cefpodoxime tablets. 520.370 Section 520.370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS 520.370 Cefpodoxime tablets. (a) Specifications. Each tablet...

  18. Touch Screen Tablets and Emergent Literacy

    ERIC Educational Resources Information Center

    Neumann, Michelle M.; Neumann, David L.

    2014-01-01

    The use of touch screen tablets by young children is increasing in the home and in early childhood settings. The simple tactile interface and finger-based operating features of tablets may facilitate preschoolers' use of tablet application software and support their educational development in domains such as literacy. This article reviews

  19. Floating ports: Design and construction practices

    SciTech Connect

    Tsinker, G.P.

    1986-01-01

    This book is a guide to designing and constructing floating piers, wharves, docks, mooring systems, and small craft marinas. It presents engineering fundamentals and techniques. After a general introduction to floating marine terminals, the book discusses design loads and forces, and examines floating pier design requirements and considerations. Buoyancy and stability of various floating designs are discussed in detail, along with mooring systems and approach bridges. The concluding chapter contains case histories.

  20. Have Floating Rates Been a Success?

    ERIC Educational Resources Information Center

    Higham, David

    1983-01-01

    Floating exchange rates have not lived up to all expectations, but neither have they performed as badly as some critics have suggested. Examined are the impact of floating rates on balance of payments adjustment, domestic economic policy, and inflation and the claim that floating rates have displayed excessive fluctuations. (Author/RM)

  1. Mathematical Modeling of Floating Ice

    NASA Astrophysics Data System (ADS)

    Holland, D. M.

    2001-05-01

    A significant fraction of the surface of the global ocean is covered by floating ice, the presence of which has profound influences on the state of the global climate system. The floating ice appears both in the form of sea-ice, created in situ over the open ocean, and in the form of ice shelves, the result of land ice sheets draining into the ocean. Ice is arguably one of the most complex fluids in the climate system, both from a dynamical and thermodynamical point of view. The former because of its inherently non-linear rheology and the later because of the ice-albedo feedback mechanism. Added to these complexities, the mathematical and computational modeling of floating has the pragmatic difficulty of properly treating phenomena that occur both on sub-grid scales and disparate time scales. Examples of sub-grid scale phenomena include the treatment of sea-ice thickness distributions and the effects of ocean geostrophic turbulence on the sea ice. This talk presents an overview of the role of floating ice in the climate system, some of the outstanding theoretical challenges, and the role in which modern applied mathematics may play in the future development of the field.

  2. Designing seaplane hulls and floats

    NASA Technical Reports Server (NTRS)

    Benoit,

    1926-01-01

    Experimental data, such as the results of tank tests of models, render it possible to predict, at least in principle, as to how a hull or float of a given shape will comport itself. We will see further along, however, how uncertain these methods are and how they leave room for empiricism, which will reign for a long time yet in seaplane research bureaus.

  3. Sugar end-capped poly-D,L-lactides as excipients in oral sustained release tablets.

    PubMed

    Vuorinen, Sirpa; Heinämäki, Jyrki; Antikainen, Osmo; Lahcini, Mohammed; Repo, Timo; Yliruusi, Jouko

    2009-01-01

    Sugar end-capped poly-D,L-lactide (SPDLA) polymers were investigated as a potential release controlling excipient in oral sustained release matrix tablets. The SPDLA polymers were obtained by a catalytic ring-opening polymerization technique using methyl alpha-D-gluco-pyranoside as a multifunctional initiator in the polymerization. Polymers of different molecular weights were synthesized by varying molar ratios of monomer/catalyst. The matrix tablets were prepared by direct compression technique from the binary mixtures of SPDLA and microcrystalline cellulose, and theophylline was used as a model drug. The tablet matrices showed in vitro reproducible drug release profiles with a zero-order or diffusion-based kinetic depending on the SPDLA polymer grade used. Further release from the tablet matrices was dependent on the molecular weight of the SPDLA polymer applied. The drug release was the fastest with the lowest molecular weight SPDLA grade, and the drug release followed zero-order rate. With the higher molecular weight SPDLAs, more prolonged dissolution profiles for the matrix tablets (up to 8-10 h) were obtained. Furthermore, the prolonged drug release was independent of the pH of the dissolution media. In conclusion, SPDLAs are a novel type of drug carrier polymers applicable in oral controlled drug delivery systems. PMID:19430908

  4. Preparation and in-vivo pharmacokinetic study of a novel extended release compression coated tablets of fenoterol hydrobromide.

    PubMed

    Elshafeey, Ahmed H; Sami, Elshaimaa I

    2008-01-01

    The aim of this study was to formulate extended release compression coated core tablets of fenoterol hydrobromide, a selective beta(2) adrenergic receptor agonist, in an attempt to prevent nocturnal asthma. Two hydrophilic polymers viz Kollidon SR, Polyox WSR 303 and a hydrophobic one (Precirol ATO5) were employed. Compression coated tablets were formulated by preparing a core tablet containing 7.5 mg drug and various amounts of polymer and Emcompress then compressed coated with the same polymeric materials. For comparison purpose different matrix tablets were also prepared employing the same polymers. In-vitro release studies were carried out at different pH (1.2 and 6.8). Pharmacokinetics of extended release tablets as well as commercially available immediate release tablets (Berotec) were studied after oral administration to beagle dogs using a new developed LC-MS/MS method with a lower limit of quantification of 1 ng/ml. Fenoterol release from compression coated tablets was significantly lower than matrix tablets. The mechanism of release was changed with the nature and content of polymer. The release pattern of drug from F16 containing 40 mg Kollidon SR divided in the core tablet (15 mg) and the rest in the compressed coat (25 mg) showed a typical zero order release kinetic that could extend drug release >10 h and reasonable time for 75% to be released (t(75)) (8.92 h). When compared to immediate release Berotec tablet the MRT was significantly extended from 7.03 +/- 0.76 to 10.93 +/- 1.25 h (P < 0.001) and HVD(t 50%Cmax) was also significantly extended from 2.71 +/- 0.68 to 6.81 +/- 0.67 h with expected prevention of nocturnal asthma. PMID:18770048

  5. Formulation and evaluation of mixed matrix gastro-retentive drug delivery for famotidine

    PubMed Central

    Patel, Dasharath M; Patel, Mehul J; Patel, Ankit N; Patel, Chhagan N

    2011-01-01

    Introduction: Present investigation describes an influence of ratio of Gelucire 43/01(hydrophobic) to hydroxypropyl methylcellulose K4M (HPMC K4M) (hydrophilic) and different fillers on release of famotidine from gastro-retentive tablets using 32 full factorial design. Ratio of Gelucire 43/01 to HPMC K4M (X1) and the type of filler (X2) were selected as independent variables while buoyancy lag time (BLT), drug release at 1h (Q1), 6h (Q6), and the 12h (Q12) were selected as dependent variables. Materials and Methods: Gastro-retentive tablets of famotidine were prepared by a solvent free melt granulation technique using Gelucire 43/01 as a hydrophobic meltable binder. HPMC K4M and sodium bicarbonate were used as matrixing agent and gas-generating agent, respectively. Prepared tablets were evaluated for in vitro dissolution, in vitro buoyancy, friability, hardness, drug content and weight variation. Dissolution data were fitted to various models to ascertain kinetics of drug release. The data were analyzed using regression analysis and analysis of variance. Results: All formulations (F1-F9) showed floating within 3min and had total floating time of more than 12h. It was observed that a type of filler and the ratio of Gelucire 43/01 to HPMC K4M had significant influence on buoyancy lag time (P = 0.037) and Q6 (P = 0.011), respectively without significant influence on Q1 and Q12. Conclusion: Formulation F5 was selected as an optimum formulation as it showed more similarity in dissolution profile with theoretical profile (Similarity factor, f2 = 83.01). The dissolution of batch F5 can be described by zero order kinetics (r2 = 0.9914) with anomalous (non-Fickian) diffusion as a release mechanism (n = 0.559). The difference observed in in vitro release profile after temperature sensitivity study at 40°C for 1 month was insignificant. PMID:23071951

  6. Three floating metatarsals and a half-floating cuneiform.

    PubMed

    Madi, Sandesh; Vijayan, Sandeep; Naik, Monappa; Rao, Sharath

    2015-01-01

    Floating metatarsals are rare and complex injury patterns in the world of foot trauma. The injury is typically characterised by concomitant dislocations of the metatarsals from both articular ends ('bipolar dislocations'). Fascination arises from the fact that there have been only 15 cases reported in the English literature from 1964 to date. The first metatarsal has been more frequently reported than the lesser metatarsals. More than one floating metatarsal is also extremely uncommon. Inter-cuneiform diastasis is another rare entity seen in low velocity injuries and sports injuries; this condition is very difficult to diagnose clinically and radiologically. The occurrence of these two injury patterns in isolation is itself rare, making their combination even more unique. PMID:26452415

  7. A floating type holographic display.

    PubMed

    Son, Jung-Young; Lee, Chun-Hae; Chernyshov, Oleksii O; Lee, Beom-Ryeol; Kim, Sung-Kyu

    2013-08-26

    A floating image type holographic display which projects an electronically generated holographic image together with a background image displayed on a monitor/TV to enhance the visual effects of the former image is introduced. This display can display a holographic image with a spatial volume floating in the front space of the display with use of PDLC sheets as the focused plane of the image. This display can preserve and enhance the main property of holographic image from a display chip, i.e., a spatial image with a volume. This property had not been appealed by the previous holographic displays due to the much brighter active surface image accompanied with the reconstructed image and the diffuser used for viewing the image. PMID:24105588

  8. Dragging a floating horizontal cylinder

    NASA Astrophysics Data System (ADS)

    Lee, Duck-Gyu; Kim, Ho-Young

    2010-11-01

    A cylinder immersed in a fluid stream experiences a drag, and it is well known that the drag coefficient is a function of the Reynolds number only. Here we study the force exerted on a long horizontal cylinder that is dragged perpendicular to its axis while floating on an air-water interface with a high Reynolds number. In addition to the flow-induced drag, the floating body is subjected to capillary forces along the contact line where the three phases of liquid/solid/gas meet. We first theoretically predict the meniscus profile around the horizontally moving cylinder assuming the potential flow, and show that the profile is in good agreement with that obtained experimentally. Then we compare our theoretical predictions and experimental measurement results for the drag coefficient of a floating horizontal cylinder that is given by a function of the Weber number and the Bond number. This study can help us to understand the horizontal motion of partially submerged objects at air-liquid interface, such as semi-aquatic insects and marine plants.

  9. Instability of floating extensional flows

    NASA Astrophysics Data System (ADS)

    Sayag, Roiy; Worster, Grae

    2015-11-01

    We study the propagation of a viscous fluid over a thin layer of a denser and inviscid fluid. The viscous fluid is released axisymmetrially at constant flux, and is driven by gravity. Near the origin, where the viscous layer is thick, the flow is dominated by vertical shear. In the outer region where the viscous layer is thinner, it floats over the inviscid layer and the dominant stress is extensional. The floating region of such flows remains axisymmetric when the viscous fluid is Newtonian. In contrast, when the viscous fluid is non Newtonian, the floating region can be distributed in an array of extensional tongues. We use experimental and theoretical analysis to study the symmetry breaking of the extensional region. Experiments using polymeric fluids show that the characteristic wavelength of the tongues increases with flux. Theoretically, we model the symmetry breaking as flow instability of a power-law fluid that becomes Newtonian at low strain rates. Our model predicts unstable modes at the strongly non-Newtonian limit, and stable, axisymmetric mode in the Newtonian limit.

  10. Can flexibility help you float?

    NASA Astrophysics Data System (ADS)

    Burton, L. J.; Bush, J. W. M.

    2012-10-01

    We consider the role of flexibility in the weight-bearing characteristics of bodies floating at an interface. Specifically, we develop a theoretical model for a two-dimensional thin floating plate that yields the maximum stable plate load and optimal stiffness for weight support. Plates small relative to the capillary length are primarily supported by surface tension, and their weight-bearing potential does not benefit from flexibility. Above a critical size comparable to the capillary length, flexibility assists interfacial flotation. For plates on the order of and larger than the capillary length, deflection from an initially flat shape increases the force resulting from hydrostatic pressure, allowing the plate to support a greater load. In this large plate limit, the shape that bears the most weight is a semicircle, which displaces the most fluid above the plate for a fixed plate length. Exact results for maximum weight-bearing plate shapes are compared to analytic approximations made in the limits of large and small plate sizes. The value of flexibility for floating to a number of biological organisms is discussed in light of our study.

  11. Float zone experiments in space

    NASA Technical Reports Server (NTRS)

    Verhoeven, J. D.; Noack, M. A.; Gill, W. N.; Hau, C. C.

    1984-01-01

    The molten zone/freezing crystal interface system and all the mechanisms were examined. If Marangoni convection produces oscillatory flows in the float zone of semiconductor materials, such as silicon, then it is unlikely that superior quality crystals can be grown in space using this process. The major goals were: (1) to determine the conditions for the onset of Marangoni flows in molten tin, a model system for low Prandtl number molten semiconductor materials; (2) to determine whether the flows can be suppressed by a thin oxide layer; and (3) based on experimental and mathematical analysis, to predict whether oscillatory flows will occur in the float zone silicon geometry in space, and if so, could it be suppressed by thin oxide or nitride films. Techniques were developed to analyze molten tin surfaces in a UHV system in a disk float zone geometry to minimize buoyancy flows. The critical Marangoni number for onset of oscillatory flows was determined to be greater than 4300 on atomically clean molten tin surfaces.

  12. Protein based tablets as reversible gelling systems for delayed release applications.

    PubMed

    Caillard, Romain; Subirade, Muriel

    2012-11-01

    Succinylated β-lactoglobulin (S-β-lg) was previously shown to be efficient as new excipient for the formation of enteric tablets, suitable for several applications including probiotics delivery. This work investigates the mechanisms leading to S-β-lg tablets delayed release. Release kinetics were evaluated in vitro. Fourier transformed infra red spectroscopy (FTIR) was used to visualize the effect of dissolution medium on matrix tablet surface. Results demonstrated that tablets release in simulated gastric fluids (SGF) might be due to water/drug diffusion through an in situ formed gel layer, as revealed by FTIR data. As SGF penetrated the tablet, regardless of protein succinylation rate (50% or 100%), molecular rearrangements occurred, allowing the development of an important band located in the 1621-1623 cm(-1) region. This band was characteristic of the formation of protein intermolecular β-sheets. The gel was showed to be reversible in intestinal conditions, allowing delayed release. While the molecular structure of the gel layer was not depending on protein succinylation rate, it appeared that 100% S-β-lg tablets showed slower release. This low release was probably related to 100% S-β-lg lower solubility, lower charge density, and their ability to form stronger intermolecular hydrogen bonds. This work highlights proteins potential for the conception of controlled drug delivery systems. PMID:22846408

  13. Pharmaceutical and analytical evaluation of triphalaguggulkalpa tablets

    PubMed Central

    Savarikar, Shreeram S.; Barbhind, Maneesha M.; Halde, Umakant K.; Kulkarni, Alpana P.

    2011-01-01

    Aim of the Study: Development of standardized, synergistic, safe and effective traditional herbal formulations with robust scientific evidence can offer faster and more economical alternatives for the treatment of disease. The main objective was to develop a method of preparation of guggulkalpa tablets so that the tablets meet the criteria of efficacy, stability, and safety. Materials and Methods: Triphalaguggulkalpa tablet, described in sharangdharsanhita and containing guggul and triphala powder, was used as a model drug. Preliminary experiments on marketed triphalaguggulkalpa tablets exhibited delayed in vitro disintegration that indicated probable delayed in vivo disintegration. The study involved preparation of triphalaguggulkalpa tablets by Ayurvedic text methods and by wet granulation, dry granulation, and direct compression method. The tablets were evaluated for loss on drying, volatile oil content, % solubility, and steroidal content. The tablets were evaluated for performance tests like weight variation, disintegration, and hardness. Results: It was observed that triphalaguggulkalpa tablets, prepared by direct compression method, complied with the hardness and disintegration tests, whereas tablets prepared by Ayurvedic text methods failed. Conclusion: Direct compression is the best method of preparing triphalaguggulkalpa tablets. PMID:21731383

  14. Condition and Error Estimates in Numerical Matrix Computations

    SciTech Connect

    Konstantinov, M. M.; Petkov, P. H.

    2008-10-30

    This tutorial paper deals with sensitivity and error estimates in matrix computational processes. The main factors determining the accuracy of the result computed in floating--point machine arithmetics are considered. Special attention is paid to the perturbation analysis of matrix algebraic equations and unitary matrix decompositions.

  15. Formulation and development of orodispersible sustained release tablet of domperidone.

    PubMed

    Patil, Hemlata G; Tiwari, Roshan V; Repka, Michael A; Singh, Kamalinder K

    2016-06-01

    Commercially available domperidone orodispersible tablets (ODT) are intended for immediate release of the drug, but none of them have been formulated for sustained action. The aim of the present research work was to develop and evaluate orodispersible sustained release tablet (ODT-SR) of domperidone, which has the convenience of ODT and benefits of controlled release product combined in one. The technology comprised of developing sustained release microspheres (MS) of domperidone, followed by direct compression of MS along with suitable excipients to yield ODT-SR which rapidly disperses within 30 seconds and yet the dispersed MS maintain their integrity to have a sustained drug release. The particle size of the MS was optimized to be less than 200 μm to avoid the grittiness in the mouth. The DSC thermograms of MS showed the absence of drug-polymer interaction within the microparticles, while SEM confirmed their spherical shape and porous nature. Angle of repose, compressibility and Hausner's ratio of the blend for compression showed good flowability and high percent compressibility. The optimized ODT-SR showed disintegration time of 21 seconds and matrix controlled drug release for 9 h. In-vivo pharmacokinetic studies in Wistar rats showed that the ODT-SR had a prolonged MRT of 11.16 h as compared 3.86 h of conventional tablet. The developed technology is easily scalable and holds potential for commercial exploitation. PMID:26472165

  16. 21 CFR 520.2150a - Stanozolol tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Administered orally to cats and small breeds of dogs, 1/2 to 1 tablet twice daily for several weeks; to large breeds of dogs, 1 to 2 tablets twice daily for several weeks. The tablets may be crushed and...

  17. 21 CFR 520.2150a - Stanozolol tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) Administered orally to cats and small breeds of dogs, 1/2 to 1 tablet twice daily for several weeks; to large breeds of dogs, 1 to 2 tablets twice daily for several weeks. The tablets may be crushed and...

  18. 21 CFR 520.804 - Enalapril tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Enalapril tablets. 520.804 Section 520.804 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.804 Enalapril tablets. (a) Specifications. Each tablet contains either 1.0, 2.5, 5.0, 10.0, or 20.0 milligrams of enalapril maleate....

  19. 21 CFR 520.531 - Cythioate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Cythioate tablets. 520.531 Section 520.531 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.531 Cythioate tablets. (a) (b) Sponsors. See No. 000859 in § 510.600(c) of this chapter for use of 30- and 90-milligram (mg) tablets...

