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1

Formulation and evaluation of floating matrix tablet of stavudine  

PubMed Central

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

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

2012-01-01

2

Effect of bioadhesion on initial in vitro buoyancy of effervescent floating matrix tablets of ciprofloxacin HCL  

PubMed Central

The purpose of this study was to investigate effect of bioadhesion on the initial in vitro buoyancy behaviour of effervescent matrix tablets of ciprofloxacin HCl (CIPRO). Tablets were prepared by direct compression using HPMC K4M and Carbopol 971P as hydrophilic-controlled release polymers, sodium bicarbonate (NaHCO3) as gas-generating agent, polyplasdone XL, Explotab and Ac-Di-Sol as swelling agents. Tablets were evaluated for normal and modified initial in vitro floating behavior, floating duration, swelling behavior and in vitro drug release studies. A modified buoyancy lag time for tablets was determined in order to include the effect of bioadhesion on initial buoyancy. The initial buoyancy was found depended on bioadhesion ability of tablets. The lowest modified buoyancy lag time of 20 seconds was obtained for Formulation F7 having both NaHCO3 and polyplasdone XL. The floating duration was also found dependent on concentration of NaHCO3 and swelling agents. The drug release of F7 was also sustained up to 12-hr duration with anomalous drug transport mechanism. PMID:22171304

Negi, Jeetendra Singh; Trivedi, Abhinav; Khanduri, Praveen; Negi, Vandana; Kasliwal, Nikhil

2011-01-01

3

Effect of bioadhesion on initial in vitro buoyancy of effervescent floating matrix tablets of ciprofloxacin HCL.  

PubMed

The purpose of this study was to investigate effect of bioadhesion on the initial in vitro buoyancy behaviour of effervescent matrix tablets of ciprofloxacin HCl (CIPRO). Tablets were prepared by direct compression using HPMC K4M and Carbopol 971P as hydrophilic-controlled release polymers, sodium bicarbonate (NaHCO(3)) as gas-generating agent, polyplasdone XL, Explotab and Ac-Di-Sol as swelling agents. Tablets were evaluated for normal and modified initial in vitro floating behavior, floating duration, swelling behavior and in vitro drug release studies. A modified buoyancy lag time for tablets was determined in order to include the effect of bioadhesion on initial buoyancy. The initial buoyancy was found depended on bioadhesion ability of tablets. The lowest modified buoyancy lag time of 20 seconds was obtained for Formulation F7 having both NaHCO(3) and polyplasdone XL. The floating duration was also found dependent on concentration of NaHCO(3) and swelling agents. The drug release of F7 was also sustained up to 12-hr duration with anomalous drug transport mechanism. PMID:22171304

Negi, Jeetendra Singh; Trivedi, Abhinav; Khanduri, Praveen; Negi, Vandana; Kasliwal, Nikhil

2011-04-01

4

Lornoxicam gastro retentive floating matrix tablets: Design and in vitro evaluation  

PubMed Central

The objective of this present investigation is to prolong the gastric residence time of Lornoxicam by fabricating it into a floating sustained release matrix tablets. Lornoxicam, a potent oxicam group of non-steroidal anti-inflammatory drugs, suffers from relatively short half life of 2 to 3 hrs showing maximal absorption in proximal gastro intestinal tract region necessitating its need to be formulated as a floating sustained release matrix tablets. In this current investigation, hydroxyl propyl methyl cellulose K15M, a high viscous grade polymer with apparent viscosity of 15,000 cps, was kept as a variable (10-50%) and calcium carbonate (13%) was used as a gas generator. The prepared blends were subjected for its pre-formulation characterization. The directly compressed tablets were evaluated for physical parameters such as weight uniformity, hardness, friability, drug content, in-vitro buoyancy with axial and radial enlargement measurement, swelling index. From the investigation it was observed that the buoyancy lasted for up to 24 hrs. Fourier transform infra-red spectroscopy peaks assured the compatibility of the drug with excipients and confirmed the presence of pure drug in the formulation. It was supported by in-vitro dissolution studies; and the dissolution data was subjected to various release kinetic models to understand the mechanism of drug release. PMID:22171312

Sathiyaraj, S.; Devi, Ramya D.; Hari, Vedha B. N.

2011-01-01

5

Lornoxicam gastro retentive floating matrix tablets: Design and in vitro evaluation.  

PubMed

The objective of this present investigation is to prolong the gastric residence time of Lornoxicam by fabricating it into a floating sustained release matrix tablets. Lornoxicam, a potent oxicam group of non-steroidal anti-inflammatory drugs, suffers from relatively short half life of 2 to 3 hrs showing maximal absorption in proximal gastro intestinal tract region necessitating its need to be formulated as a floating sustained release matrix tablets. In this current investigation, hydroxyl propyl methyl cellulose K15M, a high viscous grade polymer with apparent viscosity of 15,000 cps, was kept as a variable (10-50%) and calcium carbonate (13%) was used as a gas generator. The prepared blends were subjected for its pre-formulation characterization. The directly compressed tablets were evaluated for physical parameters such as weight uniformity, hardness, friability, drug content, in-vitro buoyancy with axial and radial enlargement measurement, swelling index. From the investigation it was observed that the buoyancy lasted for up to 24 hrs. Fourier transform infra-red spectroscopy peaks assured the compatibility of the drug with excipients and confirmed the presence of pure drug in the formulation. It was supported by in-vitro dissolution studies; and the dissolution data was subjected to various release kinetic models to understand the mechanism of drug release. PMID:22171312

Sathiyaraj, S; Devi, Ramya D; Hari, Vedha B N

2011-07-01

6

Floating Matrix Tablets of Domperidone Formulation and Optimization Using Simplex Lattice Design  

PubMed Central

The purpose of this research was to prepare a floating matrix tablet containing domperidone as a model drug. Polyethylene oxide (PEO) and hydroxypropyl methylcellulose (HPMC) were evaluated for matrix-forming properties. A simplex lattice design was applied to systemically optimize the drug release profile. The amounts of PEO WSR 303, HPMC K15M and sodium bicarbonate were selected as independent variables and floating lag time, time required to release 50% of drug (t50) and 80% of drug (t80), diffusion coefficient (n) and release rate (k) as dependent variables. The amount of PEO and HPMC both had significant influence on the dependent variables. It was found that the content of PEO had dominating role as drug release controlling factor, but using suitable concentration of sodium bicarbonate, one can tailor the desired drug release from hydrophilic matrixes. The linear regression analysis and model fitting showed that all these formulations followed Korsmeyer and Peppas model, which had a higher value of correlation coefficient (r). The tablets of promising formulation were found to be stable for 3 months under accelerated (40°C / 75% RH) stability testing. PMID:24250376

Prajapati, Shailesh; Patel, Laxmanbhai; Patel, Chhaganbhai

2011-01-01

7

Floating matrix tablets based on low density foam powder: effects of formulation and processing parameters on drug release.  

PubMed

The aim of this study was to develop and physicochemically characterize single unit, floating controlled drug delivery systems consisting of (i). polypropylene foam powder, (ii). matrix-forming polymer(s), (iii). drug, and (iv). filler (optional). The highly porous foam powder provided low density and, thus, excellent in vitro floating behavior of the tablets. All foam powder-containing tablets remained floating for at least 8 h in 0.1 N HCl at 37 degrees C. Different types of matrix-forming polymers were studied: hydroxypropyl methylcellulose (HPMC), polyacrylates, sodium alginate, corn starch, carrageenan, gum guar and gum arabic. The tablets eroded upon contact with the release medium, and the relative importance of drug diffusion, polymer swelling and tablet erosion for the resulting release patterns varied significantly with the type of matrix former. The release rate could effectively be modified by varying the "matrix-forming polymer/foam powder" ratio, the initial drug loading, the tablet geometry (radius and height), the type of matrix-forming polymer, the use of polymer blends and the addition of water-soluble or water-insoluble fillers (such as lactose or microcrystalline cellulose). The floating behavior of the low density drug delivery systems could successfully be combined with accurate control of the drug release patterns. PMID:12554071

Streubel, A; Siepmann, J; Bodmeier, R

2003-01-01

8

Preparation and evaluation of novel metronidazole sustained release and floating matrix tablets.  