  20. 21 CFR 520.531 - Cythioate tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Cythioate tablets. 520.531 Section 520.531 Food... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.531 Cythioate tablets. (a) (b) Sponsors. See No. 000859 in § 510.600(c) of this chapter for use of 30- and 90-milligram (mg) tablets...

  1. Tank Tests of Twin Seaplane Floats

    NASA Technical Reports Server (NTRS)

    Herrman, H; Kempf, G; Kloess, H

    1928-01-01

    The following report contains the most essential data for the hydrodynamic portion of the twin-float problem. The following points were successfully investigated: 1) difference between stationary and nonstationary flow; 2) effect of the shape of the step; 3) effect of distance between floats; 4) effect of nose-heavy and tail-heavy moments; 5) effect of the shape of floats; 6) maneuverability.

  2. 14 CFR 27.753 - Main float design.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Main float design. 27.753 Section 27.753... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 27.753 Main float design. (a) Bag floats. Each bag float must be designed to withstand— (1) The maximum pressure...

  3. 14 CFR 29.753 - Main float design.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Main float design. 29.753 Section 29.753... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 29.753 Main float design. (a) Bag floats. Each bag float must be designed to withstand— (1) The maximum pressure...

  4. 14 CFR 29.753 - Main float design.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main float design. 29.753 Section 29.753... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 29.753 Main float design. (a) Bag floats. Each bag float must be designed to withstand— (1) The maximum pressure...

  5. 14 CFR 27.753 - Main float design.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main float design. 27.753 Section 27.753... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 27.753 Main float design. (a) Bag floats. Each bag float must be designed to withstand— (1) The maximum pressure...

  6. Modeling International Space Station (ISS) Floating Potentials

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.; Gardner, Barbara

    2002-01-01

    The floating potential of the International Space Station (ISS) as a function of the electron current collection of its high voltage solar array panels is derived analytically. Based on Floating Potential Probe (FPP) measurements of the ISS potential and ambient plasma characteristics, it is shown that the ISS floating potential is a strong function of the electron temperature of the surrounding plasma. While the ISS floating potential has so far not attained the pre-flight predicted highly negative values, it is shown that for future mission builds, ISS must continue to provide two-fault tolerant arc-hazard protection for astronauts on EVA.

  7. Accuracy of tablet splitting: Comparison study between hand splitting and tablet cutter

    PubMed Central

    Habib, Walid A.; Alanizi, Abdulaziz S.; Abdelhamid, Magdi M.; Alanizi, Fars K.

    2013-01-01

    Background Tablet splitting is often used in pharmacy practice to adjust the administered doses. It is also used as a method of reducing medication costs. Objective To investigate the accuracy of tablet splitting by comparing hand splitting vs. a tablet cutter for a low dose drug tablet. Methods Salbutamol tablets (4 mg) were chosen as low dose tablets. A randomly selected equal number of tablets were split by hand and a tablet cutter, and the remaining tablets were kept whole. Weight variation and drug content were analysed for salbutamol in 0.1 N HCl using a validated spectrophotometric method. The percentages by which each whole tablet’s or half-tablet’s drug content and weight difference from sample mean values were compared with USP specification ranges for drug content. The %RSD was also calculated in order to determine whether the drugs met USP specification for %RSD. The tablets and half tablets were scanned using electron microscopy to show any visual differences arising from splitting. Results 27.5% of samples differed from sample mean values by a percentage that fell outside of USP specification for weight, of which 15% from the tablet cutter and 25% from those split by hand fell outside the specifications. All whole tablets and half tablets met the USP specifications for drug content but the variation of content between the two halves reached 21.3% of total content in case of hand splitting, and 7.13% only for the tablet cutter. The %RSDs for drug content and weight met the USP specification for whole salbutamol tablets and the half tablets which were split by tablet cutter. The halves which were split by hand fell outside the specification for %RSD (drug content = 6.43%, weight = 8.33%). The differences were visually clear in the electron microscope scans. Conclusion Drug content variation in half-tablets appeared to be attributable to weight variation occurring during the splitting process. This could have serious clinical consequences for medications with a narrow therapeutic-toxic range. On the basis of our results, we recommend to avoid tablet splitting whenever possible or the use of an accurate tablet splitting device when splitting cannot be avoided. PMID:25473334

  8. Floating platform well production apparatus

    SciTech Connect

    Nobileau, P.C.

    1980-10-21

    A plurality of wells are clustered around a central riser which is maintained under tension from a floating platform. A plurality of spiders on the riser carry funnels in vertical alignment with the wells. The funnels are sufficiently large to permit the passage of wellhead connectors and master block valves, and the production risers include centralizers which brace the production riser from the funnels through a limited vertical range. Tensioning of the production riser is with a lower force and through a limited range which precludes disengagement of the centralizers from the funnel. Some centralizers are located to facilitate entry and attachment to the wellhead.

  9. Wave drag on floating bodies

    PubMed Central

    Le Merrer, Marie; Clanet, Christophe; Quéré, David; Raphaël, Élie; Chevy, Frédéric

    2011-01-01

    We measure the deceleration of liquid nitrogen drops floating at the surface of a liquid bath. On water, the friction force is found to be about 10 to 100 times larger than on a solid substrate, which is shown to arise from wave resistance. We investigate the influence of the bath viscosity and show that the dissipation decreases as the viscosity is increased, owing to wave damping. The measured resistance is well predicted by a model imposing a vertical force (i.e., the drop weight) on a finite area, as long as the wake can be considered stationary. PMID:21876186

  10. Floating Ice-Algal Aggregates below Melting Arctic Sea Ice

    PubMed Central

    Assmy, Philipp; Ehn, Jens K.; Fernández-Méndez, Mar; Hop, Haakon; Katlein, Christian; Sundfjord, Arild; Bluhm, Katrin; Daase, Malin; Engel, Anja; Fransson, Agneta; Granskog, Mats A.; Hudson, Stephen R.; Kristiansen, Svein; Nicolaus, Marcel; Peeken, Ilka; Renner, Angelika H. H.; Spreen, Gunnar; Tatarek, Agnieszka; Wiktor, Jozef

    2013-01-01

    During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year. PMID:24204642

  11. Floating ice-algal aggregates below melting arctic sea ice.

    PubMed

    Assmy, Philipp; Ehn, Jens K; Fernández-Méndez, Mar; Hop, Haakon; Katlein, Christian; Sundfjord, Arild; Bluhm, Katrin; Daase, Malin; Engel, Anja; Fransson, Agneta; Granskog, Mats A; Hudson, Stephen R; Kristiansen, Svein; Nicolaus, Marcel; Peeken, Ilka; Renner, Angelika H H; Spreen, Gunnar; Tatarek, Agnieszka; Wiktor, Jozef

    2013-01-01

    During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year. PMID:24204642

  12. Formulation and optimization of gastric floating drug delivery system using Central composite design and its biopharmaceutical evaluation.

    PubMed

    Meka, Venkata Srikanth; Thing, Lim Kee; Gorajana, Adinarayana; Kolapalli, Venkata Ramana-Murthy

    2015-07-01

    The present work investigates the formulation and biopharmaceutical estimation of gastric floating drug delivery system (GFDDS) of propranolol HCl using semi-synthetic polymer carboxymethyl ethyl cellulose (CMEC) and a synthetic polymer polyethylene oxide (PEO). A central composite design was applied for optimization of polymer quantity (CMEC or PEO) and sodium bicarbonate concentration as independent variables. The dependent variables evaluated were: % of drug release at 1 hr (D1hr), % drug release at 3 hr (D3hr) and time taken for 95% of drug release (t95). Numerical optimization and graphical optimization were conducted to optimize the response variables. All observed responses of statistically optimized formulations were in high treaty with predicted values. Accelerated stability studies were conducted on the optimized formulations at 40 ± 2°C/75% ± 5% RH and confirm that formulations were stable. Optimized formulations were evaluated for in vivo buoyancy characterization in human volunteers and were found buoyant in gastric fluid. Gastric residence time was enhanced in the fed but not the fasted state. The optimized formulations and marketed formulation were administered to healthy human volunteers and evaluated for pharmacokinetic parameters. Mean residence time (MRT) was prolonged and AUC levels were increased for both optimized floating tablets when compared with marketed product. High relative bioavailability obtained with optimized gastric floating tablets compared to commercial formulation, indicated the improvement of bioavailability. PMID:26142528

  13. Application of Design of Experiment for Polyox and Xanthan Gum Coated Floating Pulsatile Delivery of Sumatriptan Succinate in Migraine Treatment

    PubMed Central

    Jagdale, Swati C.; Pawar, Chandrakala R.

    2014-01-01

    Migraine follows circadian rhythm in which headache is more painful at the awakening time. This needs administration of dosage form at night time to release drug after lag period when pain gets worse. Sumatriptan succinate is a drug of choice for migraine. Sumatriptan succinate has bitter taste, low oral bioavailability, and shorter half-life. Present work deals with application of design of experiment for polyox and xanthan gum in development of press coated floating pulsatile tablet. Floating pulsatile concept was applied to increase gastric residence of the dosage form. Burst release was achieved through immediate release tablet using crospovidone as superdisintegrant (10%). Pulse lag time was achieved using swellable polymer polyox WSR 205 and xanthan gum. 32 experimental design was applied. Optimized formulation was evaluated for physical characteristics and in-vitro and in-vivo study. From results, it can be concluded that optimized batch F8 containing polyox WSR205 (72.72%) and xanthan gum (27.27%) of total weight of polymer has shown floating lag time of 55 ± 2 sec, drug content of 100.35 ± 0.4%, hardness of 6 ± 0.1 Kg/cm2, and 98.69 ± 2% drug release in pulse manner with lag time of 7 ± 0.1 h. Optimized batch showed prolong gastric residence which was confirmed by in-vivo X-ray study. PMID:25530963

  14. Application of design of experiment for polyox and xanthan gum coated floating pulsatile delivery of sumatriptan succinate in migraine treatment.

    PubMed

    Jagdale, Swati C; Pawar, Chandrakala R

    2014-01-01

    Migraine follows circadian rhythm in which headache is more painful at the awakening time. This needs administration of dosage form at night time to release drug after lag period when pain gets worse. Sumatriptan succinate is a drug of choice for migraine. Sumatriptan succinate has bitter taste, low oral bioavailability, and shorter half-life. Present work deals with application of design of experiment for polyox and xanthan gum in development of press coated floating pulsatile tablet. Floating pulsatile concept was applied to increase gastric residence of the dosage form. Burst release was achieved through immediate release tablet using crospovidone as superdisintegrant (10%). Pulse lag time was achieved using swellable polymer polyox WSR 205 and xanthan gum. 3(2) experimental design was applied. Optimized formulation was evaluated for physical characteristics and in-vitro and in-vivo study. From results, it can be concluded that optimized batch F8 containing polyox WSR205 (72.72%) and xanthan gum (27.27%) of total weight of polymer has shown floating lag time of 55 ± 2 sec, drug content of 100.35 ± 0.4%, hardness of 6 ± 0.1 Kg/cm(2), and 98.69 ± 2% drug release in pulse manner with lag time of 7 ± 0.1 h. Optimized batch showed prolong gastric residence which was confirmed by in-vivo X-ray study. PMID:25530963

  15. Floating liquid bridge charge dynamics

    NASA Astrophysics Data System (ADS)

    Teschke, Omar; Soares, David Mendez; Gomes, Whyllerson Evaristo; Valente Filho, Juracyr Ferraz

    2016-01-01

    The interaction of liquid with electric fields is investigated in a configuration where up to 13 kV are applied between electrodes resulting in a 106 V/m electric field in the capillaries and where there is the formation of a free-standing fluid bridge in the interelectrode gap. The Mott-Gurney equation was fitted to the measured ionization current vs applied voltage curve which indicates that the ionization rate at the high-voltage anode electrode dimethylsulfoxide (DMSO) interface and space charging in the interelectrode gap determine the floating liquid bridge current for a given cathode-to-anode voltage. Space charge effects were measured in the cathode becker and also at the liquid bridge since the ionized charges at the anode migrate to the bridge outer surface and decrease the interfacial tension from 43 mJ/m2 to 29 mJ/m2. Two distinct structural regions then form the bridge, a charged plastic (bulk modulus ˜100 MPa) conducting outer layer with a surface conductivity of ˜10-9 Ω-1, which shapes and supports the floating fluid structure, and an inner liquid cylinder, where DMSO molecules flow.

  16. Whatever Floats Your Boat: A Design Challenge

    ERIC Educational Resources Information Center

    Kornoelje, Joanne; Roman, Harry T.

    2012-01-01

    This article presents a simple design challenge, based on the PBS program "Design Squad's" "Watercraft" activity that will prove engaging to most technology and engineering students. In this floating boat challenge, students are to build a boat that can float and support 25 pennies for at least 10 seconds--without leaking, sinking, or tipping…

  17. Future float zone development in industry

    NASA Technical Reports Server (NTRS)

    Sandfort, R. M.

    1980-01-01

    The present industrial requirements for float zone silicon are summarized. Developments desired by the industry in the future are reported. The five most significant problems faced today by the float zone crystal growth method in industry are discussed. They are economic, large diameter, resistivity uniformity, control of carbon, and swirl defects.

  18. Whatever Floats Your Boat: A Design Challenge

    ERIC Educational Resources Information Center

    Kornoelje, Joanne; Roman, Harry T.

    2012-01-01

    This article presents a simple design challenge, based on the PBS program "Design Squad's" "Watercraft" activity that will prove engaging to most technology and engineering students. In this floating boat challenge, students are to build a boat that can float and support 25 pennies for at least 10 seconds--without leaking, sinking, or tipping

  19. 32 CFR 935.165 - Floating objects.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Floating objects. 935.165 Section 935.165 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Public Safety § 935.165 Floating objects. No person may anchor, moor, or...

  20. 32 CFR 935.165 - Floating objects.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Floating objects. 935.165 Section 935.165 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Public Safety § 935.165 Floating objects. No person may anchor, moor, or...

  1. 32 CFR 935.165 - Floating objects.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Floating objects. 935.165 Section 935.165 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Public Safety § 935.165 Floating objects. No person may anchor, moor, or...

  2. 32 CFR 935.165 - Floating objects.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Floating objects. 935.165 Section 935.165 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Public Safety § 935.165 Floating objects. No person may anchor, moor, or...

  3. 32 CFR 935.165 - Floating objects.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Floating objects. 935.165 Section 935.165 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Public Safety § 935.165 Floating objects. No person may anchor, moor, or...

  4. Vertical pump with free floating check valve

    DOEpatents

    Lindsay, Malcolm

    1980-01-01

    A vertical pump with a bottom discharge having a free floating check valve isposed in the outlet plenum thereof. The free floating check valve comprises a spherical member with a hemispherical cage-like member attached thereto which is capable of allowing forward or reverse flow under appropriate conditions while preventing reverse flow under inappropriate conditions.

  5. Relationship between planar and all-surface rate constants for drugs formulated in nondisintegrating cylindrical slow-release tablets.

    PubMed

    Jambhekar, S S; Makoid, M C; Cobby, J

    1987-02-01

    The release of drug through the planar surface of a nondisintegrating tablet with an insoluble matrix has been described mathematically using the Higuchi release rate constant (kH). The release of drug through a similar all-surface tablet has been described by using a cubic equation and the all-surface rate constant (kr). Using sodium salicylate and quinidine sulfate as model drugs, the relationship between kH and kr was verified for cylindrical slow-release tablets. Accordingly, the rate constant obtained from a single exposed planar surface can be used to predict the rate constant (kr) when all surfaces of the tablet are exposed to dissolution fluid. PMID:3572753

  6. 21 CFR 520.2088 - Roxarsone tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... period. Withdraw 5 days before slaughter. Use as sole source of organic arsenic. (ii) Growing chickens—(a.... Withdraw 5 days before slaughter. Use as sole source of organic arsenic. (b)(1) Specifications. Each tablet... slaughter. Use as sole source of organic arsenic. (ii) (c)(1) Specifications. Each tablet contains...

  7. 21 CFR 520.2088 - Roxarsone tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... period. Withdraw 5 days before slaughter. Use as sole source of organic arsenic. (ii) Growing chickens—(a.... Withdraw 5 days before slaughter. Use as sole source of organic arsenic. (b)(1) Specifications. Each tablet... slaughter. Use as sole source of organic arsenic. (ii) (c)(1) Specifications. Each tablet contains...

  8. 21 CFR 520.312 - Carnidazole tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... this chapter. (c) Conditions of use—(1) Amount. Adult pigeons: 1 tablet (10 milligrams); newly weaned pigeons: 1/2 tablet (5 milligrams). (2) Indications for use. For treating trichomoniasis (canker) in ornamental and homing pigeons. (3) Limitations. Not for use in pigeons intended for human food. Consult...

  9. 21 CFR 520.312 - Carnidazole tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... this chapter. (c) Conditions of use(1) Amount. Adult pigeons: 1 tablet (10 milligrams); newly weaned pigeons: 1/2 tablet (5 milligrams). (2) Indications for use. For treating trichomoniasis (canker) in ornamental and homing pigeons. (3) Limitations. Not for use in pigeons intended for human food. Consult...

  10. 21 CFR 520.312 - Carnidazole tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... this chapter. (c) Conditions of use—(1) Amount. Adult pigeons: 1 tablet (10 milligrams); newly weaned pigeons: 1/2 tablet (5 milligrams). (2) Indications for use. For treating trichomoniasis (canker) in ornamental and homing pigeons. (3) Limitations. Not for use in pigeons intended for human food. Consult...

  11. Putting Tablet PCs to the Test

    ERIC Educational Resources Information Center

    Amirian, Susan

    2004-01-01

    Like many educators, the author and her colleagues (five faculty members and two IT techs) in the department of Media Communications and Technology at East Stroudsburg University in Pennsylvania were interested to find out the status of tablet PCs in education. Microsoft listed 10 manufacturers of tablet PCs following two forms: the slate and the

  12. Enhancing Student Performance Using Tablet Computers

    ERIC Educational Resources Information Center

    Enriquez, Amelito G.

    2010-01-01

    Tablet PCs have the potential to change the dynamics of classroom interaction through wireless communication coupled with pen-based computing technology that is suited for analyzing and solving engineering problems. This study focuses on how tablet PCs and wireless technology can be used during classroom instruction to create an Interactive

  13. 21 CFR 520.1408 - Methylprednisolone tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... tablets. (a) Specifications. Each table contains 1, 2, or 4 milligrams of methylprednisolone. (b) Sponsor... for use of 1- and 2-milligram tablets. (c) NAS/NRC status. The conditions of use have been NAS/NRC... of use—(1) Amount. Dogs and cats: 5 to 15 pounds, 2 milligrams; 15 to 40 pounds, 2 to 4...

  14. 21 CFR 520.1408 - Methylprednisolone tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... tablets. (a) Specifications. Each table contains 1, 2, or 4 milligrams of methylprednisolone. (b) Sponsor... for use of 1- and 2-milligram tablets. (c) NAS/NRC status. The conditions of use have been NAS/NRC... of use—(1) Amount. Dogs and cats: 5 to 15 pounds, 2 milligrams; 15 to 40 pounds, 2 to 4...