PubMed

In the present study, metronidazole was used for preparing floating dosage forms that are designed to retain in the stomach for a long time and have developed as a drug delivery system for better eradication of Helicobacter Pylori in peptic ulcer diseases. For this means, various formulations were designed using multi-factorial design. HPMC, psyllium and carbopol in different concentrations were used as floating agents, and sodium bicarbonate was added as a gas-forming agent. Hardness, friability, drug loading, floating ability and release profiles as well as kinetics of release were assessed. Formulations containing HPMC as filler showed prolonged lag times for buoyancy. Adding psyllium to these formulations had reduced relative lag times. Overall, selected formulations were able to float immediately and showed buoyancy for at least 8?h. Meanwhile, sustained profiles of drug release were also obtained. Kinetically, among the 10 assessed models, the release pattern of metronidazole from the tablets fitted best to Power law, Weibull and Higuchi models in respect overall to mean percentage error values of 3.8, 4.73 and 5.77, respectively, for calcium carbonate-based tablets and, 2.95, 6.39 and 3.9, respectively, for calcium silicate-based tablets. In general, these systems can float in the gastric condition and control the drug release from the tablets. PMID:20429828

Asnaashari, Solmaz; Khoei, Nazaninossadat Seyed; Zarrintan, Mohammad Hosein; Adibkia, Khosro; Javadzadeh, Yousef

2011-08-01

9

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

PubMed Central

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

Gande, S

2011-01-01

10

Development and evaluation of gastroretentive norfloxacin floating tablets.  

PubMed

Floating matrix tablets of norfloxacin were developed to prolong gastric residence time, leading to an increase in drug bioavailability. Tablets were prepared by the wet granulation technique, using polymers such as hydroxypropyl methylcellulose (HPMC K4M, HPMC K100M) and xanthan gum. Tablets were evaluated for their physical characteristics, viz., hardness, thickness, friability, and mass variation, drug content and floating properties. Further, tablets were studied for in vitro drug release characteristics for 9 hours. The tablets exhibited controlled and prolonged drug release profiles while floating over the dissolution medium. Non-Fickian diffusion was confirmed as the drug release mechanism from these tablets, indicating that water diffusion and polymer rearrangement played an essential role in drug release. The best formulation (F4) was selected based on in vitro characteristics and was used in vivo radiographic studies by incorporating BaSO4. These studies revealed that the tablets remained in the stomach for 180 +/- 30 min in fasting human volunteers and indicated that gastric retention time was increased by the floating principle, which was considered desirable for the absorption window drugs. PMID:19564145

Bomma, Ramesh; Swamy Naidu, Rongala Appala; Yamsani, Madhusudan Rao; Veerabrahma, Kishan

2009-06-01

11

Formulation and evaluation of effervescent floating tablets of tizanidine hydrochloride.  

PubMed

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

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

2011-06-01

12

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

PubMed

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

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

2011-09-01

13

Comparative evaluation of single and bilayered lamotrigine floating tablets  

PubMed Central

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

Lakshmi, PK; Sridhar, M; Shruthi, B

2013-01-01

14

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

PubMed Central

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.

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

2014-01-01

15

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

PubMed

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

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

2014-12-01

16

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

PubMed

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

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

2009-01-01

17

Optimization of a metformin effervescent floating tablet containing hydroxypropylmethylcellulose and stearic acid.  

PubMed

This study optimizes the composition of an effervescent floating tablet (EFT) containing metformin hydrochloride (M) regarding tablet hardness (H), time to dissolve 60% of the embedded drug (t60%), and buoyancy, the floating lag time (FLT). A simplex lattice experimental design has been used comprising different levels of hydroxypropylmethylcellulose (HPMC), stearic acid (SA), sodium bicarbonate (SB) as tablet matrix components, and hardness (H), t60%, FLT as response variables. Two models have been applied to decide which composition will result in Fickian diffusion or in overlapping of two dissolution mechanisms, diffusion and matrix erosion. Three of EFT showed the two dissolution mechanisms but most of EFT showed Fickian diffusion only. Checking the experimental response by a linear, quadratic, special cubic and cubic model using multivariate regression analysis resulted in best fit for the cubic model. Overlaying the results for the cubic model under constraints defined shows the domain of accepted values of response variables. The optimized EFT shall have been included HPMC between 15.6% and 24.2%, SA between 12.8 and 15.6% and SB between 16.1% and 17.5%. The result of this study has been critically evaluated considering analogous EFT described in literature. PMID:20225651