  15. 21 CFR 520.1380 - Methocarbamol tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Methocarbamol tablets. 520.1380 Section 520.1380... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1380 Methocarbamol tablets. (a) Chemical name. 3-(O-Methoxyphenoxy)-1,2-propanediol 1-carbamate. (b) Specifications. Each...

  16. 21 CFR 520.1380 - Methocarbamol tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Methocarbamol tablets. 520.1380 Section 520.1380... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1380 Methocarbamol tablets. (a) Chemical name. 3-(O-Methoxyphenoxy)-1,2-propanediol 1-carbamate. (b) Specifications. Each...

  17. Enhancing Student Performance Using Tablet Computers

    ERIC Educational Resources Information Center

    Enriquez, Amelito G.

    2010-01-01

    Tablet PCs have the potential to change the dynamics of classroom interaction through wireless communication coupled with pen-based computing technology that is suited for analyzing and solving engineering problems. This study focuses on how tablet PCs and wireless technology can be used during classroom instruction to create an Interactive…

  18. Putting Tablet PCs to the Test

    ERIC Educational Resources Information Center

    Amirian, Susan

    2004-01-01

    Like many educators, the author and her colleagues (five faculty members and two IT techs) in the department of Media Communications and Technology at East Stroudsburg University in Pennsylvania were interested to find out the status of tablet PCs in education. Microsoft listed 10 manufacturers of tablet PCs following two forms: the slate and the…

  19. 21 CFR 520.1408 - Methylprednisolone tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Methylprednisolone tablets. 520.1408 Section 520.1408 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1408 Methylprednisolone tablets. (a) Specifications. Each...

  20. Tablet PCs: A Physical Educator's New Clipboard

    ERIC Educational Resources Information Center

    Nye, Susan B.

    2010-01-01

    Computers in education have come a long way from the abacus of 5,000 years ago to the desktop and laptop computers of today. Computers have transformed the educational environment, and with each new iteration of smaller and more powerful machines come additional advantages for teaching practices. The Tablet PC is one. Tablet PCs are fully…

  1. 21 CFR 520.312 - Carnidazole tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... this chapter. (c) Conditions of use—(1) Amount. Adult pigeons: 1 tablet (10 milligrams); newly weaned pigeons: 1/2 tablet (5 milligrams). (2) Indications for use. For treating trichomoniasis (canker) in ornamental and homing pigeons. (3) Limitations. Not for use in pigeons intended for human food. Consult...

  2. Smartphones and tablets: Reshaping radiation oncologists’ lives

    PubMed Central

    Gomez-Iturriaga, Alfonso; Bilbao, Pedro; Casquero, Francisco; Cacicedo, Jon; Crook, Juanita

    2012-01-01

    Background Smartphones and tablets are new handheld devices always connected to an information source and capable of providing instant updates, they allow doctors to access the most updated information and provide decision support at the point of care. Aim The practice of radiation oncology has always been a discipline that relies on advanced technology. Smartphones provide substantial processing power, incorporating innovative user interfaces and applications. Materials and methods The most popular smartphone and tablet app stores were searched for “radiation oncology” and “oncology” related apps. A web search was also performed searching for smartphones, tablets, oncology, radiology and radiation oncology. Results Smartphones and tablets allow rapid access to information in the form of podcasts, apps, protocols, reference texts, recent research and more. Conclusion With the rapidly changing advances in radiation oncology, the trend toward accessing resources via smartphones and tablets will only increase, future will show if this technology will improve clinical care. PMID:24669308

  3. Gastric emptying of enteric-coated tablets

    SciTech Connect

    Park, H.M.; Chernish, S.M.; Rosenek, B.D.; Brunelle, R.L.; Hargrove, B.; Wellman, H.N.

    1984-03-01

    To evaluate the gastric emptying time of pharmaceutical dosage forms in a clinical setting, a relatively simple dual-radionuclide technique was developed. Placebo tablets of six different combinations of shape and size were labeled with indium-111 DTPA and enteric coated. Six volunteers participated in a single-blind and crossover study. Tablets were given in the morning of a fasting stomach with 6 oz of water containing /sup 99m/Tc pertechnetate and continuously observed with a gamma camera. A scintigraph was obtained each minute. The results suggested that the size, shape, or volume of the tablet used in this study had no significant effect in the rate of gastric emptying. The tablets emptied erratically and unpredictably, depending upon their time of arrival in the stomach in relation to the occurrence of interdigestive myoelectric contractions. The method described is a relatively simple and accurate technique to allow one to follow the gastric emptying of tablets.

  4. Wet granulation fine particle ethylcellulose tablets: effect of production variables and mathematical modeling of drug release.

    PubMed

    Agrawal, Anjali M; Neau, Steven H; Bonate, Peter L

    2003-01-01

    In the present study, the applicability of fine particle ethylcellulose (FPEC) to produce matrix tablets by a wet granulation technique was evaluated. The effect of various formulation and process variables, such as FPEC content, hardness of the tablet, and solubility of the drug, on the release of drug from these tablets was examined. Tablets were prepared by wet granulation of drug and FPEC in an appropriate mass ratio. Theophylline, caffeine, and dyphylline were selected as nonionizable model drugs with solubilities from 8.3 to 330 mg/mL at 25 degrees C. Ibuprofen, phenylpropanolamine hydrochloride, and pseudoephedrine hydrochloride were selected as ionizable drugs with solubilities from 0.1 to 2000 mg/mL at 25 degrees C. Drug release studies were conducted in 37 degrees C water with UV detection. As the FPEC content and the hardness of the tablets increased, the release rate of the drug decreased. The drug release rate increased with an increase in the solubility of the drug. Model equations, intended to elucidate the drug release mechanism, were fitted to the release data. Parameters were generated and data presented by SAS software. The Akaike Information Criterion was also considered to ascertain the best-fit equation. Fickian diffusion and polymer relaxation were the release mechanisms for nonionizable and ionizable drugs. PMID:12866940

  5. Fast relief from migraine attacks using fast-disintegrating sublingual zolmitriptan tablets.

    PubMed

    Mahmoud, Azza A; Salah, Salwa

    2012-06-01

    Zolmitriptan is a potent molecule for treatment of migraine. Its current oral therapies present drawbacks such as slow onset of action, low bioavailability and large inter-subject variability. Fast disintegrating sublingual zolmitriptan tablet (FDST) using freeze-drying technique has been developed to enhance tablet disintegration and dissolution with the intention of speeding drug absorption and onset of effect, hence mitigating the effects on the gastrointestinal dysmotility that typically accompanies the migraine attack. The FDSTs were prepared using different concentrations of gelatin as binder and mannitol or L-alanine as matrix supporting/disintegration enhancing agents. The effect of formulation variables on the physicochemical and solid-state properties, as well as the dissolution behaviour of the tablets, was studied. The formulated FDSTs disintegrated within 30 s and showed significantly faster dissolution rate of zolmitriptan compared to the zolmitriptan oral tablet. Tablet containing 2% gelatin and mannitol showed acceptable weight variation, drug content and friability values. Furthermore, it had a low in-vitro and in-vivo disintegration time (11 s) and it reached 100% of drug release within 30 s. This sublingual formulation gave faster and higher zolmitriptan plasma concentration in rabbits compared to the oral zolmetriptan market product. Zolmitriptan FDST may therefore constitute an advance in the management of acute migraine attacks. PMID:22023340

  6. Effect of Different Polymer Concentration on Drug Release Rate and Physicochemical Properties of Mucoadhesive Gastroretentive Tablets

    PubMed Central

    Agarwal, Shweta; Murthy, R. S. R.

    2015-01-01

    Mucoadhesive tablets have emerged as potential candidates for gastroretentive drug delivery providing controlled release along with prolonged gastric residence time. Gastroretentive mucoadhesive tablets could result in increased bioavailability due to prolonged gastric residence time. A hydrophilic matrix system was developed as mucoadhesion is achievable on appropriate wetting and swelling of the polymers used. The polymers were so chosen so as to provide a balance between swelling, mucoadhesion and drug release. The polymers chosen were hydroxypropyl methylcellulose K4M, chitosan, and Carbopol 934. The concentrations of these polymers used has a great impact on the physicochemical properties of the resulting formulation. The tablets were formulated using wet granulation method and tranexamic acid was used as the model drug. The prepared tablets were characterized for size, shape, appearance, hardness, friability, weight variation, swelling, mucoadhesion and in vitro drug release. Several batches of tablets were prepared by varying the ratio of hydroxypropyl methylcellulose K4M and Chitosan. The batches having a greater ratio of chitosan showed higher rate of swelling, greater erosion, less mucoadhesion and faster release rate of the drug whereas the batches having greater ratio of hydroxypropyl methylcellulose K4M showed lesser rate of swelling, less erosion, better mucoadhesion and a smaller drug release rate. The level of carbopol was kept constant in all the batches. PMID:26997698

  7. Formulation of a modified-release pregabalin tablet using hot-melt coating with glyceryl behenate.

    PubMed

    Jeong, Kyu Ho; Woo, Hye Seung; Kim, Chae Jin; Lee, Kyung Hwa; Jeon, Jun Young; Lee, Sang Young; Kang, Jae-Hoon; Lee, Sangkil; Choi, Young Wook

    2015-11-10

    A modified-release (MR) tablet of the anti-anxiety drug pregabalin (PRE) was prepared by hot-melt coating PRE with glyceryl behenate (GB) as a release retardant and compressing to form a matrix with microcrystalline cellulose (MCC) as a hydrophilic diluent. GB-coated PRE had a size in the range of 177-290 μm with good to acceptable flowability. Tablet hardness decreased slightly as GB content increased. PRE release from the tablet matrices was successfully modified by altering the ratio of MCC and GB, and it was found that dissolution- or diffusion-controlled release depended on the amount of GB used. Drug release was pH-independent. An accelerated stability test on the most promising MR tablet at 40°C and 75% relative humidity for 6 months showed no significant changes in PRE content, and the occurrence of total impurities--including PRE-lactam--was within acceptable limits. After oral administration of the selected MR tablet or a commercial IR capsule (Lyrica) to healthy human volunteers, pharmacokinetic parameters including Tmax, Cmax, AUC0-24, and T1/2 were compared. The confidence interval of AUC0-24 was within the adequate range, but that of Cmax was inadequate. This study demonstrated the potential use of GB for PRE-containing MR formulations. PMID:26315121

  8. 21 CFR 520.1284 - Sodium liothyronine tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium liothyronine tablets. 520.1284 Section 520...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1284 Sodium liothyronine tablets. (a) Specifications. Sodium liothyronine tablets consist of tablets intended for...

  9. 21 CFR 520.1284 - Sodium liothyronine tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium liothyronine tablets. 520.1284 Section 520...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1284 Sodium liothyronine tablets. (a) Specifications. Sodium liothyronine tablets consist of tablets intended for...

  10. 21 CFR 520.1284 - Sodium liothyronine tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium liothyronine tablets. 520.1284 Section 520...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1284 Sodium liothyronine tablets. (a) Specifications. Sodium liothyronine tablets consist of tablets intended for...

  11. 21 CFR 520.1199 - Ivermectin, pyrantel, and praziquantel tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ivermectin, pyrantel, and praziquantel tablets... Ivermectin, pyrantel, and praziquantel tablets. (a) Specifications. Each chewable tablet contains: (1) 34...) Amount. Administer monthly according to body weight as follows: (i) 6 to 12 lb: one tablet as...

  12. 21 CFR 520.1242e - Levamisole hydrochloride effervescent tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Levamisole hydrochloride effervescent tablets. 520....1242e Levamisole hydrochloride effervescent tablets. (a) Specifications. Each tablet contains 907... water from pigs before treatment is not necessary. Add one tablet for each 21/2 gallons of water;...

  13. 21 CFR 529.400 - Chlorhexidine tablets and suspension.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Chlorhexidine tablets and suspension. 529.400... Chlorhexidine tablets and suspension. (a) Specification. Each tablet and each 28-milliliter syringe of.... 000856 in § 510.600(c) of this chapter. (c) Conditions of use—(1) Amount. Place 1 or 2 tablets deep...

  14. 21 CFR 520.2280 - Sulfamethizole and methenamine mandelate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sulfamethizole and methenamine mandelate tablets... Sulfamethizole and methenamine mandelate tablets. (a) Specifications. Each tablet contains 250 milligrams of... urethra and bladder. (2) It is administered at a dosage level of one tablet for each 20 pounds of...

  15. 21 CFR 520.1200 - Ivermectin, fenbendazole, and praziquantel tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Ivermectin, fenbendazole, and praziquantel tablets... Ivermectin, fenbendazole, and praziquantel tablets. (a) Specifications. Each chewable tablet contains either... § 510.600(c) of this chapter. (c) Conditions of use in dogs—(1) Amount. Administer tablets to provide...

  16. 21 CFR 520.1720a - Phenylbutazone tablets and boluses.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Phenylbutazone tablets and boluses. 520.1720a... Phenylbutazone tablets and boluses. (a) Specifications. Each tablet contains 100, 200, or 400 milligrams (mg), or...-mg or 1-g tablets, or 2- or 4-g boluses, in dogs and horses. (2) Nos. 000010 and 059130 for use...

  17. 21 CFR 520.1446 - Milbemcyin oxime and lufenuron tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Milbemcyin oxime and lufenuron tablets. 520.1446... oxime and lufenuron tablets. (a) Specifications—(1) Tablets containing: 2.3 milligrams (mg) milbemycin... 230 mg lufenuron, or 23 mg milbemycin oxime and 460 mg lufenuron. (2) Flavored tablets containing:...

  18. 21 CFR 520.1446 - Milbemcyin oxime and lufenuron tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Milbemcyin oxime and lufenuron tablets. 520.1446... oxime and lufenuron tablets. (a) Specifications—(1) Tablets containing: 2.3 milligrams (mg) milbemycin... 230 mg lufenuron, or 23 mg milbemycin oxime and 460 mg lufenuron. (2) Flavored tablets containing:...

  19. 21 CFR 520.1199 - Ivermectin, pyrantel, and praziquantel tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Ivermectin, pyrantel, and praziquantel tablets... Ivermectin, pyrantel, and praziquantel tablets. (a) Specifications. Each chewable tablet contains: (1) 34...) Amount. Administer monthly according to body weight as follows: (i) 6 to 12 lb: one tablet as...

  20. 21 CFR 520.82a - Aminopropazine fumarate tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aminopropazine fumarate tablets. 520.82a Section 520.82a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Aminopropazine fumarate tablets. (a) Specifications. The drug is in tablet form. Each tablet...

  1. 21 CFR 529.400 - Chlorhexidine tablets and suspension.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Chlorhexidine tablets and suspension. 529.400... Chlorhexidine tablets and suspension. (a) Specification. Each tablet and each 28-milliliter syringe of.... 000856 in § 510.600(c) of this chapter. (c) Conditions of use—(1) Amount. Place 1 or 2 tablets deep...

  2. 21 CFR 520.1200 - Ivermectin, fenbendazole, and praziquantel tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ivermectin, fenbendazole, and praziquantel tablets... Ivermectin, fenbendazole, and praziquantel tablets. (a) Specifications. Each chewable tablet contains either... § 510.600(c) of this chapter. (c) Conditions of use in dogs—(1) Amount. Administer tablets to provide...

  3. 21 CFR 520.82a - Aminopropazine fumarate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Aminopropazine fumarate tablets. 520.82a Section 520.82a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Aminopropazine fumarate tablets. (a) Specifications. The drug is in tablet form. Each tablet...

  4. WindWaveFloat Final Report

    SciTech Connect

    Alla Weinstein, Dominique Roddier, Kevin Banister

    2012-03-30

    Principle Power Inc. and National Renewable Energy Lab (NREL) have completed a contract to assess the technical and economic feasibility of integrating wave energy converters into the WindFloat, resulting in a new concept called the WindWaveFloat (WWF). The concentration of several devices on one platform could offer a potential for both economic and operational advantages. Wind and wave energy converters can share the electrical cable and power transfer equipment to transport the electricity to shore. Access to multiple generation devices could be simplified, resulting in cost saving at the operational level. Overall capital costs may also be reduced, provided that the design of the foundation can be adapted to multiple devices with minimum modifications. Finally, the WindWaveFloat confers the ability to increase energy production from individual floating support structures, potentially leading to a reduction in levelized energy costs, an increase in the overall capacity factor, and greater stability of the electrical power delivered to the grid. The research conducted under this grant investigated the integration of several wave energy device types into the WindFloat platform. Several of the resulting system designs demonstrated technical feasibility, but the size and design constraints of the wave energy converters (technical and economic) make the WindWaveFloat concept economically unfeasible at this time. Not enough additional generation could be produced to make the additional expense associated with wave energy conversion integration into the WindFloat worthwhile.

  5. Continuous manufacturing of extended release tablets via powder mixing and direct compression.

    PubMed

    Ervasti, Tuomas; Simonaho, Simo-Pekka; Ketolainen, Jarkko; Forsberg, Peter; Fransson, Magnus; Wikström, Håkan; Folestad, Staffan; Lakio, Satu; Tajarobi, Pirjo; Abrahmsén-Alami, Susanna

    2015-11-10

    The aim of the current work was to explore continuous dry powder mixing and direct compression for manufacturing of extended release (ER) matrix tablets. The study was span out with a challenging formulation design comprising ibuprofen compositions with varying particle size and a relatively low amount of the matrix former hydroxypropyl methylcellulose (HPMC). Standard grade HPMC (CR) was compared to a recently developed direct compressible grade (DC2). The work demonstrate that ER tablets with desired quality attributes could be manufactured via integrated continuous mixing and direct compression. The most robust tablet quality (weight, assay, tensile strength) was obtained using high mixer speed and large particle size ibuprofen and HPMC DC2 due to good powder flow. At low mixer speed it was more difficult to achieve high quality low dose tablets. Notably, with HPMC DC2 the processing conditions had a significant effect on drug release. Longer processing time and/or faster mixer speed was needed to achieve robust release with compositions containing DC2 compared with those containing CR. This work confirms the importance of balancing process parameters and material properties to find consistent product quality. Also, adaptive control is proven a pivotal means for control of continuous manufacturing systems. PMID:26320548

  6. Floating point arithmetic in future supercomputers

    NASA Technical Reports Server (NTRS)

    Bailey, David H.; Barton, John T.; Simon, Horst D.; Fouts, Martin J.

    1989-01-01

    Considerations in the floating-point design of a supercomputer are discussed. Particular attention is given to word size, hardware support for extended precision, format, and accuracy characteristics. These issues are discussed from the perspective of the Numerical Aerodynamic Simulation Systems Division at NASA Ames. The features believed to be most important for a future supercomputer floating-point design include: (1) a 64-bit IEEE floating-point format with 11 exponent bits, 52 mantissa bits, and one sign bit and (2) hardware support for reasonably fast double-precision arithmetic.

  7. A comparative study of the dissolution characteristics of capsule and tablet dosage forms of melt granulations of paracetamol--diluent effects.