Rajab, M; Jouma, M; Neubert, R H; Dittgen, M

2010-02-01

18

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

PubMed

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

Sungthongjeen, Srisagul; Sriamornsak, Pornsak; Puttipipatkhachorn, Satit

2008-05-01

19

Development of bilayer floating tablet of amoxicillin and Aloe vera gel powder for treatment of gastric ulcers.  

PubMed

Usual treatment for Helicobacter pylori-induced peptic ulcer includes a 'triple therapy' consisting of two antibiotics (amoxicillin and clarithromycin) and a proton pump inhibitor (omeprazole). The objective of this project work was defined with a view to retain the drug in stomach for better antiulcer activity and substituting one of the synthetic drugs in this therapy with a herbal alternative. Hence, aim of the present work was to design and develop a bilayer floating tablet of amoxicillin and Aloe vera gel powder for the treatment of peptic ulcer. A. vera gel powder is used for its cytoprotective action. Bilayer floating tablets were prepared by applying direct compression technique. The proportion of sodium bicarbonate and citric acid was adjusted to get the least possible lag time with good matrix integrity and total floating time. Polymer concentration was adjusted to get the maximum release in 8 h. The formulation was developed using hydroxypropyl methyl cellulose (HPMC) K4M and HPMC K100M in a ratio of 85:15 along with 1:4 ratio of effervescent agents was found to give floating lag time of less than 1 min with total floating time of more than 8 h and 97.0% drug release in 8 h. In vivo study in rats meets the requirement of antiulcer activity for bilayer tablet in comparison to single amoxicillin as standard. PMID:23135966

Ranade, Arati N; Wankhede, Sonali S; Ranpise, Nisharani S; Mundada, Mayur S

2012-12-01

20

Development and evaluation of gastroretentive floating tablets of an antihypertensive drug using hydrogenated cottonseed oil.  

PubMed

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

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

2013-12-18

21

Physiological relevant in vitro evaluation of polymer coats for gastroretentive floating tablets.  

PubMed

Gastroretentive drug delivery systems are retained in the stomach for a sufficient time interval, releasing the drug in a controlled manner. According to literature, the floating principle is the most frequently used formulation approach for gastric retention. However, many publications lack information of the floating forces, the impact of different pH-values and almost no information exist concerning the resistance of the floating performance against physiological relevant stress. Therefore, we evaluated the performance of CO2-generating floating bilayer (drug and floating layer) tablets with respect to robustness, drug release profile, pH dependence and floating behaviour. Bilayer tablets were coated with a flexible and water permeable, but CO2-retaining polymer film of either polyvinyl acetate or ammonio-methacrylate copolymer type A. Metformin-HCl was used as a relevant model drug due to its dose-dependent and saturable absorption from the proximal part of the small intestine. To mimic physiological relevant mechanical stress conditions, recently developed dissolution stress tests with pulsed pressures were applied in addition to release studies according to the pharmacopeia. Bilayer tablets coated with polyvinyl acetate showed short floating lag times, reasonable floating strength values, floating durations of more than 24h in simulated gastric fluid and a robust and pH independent release of Metformin-HCl. Tablets coated with ammonio-methacrylate copolymer type A showed a higher permeability for the active ingredient combined with a decreased robustness of the inflated tablets. Both polymers can be used for balloon-like floating devices. The appropriate polymer has to be chosen dependent from the properties of the active ingredient and requested application of the delivery device. Furthermore, the dissolution stress test analysis is able to indicate possible safety issues of gastroretentive formulations as well as to characterise the robustness of formulation principles towards mechanical stresses of bio-relevant intensity. PMID:25086221

Eisenächer, Friederike; Garbacz, Grzegorz; Mäder, Karsten

2014-11-01

22

Evaluating Energy Efficiency of Floating Point Matrix Multiplication on FPGAs  

E-print Network

Evaluating Energy Efficiency of Floating Point Matrix Multiplication on FPGAs Kiran Kumar Matam, prasanna}@usc.edu Abstract--Energy efficiency has emerged as one of the key performance metrics in scientific computing. In this work, we evaluate the energy efficiency of floating point matrix multipli

Prasanna, Viktor K.