    PubMed

    Uhumwangho, Michael U; Okor, Roland S

    2007-01-01

    The dissolution characteristics of melt granulations of paracetamol in capsule and tablet dosage form were compared to determine whether the dissolution characteristics of the granules can be actualized by formulating them as rapidly disintegrating tablets. The term melt granulation refers here to the wax-matrix granules that were formed by triturating the drug powder (paracetamol) with a melted carnauba wax. The matrix granules were admixed with diluents (lactose, alpha-cellulose or microcrystalline cellulose) also in granular form to prevent size separation during encapsulation or tableting. The granules were filled into hard gelatin capsules (mean content weight, 500 +/- 6.2 mg) or tableted (mean weight 500 +/- 5.1 mg, and tensile strength 1.36 +/- 0.2 to 1.7 +/- 0.3 MN/m2). The capsules and tablets were subjected to disintegration and in vitro dissolution tests. The dissolution data were analyzed on the basis of zero, first order rate kinetics and Higuchi square root of time relationship. The results showed that the dissolution profiles were generally consistent with a first order rate kinetics (r = 0.95). The first order dissolution rate constants of capsules and tablets of the matrix granules only (without diluents) were 0.31 +/- 0.02 min(-1) and 0.20 +/- 0.03 min(-1), respectively, indicating faster dissolution from the capsules. Therefore, the dissolution characteristics of the matrix particles were not intact after tableting. Addition of diluents to the capsule formulations had no effect on dissolution rates, whereas in the tablets, dissolution rates increased. For instance, inclusion of a diluent up to 50% w/w in the tablets increased the dissolution rate constants to 0.34 +/- 0.04 min(-1) (lactose), 0.42 +/- 0.02 min(-1) (alpha-cellulose), and 0.46 +/- 0.03 min(-1) (microcrystalline cellulose). Thus, alpha-cellulose and microcrystalline cellulose produced greater enhancer effect on the tablet dissolution rates compared to lactose. Both the capsules and the tablets disintegrated rapidly within 2 to 3 minutes. The dissolution enhancer effect of the diluents in the tablets only, relates to the aqueous swelling of the disintegrated particles. PMID:17665854

  8. Design, development and in-vitro evaluation of metoprolol tartrate tablets containing xanthan-tragacanth.

    PubMed

    Rasul, Akhtar; Iqbal, Muhammad; Murtaza, Ghulam; Waqas, Muhammad K; Hanif, Muhammad; Khan, Shujaat A; Bhatti, Naveed S

    2010-01-01

    The present study was undertaken to develop oral sustained release tablets of metoprolol tartrate using natural hydrophilic matrix formers (xanthan gum and tragacanth). Sustained release matrix tablets of metoprolol tartrate were prepared by using different ratios of drug, xanthan gum and tragacanth. Microcrystalline cellulose (MCC) was used as diluent. The polymer was incorporated into a matrix system using direct compression technique. All the lubricated formulations were compressed using concave punches in compression machine. Compressed tablets were evaluated for diameter, hardness, friability, weight variation and in vitro dissolution using USP dissolution apparatus-II. Different formulations were evaluated with respect to dissolution profile in 900 mL phosphate buffer (pH 6.8), 0.1 M HCl solution and distilled water for 12 h at 37 degrees C. Increasing the amount of polymer (xanthan gum) in the formulation led to slow release of drug and decreasing the amount of polymer gave enhanced release of metoprolol tartrate. The kinetic treatment showed the best fitted different mathematical models (Zero order, First order, Higuchi's and Hixson-Crowell). Most of the solid matrix formulations followed Higuchi or zero order kinetics. The formulations F1, F2, F3 and F7, F8, F9 showed maximum linearity while the formulations F4, F5, F6 were not of linear behavior. The results showed that the formulation F9 containing 30% xanthan gum and 10% gum tragacanth is the most similar to that of the reference marketed preparation. PMID:20873420

  9. Stability of paracetamol in packaged tablet formulations.

    PubMed

    Ahmad, I; Shaikh, R H

    1993-07-01

    A study of the influence of various temperature and humidity conditions on the stability of a number of commercial paracetamol tablet formulations in original packaging has been conducted over a period of six months. Paracetamol degradation in tablets follows apparent first-order kinetics and the shelf-lives (t(90)) range from 9.8 to 23.0 months. PVC/PVDC/Al foil and polycoated paper packaging offer better protection to the tablets compared to that of viscose film. PMID:16414737

  10. 14 CFR 23.753 - Main float design.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Main float design. 23.753 Section 23.753... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Design and Construction Floats and Hulls § 23.753 Main float design. Each seaplane main float must meet the requirements of § 23.521....

  11. 14 CFR 23.753 - Main float design.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main float design. 23.753 Section 23.753... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Design and Construction Floats and Hulls § 23.753 Main float design. Each seaplane main float must meet the requirements of § 23.521....

  12. 33 CFR 144.01-1 - Life floats.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CONTINENTAL SHELF ACTIVITIES LIFESAVING APPLIANCES Manned Platforms § 144.01-1 Life floats. Each manned platform shall be provided with at least two approved life floats. The life floats shall have sufficient... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Life floats. 144.01-1 Section...

  13. 33 CFR 144.01-1 - Life floats.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... CONTINENTAL SHELF ACTIVITIES LIFESAVING APPLIANCES Manned Platforms § 144.01-1 Life floats. Each manned platform shall be provided with at least two approved life floats. The life floats shall have sufficient... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Life floats. 144.01-1 Section...

  14. 33 CFR 144.01-1 - Life floats.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CONTINENTAL SHELF ACTIVITIES LIFESAVING APPLIANCES Manned Platforms § 144.01-1 Life floats. Each manned platform shall be provided with at least two approved life floats. The life floats shall have sufficient... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Life floats. 144.01-1 Section...

  15. 14 CFR 27.751 - Main float buoyancy.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Main float buoyancy. 27.751 Section 27.751... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 27.751 Main float buoyancy. (a) For main floats, the buoyancy necessary to support the maximum weight of the rotorcraft in...

  16. 14 CFR 27.751 - Main float buoyancy.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Main float buoyancy. 27.751 Section 27.751... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 27.751 Main float buoyancy. (a) For main floats, the buoyancy necessary to support the maximum weight of the rotorcraft in...

  17. 14 CFR 27.751 - Main float buoyancy.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Main float buoyancy. 27.751 Section 27.751... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 27.751 Main float buoyancy. (a) For main floats, the buoyancy necessary to support the maximum weight of the rotorcraft in...

  18. 14 CFR 27.751 - Main float buoyancy.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Main float buoyancy. 27.751 Section 27.751... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 27.751 Main float buoyancy. (a) For main floats, the buoyancy necessary to support the maximum weight of the rotorcraft in...

  19. 14 CFR 25.751 - Main float buoyancy.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main float buoyancy. 25.751 Section 25.751 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Floats and Hulls § 25.751 Main float buoyancy. Each main float must have— (a)...

  20. 14 CFR 29.751 - Main float buoyancy.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main float buoyancy. 29.751 Section 29.751 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 29.751 Main float buoyancy. (a) For main floats,...

  1. 14 CFR 27.751 - Main float buoyancy.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main float buoyancy. 27.751 Section 27.751 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Floats and Hulls § 27.751 Main float buoyancy. (a) For main floats, the...

  2. Verification of floating-point software

    NASA Technical Reports Server (NTRS)

    Hoover, Doug N.

    1990-01-01

    Floating point computation presents a number of problems for formal verification. Should one treat the actual details of floating point operations, or accept them as imprecisely defined, or should one ignore round-off error altogether and behave as if floating point operations are perfectly accurate. There is the further problem that a numerical algorithm usually only approximately computes some mathematical function, and we often do not know just how good the approximation is, even in the absence of round-off error. ORA has developed a theory of asymptotic correctness which allows one to verify floating point software with a minimum entanglement in these problems. This theory and its implementation in the Ariel C verification system are described. The theory is illustrated using a simple program which finds a zero of a given function by bisection. This paper is presented in viewgraph form.

  3. Exploring Floating Concrete and Beam Design.

    ERIC Educational Resources Information Center

    Snell, Billie G.; Snell, Luke M.

    2002-01-01

    Presents two construction activities that address both state and federal science standards and encourage students to consider career options in mathematics and science. Includes floating concrete and paper bridge activities. (YDS)

  4. The Sea Peoples, from cuneiform tablets to carbon dating.

    PubMed

    Kaniewski, David; Van Campo, Elise; Van Lerberghe, Karel; Boiy, Tom; Vansteenhuyse, Klaas; Jans, Greta; Nys, Karin; Weiss, Harvey; Morhange, Christophe; Otto, Thierry; Bretschneider, Joachim

    2011-01-01

    The 13(th) century BC witnessed the zenith of the Aegean and Eastern Mediterranean civilizations which declined at the end of the Bronze Age, ∼3200 years ago. Weakening of this ancient flourishing Mediterranean world shifted the political and economic centres of gravity away from the Levant towards Classical Greece and Rome, and led, in the long term, to the emergence of the modern western civilizations. Textual evidence from cuneiform tablets and Egyptian reliefs from the New Kingdom relate that seafaring tribes, the Sea Peoples, were the final catalyst that put the fall of cities and states in motion. However, the lack of a stratified radiocarbon-based archaeology for the Sea People event has led to a floating historical chronology derived from a variety of sources spanning dispersed areas. Here, we report a stratified radiocarbon-based archaeology with anchor points in ancient epigraphic-literary sources, Hittite-Levantine-Egyptian kings and astronomical observations to precisely date the Sea People event. By confronting historical and science-based archaeology, we establish an absolute age range of 1192-1190 BC for terminal destructions and cultural collapse in the northern Levant. This radiocarbon-based archaeology has far-reaching implications for the wider Mediterranean, where an elaborate network of international relations and commercial activities are intertwined with the history of civilizations. PMID:21687714

  5. The Sea Peoples, from Cuneiform Tablets to Carbon Dating

    PubMed Central

    Kaniewski, David; Van Campo, Elise; Van Lerberghe, Karel; Boiy, Tom; Vansteenhuyse, Klaas; Jans, Greta; Nys, Karin; Weiss, Harvey; Morhange, Christophe; Otto, Thierry; Bretschneider, Joachim

    2011-01-01

    The 13th century BC witnessed the zenith of the Aegean and Eastern Mediterranean civilizations which declined at the end of the Bronze Age, ∼3200 years ago. Weakening of this ancient flourishing Mediterranean world shifted the political and economic centres of gravity away from the Levant towards Classical Greece and Rome, and led, in the long term, to the emergence of the modern western civilizations. Textual evidence from cuneiform tablets and Egyptian reliefs from the New Kingdom relate that seafaring tribes, the Sea Peoples, were the final catalyst that put the fall of cities and states in motion. However, the lack of a stratified radiocarbon-based archaeology for the Sea People event has led to a floating historical chronology derived from a variety of sources spanning dispersed areas. Here, we report a stratified radiocarbon-based archaeology with anchor points in ancient epigraphic-literary sources, Hittite-Levantine-Egyptian kings and astronomical observations to precisely date the Sea People event. By confronting historical and science-based archaeology, we establish an absolute age range of 1192–1190 BC for terminal destructions and cultural collapse in the northern Levant. This radiocarbon-based archaeology has far-reaching implications for the wider Mediterranean, where an elaborate network of international relations and commercial activities are intertwined with the history of civilizations. PMID:21687714

  6. Video tracking for high-similarity drug tablets based on reflective lightness intensity and fuzzy recognition system.

    PubMed

    Liang, Zhongwei; Liu, Xiaochu; Tan, Shisong; Wen, Yiheng

    2016-03-01

    Video tracking of drug tablet exerts important influences on the efficiency and reliability of its mass production; this topic also becomes a difficult and targeted focus for pharmaceutical production monitory in the past several years due to the high similarity and random distribution of those objectives to be searched for. By measuring the reflective lightness intensity of illumination lightness on tablet surface, reflective lightness intensity matrix was established and demonstrated in the form of grey image, presenting its shape topology and topography details in return. On this basis, a series of mathematical properties for describing reflective lightness intensity images were proposed, thereafter a set of fuzzy recognition system and its identification rules can be employed to classify those moving tablets with inputted image properties, which facilitates the determination of their instantaneous coordinate positions on given image frame accordingly. By repeating identical operations on the next frame, the real-time motions of tablet objectives were traced successfully. Orthogonal tracking experiment and performance comparisons verified the accuracy and reliability of this new method in pharmaceutical industry. With original suggestions concerning imaging arrangements, tablet descriptions and video tracking, this article provides reliable references and new research ideas for tablet tracking performance in high-yielding production domain. PMID:26893227

  7. Archimedes' floating bodies on a spherical Earth

    NASA Astrophysics Data System (ADS)

    Rorres, Chris

    2016-01-01

    Archimedes was the first to systematically find the centers of gravity of various solid bodies and to apply this concept in determining stable configurations of floating bodies. In this paper, we discuss an error in a proof developed by Archimedes that involves determining whether a uniform, spherical cap will float stably with its base horizontal in a liquid on a spherical Earth. We present a simpler, corrected proof and discuss aspects of his proof regarding a spherical cap that is not uniform.

  8. Multiple valued floating potentials of Langmuir probes

    NASA Technical Reports Server (NTRS)

    Nam, Cheol-Hee; Hershkowitz, N.; Cho, M. H.; Intrator, T.; Diebold, D.

    1988-01-01

    It is shown that Langmuir probes can have three different floating potentials in plasmas produced by a hot filament discharge in a multi-dipole device when the primary and secondary electron currents are comparable. The measured floating potential depends on the probe's initial condition - the most negative and the least negative potentials are found to be stable and the in-between value is found to be unstable. Results are compared to a simple theoretical model.

  9. Cadmium uptake by floating macrophytes.

    PubMed

    Maine, M A; Duarte, M V; Su, N L

    2001-08-01

    Cd uptake capacity of a group of floating macrophytes (Salvinia herzogii, Pistia stratiotes, Hydromistia stolonifera and Eichhornia crassipes) was determined in outdoors experiments during the lowest temperature period of the year. Although all studied species were highly efficient in the Cd uptake, Pistia stratiotes was selected for further research because of its superior performance and its higher average relative growth rate. Cadmium% removal by Pistia stratiotes was greater in the first 24 h of the experiments (63, 65, 72 and 74% of the added Cd for 1, 2, 4 and 6 mg Cd 1(-1), respectively). After 31 days of growth, Pistia statiotes efficiently removed Cd at the studied concentrations. The macrophyte was able to keep its capacity for Cd removal even though some toxicity symptoms appeared at 4 and 6 mg Cd 1(-1). The greater the initial concentration, the greater Cd bioaccumulation rates. The increase of Cd concentration in plant tissues occurred especially in roots and was linearly related to the quantity of Cd added. Cd sorption by roots is faster than translocation to the plant aerial part and it occurs mainly during the first 24h. PMID:11456161

  10. Floating intake reduces pump damage

    SciTech Connect

    Kronig, A.

    1993-12-31

    The solution to a costly sand erosion problem at the Grande Dixence hydroelectric project in Switzerland turned out to be as simple as a floating pump. The 726-MW Grande Dixence project drains a 350-square-kilometer reach of the Zermatt and Herens valleys in the southwestern Swiss Alps. About half of the drainage area is covered by active glaciers. Because the glaciers in Zermatt Valley are so low in altitude, their water is collected in Z`mutt Reservoir at the base of the Matterhorn, then pumped up 500 meters for transport to the main Grande Disence Reservoir near Sion. The glacier water is heavily laden with sand. In spite of a gravel pass and a desilter, the 700,000-acubic-meter Z`mutt Reservoir receives large quantities of sand. The sand tends to remain in solution because of the low water temperatures (1 to 2 degrees Centigrade). In the original intake system, the sand would be sucked into the pump intakes, causing extensive erosion to the pump wheels and an expensive yearly program of repair. (Pump damage averaged 200,000 Swiss Francs ($284,000 U.S.) per year between 1980 and 1985.)

  11. Electronic acquisition of OSCE performance using tablets

    PubMed Central

    Hochlehnert, Achim; Schultz, Jobst-Hendrik; Möltner, Andreas; Tımbıl, Sevgi; Brass, Konstantin; Jünger, Jana

    2015-01-01

    Background: Objective Structured Clinical Examinations (OSCEs) often involve a considerable amount of resources in terms of materials and organization since the scores are often recorded on paper. Computer-assisted administration is an alternative with which the need for material resources can be reduced. In particular, the use of tablets seems sensible because these are easy to transport and flexible to use. Aim: User acceptance concerning the use of tablets during OSCEs has not yet been extensively investigated. The aim of this study was to evaluate tablet-based OSCEs from the perspective of the user (examiner) and the student examinee. Method: For two OSCEs in Internal Medicine at the University of Heidelberg, user acceptance was analyzed regarding tablet-based administration (satisfaction with functionality) and the subjective amount of effort as perceived by the examiners. Standardized questionnaires and semi-standardized interviews were conducted (complete survey of all participating examiners). In addition, for one OSCE, the subjective evaluation of this mode of assessment was gathered from a random sample of participating students in semi-standardized interviews. Results: Overall, the examiners were very satisfied with using tablets during the assessment. The subjective amount of effort to use the tablet was found on average to be “hardly difficult”. The examiners identified the advantages of this mode of administration as being in particular the ease of use and low rate of error. During the interviews of the examinees, acceptance for the use of tablets during the assessment was also detected. Discussion: Overall, it was found that the use of tablets during OSCEs was well accepted by both examiners and examinees. We expect that this mode of assessment also offers advantages regarding assessment documentation, use of resources, and rate of error in comparison with paper-based assessments; all of these aspects should be followed up on in further studies. PMID:26483854

  12. Preparation and evaluation of once-daily sustained-release coated tablets of tolterodine-L-tartrate.

    PubMed

    Pradhan, Roshan; Kim, Yong-Il; Chang, Sun Woo; Kim, Jong Oh

    2014-01-01

    In this study, once-daily, sustained-release matrix tablets of tolterodine l-tartrate (TOL) for treatment of overactive bladder (OAB) were prepared by direct compression using various amounts of hydrophilic polymers such as HPMC 2910 and HPMC 2208 along with other tablet excipients; the tablets were then coated. In vitro dissolution studies were carried out under different pH conditions. The dissolution data were fitted into zero-order, first-order, Higuchi and Korsemeyer-Peppas models to identify the pharmacokinetics and mechanism of drug release. Among the four formulations (F1-F4), the dissolution profiles of formulation F2 were most similar to the marketed product with similarity and difference factors of 70.25 and 1.59 respectively. Furthermore, pharmacokinetic studies were carried out in healthy human volunteers after oral administration of the prepared TOL sustained-release matrix-coated tablet and the marketed product. The results revealed that the pharmacokinetic parameters of AUC, Cmax, Tmax, t1/2, Kel, and MRT of TOL for the developed formulation (F2) were not significantly different from that for the marketed product, suggesting that they were bioequivalent. Therefore, the developed sustained-release tablet formulation of TOL could be an alternative dosage form to the SR capsule for treatment of OAB. PMID:24184032

  13. Comparative evaluation of drug release from aged prolonged polyethylene oxide tablet matrices: effect of excipient and drug type.

    PubMed

    Shojaee, Saeed; Kaialy, Waseem; Cumming, Kenneth Iain; Nokhodchi, Ali

    2016-03-01

    Polyethylene oxide (PEO) undergoes structural adjustments caused by elevated temperatures, which results in loss of its stability within direct compression tablets. The aim of this study was to evaluate the influence of filler solubility on the drug delivery process of matrix tablets containing drugs with different water-solubility properties and stored at elevated temperature. The results demonstrated that in the case of propranolol HCl (highly water-soluble) tablet matrices, soluble lactose promoted drug release, whereas, a stable release of drug was observed with insoluble DCP. A drug release pattern similar to the propranolol HCl formulation containing DCP was obtained for hydrophilic matrix tablets containing either lactose or DCP for the less water-soluble drug, zonisamide. In the case of the partially water-soluble drug, theophylline, formulated with lower molecular weight PEO 750, drug release increased considerably in the presence of both fillers with increasing storage time, however a stable release rate (similar to fresh samples) was observed in the case of higher molecular weight PEO 303 tablet matrices containing theophylline with either lactose or DCP. The hydration properties (e.g. solubility) of the diluents had a considerable effect on drug release behavior from various model matrices; this effect was dependent on both molecular weight of PEO and solubility of drug. PMID:25410967

  14. Mechanical properties of excipients do not affect polymer matrix formation.

    PubMed

    Chatterjee, Lipika; Rades, Thomas; Tucker, Ian G

    2010-01-15

    Coalescence of polymer particles has been identified as a crucial step in film formation on tablets, pellets and granules. Though the significance of thermal treatment on matrix dosage forms is well established the process of coalescence in matrix formation and the forces driving it remain unexplored. The aim of this study was to investigate whether stresses in tablets, caused by deformation of excipient during compression, provide a driving force for polymer matrix formation. Polymer matrix tablets containing Eudragit-RLPO, a pH independent and permeable polymer at two levels 10 and 40% (w/w) were prepared by direct compression. Either lactose monohydrate (brittle) or mannitol (plastic) was used as a diluent at 80 or 50% (w/w) and indomethacin, a model drug was present at 10% (w/w). Tablets from each formulation type were prepared at two compression pressures either 221 MPa (above the yield pressure of both excipients) or 74 MPa (below the yield pressure of both excipients). Tablets from each formulation type compressed at the two compression pressures were thermally treated at 40 degrees C (below Tg) or 70 degrees C (above Tg) for 24 h. The rotating basket (100 rpm) method was used for the release studies conducted at 37 degrees C in 900 ml phosphate buffer (0.2 M) pH 7.2 as the dissolution medium. Morphological characteristics of the tablets were observed by scanning electron microscopy. Differences in tablet structure due to the formulation and processing variables were further evaluated by disintegration and tensile strength testing. Data from this factorial study were analysed by analysis of variance. Excipient mechanical properties determine matrix properties only at low polymer level independent of curing temperature and at high polymer level cured at 40 degrees C only. Though lactose and mannitol have different mechanical properties and therefore different deformation behaviors, this did not influence the properties of tablets containing 40% (w/w) polymer cured at 70 degrees C, suggesting stresses in these tablets are not a significant driving force for matrix formation. PMID:19819317

  15. The origin of tablet boudinage: Results from experiments using power-law rock analogs

    NASA Astrophysics Data System (ADS)

    Zulauf, J.; Zulauf, G.; Kraus, R.; Gutiérrez-Alonso, G.; Zanella, F.

    2011-10-01

    We used power-law viscous plasticine ( n = ca. 7) as a rock analog to simulate boudinage of rocks undergoing dislocation creep and brittle fracture. A competent plasticine layer, oriented perpendicular to the main shortening direction, Z, underwent bulk pure flattening inside a less competent plasticine matrix. Computer tomographic analyses of the deformed samples revealed that boudinage results from an initial phase of viscous necking followed by tensile failure along the previously formed necks. The resulting boudins display a polygonal shape in plan-view and are referred to as 'tablet boudins' (in contrast to the square to rectangular shaped chocolate-tablet boudins). The ratio between the plan-view long and short axis, R, ranges from 1.2 to 2.6. The polygonal, non-isometric shape of the tablet boudins can be explained by the strong interaction of concentric and radial tensile fractures. With increasing layer thickness, Hi, the mean diameter of the boudin tablets, Wa, increases, while the number of boudins, N, decreases. Progressive finite strain results in a higher number of the boudins and a smaller mean diameter. The thickness of the boudins, Hf, is almost the same as the initial layer thickness, Hi, while the aspect ratio ( Wd = Wa / Hf) decreases with layer thickness and finite strain. The mean Wd values obtained from all experiments span from ca. 4 to ca. 11. Tablet boudins, described in the present paper, have yet not been described from natural outcrops. The reasons might be that pure flattening strain is not common in nature, and the characterization and evaluation of tablet boudins requires geometrical analysis in three dimensions, which is a difficult task when such structures occur in nature.

  16. Formulation and optimization of potassium iodide tablets.

    PubMed

    Al-Achi, Antoine; Patel, Binit

    2015-01-01

    The use of potassium iodide (KI) as a protective agent against accidental radioactive exposure is well established. In this study, we aimed to prepare a KI tablet formulation using a direct compression method. We utilized Design of Experiment (DoE)/mixture design to define the best formulation with predetermined physical qualities as to its dissolution, hardness, assay, disintegration, and angle of repose. Based on the results from the DoE, the formulation had the following components (%w/w): Avicel 48.70%, silicon dioxide 0.27%, stearic acid (1.00%), magnesium stearate 2.45%, and dicalcium phosphate 18.69%, in addition to potassium iodide 28.89% (130 mg/tablet). This formulation was scaled-up using two tablet presses, a single-punch press and a rotary mini tablet press. The final scaled-up formulation was subjected to a variety of quality control tests, including photo-stability testing. The results indicate that potassium iodide tablets prepared by a rotary mini tablet press had good pharmaceutical characteristics and a shelf-life of 25 days when stored at room temperature protected from light. PMID:25685048

  17. Recycling of ceramic particulate reinforced aluminium metal matrix composites

    SciTech Connect

    Sharma, S.C.; Murthy, C.S.C.; Kamath, R.; Vinai Babu, B.R.; Satish, B.M.; Girish, B.M.

    1995-12-31

    The aluminum matrix composites with ceramic dispersoids can be separated by the density difference concept. In the proposed work, composite scrap is recycled using an oil fired furnace. The scrap is melted in the furnace and temperature is maintained below 740 degree centigrade. Because of the density difference the lighter dispersoids will float and heavier dispersoids will settle down. The clean melt is separated be removing the floating and settled dispersoids, and then filtering using ceramic filters.

  18. Airship-floated wind turbine

    SciTech Connect

    Watson, W. K.

    1985-01-01

    A wind turbine, by use of a tethered airship for support, may be designed for the economical recovery of power at heights of 2,000 feet or more above ground, at which height power density in the wind is typically three times the power density available to a conventionally supported wind turbine. Means can be added to such an airship-floated wind turbine which will permit its generators to be used to meet load demand even during periods of little or no wind. Described to this end is a wind turbine system which combines, among other novel features: a novel tether line system which provides access for men and materials to the supporting airship while in active service, a novel system for providing additional buoyant lift at the nose of the turbine-supporting airship to offset the vertical component of tension induced in the tether line by the downwind force exerted by the turbine blades, a novel bearing assembly at the nose of the supporting airship which permits the airship to rotate as a unit with the turbine it supports without causing a similar rotation of the tether line, a novel turbine airship structure which handles concentrated loads from the turbine efficiently and also permits the safe use of hydrogen for buoyancy, a novel ''space frame'' structure which supports the turbine blades and greatly reduces blade weight, a novel system for controlling turbine blade angle of incidence and for varying blade incidene in synchrony with blade angular position abut the turbine axis to provide greater control over airship movement, a novel system for locating propellor-driven generators out at the wind turbine perimeter and for using lightweight, high-RPM generators to produce electrical energy at a power line frequency, which greatly reduces the weight required to convert turbine blade torque into useful power, and a novel system for incorporating compressed air storage and combustion turbine components into the wind turbine's generator drive systems.

  19. 40 CFR 65.45 - External floating roof converted into an internal floating roof.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 15 2010-07-01 2010-07-01 false External floating roof converted into an internal floating roof. 65.45 Section 65.45 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Storage Vessels §...

  20. Floating-Point Units and Algorithms for field-programmable gate arrays

    Energy Science and Technology Software Center (ESTSC)

    2005-11-01

    The software that we are attempting to copyright is a package of floating-point unit descriptions and example algorithm implementations using those units for use in FPGAs. The floating point units are best-in-class implementations of add, multiply, divide, and square root floating-point operations. The algorithm implementations are sample (not highly flexible) implementations of FFT, matrix multiply, matrix vector multiply, and dot product. Together, one could think of the collection as an implementation of parts of themore » BLAS library or something similar to the FFTW packages (without the flexibility) for FPGAs. Results from this work has been published multiple times and we are working on a publication to discuss the techniques we use to implement the floating-point units, For some more background, FPGAS are programmable hardware. "Programs" for this hardware are typically created using a hardware description language (examples include Verilog, VHDL, and JHDL). Our floating-point unit descriptions are written in JHDL, which allows them to include placement constraints that make them highly optimized relative to some other implementations of floating-point units. Many vendors (Nallatech from the UK, SRC Computers in the US) have similar implementations, but our implementations seem to be somewhat higher performance. Our algorithm implementations are written in VHDL and models of the floating-point units are provided in VHDL as well. FPGA "programs" make multiple "calls" (hardware instantiations) to libraries of intellectual property (IP), such as the floating-point unit library described here. These programs are then compiled using a tool called a synthesizer (such as a tool from Synplicity, Inc.). The compiled file is a netlist of gates and flip-flops. This netlist is then mapped to a particular type of FPGA by a mapper and then a place- and-route tool. These tools assign the gates in the netlist to specific locations on the specific type of FPGA chip used and constructs the required routes between them. The result is a "bitstream" that is analogous to a compiled binary. The bitstream is loaded into the FPGA to create a specific hardware configuration.« less

  1. Floating-Point Units and Algorithms for field-programmable gate arrays

    SciTech Connect

    Underwood, Keith D.; Hemmert, K. Scott

    2005-11-01

    The software that we are attempting to copyright is a package of floating-point unit descriptions and example algorithm implementations using those units for use in FPGAs. The floating point units are best-in-class implementations of add, multiply, divide, and square root floating-point operations. The algorithm implementations are sample (not highly flexible) implementations of FFT, matrix multiply, matrix vector multiply, and dot product. Together, one could think of the collection as an implementation of parts of the BLAS library or something similar to the FFTW packages (without the flexibility) for FPGAs. Results from this work has been published multiple times and we are working on a publication to discuss the techniques we use to implement the floating-point units, For some more background, FPGAS are programmable hardware. "Programs" for this hardware are typically created using a hardware description language (examples include Verilog, VHDL, and JHDL). Our floating-point unit descriptions are written in JHDL, which allows them to include placement constraints that make them highly optimized relative to some other implementations of floating-point units. Many vendors (Nallatech from the UK, SRC Computers in the US) have similar implementations, but our implementations seem to be somewhat higher performance. Our algorithm implementations are written in VHDL and models of the floating-point units are provided in VHDL as well. FPGA "programs" make multiple "calls" (hardware instantiations) to libraries of intellectual property (IP), such as the floating-point unit library described here. These programs are then compiled using a tool called a synthesizer (such as a tool from Synplicity, Inc.). The compiled file is a netlist of gates and flip-flops. This netlist is then mapped to a particular type of FPGA by a mapper and then a place- and-route tool. These tools assign the gates in the netlist to specific locations on the specific type of FPGA chip used and constructs the required routes between them. The result is a "bitstream" that is analogous to a compiled binary. The bitstream is loaded into the FPGA to create a specific hardware configuration.

  2. Amorphous Formulation and in Vitro Performance Testing of Instantly Disintegrating Buccal Tablets for the Emergency Delivery of Naloxone.

    PubMed

    Alqurshi, Abdulmalik; Kumar, Zahrae; McDonald, Rebecca; Strang, John; Buanz, Asma; Ahmed, Shagufta; Allen, Elizabeth; Cameron, Peter; Rickard, James A; Sandhu, Verity; Holt, Chris; Stansfield, Rebecca; Taylor, David; Forbes, Ben; Royall, Paul G

    2016-05-01

    The aim of this study was to develop a freeze-dried buccal tablet for the rapid delivery of naloxone in opioid overdose. The tablet composition was optimized to produce an amorphous matrix, which was confirmed by the absence of peaks associated with crystallinity observed by differential scanning calorimetry and powder X-ray diffraction. Tablets with high gelatin content lacked adequate porosity. Mannitol was added to the formulation to bridge and intercalate gelatin's tight polymer aggregates, however sodium bicarbonate was also required to prevent crystallization within the tablets. A linear reduction in mannitol's recrystallization enthalpy was observed with increasing sodium bicarbonate concentration (ΔrecryH = -20.3[NaHCO3] + 220.9; r(2) = 0.9, n = 18). The minimum sodium bicarbonate concentration for full inhibition of mannitol crystallization was 10.9% w/w. Freeze-dried tablets with lower amounts of sodium bicarbonate possessed a crystalline fraction that PXRD identified as mannitol hemihydrate from the unique peak at 9.7° 2θ. Mannitol's greater affinity for both ions and residual water rather than its affinity for self-association was the mechanism for the inhibition of crystallization observed here. The optimized tablet (composition mannitol 24% w/w (4.26 mg), gelatin 65% w/w (11.7 mg), sodium bicarbonate 11% w/w (1.98 mg), and naloxone 800 μg) formed predominantly amorphous tablets that disintegrated in less than 10 s. Optimized tablets were chemically and physically stable over 9 months storage at 25 °C. As speed of drug liberation is the critical performance attribute for a solid dosage form designed to deliver drug in an emergency, a novel imaging based in vitro disintegration assay for buccal tablets was developed. The assay was optimized with regard to conditions in the buccal cavity: i.e., temperature 33-37 °C, volume of medium (0.1-0.7 mL), and use of mucin-containing biorelevant medium. The disintegration assay was sensitive to temperature, medium volume, and medium composition; naloxone tablet disintegration was extremely rapid, with full disintegration ranging from 5 to 20 s. In conclusion, rapidly disintegrating tablets have been developed which are suitable for proof-of-concept clinical trial in humans to determine the pharmacokinetics of naloxone delivered via the buccal route. PMID:26977787

  3. Application of chemometric algorithms to MALDI mass spectrometry imaging of pharmaceutical tablets.

    PubMed

    Gut, Yoann; Boiret, Mathieu; Bultel, Laurent; Renaud, Tristan; Chetouani, Aladine; Hafiane, Adel; Ginot, Yves-Michel; Jennane, Rachid

    2015-02-01

    During drug product development, the nature and distribution of the active substance have to be controlled to ensure the correct activity and the safety of the final medication. Matrix assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), due to its structural and spatial specificities, provides an excellent way to analyze these two critical parameters in the same acquisition. The aim of this work is to demonstrate that MALDI-MSI, coupled with four well known multivariate statistical analysis algorithms (PCA, ICA, MCR-ALS and NMF), is a powerful technique to extract spatial and spectral information about chemical compounds from known or unknown solid drug product formulations. To test this methodology, an in-house manufactured tablet and a commercialized Coversyl(®) tablet were studied. The statistical analysis was decomposed into three steps: preprocessing, estimation of the number of statistical components (manually or using singular value decomposition), and multivariate statistical analysis. The results obtained showed that while principal component analysis (PCA) was efficient in searching for sources of variation in the matrix, it was not the best technique to estimate an unmixing model of a tablet. Independent component analysis (ICA) was able to extract appropriate contributions of chemical information in homogeneous and heterogeneous datasets. Non-negative matrix factorization (NMF) and multivariate curve resolution-alternating least squares (MCR-ALS) were less accurate in obtaining the right contribution in a homogeneous sample but they were better at distinguishing the semi-quantitative information in a heterogeneous MALDI dataset. PMID:25543287

  4. An empirical model for dissolution profile and its application to floating dosage forms.

    PubMed

    Weiss, Michael; Kriangkrai, Worawut; Sungthongjeen, Srisagul

    2014-06-01

    A sum of two inverse Gaussian functions is proposed as a highly flexible empirical model for fitting of in vitro dissolution profiles. The model was applied to quantitatively describe theophylline release from effervescent multi-layer coated floating tablets containing different amounts of the anti-tacking agents talc or glyceryl monostearate. Model parameters were estimated by nonlinear regression (mixed-effects modeling). The estimated parameters were used to determine the mean dissolution time, as well as to reconstruct the time course of release rate for each formulation, whereby the fractional release rate can serve as a diagnostic tool for classification of dissolution processes. The approach allows quantification of dissolution behavior and could provide additional insights into the underlying processes. PMID:24613489

  5. Modulation of drug (metoprolol succinate) release by inclusion of hydrophobic polymer in hydrophilic matrix.

    PubMed

    Siddique, Sabahuddin; Bose, Anirbandeep; Khanam, Jasmina

    2011-09-01

    The objective of this study was to develop sustained release (SR) matrix tablets of metoprolol succinate (MS), by using different polymer combinations and fillers, to optimize by response surface methodology and to evaluate biopharmaceutical parameters of the optimized product. Matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and ethyl cellulose (EC); and lactose and dibasic calcium phosphate dihydrate (DCP) as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was subjected to further study like scanning electron microscopy, swelling study and in vivo study in rabbit model. Both in vitro and in vivo study revealed that combining of HPMC K100M (21.95%) with EC (8.85%), and use of DCP as filler sustained the action up to 12 h. The in vivo study of new SR tablets showed significant improvement in the oral bioavailability of MS in rabbits after a single oral dose of 25 mg. The delayed T(max) and lower C(max) indicated a slow and SR of MS from the optimized matrix tablets in comparison with the immediate release dosage form. The developed SR (MS) tablet of improved efficacy can perform therapeutically better than conventional tablet. PMID:21401340

  6. Floating seal system for rotary devices

    DOEpatents

    Banasiuk, H.A.

    1983-08-23

    This invention relates to a floating seal system for rotary devices to reduce gas leakage around the rotary device in a duct and across the face of the rotary device to an adjacent duct. The peripheral seal bodies are made of resilient material having a generally U-shaped cross section wherein one of the legs is secured to a support member and the other of the legs forms a contacting seal against the rotary device. The legs of the peripheral seal form an extended angle of intersection of about 10[degree] to about 30[degree] in the unloaded condition to provide even sealing forces around the periphery of the rotary device. The peripheral seal extends around the periphery of the support member except where intersected by radial seals which reduce gas leakage across the face of the rotary device and between adjacent duct portions. The radial seal assembly is fabricated from channel bars, the smaller channel bar being secured to the divider of the support member and a larger inverted rigid floating channel bar having its legs freely movable over the legs of the smaller channel bar forming therewith a tubular channel. A resilient flexible tube is positioned within the tubular channel for substantially its full length to reduce gas leakage across the tubular channel. A spacer extends beyond the face of the floating channel near each end of the floating channel a distance to provide desired clearance between the floating channel and the face of the rotary device. 5 figs.

  7. Battery charging in float vs. cycling environments

    SciTech Connect

    COREY,GARTH P.