23

Energy Performance of Floating-Point Matrix Multiplication on FPGAs  

Microsoft Academic Search

Floating-point matrix multiplication is a basic kernel in sci- entific computing. It has been shown that implementations of this kernel on FPGAs can achieve high sustained performance (1). However, to the best of our knowledge, existing work on FPGA-based floating-point matrix multiplication considers the optimization of latency or area only. In this paper, we analyze the impact of various parameters

Ling Zhuo; Viktor K. Prasanna

2004-01-01

24

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

PubMed

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

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

2013-03-01

25

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

PubMed

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

U?urlu, Timucin; Karaçiçek, U?ur; Rayaman, Erkan

2014-01-01

26

Formulation, release characteristics and bioavailability of novel monolithic hydroxypropylmethylcellulose matrix tablets containing acetaminophen  

Microsoft Academic Search

Effect of incorporating pharmaceutical excipients on the in vitro release profiles and the release mechanism of monolithic hydroxypropylmethylcellulose (4000 cps) matrix tablets (m-HPMC tablets) in terms of mimicking the dual drug release character of bi-layered Tylenol® ER tablets was studied. We also compared the in vitro release profiles of optimized m-HPMC matrix tablet and Tylenol® ER tablet in water, pH

Qing-Ri Cao; Yun-Woong Choi; Jing-Hao Cui; Beom-Jin Lee

2005-01-01

27

Scalable and Modular Algorithms for Floating-Point Matrix Multiplication on FPGAs  

E-print Network

. The processing elements(PEs) used in our algorithms are modular so that floating-point units can be easilyScalable and Modular Algorithms for Floating-Point Matrix Multiplication on FPGAs Ling Zhuo computations. In this paper, we propose two FPGA-based algorithms for floating-point matrix multiplication

Prasanna, Viktor K.

28

Optimization of HPMC and carbopol concentrations in non-effervescent floating tablet through factorial design.  

PubMed

This study was to optimize HPMC K4M and carbopol 934 concentration in the development of non-effervescent floating tablets (NEFTs) of glipizide as model drug using 3(2) factorial design. The time required for releasing drug of 50% and 80% and similarity factor were the target responses. HPMC K4M and carbopol 934 concentrations were the variables. The response surface methodology and optimized polynomial equations were used to select the optimal formulation with desired responses. The excipients used in tablets were compatible with glipizide as per the results of isothermal stress testing and DSC study. The drug release of entire NEFTs followed zero order kinetics and non-Fickian diffusion mechanism. Validation of the optimization technique demonstrated the reliability of the model. The optimized formulation containing 124.33 mg HPMC K4M and 25.76 mg carbopol 934 was prepared according to the software determined levels. The stability study of the optimized formulation proved the integrity of the developed formulation. PMID:24507292

Acharya, Sujata; Patra, Sradhanjali; Pani, Nihar Ranjan

2014-02-15

29

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

PubMed Central

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

Jeon, Imjak; Gilli, Tiziana; Betz, Gabriele

2011-01-01

30

Development and Evaluation of Hydrophilic Colloid Matrix of Famotidine Tablets  

Microsoft Academic Search

The objective of the present study was to develop a once-daily sustained-release (SR) matrix tablet of famotidine. Nine different\\u000a formulations (F1–F9) were prepared by direct compression method using Avicel PH101 as filler\\/binder in the range of 41–27%\\u000a 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\\u000a in F1–F3 from 19% to

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

2010-01-01

31

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

Microsoft Academic Search

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

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

2009-01-01

32

Optimization of matrix tablets controlled drug release using Elman dynamic neural networks and decision trees.  

PubMed

The main objective of the study was to develop artificial intelligence methods for optimization of drug release from matrix tablets regardless of the matrix type. Static and dynamic artificial neural networks of the same topology were developed to model dissolution profiles of different matrix tablets types (hydrophilic/lipid) using formulation composition, compression force used for tableting and tablets porosity and tensile strength as input data. Potential application of decision trees in discovering knowledge from experimental data was also investigated. Polyethylene oxide polymer and glyceryl palmitostearate were used as matrix forming materials for hydrophilic and lipid matrix tablets, respectively whereas selected model drugs were diclofenac sodium and caffeine. Matrix tablets were prepared by direct compression method and tested for in vitro dissolution profiles. Optimization of static and dynamic neural networks used for modeling of drug release was performed using Monte Carlo simulations or genetic algorithms optimizer. Decision trees were constructed following discretization of data. Calculated difference (f(1)) and similarity (f(2)) factors for predicted and experimentally obtained dissolution profiles of test matrix tablets formulations indicate that Elman dynamic neural networks as well as decision trees are capable of accurate predictions of both hydrophilic and lipid matrix tablets dissolution profiles. Elman neural networks were compared to most frequently used static network, Multi-layered perceptron, and superiority of Elman networks have been demonstrated. Developed methods allow simple, yet very precise way of drug release predictions for both hydrophilic and lipid matrix tablets having controlled drug release. PMID:22402474

Petrovi?, Jelena; Ibri?, Svetlana; Betz, Gabriele; ?uri?, Zorica

2012-05-30

33

Floating matrix dosage form for dextromethorphan hydrobromide based on gas forming technique: in vitro and in vivo evaluation in healthy volunteers.  

PubMed

The objective of this study was to develop the dextromethorphan hydrobromide sustained-release (DMB-SR) tablets using floating technique to prolong the gastric residence time and compared their pharmacokinetic behavior with conventional sustained release tablets. DMB-SR floating tablets were prepared employing hydroxypropyl methylcellulose (HPMC) as hydrophilic gel material, sodium bicarbonate as gas-generating agent and hexadecanol as floating assistant agent. An orthogonal experiment design method was used to select the optimized formulation. The floating tablets were evaluated for uniformity of weight, hardness, friability, drug content, floating characteristics, in vitro release and in vivo bioavailability. The optimized tablets were prepared with HPMC K4M 25 mg, sodium bicarbonate 20 mg and hexadecanol 18 mg. The prepared tablets could float within 3 min and maintain for more than 24 h. The data of physical parameters were all lie within the limits. Drug release at 12 h was more than 85%. The comparative pharmacokinetic study was performed by administration of the DMB-SR floating tablets and conventional DMB-SR tablets. The area under curve of plasma concentration-time (AUC) of floating tablets was slightly higher than that of reference tablets, T(max) was prolonged apparently. The results showed the floating tablets are a feasible approach for the sustained-release preparation of drugs, which have limited absorption sites in the stomach. PMID:21050887

Hu, Liandong; Li, Li; Yang, Xun; Liu, Wei; Yang, Jianxue; Jia, Yanhong; Shang, Chuang; Xu, Hongxin

2011-01-18

34

Formulation and in vitro evaluation of floating tablets of hydroxypropyl methylcellulose and polyethylene oxide using ranitidine hydrochloride as a model drug  

PubMed Central

The present study was carried out with an objective of preparation and in vitro evaluation of floating tablets of hydroxypropyl methyl cellulose (HPMC) and polyethylene oxide (PEO) using ranitidine hydrochloride as a model drug. The floating tablets were based on effervescent approach using sodium bicarbonate a gas generating agent. The tablets were prepared by dry granulation method. The effect of polymers concentration and viscosity grades of HPMC on drug release profile was evaluated. The effect of sodium bicarbonate and stearic acid on drug release profile and floating properties were also investigated. The result of in vitro dissolution study showed that the drug release profile could be sustained by increasing the concentration of HPMC K15MCR and Polyox WSR303. The formulation containing HPMC K15MCR and Polyox WSR303 at the concentration of 13.88% showed 91.2% drug release at the end of 24 hours. Changing the viscosity grade of HPMC from K15MCR to K100MCR had no significant effect on drug release profile. Sodium bicarbonate and stearic acid in combination showed no significant effect on drug release profile. The formulations containing sodium bicarbonate 20 mg per tablet showed desired buoyancy (floating lag time of about 2 minutes and total floating time of >24 hours). The present study shows that polymers like HPMC K15MCR and Polyox WSR303 in combination with sodium bicarbonate as a gas generating agent can be used to develop sustained release floating tablets of ranitidine hydrochloride. PMID:23493037

Gharti, KP; Thapa, P; Budhathoki, U; Bhargava, A

2012-01-01

35

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

PubMed

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

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

2014-01-01

36

Divisability of diltiazem matrix sustained-release tablets.  