    2000-04-20

    In lead-acid battery systems, cycling systems are often managed using float management strategies. There are many differences in battery management strategies for a float environment and battery management strategies for a cycling environment. To complicate matters further, in many cycling environments, such as off-grid domestic power systems, there is usually not an available charging source capable of efficiently equalizing a lead-acid battery let alone bring it to a full state of charge. Typically, rules for battery management which have worked quite well in a floating environment have been routinely applied to cycling batteries without full appreciation of what the cycling battery really needs to reach a full state of charge and to maintain a high state of health. For example, charge target voltages for batteries that are regularly deep cycled in off-grid power sources are the same as voltages applied to stand-by systems following a discharge event. In other charging operations equalization charge requirements are frequently ignored or incorrectly applied in cycled systems which frequently leads to premature capacity loss. The cause of this serious problem: the application of float battery management strategies to cycling battery systems. This paper describes the outcomes to be expected when managing cycling batteries with float strategies and discusses the techniques and benefits for the use of cycling battery management strategies.

  8. Floating seal system for rotary devices

    DOEpatents

    Banasiuk, Hubert A.

    1983-01-01

    This invention relates to a floating seal system for rotary devices to reduce gas leakage around the rotary device in a duct and across the face of the rotary device to an adjacent duct. The peripheral seal bodies are made of resilient material having a generally U-shaped cross section wherein one of the legs is secured to a support member and the other of the legs forms a contacting seal against the rotary device. The legs of the peripheral seal form an extended angle of intersection of about 10.degree. to about 30.degree. in the unloaded condition to provide even sealing forces around the periphery of the rotary device. The peripheral seal extends around the periphery of the support member except where intersected by radial seals which reduce gas leakage across the face of the rotary device and between adjacent duct portions. The radial seal assembly is fabricated from channel bars, the smaller channel bar being secured to the divider of the support member and a larger inverted rigid floating channel bar having its legs freely movable over the legs of the smaller channel bar forming therewith a tubular channel. A resilient flexible tube is positioned within the tubular channel for substantially its full length to reduce gas leakage across the tubular channel. A spacer extends beyond the face of the floating channel near each end of the floating channel a distance to provide desired clearance between the floating channel and the face of the rotary device.

  9. Astronomy Learning Activities for Tablets

    NASA Astrophysics Data System (ADS)

    Pilachowski, Catherine A.; Morris, Frank

    2015-08-01

    Four web-based tools allow students to manipulate astronomical data to learn concepts in astronomy. The tools are HTML5, CSS3, Javascript-based applications that provide access to the content on iPad and Android tablets. The first tool “Three Color” allows students to combine monochrome astronomical images taken through different color filters or in different wavelength regions into a single color image. The second tool “Star Clusters” allows students to compare images of stars in clusters with a pre-defined template of colors and sizes in order to produce color-magnitude diagrams to determine cluster ages. The third tool adapts Travis Rector’s “NovaSearch” to allow students to examine images of the central regions of the Andromeda Galaxy to find novae. After students find a nova, they are able to measure the time over which the nova fades away. A fourth tool, Proper Pair, allows students to interact with Hipparcos data to evaluate close double stars are physical binaries or chance superpositions. Further information and access to these web-based tools are available at www.astro.indiana.edu/ala/.

  10. Spectroscopic insight for tablet compression.

    PubMed

    Lakio, S; Ylinärä, H; Antikainen, O; Räikkönen, H; Yliruusi, J

    2015-02-01

    Tablet compression process has been studied over the years from various perspectives. However what exactly happens to material during compression is still unknown. In this study a novel compression die which enables real-time spectroscopic measurements during the compression of material is represented. Both near infrared and Raman spectroscope probes can be attached to the die. In this study the usage of the die is demonstrated by using Raman spectroscopy. Eicosane, d-glucose anhydrate, α-lactose monohydrate and xylitol were used in the study because their compression behavior and bonding properties during compression were assumed to be different. The intensity of the Raman signal changed during compression with all of the materials. However, the intensity changes were different within the materials. The biggest differences were within the xylitol spectra. It was noticed that some peaks disappeared with higher compression pressures indicating that the pressure affected variously on different bonds in xylitol structure. These reversible changes were supposed to relate the changes in conformation and crystal structure. As a conclusion, the die was found to be a significant addition for studying compression process in real-time. It can help to reveal Process induced transformations (PITs) occurring during powder compaction. PMID:25448072

  11. Swelling/Floating Capability and Drug Release Characterizations of Gastroretentive Drug Delivery System Based on a Combination of Hydroxyethyl Cellulose and Sodium Carboxymethyl Cellulose

    PubMed Central

    Chen, Ying-Chen; Ho, Hsiu-O; Liu, Der-Zen; Siow, Wen-Shian; Sheu, Ming-Thau

    2015-01-01

    The aim of this study was to characterize the swelling and floating behaviors of gastroretentive drug delivery system (GRDDS) composed of hydroxyethyl cellulose (HEC) and sodium carboxymethyl cellulose (NaCMC) and to optimize HEC/NaCMC GRDDS to incorporate three model drugs with different solubilities (metformin, ciprofloxacin, and esomeprazole). Various ratios of NaCMC to HEC were formulated, and their swelling and floating behaviors were characterized. Influences of media containing various NaCl concentrations on the swelling and floating behaviors and drug solubility were also characterized. Finally, release profiles of the three model drugs from GRDDS formulation (F1-4) and formulation (F1-1) were examined. Results demonstrated when the GRDDS tablets were tested in simulated gastric solution, the degree of swelling at 6 h was decreased for each formulation that contained NaCMC in comparison to those in de-ionized water (DIW). Of note, floating duration was enhanced when in simulated gastric solution compared to DIW. Further, the hydration of tablets was found to be retarded as the NaCl concentration in the medium increased resulting in smaller gel layers and swelling sizes. Dissolution profiles of the three model drugs in media containing various concentrations of NaCl showed that the addition of NaCl to the media affected the solubility of the drugs, and also their gelling behaviors, resulting in different mechanisms for controlling a drug’s release. The release mechanism of the freely water-soluble drug, metformin, was mainly diffusion-controlled, while those of the water-soluble drug, ciprofloxacin, and the slightly water-soluble drug, esomeprazole, were mainly anomalous diffusion. Overall results showed that the developed GRDDS composed of HEC 250HHX and NaCMC of 450 cps possessed proper swelling extents and desired floating periods with sustained-release characteristics. PMID:25617891

  12. Floating point fault tolerance with backward error assertions

    SciTech Connect

    Boley, D.; Golub, G.H.; Makar, S.; Saxena, N.; Mccluskey, E.J.

    1995-02-01

    This paper introduces an assertion scheme based on the backward error analysis for error detection in algorithms that solve dense systems of linear equations, Ax = b. Unlike previous methods, this Backward Error Assertion Model is specifically designed to operate in an environment of floating point arithmetic subject to round-off errors, and it can be easily instrumented in a Watchdog processor environment. The complexity of verifying assertions is Omicron (n(sup 2)), compared to the Omicron (n(sup 3)) complexity of algorithms solving Ax = b. Unlike other proposed error detection methods, this assertion model does not require any encoding of the matrix A. Experimental results under various error models are presented to validate the effectiveness of this assertion scheme. 22 refs.

  13. Design and evaluation of a specific, bi-phase extended release system based on differently coated mini-tablets.

    PubMed

    Aleksovski, Aleksandar; Luštrik, Matevž; Šibanc, Rok; Dreu, Rok

    2015-07-30

    Mini-tablets are gaining great attention as systems capable of being formulated into multiple unit systems providing a specific drug release pattern. Within the presented research a combined, multiple-unit system, based on different coated matrix mini-tablets, has been developed in order to achieve 24-h specific sigmoid extended release of the model drug paliperidone. The mini-tablets were based on different amounts of polyvinyl acetate/polyvinyl pyrolidone mixture as the matrix former, providing extended release, and two different types of pH-dependent, acrylic polymer coatings, providing delay in release onset, and thus achieving the required specific sigmoid release pattern imposed by the original drug on the market. The selected formulation proved to be consistent with pharmacopoeial requirements. It was also in vitro similar (f2) to the original drug and the theoretical linear release profile, as well as robust and reproducible regarding in vitro release in different fasted gastro-intestinal conditions. This is proof of concept that 24-h, specific, and almost linear release profile of drugs with high solubility can be achieved by employing technology of coated matrix mini-tablets. PMID:25845632

  14. 21 CFR 520.2150b - Stanozolol chewable tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... treatment in dogs. (2) Administered orally to small breeds of dogs, 1/2 to 1 tablet twice daily for several weeks; to large breeds of dogs, 1 to 2 tablets twice daily for several weeks. (3) Federal law...

  15. 21 CFR 520.2150b - Stanozolol chewable tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... treatment in dogs. (2) Administered orally to small breeds of dogs, 1/2 to 1 tablet twice daily for several weeks; to large breeds of dogs, 1 to 2 tablets twice daily for several weeks. (3) Federal law...

  16. 21 CFR 520.2150b - Stanozolol chewable tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... treatment in dogs. (2) Administered orally to small breeds of dogs, 1/2 to 1 tablet twice daily for several weeks; to large breeds of dogs, 1 to 2 tablets twice daily for several weeks. (3) Federal law...

  17. 21 CFR 520.2150b - Stanozolol chewable tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... treatment in dogs. (2) Administered orally to small breeds of dogs, 1/2 to 1 tablet twice daily for several weeks; to large breeds of dogs, 1 to 2 tablets twice daily for several weeks. (3) Federal law...

  18. 21 CFR 520.2150b - Stanozolol chewable tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... treatment in dogs. (2) Administered orally to small breeds of dogs, 1/2 to 1 tablet twice daily for several weeks; to large breeds of dogs, 1 to 2 tablets twice daily for several weeks. (3) Federal law...

  19. Fast-melting tablets based on highly plastic granules.

    PubMed

    Fu, Yourong; Jeong, Seong Hoon; Park, Kinam

    2005-12-01

    Highly plastic granules that can be compressed into tablets at low pressure were developed to make fast-melting tablets (FMTs) by compression method. The highly plastic granules are composed of three components: a plastic material, a material enhancing water penetration, and a wet binder. One of the unique properties of the highly plastic granules is that they maintain a porous structure even after compression into tablets. The porous and plastic nature of the granules allows fast absorption of water into the compressed tablet for fast melting/dissolution of the tablet. The prepared tablets possess tablet strength and friability that are suitable for multi-tablet packages. The three-component highly plastic granules provide an effective way of making FMTs by compression. PMID:16260059

  20. Novel approach of aceclofenac fast dissolving tablet.

    PubMed

    Dave, Vivek; Yadav, Sachdev; Sharma, Swapnil; Vishwakarma, Pushpendra; Ali, Nasir

    2015-01-01

    Fast disintegrating tablets (FDTs) have received ever increasing demand during the last decade, and the field has become a hastily growing area in the pharmaceutical industry. Upon introduction into the mouth, these tablets dissolve or disintegrate in the mouth in the absence of additional water for easy administration of active pharmaceutical ingredients. Aceclofenac, an NSAID, has been recommended orally for the treatment of bone and connective tissue disorder and thus the formulation of the same resulted in development of several FDT technologies. The present aim is to formulate a tablet which disintegrate and dissolve rapidly and give its rapid onset of action: analgesic, antipyretic and anti-inflammatory action. Besides, the conventional tablets also show poor patient compliance an attempt had been made to formulate for FDT of aceclofenac by using various super disintegrants like sodium starch glycolate, croscarmellose sodium and crosspovidone (polyplasdone XL) and PEG 6000 followed by novel technique. The tablets were evaluated for friability, hardness, weight variation, disintegration time, wetting time, in vitro dissolution studies and drug content studies. It was concluded that the batch which was prepared by using combination of crosspovidone and sodium starch glycolate as a super disintegrant shows excellent disintegration time, enhance dissolution rate, taste masking and hence lead to improve efficacy and bioavailability of drug. PMID:25553683

  1. The tableting properties of melibiose monohydrate.

    PubMed

    Lakio, Satu; Sainio, Janne; Heljo, Petteri; Ervasti, Tuomas; Kivikero, Niina; Juppo, Anne

    2013-11-18

    In this research, the tableting properties of α-melibiose monohydrate were studied. Melibiose is a disaccharide which bears structural resemblance to lactose, because they both consist of galactose and glucose monosaccharide subunits. Compactibility and deformation behavior of two melibiose batches from different suppliers were studied and compared with α-lactose monohydrate and some other typical tableting excipients. Differences in the deformation behavior were determined comparing the shape of the Heckel plots, the yield pressure values and the strain rate sensitivity (SRS) indexes. In addition, the effect of moisture on the tabletability was studied. According to the yield pressures and SRS indexes melibiose was concluded to be fragmenting, even at higher degree than lactose monohydrate. However, the overall deformation behavior of melibiose was found to be similar to that of lactose monohydrate. Increase in moisture content resulted in higher tensile strengths of tablets for both melibiose batches, but it seemed to have more effect on compactibility of the other batch. In conclusion, melibiose has potential to be used as an excipient in tablet formulations. PMID:23994759

  2. Vibration characteristics of floating slab track

    NASA Astrophysics Data System (ADS)

    Kuo, Chen-Ming; Huang, Cheng-Hao; Chen, Yi-Yi

    2008-11-01

    Coupled equilibrium equations of suspended wheels and floating slab track system were solved with the fourth-order Runge-Kutta method to obtain the deflections, vibration velocities, and wheel-rail contact forces. The program was validated through several aspects. Cases with various vehicle speed, slab mass, and stiffness of slab bearing were analyzed to reveal the effects of slab bearing on track responses. The correlation between wheel-rail resonance and train speed was also discussed. It was found that rail deflections increase significantly as train speed increases. Although large slab mass may lower tuning frequency, it could also result in higher wheel-rail contact force and rail deflections. The floating slab track is effective in isolating loading above 10 Hz, which might present in some railway sections with irregularities. Adopting floating slab track for vibration control for environment along the railway may cause concerns about ride quality and track damages.

  3. Floating mechanism of a small liquid marble

    NASA Astrophysics Data System (ADS)

    Ooi, Chin Hong; Plackowski, Chris; Nguyen, Anh V.; Vadivelu, Raja K.; John, James A. St.; Dao, Dzung Viet; Nguyen, Nam-Trung

    2016-02-01

    Flotation of small solid objects and liquid droplets on water is critical to natural and industrial activities. This paper reports the floating mechanism of liquid marbles, or liquid droplets coated with hydrophobic microparticles. We used X-ray computed tomography (XCT) to acquire cross-sectional images of the floating liquid marble and interface between the different phases. We then analysed the shape of the liquid marble and the angles at the three-phase contact line (TPCL). We found that the small floating liquid marbles follow the mechanism governing the flotation of solid objects in terms of surface tension forces. However, the contact angles formed and deformation of the liquid marble resemble that of a sessile liquid droplet on a thin, elastic solid. For small liquid marbles, the contact angle varies with volume due to the deformability of the interface.

  4. Floating mechanism of a small liquid marble.

    PubMed

    Ooi, Chin Hong; Plackowski, Chris; Nguyen, Anh V; Vadivelu, Raja K; John, James A St; Dao, Dzung Viet; Nguyen, Nam-Trung

    2016-01-01

    Flotation of small solid objects and liquid droplets on water is critical to natural and industrial activities. This paper reports the floating mechanism of liquid marbles, or liquid droplets coated with hydrophobic microparticles. We used X-ray computed tomography (XCT) to acquire cross-sectional images of the floating liquid marble and interface between the different phases. We then analysed the shape of the liquid marble and the angles at the three-phase contact line (TPCL). We found that the small floating liquid marbles follow the mechanism governing the flotation of solid objects in terms of surface tension forces. However, the contact angles formed and deformation of the liquid marble resemble that of a sessile liquid droplet on a thin, elastic solid. For small liquid marbles, the contact angle varies with volume due to the deformability of the interface. PMID:26902930

  5. Anti-pollution and antifire floating barrier

    SciTech Connect

    Bossa, E.D.

    1981-07-21

    The barrier of this invention is formed by barrier sections and each of them can be wound up about a reel or bobbin, which is pivotably mounted within a main floating hollow element, which not only has the task of receiving, transporting, towing, launching and trawling the barrier section housed therein, but also it serves to provide anchoring points for this barrier. Each main barrier element is shaped in the form of a cage-like container provided with at least a side vertical entrance passage , through which a barrier section can be returned inside the container, or this section can be caused to come out, each main floating element thus serving as floating container for the transport of at least one of the barrier sections to or from their use place.

  6. Floating zone melting of cadmium telluride

    NASA Technical Reports Server (NTRS)

    Chang, Wen-Ming; Regel, L. L.; Wilcox, W. R.

    1992-01-01

    To produce superior crystals of cadmium telluride, floating zone melting in space has been proposed. Techniques required for floating zone melting of cadmium telluride are being developed. We have successfully float-zoned cadmium telluride on earth using square rods. A resistance heater was constructed for forming the molten zone. Evaporation of the molten zone was controlled by adding excess cadmium to the growth ampoule combined with heating of the entire ampoule. An effective method to hold the feed rod was developed. Slow rotation of the growth ampoule was proven experimentally to be necessary to achieve a complete symmetric molten zone. Most of the resultant cylindrical rods were single crystals with twins. Still needed is a suitable automatic method to control the zone length. We tried a fiber optical technique to control the zone length, but experiments showed that application of this technique to automate zone length control is unlikely to be successful.

  7. Floating mechanism of a small liquid marble

    PubMed Central

    Ooi, Chin Hong; Plackowski, Chris; Nguyen, Anh V.; Vadivelu, Raja K.; John, James A. St.; Dao, Dzung Viet; Nguyen, Nam-Trung

    2016-01-01

    Flotation of small solid objects and liquid droplets on water is critical to natural and industrial activities. This paper reports the floating mechanism of liquid marbles, or liquid droplets coated with hydrophobic microparticles. We used X-ray computed tomography (XCT) to acquire cross-sectional images of the floating liquid marble and interface between the different phases. We then analysed the shape of the liquid marble and the angles at the three-phase contact line (TPCL). We found that the small floating liquid marbles follow the mechanism governing the flotation of solid objects in terms of surface tension forces. However, the contact angles formed and deformation of the liquid marble resemble that of a sessile liquid droplet on a thin, elastic solid. For small liquid marbles, the contact angle varies with volume due to the deformability of the interface. PMID:26902930

  8. Formulation Optimization of Hydrodynamically Balanced Oral Controlled Release Bioadhesive Tablets of Tramadol Hydrochloride

    PubMed Central

    Singh, Bhupinder; Rani, Ashu; Babita; Ahuja, Naveen; Kapil, Rishi

    2010-01-01

    The directly compressible floating-bioadhesive tablets of tramadol were formulated using varying amounts Carbopol 971P (CP) and hydroxy-propylmethyl cellulose (HPMC), along with other requisite excipients. In vitro drug release profile, floatational characteristics and ex vivo bioadhesive strength using texture analyzer were determined, and systematically optimized using a 32 central composite design (CCD). The studies indicated successful formulation of gastroretentive compressed matrices with excellent controlled release, mucoadhesion and hydrodynamic balance. Comparison of the dissolution profiles of the optimized formulation, with optimal composition of CP:HPMC :: 80.0:125.0, with that of the marketed controlled release formulation other indicated analogy of drug release performance with each other. Validation of optimization study using eight confirmatory experimental runs indicated very high degree of prognostic ability of CCD with mean ± SEM of −0.06% ± 0.37. Further, the study successfully unravels the effect of the polymers on the selected response variables. PMID:21179349

  9. Well casing float shoe or collar

    SciTech Connect

    Kaufman, H. J.

    1985-08-06

    A well casing float shoe which is adapted for a variety of well installations consists of a tubular metal shoe member filled with cementitious material having a longitudinal bore surrounding and securing in place a tubular metal sleeve. The metal sleeve is threaded at the top and bottom ends to receive a variety of sizes and types of check valves. A well casing float collar has the same construction, but the tubular shoe member is replaced with a tubular metal collar with threaded connections both above and below the cementitious filler material.

  10. Force inversion in floating plate dynamics

    NASA Astrophysics Data System (ADS)

    Dempsey, Kevin M.; Grossman, Nathaniel; Vasileva, Irina V.

    2006-02-01

    An axisymmetric floating plate of infinite extent is subjected to prescribed dynamics under the action of a point load. The problem of inverting the forcing is studied mathematically with a view to classifying its properties within the framework of integral equations. In the process, the floating plate problem is shown to be moderately ill-posed and the rate of change of the forcing is shown to initially be directly proportional to the acceleration of the plate. This latter result is incorporated into the numerical study that follows. Throughout the paper, a model problem is used as an analytical and numerical benchmark.

  11. [Simultaneous determination of three components in compound clorprenaline tablet by using the derivative-complementary tristimulus method].

    PubMed

    Li, Q Y; Zhuo, Z L; Chen, Y W

    1990-01-01

    Clorprenaline hydrochloride (a), bromhexine hydrochloride (b) and decloxizine hydrochloride (c) are three main components in clorprenaline compound tablet. The serious overlapping bands of their absorption spectra cause the interference in the determinations, especially the component of (a) which has both minor content and low absorption coefficient, thus making the analysis difficult. In this paper, the interference from matrix is eliminated by using first order derivative transformation. In combination with complementary tristimulus method and with the technique of additions, the concentrations of three components in tablets can be successfully determined simultaneously. A software developed in this laboratory makes possible the ease of parameter selection, reporting data in various formats and printing figures of dissolution process, showing a clear locus. This method will be of value to quality control in manufacturing process and to the research of the dissolution dynamics of tablets in simulated stomach. PMID:2284956

  12. 21 CFR 520.1696d - Penicillin V tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Penicillin V tablets. 520.1696d Section 520.1696d... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1696d Penicillin V tablets. (a) Specifications. Each tablet contains penicillin V potassium equivalent to 125 milligrams...

  13. 21 CFR 520.1696d - Penicillin V tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Penicillin V tablets. 520.1696d Section 520.1696d... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1696d Penicillin V tablets. (a) Specifications. Each tablet contains penicillin V potassium equivalent to 125 milligrams...

  14. 21 CFR 520.1446 - Milbemcyin oxime and lufenuron tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... oxime and lufenuron tablets. (a) Specifications—(1) Tablets containing: 2.3 milligrams (mg) milbemycin oxime and 46 mg lufenuron, 5.75 mg milbemycin oxime and 115 mg lufenuron, 11.5 mg milbemycin oxime and 230 mg lufenuron, or 23 mg milbemycin oxime and 460 mg lufenuron. (2) Flavored tablets containing:...

  15. 21 CFR 520.1696d - Penicillin V potassium tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Penicillin V potassium tablets. 520.1696d Section... Penicillin V potassium tablets. (a) Specifications. Each tablet contains penicillin V potassium equivalent to... susceptible to penicillin V potassium. (3) Limitations. Administer orally 1 to 2 hours prior to feeding...

  16. 21 CFR 520.1331 - Meclofenamic acid tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Meclofenamic acid tablets. 520.1331 Section 520...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1331 Meclofenamic acid tablets. (a) Specifications. Each tablet contains either 10 or 20 milligrams of meclofenamic acid....

  17. 21 CFR 520.1409 - Methylprednisolone, aspirin tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... tablet daily; 15 to 60 pounds, 1 to 2 tablets daily; 60 pounds and over, 2 tablets daily. (2) Indications... considerations. (1) Clinical and experimental data have demonstrated that corticosteroids administered orally or... placenta, and metritis. (2) Systemic therapy with methylprednisolone is contraindicated in animals...

  18. 21 CFR 520.1409 - Methylprednisolone, aspirin tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... tablet daily; 15 to 60 pounds, 1 to 2 tablets daily; 60 pounds and over, 2 tablets daily. (2) Indications... considerations. (1) Clinical and experimental data have demonstrated that corticosteroids administered orally or... placenta, and metritis. (2) Systemic therapy with methylprednisolone is contraindicated in animals...

  19. 21 CFR 520.1409 - Methylprednisolone, aspirin tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... tablet daily; 15 to 60 pounds, 1 to 2 tablets daily; 60 pounds and over, 2 tablets daily. (2) Indications... considerations. (1) Clinical and experimental data have demonstrated that corticosteroids administered orally or... placenta, and metritis. (2) Systemic therapy with methylprednisolone is contraindicated in animals...

  20. 21 CFR 520.2220d - Sulfadimethoxine-ormetoprim tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sulfadimethoxine-ormetoprim tablets. 520.2220d Section 520.2220d Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Sulfadimethoxine-ormetoprim tablets. (a) Specifications. Each tablet contains 120 milligrams (100 milligrams...

  1. 21 CFR 520.540c - Dexamethasone chewable tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Dexamethasone chewable tablets. 520.540c Section 520.540c Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Dexamethasone chewable tablets. (a) Specifications. Each half-scored tablet contains 0.25 milligram...

  2. 21 CFR 520.2158b - Dihydrostreptomycin tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Dihydrostreptomycin tablets. 520.2158b Section 520.2158b Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Dihydrostreptomycin tablets. (a) Specifications. Each tablet contains 37.5 milligrams dihydrostreptomycin (as...

  3. 21 CFR 520.2158b - Dihydrostreptomycin tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Dihydrostreptomycin tablets. 520.2158b Section 520.2158b Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Dihydrostreptomycin tablets. (a) Specifications. Each tablet contains 37.5 milligrams dihydrostreptomycin (as...

  4. 21 CFR 520.434 - Chlorphenesin carbamate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Chlorphenesin carbamate tablets. 520.434 Section 520.434 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Chlorphenesin carbamate tablets. (a) Specifications. Each tablet contains 400 milligrams of...

  5. 21 CFR 520.2362 - Thenium closylate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Thenium closylate tablets. 520.2362 Section 520... tablets. (a) Chemical name. (N,N-Dimethyl-N-2-phenoxyethyl-N-2′-thenylammo-nium)-p-chlorobenzene-sulfonate. (b) Specifications. Thenium closylate tablets contain thenium closylate equivalent to 500...

  6. 21 CFR 520.62 - Aminopentamide hydrogen sulphate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Aminopentamide hydrogen sulphate tablets. 520.62... Aminopentamide hydrogen sulphate tablets. (a) Chemical name. 4-(Dimethylamino)-2,2-diphenylvaleramide hydrogen sulfate. (b) Specifications. Each tablet contains 0.2 milligram of the drug. (c) Sponsor. See No....

  7. 21 CFR 520.763a - Dithiazanine iodide tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Dithiazanine iodide tablets. 520.763a Section 520... iodide tablets. (a) Chemical name. 3-Ethyl-2- -benzothiazolium iodide. (b) Specifications. Dithiazanine iodide tablets contain 10 milligrams, 50 milligrams, 100 milligrams, or 200 milligrams of...

  8. 21 CFR 520.784 - Doxylamine succinate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Doxylamine succinate tablets. 520.784 Section 520.784 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... succinate tablets. (a) Specifications. The drug is in tablet form and contains doxylamine succinate as...

  9. 21 CFR 520.246 - Butorphanol tartrate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Butorphanol tartrate tablets. 520.246 Section 520.246 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... tartrate tablets. (a) Specifications. Each tablet contains 1, 5, or 10 milligrams of butorphanol...

  10. 21 CFR 520.434 - Chlorphenesin carbamate tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Chlorphenesin carbamate tablets. 520.434 Section 520.434 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Chlorphenesin carbamate tablets. (a) Specifications. Each tablet contains 400 milligrams of...

  11. 21 CFR 520.2041 - Pyrantel pamoate chewable tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Pyrantel pamoate chewable tablets. 520.2041 Section 520.2041 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... pamoate chewable tablets. (a) Specifications. Each tablet contains pyrantel pamoate equivalent to 22.7...

  12. 21 CFR 520.784 - Doxylamine succinate tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Doxylamine succinate tablets. 520.784 Section 520.784 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... succinate tablets. (a) Specifications. The drug is in tablet form and contains doxylamine succinate as...

  13. 21 CFR 520.763a - Dithiazanine iodide tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Dithiazanine iodide tablets. 520.763a Section 520... iodide tablets. (a) Chemical name. 3-Ethyl-2- -benzothiazolium iodide. (b) Specifications. Dithiazanine iodide tablets contain 10 milligrams, 50 milligrams, 100 milligrams, or 200 milligrams of...

  14. 21 CFR 520.540c - Dexamethasone chewable tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Dexamethasone chewable tablets. 520.540c Section 520.540c Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Dexamethasone chewable tablets. (a) Specifications. Each half-scored tablet contains 0.25 milligram...

  15. 21 CFR 520.2042 - Pyrantel pamoate tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Pyrantel pamoate tablets. 520.2042 Section 520.2042 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... tablets. (a) Specifications. Each tablet contains pyrantel pamoate equivalent to 22.7, 45.4, or...

  16. 21 CFR 520.863 - Ethylisobutrazine hydrochloride tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ethylisobutrazine hydrochloride tablets. 520.863 Section 520.863 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Ethylisobutrazine hydrochloride tablets. (a) Specifications. Each tablet contains either 10 milligrams or...

  17. 21 CFR 520.246 - Butorphanol tartrate tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Butorphanol tartrate tablets. 520.246 Section 520.246 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... tartrate tablets. (a) Specifications. Each tablet contains 1, 5, or 10 milligrams of butorphanol...

  18. 21 CFR 520.2362 - Thenium closylate tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Thenium closylate tablets. 520.2362 Section 520... tablets. (a) Chemical name. (N,N-Dimethyl-N-2-phenoxyethyl-N-2′-thenylammo-nium)-p-chlorobenzene-sulfonate. (b) Specifications. Thenium closylate tablets contain thenium closylate equivalent to 500...

  19. 21 CFR 520.2041 - Pyrantel pamoate chewable tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Pyrantel pamoate chewable tablets. 520.2041 Section 520.2041 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... pamoate chewable tablets. (a) Specifications. Each tablet contains pyrantel pamoate equivalent to 22.7...

  20. 21 CFR 520.863 - Ethylisobutrazine hydrochloride tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Ethylisobutrazine hydrochloride tablets. 520.863 Section 520.863 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Ethylisobutrazine hydrochloride tablets. (a) Specifications. Each tablet contains either 10 milligrams or...

  1. 21 CFR 520.2042 - Pyrantel pamoate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Pyrantel pamoate tablets. 520.2042 Section 520.2042 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... tablets. (a) Specifications. Each tablet contains pyrantel pamoate equivalent to 22.7, 45.4, or...

  2. 21 CFR 520.1199 - Ivermectin, pyrantel, and praziquantel tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Ivermectin, pyrantel, and praziquantel tablets... Ivermectin, pyrantel, and praziquantel tablets. (a) Specifications. Each chewable tablet contains: (1) 34 micrograms (mcg) ivermectin, 28.5 milligrams (mg) pyrantel pamoate, and 28.5 mg praziquantel; (2) 68...

  3. 21 CFR 520.1200 - Ivermectin, fenbendazole, and praziquantel tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Ivermectin, fenbendazole, and praziquantel tablets... Ivermectin, fenbendazole, and praziquantel tablets. (a) Specifications. Each chewable tablet contains either: (1) 68 micrograms (g) ivermectin, 1.134 grams fenbendazole, and 57 milligrams (mg) praziquantel;...

  4. 21 CFR 520.1199 - Ivermectin, pyrantel, and praziquantel tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Ivermectin, pyrantel, and praziquantel tablets... Ivermectin, pyrantel, and praziquantel tablets. (a) Specifications. Each chewable tablet contains: (1) 34 micrograms (mcg) ivermectin, 28.5 milligrams (mg) pyrantel pamoate, and 28.5 mg praziquantel; (2) 68...

  5. 21 CFR 520.1200 - Ivermectin, fenbendazole, and praziquantel tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Ivermectin, fenbendazole, and praziquantel tablets... Ivermectin, fenbendazole, and praziquantel tablets. (a) Specifications. Each chewable tablet contains either: (1) 68 micrograms (g) ivermectin, 1.134 grams fenbendazole, and 57 milligrams (mg) praziquantel;...

  6. 21 CFR 520.1200 - Ivermectin, fenbendazole, and praziquantel tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Ivermectin, fenbendazole, and praziquantel tablets... Ivermectin, fenbendazole, and praziquantel tablets. (a) Specifications. Each chewable tablet contains either: (1) 68 micrograms (g) ivermectin, 1.134 grams fenbendazole, and 57 milligrams (mg) praziquantel;...

  7. 21 CFR 520.1199 - Ivermectin, pyrantel, and praziquantel tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Ivermectin, pyrantel, and praziquantel tablets... Ivermectin, pyrantel, and praziquantel tablets. (a) Specifications. Each chewable tablet contains: (1) 34 micrograms (mcg) ivermectin, 28.5 milligrams (mg) pyrantel pamoate, and 28.5 mg praziquantel; (2) 68...

  8. 21 CFR 520.784 - Doxylamine succinate tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Doxylamine succinate tablets. 520.784 Section 520...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS 520.784 Doxylamine succinate tablets. (a) Specifications. The drug is in tablet form and contains doxylamine succinate as...

  9. 21 CFR 520.784 - Doxylamine succinate tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Doxylamine succinate tablets. 520.784 Section 520...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS 520.784 Doxylamine succinate tablets. (a) Specifications. The drug is in tablet form and contains doxylamine succinate as...

  10. 21 CFR 520.784 - Doxylamine succinate tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Doxylamine succinate tablets. 520.784 Section 520...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS 520.784 Doxylamine succinate tablets. (a) Specifications. The drug is in tablet form and contains doxylamine succinate as...

  11. Damage-tolerance strategies for nacre tablets.

    PubMed

    Wang, Shengnan; Zhu, Xinqiao; Li, Qiyang; Wang, Rizhi; Wang, Xiaoxiang

    2016-05-01

    Nacre, a natural armor, exhibits prominent penetration resistance against predatory attacks. Unraveling its hierarchical toughening mechanisms and damage-tolerance design strategies may provide significant inspiration for the pursuit of high-performance artificial armors. In this work, relationships between the structure and mechanical performance of nacre were investigated. The results show that other than their brick-and-mortar structure, individual nacre tablets significantly contribute to the damage localization of nacre. Affected by intracrystalline organics, the tablets exhibit a unique fracture behavior. The synergistic action of the nanoscale deformation mechanisms increases the energy dissipation efficiency of the tablets and contributes to the preservation of the structural and functional integrity of the shell. PMID:26892674

  12. Salbutamol: tablets, inhalational powder, or nebuliser?

    PubMed Central

    Grimwood, K; Johnson-Barrett, J J; Taylor, B

    1981-01-01

    A study was carried out to ascertain the most effective method of giving salbutamol. Seventeen children with severe asthma received active salbutamol (4 mg via a nebuliser, 400 micrograms as an inhalational powder, or a 4 mg tablet) together with complementary placebos on a double-blind, triple-dummy randomly allocated basis. The bronchodilatation effect was assessed by measuring the peak expiratory flow rate. The bronchodilatation effect was greatest when patients received nebulised salbutamol (p less than 0.05) but lasted longest when they received the tablet (p less than 0.0001); the onset of the effect was rapid with all forms of administration. These results indicate that nebulised salbutamol gives the best relief in severe asthma; in less severe cases, however, a regimen combining the inhalational powder and tablets is sufficient and more convenient. PMID:6779890

  13. Spectrophotometric Estimation of Azithromycin in Tablets

    PubMed Central

    Jayanna, B. K.; Nagendrappa, G.; Arunkumar; Gowda, N.

    2012-01-01

    The present manuscript describes a simple, sensitive, accurate, precise and economical visible spectrophotometric method for the estimation of azithromycin from tablet formulation. The method is based on the reduction of potassium permanganate in alkaline medium with azithromycin. The measurement of decrease in absorbance of potassium permanganate at 547 nm was done, as it decolourises upon reduction by azithromycin. The method was used to determine between 2 and 20 μg/ml of azithromycin in the final measured solution. There is no interference from the ingredients commonly found in azithromycin tablets with this method. The results for the determination of azithromycin in tablets were in good agreement with the labelled quantities and related analytical parameters are calculated. PMID:23626394

  14. Improvements in floating point addition/subtraction operations

    DOEpatents

    Farmwald, P.M.

    1984-02-24

    Apparatus is described for decreasing the latency time associated with floating point addition and subtraction in a computer, using a novel bifurcated, pre-normalization/post-normalization approach that distinguishes between differences of floating point exponents.

  15. In vitro-in vivo evaluation of xanthan gum and eudragit inter polyelectrolyte complex based sustained release tablets

    PubMed Central

    Deb, Tamal Krishna; Ramireddy, B.; Moin, Afrasim; Shivakumar, H.G.

    2015-01-01

    Introduction: Polyelectrolyte complexes (PECs) are the association complexes formed between oppositely charged particles (e.g., polymer-polymer, polymer-drug and polymer-drug-polymer). These are formed due to electrostatic interaction between oppositely charged polyions. Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) advocated in use of painful and inflammatory rheumatic and certain non-rheumatic conditions. The drug has a relatively short elimination half-life, which limits the potential for drug accumulation. As an analgesic, it has a fast onset and long duration of action. Aim: invitro-invivo evaluation of Xanthan gum and Eudragit E100 inter polyelectrolyte complex based sustained release tablet. Materials and Method: Xanthan gum and Eudragit E100 were used as PEC and were prepared using different proportions i.e. in 1:1 to 1:6 ratio. The optimum ratio of E100 and XG was 1:6 used to characterize the IPC and the formulation of tablet. The tablets were prepared by wet granulation using PVP K30 as binder. Results and Discussion: FT-IR and DSC studies confirmed the formation of IPC. Scanning Electron Microscopy (SEM) studies showed highly porous tablet surface. The tablets were evaluated for hardness, weight variation, and drug content, found to be within limits. In vitro and in vivo studies concluded that tablets showed sustained release profile. The short term stability study of the optimized formulation indicated that the formulation was stable. Conclusion: Since the Poly Electrolyte Complex delay the release of the drug, it can be employed in formulating sustained release matrix tablets. PMID:25599035

  16. Leveraging Electronic Tablets for General Pediatric Care

    PubMed Central

    McKee, S.; Dugan, T.M.; Downs, S.M.