PubMed

The objective of this work was to study the possibility of a solid sustained-release dosage form, like a tablet, be divided without changing its release characteristics. Diltiazem hydrochloride Sustained-Release (SR) tablets with a standard groove on one face, were tested and the following dissolution parameters were evaluated: t10%, t25%, and t50% dissolution time, and dissolution efficiency at t120, and at t360. To analyze the release mechanism, several release models were tested such as Higuchi, zero order, first order, Baker-Lonsdale, Hixson-Crowell, Weibull, and Korsmeyer-Peppas. The similarities between two in vitro dissolution profiles were assessed by the difference factor (f1), the similarity factor (f2) and the Rescigno index (xi(i)). The in vitro release kinetics of diltiazem hydrochloride tablets were evaluated using USP apparatus 4. Using a one-way ANOVA (a = 0.05), statistically significant differences were found for t10%, t25%, and t50% dissolution times with a constant and with a variable pH dissolution fluid. The variation coefficient for the divisibility assay (Portuguese Pharmacopoeia VI) was lower than the limit value of 10%. The diltiazem release rate from this pharmaceutical system was not constant, and diminished with the square root of time (Higuchi model) showing that the phenomenon controlling drug release was the diffusion occurring inside the swelled polymeric matrix. Diltiazem release rate was a function of the area in direct contact with the dissolution fluid and not of the pharmaceutical matrix volume. The results obtained permit us to conclude that the division, in this case, affects the drug release characteristics. PMID:11485176

Costa, P; Sousa Lobo, J M

2001-08-01

37

FORMULATION AND IN VITRO EVALUATION OF SUSTAINED RELEASE MATRIX TABLETS OF METOPROLOL SUCCINATE USING HYDROPHILIC POLYMERS  

Microsoft Academic Search

The objective of the present study was to develop sustained-release matrix tablets of metoprolol succinate, ?1- selective adrenergic receptor blocking agent. The tablets were prepared by the wet granulation method. Ethanolic solutions of ethylcellulose (EC) and polyvinylpyrrolidone were used as granulating agents along with hydrophilic matrix materials like hydroxypropyl methylcellulose (HPMC) and guar gum. The granules were evaluated for angle

Antesh K Jha; Bhattacharya A; Pankaj Verm

38

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

PubMed

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

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

2009-08-01

39

Use of Propranolol-Magnesium Aluminium Silicate Intercalated Complexes as Drug Reservoirs in Polymeric Matrix Tablets  

PubMed Central

The objective of the present study was to investigate the use of propranolol–magnesium aluminium silicate intercalated complexes as drug reservoirs in hydroxypropylmethylcellulose tablets. The matrix tablets containing the complexes were prepared and characterised with respect to propranolol release and were subsequently compared with those loading propranolol or a propranolol–magnesium aluminium silicate physical mixture. Additionally, the effects of varying viscosity grades of hydroxypropyl methylcellulose, compression pressures and calcium acetate incorporation on the drug release characteristics of the complex-loaded tablets were also examined. The results showed that the complex-loaded tablets have higher tablet hardness than those containing propranolol or a physical mixture. The drug release from the complex-loaded tablets followed a zero-order release kinetic, whereas an anomalous transport was found in the propranolol or physical mixture tablets. The drug release rate of the complex tablet significantly decreased with increasing hydroxypropylmethylcellulose viscosity grade. Increase in the compression pressure caused a decrease in the drug release rate of the tablets. Furthermore, the incorporation of calcium ions could accelerate propranolol release, particularly in acidic medium, because calcium ions could be exchanged with propranolol molecules intercalated in the silicate layers of magnesium aluminium silicate. These findings suggest that propranolol-magnesium aluminium silicate intercalated complexes show strong potential for use as drug reservoirs in matrix tablets intended for modifying drug release. PMID:23626384

Pongjanyakul, T.; Rojtanatanya, S.