    2015-01-01

    Summary Background We have previously shown that a scan-able paper based interface linked to a computerized clinical decision support system (CDSS) can effectively screen patients in pediatric waiting rooms and support the physician using evidence based care guidelines at the time of clinical encounter. However, the use of scan-able paper based interface has many inherent limitations including lacking real time communication with the CDSS and being prone to human and system errors. An electronic tablet based user interface can not only overcome these limitations, but may also support advanced functionality for clinical and research use. However, use of such devices for pediatric care is not well studied in clinical settings. Objective In this pilot study, we enhance our pediatric CDSS with an electronic tablet based user interface and evaluate it for usability as well as for changes in patient questionnaire completion rates. Methods Child Health Improvement through Computers Leveraging Electronic Tablets or CHICLET is an electronic tablet based user interface. It is developed to augment the existing scan-able paper interface to our CDSS. For the purposes of this study, we deployed CHICLET in one outpatient pediatric clinic. Usability factors for CHICLET were evaluated via caregiver and staff surveys. Results When compared to the scan-able paper based interface, we observed an 18% increase or 30% relative increase in question completion rates using CHICLET. This difference was statistically significant. Caregivers and staff survey results were positive for using CHICLET in clinical environment. Conclusions Electronic tablets are a viable interface for capturing patient self-report in pediatric waiting rooms. We further hypothesize that the use of electronic tablet based interfaces will drive advances in computerized clinical decision support and create opportunities for patient engagement. PMID:25848409

  17. Influence of ethanol on swelling and release behaviors of Carbopol()-based tablets.

    PubMed

    Rahim, Safwan Abdel; Al-Ghazawi, Mutasim; Al-Zoubi, Nizar

    2013-01-01

    The aim of this work was to investigate the effect of ethanol on the in vitro swelling and release behaviors of Carbopol()-based tablets. The swelling behavior of drug-free compacts and the release of model drugs (metformin HCl, caffeine and theophylline) from matrix tablets were evaluated in acidic and buffered media with 0, 20 and 40% (v/v) ethanol. Release data were analyzed by fitting to Higuchi and Peppas models and calculation of similarity factor (f2). ANOVA tests were performed to determine significant factors on swelling and release. It was found that ethanol affects swelling and erosion of drug-free Carbopol() compacts, and the effect was highly dependent on medium pH. For matrix tablets, no dose dumping due to ethanol was manifested. The release rate and mechanism, however, were significantly affected by ethanol concentration as indicated by ANOVA applied to the constant, KH, from Higuchi model and the exponent, n, from Peppas model, respectively. The effect of ethanol on release was further confirmed by similarity factor results, which indicated that ethanol led to different release profiles (f2 < 50) in seven of eight cases for matrices containing metformin HCl and in three of eight cases for matrices containing caffeine and theophylline. PMID:22775444

  18. Water hyacinth: a possible alternative rate retarding natural polymer used in sustained release tablet design.

    PubMed

    Khatun, Sabera; Sutradhar, Kumar B

    2014-01-01

    In recent years natural polymers have been widely used because of their effectiveness and availability over synthetic polymers. In this present investigation matrix tablets of Metformin hydrochloride were formulated using Water hyacinth powder and its rate retardant activity was studied. Tablets were prepared using wet granulation method with 8% starch as granulating agent and 5, 10, 15, 20, 25 and 30% of Water hyacinth powder to the drug. In preformulation study, angle of repose, Carr's Index and Hausner ratio were calculated. Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) studies were performed and no interactions were found between drug and excipients. Weight variation, friability, hardness, thickness, diameter, and in vitro release study were performed with the prepared matrix tablets. Dissolution studies were conducted using USP type II apparatus at a speed of 100 rpm at 37°C ± 0.5 temperature for 8 h. Though all the formulations comply with both BP and USP requirements, formulation F-1 (5% of Water hyacinth) was the best fitted formula. The drug release patterns were explained in different kinetic models such as Zero order, First order, Higuchi, Hixson Crowell, and Korsmeyer-Peppas equations. The current investigation implies that Water hyacinth has the potential to be used as a rate-retarding agent in sustained release drug formulations. PMID:24966835

  19. Water hyacinth: a possible alternative rate retarding natural polymer used in sustained release tablet design

    PubMed Central

    Khatun, Sabera; Sutradhar, Kumar B.

    2014-01-01

    In recent years natural polymers have been widely used because of their effectiveness and availability over synthetic polymers. In this present investigation matrix tablets of Metformin hydrochloride were formulated using Water hyacinth powder and its rate retardant activity was studied. Tablets were prepared using wet granulation method with 8% starch as granulating agent and 5, 10, 15, 20, 25 and 30% of Water hyacinth powder to the drug. In preformulation study, angle of repose, Carr's Index and Hausner ratio were calculated. Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) studies were performed and no interactions were found between drug and excipients. Weight variation, friability, hardness, thickness, diameter, and in vitro release study were performed with the prepared matrix tablets. Dissolution studies were conducted using USP type II apparatus at a speed of 100 rpm at 37°C ± 0.5 temperature for 8 h. Though all the formulations comply with both BP and USP requirements, formulation F-1 (5% of Water hyacinth) was the best fitted formula. The drug release patterns were explained in different kinetic models such as Zero order, First order, Higuchi, Hixson Crowell, and Korsmeyer-Peppas equations. The current investigation implies that Water hyacinth has the potential to be used as a rate-retarding agent in sustained release drug formulations. PMID:24966835

  20. Pulse release of doxazosin from hydroxyethylcellulose compression coated tablet: mechanistic and in vivo study.

    PubMed

    Biswas, Nikhil; Guha, Arijit; Sahoo, Ranjan Kumar; Kuotsu, Ketousetuo

    2015-01-01

    Chronotherapeutically programmed hydroxyethylcellulose (HEC) based compression coated doxazosin tablets were prepared and the influence of disintegrants croscarmellose sodium, L-hydroxypropylcellulose (L-HPC), gellan gum on drug release and in vivo performance were investigated. Infrared spectroscopy and differential scanning calorimetric studies did not indicate any excipient incompatibility in the tablets. The disintegrants induced a continuous water influx resulting in a rapid expansion of the membrane. The subsequent formation of fractures into the coats leads to a fast drug release after an initial lag time. Release rates indicated that croscarmellose sodium and L-HPC were directly proportional to their concentration in the formulations. In vitro optimized croscarmellose sodium-HEC matrix showed significantly faster (p < 0.05) drug release (t90% = 46 min) after an initial lag of 243 min. Disintegrant-HEC blended matrices were found significantly superior (p < 0.05) in terms of in vitro release and bioavailability in comparison to plain HEC matrices. Drug release kinetics followed modified power law and Weibull model (r > 0.99). The mechanism involved in release was anomalous transport and super case II transport with matrix swelling. The pulsatile tablets showed no changes either in physicochemical appearance, drug content or in dissolution pattern during its accelerated stability studies. PMID:25179280

  1. Potential of carnuba wax in ameliorating brittle fracture during tableting.

    PubMed

    Uhumwangho, M U; Okor, R S; Adogah, J T

    2009-01-01

    Carnuba wax (as binder) forms hard tablets even at low compression load attributable to its high plasticity. The aim of the present study is to investigate its potential in ameliorating brittle fracture (i.e., lamination and capping) a problem often encountered during tableting. Granules of paracetamol (test drug) were made by triturating the drug powder with the melted wax or starch mucilage (20%w/v). Resulting granules were separated into different size fractions which were separately compressed into tablets with and without a centre hole (as in- built defect) using different compression loads. The tablets were evaluated for tensile strength and the data used to calculate the brittle fracture index (BFI), using the expression: BFI = 0.5(T/T(0)-1) where T0 and T are the tensile strength of tablets with and without a centre hole respectively. The BFI values were significantly lower (p<0.05) in tablets made with carnuba wax compared with tablets made with maize starch as binders. Increase in particle size of the granules or lowering of the compression load further ameliorated the brittle fracture tendency of the tablets. Using granules with the larger particle size (850microm) and applying the lowest unit of load (6 arbitrary unit on the load scale of the tableting machine) the BFI values were 0.03 (carnuba wax tablets) and 0.11 (maize starch tablets). When the conditions were reversed (i.e., a highest load, 8 units and the smallest particle size, 212microm) the BFI values now became 0.17 (carnuba wax tablets) and 0.26 (maize starch tablets). The indication is that the use of large granules and low compression loads to form tablets can further enhance the potential of carnuba wax in ameliorating brittle fracture tendency of tablets during their manufacture. PMID:19168422

  2. 14 CFR 25.753 - Main float design.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Main float design. 25.753 Section 25.753 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Floats and Hulls § 25.753 Main float...

  3. 14 CFR 25.535 - Auxiliary float loads.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Auxiliary float loads. 25.535 Section 25.535 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Water Loads § 25.535 Auxiliary float loads. (a) General. Auxiliary floats and...

  4. 14 CFR 25.535 - Auxiliary float loads.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Water Loads § 25.535 Auxiliary float loads. (a..., the prescribed water loads may be distributed over the float bottom to avoid excessive local loads.... The resultant water load must be applied in the plane of symmetry of the float at a point...

  5. 14 CFR 25.753 - Main float design.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main float design. 25.753 Section 25.753 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Floats and Hulls § 25.753 Main float...

  6. 46 CFR 131.870 - Life floats and buoyant apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats and buoyant apparatus. (a) The name of the vessel must be plainly marked or painted on each life float or buoyant apparatus... 46 Shipping 4 2011-10-01 2011-10-01 false Life floats and buoyant apparatus. 131.870 Section...

  7. 46 CFR 131.870 - Life floats and buoyant apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats and buoyant apparatus. (a) The name of the vessel must be plainly marked or painted on each life float or buoyant apparatus... 46 Shipping 4 2010-10-01 2010-10-01 false Life floats and buoyant apparatus. 131.870 Section...

  8. 40 CFR 63.1063 - Floating roof requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... subpart, whichever occurs first. (ii) External floating roof. An EFR shall be equipped with one of the... degassed, or every 5 years, whichever occurs first. (2) External floating roofs. External floating roofs...) The length of each gap shall be determined by inserting the probe into the gap (vertically)...

  9. 14 CFR 29.757 - Hull and auxiliary float strength.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hull and auxiliary float strength. 29.757 Section 29.757 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... § 29.757 Hull and auxiliary float strength. The hull, and auxiliary floats if used, must withstand...

  10. Erect floating stumps in Spirit Lake, Washington

    NASA Astrophysics Data System (ADS)

    Coffin, Harold G.

    1983-05-01

    The eruption of Mount St. Helens in May 1980 carried thousands of trees into Spirit Lake, where a giant log raft formed. Many of these broken stumps, especially those with roots, now float suspended vertically in the water. This phenomenon could have been responsible for erect petrified trees in other volcanic areas such as Yellowstone.

  11. Genetics Home Reference: Floating-Harbor syndrome

    MedlinePlus

    ... by age 6 to 12. Delay in speech development (expressive language delay) may be severe in Floating-Harbor syndrome , and language impairment can lead to problems in verbal communication. Most affected ... Their development of motor skills, such as sitting and crawling, ...

  12. Fast disintegrating crystalline solid dispersions of simvastatin for incorporation into orodispersible tablets

    PubMed Central

    Pabari, Ritesh M; Jamil, Asha; Kelly, John G; Ramtoola, Zebunnissa

    2014-01-01

    Aim: Spray dried solid dispersion (SDP) of crystalline simvastatin (SIM) in a fast disintegrating matrix of superdisintegrants was studied as a method to enhance SIM dispersibility, rheology, compactibility and compressibility for incorporation into orodispersible tablets (ODTs). Materials and Methods: The superdisintegrants investigated were crospovidone (CP), sodium starch glycollate (SSG) and calcium silicate (CS) were spray dried with simvastatin to form SDPs. Results: The SDPs were characterized and the median particle size of SDPs was similar or greater than the SIM, contributing to good rheology of SDPs, while the low bulk density of SDPs indicated a high compactibility. Interestingly electron micrographs for SDPs showed a CP or CS carrier coating of the SIM crystals, contributing to its rheology. Thermal analysis and X-ray diffraction confirmed that SIM was crystalline in the SDPs and no interaction between SIM and any of the carrier(s) was shown by Fourier transform-infra red. Drug content analysis showed a SIM content of 90-95% in SDPs containing CP or CS, while a higher SIM content of 143% was found in SDP containing SSG. When formulated as ODTs, blend containing SIM SDPs in CP showed ease of tableting, regardless of the turret speed. In comparison, tablet blend consisting of a physical mix (PM) of SIM and CP could only be tableted at the lower turret speed of 7 rpm. ODTs formulated using SIM SDPs in CP showed a higher extent of dissolution, compared to the ODTs containing corresponding PM or the commercially available SIM Zocor® tablets (ANOVA, P < 0.05). Conclusion: SDP using disintegrants as carriers may offer an alternative formulation approach for ODTs of poorly soluble drugs. PMID:25006549

  13. Instrumentation for diode laser spectroscopy using 32-bit microcontrollers and a Nexus 7 Android tablet

    NASA Astrophysics Data System (ADS)

    Eyler, Edward

    2013-05-01

    Last year, I described a low-cost ramp and timing generator using a 32-bit microcontroller, connected via USB to an Android tablet that provides a bidirectional touch-screen interface. I have since developed several additional designs to support experiments involving diode laser spectroscopy and cold atom manipulation. One circuit card can be used either as a high-resolution temperature controller or as a dual high-voltage driver for PZT positioners. A second provides a flexible user interface to commercial laser current driver modules, with support for floating ground connections. A third supports a pair of inexpensive rf frequency synthesizer chips (ADF4351) that are usable from 35-4000 MHz. A fast rf switch provides numerous options, including phase-coherent frequency shifting at MHz rates for high-bandwidth laser stabilization and studies of polychromatic optical forces. Additional circuits for laser frequency locking are under development. All of these devices are controllable from a Google Nexus 7 tablet, which is inexpensive yet has graphics processing speeds that allow seamless real-time updates of charts and oscilloscope-like displays. Supported in part by the National Science Foundation.

  14. Using Raman spectroscopy in tablet moisture surface analysis: tablet surface markers.

    PubMed

    Atef, Eman; Chauhan, Harsh; Ceresia, Michelle; Pidgeon, Charles

    2010-12-01

    A method was developed to monitor the hydration of a tablet surface using chemical functional groups able to bind atmospheric water through H-bonding. In this study, generic oral dissolving loratadine tablets were used. These tablets have relatively high mannitol and lactose concentrations. Both mannitol and lactose have C-OH alcohol functional groups, several of which are potentially available for H-bonding with atmospheric water. The Raman intensity of the alcohol functional groups decreases upon hydration. This observation can be used to indirectly monitor water adsorbed to tablet surfaces at the alcohol sites. The hydration assay is based on the change in the Raman peak intensity of the alcohol C-OH stretching at 875.5 cm(-1). Consequently the decrease in the Raman intensity of this vibration can be used to monitor water adsorption. The Raman measurement of tablet surface water was compared to the direct moisture measurement method using a microbalance. The Raman spectroscopy is used to monitor the water that is specifically bound to the C-OH alcohol functional groups available for hydration. The microbalance was used to monitor the tablets' weight change during water adsorption and desorption. The distribution of the ratio of the Raman intensity of C-OH peak at 875.5 cm(-1) divided by the intensity of loratadine's C-Cl peak at 712.6 cm(-1) was experimentally determined to be a Gaussian distribution with a mean of 3.22+/-0.277. Raman analysis indicates that there is both tightly and loosely bound water at the tablet surface. This can be a useful technique with regard to inspecting and controlling the tablet drying process. PMID:20674214

  15. Comparison of tablets and paper discs for antibiotic sensitivity testing.

    PubMed Central

    Brown, D F; Kothari, D

    1975-01-01

    The value of tablets and paper discs as reservoirs of antimicrobial agents for use in sensitivity testing was compared. Antibiotics that were unstable in paper discs showed no demonstrable loss of activity in tablets over a period of 50 days under adverse storage conditions. The antibiotic content of commercially prepared tablets is very high in comparison with the accepted content of paper discs used in Britain, but not all of the agent is released from tablets during tests. Comparison of the size of zones of inhibition around tablets and standard paper discs indicated that the amount of the various agents released from the tablets varied between 2-6% and 69% of the stated content. In tests of the sensitivity of a range of common pathogenic organisms, the results obtained with the tablet method--when interpreted as recommended by the manufacturer--were generally similar to those obtained with a paper disc method commonly used in British laboratories. In 47% of tests with aminoglycoside antibiotics, however, strains sensitive by the disc method were 'intermediate' or resistant by the tablet method. As with paper discs, it was necessary to press the tablets on to the medium. With adjustment of the 'effective antibiotic content of tablets to bring it into line with the accepted content in paper discs, the stability of antibiotics in the tablets might make them an acceptable alternative to paper discs. PMID:1206124

  16. Optimization of fast dissolving etoricoxib tablets prepared by sublimation technique.

    PubMed

    Patel, D M; Patel, M M

    2008-01-01

    The purpose of this investigation was to develop fast dissolving tablets of etoricoxib. Granules containing etoricoxib, menthol, crospovidone, aspartame and mannitol were prepared by wet granulation technique. Menthol was sublimed from the granules by exposing the granules to vacuum. The porous granules were then compressed in to tablets. Alternatively, tablets were first prepared and later exposed to vacuum. The tablets were evaluated for percentage friability and disintegration time. A 3(2) full factorial design was applied to investigate the combined effect of 2 formulation variables: amount of menthol and crospovidone. The results of multiple regression analysis indicated that for obtaining fast dissolving tablets; optimum amount of menthol and higher percentage of crospovidone should be used. A surface response plots are also presented to graphically represent the effect of the independent variables on the percentage friability and disintegration time. The validity of a generated mathematical model was tested by preparing a checkpoint batch. Sublimation of menthol from tablets resulted in rapid disintegration as compared with the tablets prepared from granules that were exposed to vacuum. The optimized tablet formulation was compared with conventional marketed tablets for percentage drug dissolved in 30 min (Q(30)) and dissolution efficiency after 30 min (DE(30)). From the results, it was concluded that fast dissolving tablets with improved etoricoxib dissolution could be prepared by sublimation of tablets containing suitable subliming agent. PMID:20390084

  17. 21 CFR 520.455 - Clomipramine tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.455 Clomipramine tablets. (a... comprehensive behavioral management program to treat separation anxiety in dogs greater than 6 months of age....

  18. 21 CFR 520.455 - Clomipramine tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.455 Clomipramine tablets. (a... comprehensive behavioral management program to treat separation anxiety in dogs greater than 6 months of age....

  19. 21 CFR 520.455 - Clomipramine tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.455 Clomipramine tablets. (a... comprehensive behavioral management program to treat separation anxiety in dogs greater than 6 months of age....

  20. 21 CFR 520.455 - Clomipramine tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.455 Clomipramine tablets. (a... comprehensive behavioral management program to treat separation anxiety in dogs greater than 6 months of age....