2012-01-01

40

Matrix tablets are drug delivery devices that release a water-soluble drug over an extended period of time. Such matrix tablets are formulated from mixtures of drug, polymer, and excipient  

E-print Network

Summary Matrix tablets are drug delivery devices that release a water-soluble drug over an extended tablets are drug delivery devices designed to release a drug in a controlled manner over an extended numbers: 87.85.Qr Keywords: drug delivery, matrix tablets, cellular automata e@catfact.net hinow

Hinow, Peter

41

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

PubMed

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

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

2011-12-01

42

Investigation of critical polymer properties for polymer release and swelling of HPMC matrix tablets  

Microsoft Academic Search

Four different HPMC batches were characterized to investigate properties related to critical functionality for their use in hydrophilic matrix tablets. In this study, the HPMC batches were chemically characterized and correlated to the behaviour of pure HPMC tablets. Parameters such as the molecular weight, viscosity, intrinsic viscosity and radius of gyration were kept in a rather limited range, which resulted

Anna Viridén; Bengt Wittgren; Anette Larsson

2009-01-01

43

Design, Fabrication and Evaluation of Drug Release Kinetics from Aceclofenac Matrix Tablets using Hydroxypropyl Methyl Cellulose  

Microsoft Academic Search

The objective of this study was to develop a sustained release matrix tablet of aceclofenac using hydroxypropyl methylcellulose (HPMC K15M and HPMC K100M CR) in various proportions as release controlling factor by direct compression method. The powders for tableting were evaluated for angle of repose, loose bulk density, tapped bulk density, compressibility index, total porosity and drug content etc. The

Abul Kalam Lutful Kabir; Bishyajit Kumar Biswas; Abu Shara Shasur Rouf

2010-01-01

44

Scalable and Modular Algorithms for Floating-Point Matrix Multiplication on Ling Zhuo and Viktor K. Prasanna  

E-print Network

. The processing elements(PEs) used in our algo- rithms are modular so that floating-point units can be easilyScalable and Modular Algorithms for Floating-Point Matrix Multiplication on FPGAs £ Ling Zhuo, we propose two FPGA-based algorithms for floating-point matrix multiplication, a fundamental kernel

Prasanna, Viktor K.

45

pH-independent sustained release matrix tablet containing doxazosin mesylate: Effect of citric acid  

Microsoft Academic Search

The aim of this study was to develop a pH-independent sustained release matrix tablets of doxazosin mesylate. The matrix tablets\\u000a were prepared by direct compression technique using polyethylene oxide, sodium alginate and citric acid as a pH modifier.\\u000a Formulations were evaluated for an in vitro drug release study, erosion study, and the microenvironmental pH was studied using the pH indicator

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

2010-01-01

46

Bioavailability of carbamazepine:?-cyclodextrin complex in beagle dogs from hydroxypropylmethylcellulose matrix tablets  

Microsoft Academic Search

The bioavailability of a carbamazepine:?-cyclodextrin (CBZ:?CD) complex from hydroxypropylmethylcellulose (HPMC) matrix tablets was evaluated in beagle dogs. A solubility study demonstrated the improvement of CBZ aqueous solubility by adding increasing amounts of ?CD. The 1:1 CBZ:?CD molar ratio was chosen to produce the complex, which was obtained by spray-drying. Matrix tablets were prepared by direct compressing either a CBZ:?CD complex

Let??cia S Koester; Juliana B Bertuol; Kátia R Groch; Clarissa R Xavier; Roseli Moellerke; Paulo Mayorga; Teresa Dalla Costa; Valquiria L Bassani

2004-01-01

47

Once-daily sustained-release matrix tablets of nicorandil: Formulation and in vitro evaluation  

Microsoft Academic Search

The objective of the present study was to develop once-daily sustained-release matrix tablets of nicorandil, a novel potassium\\u000a channel opener used in cardiovascular diseases. The tablets were prepared by the wet granulation method. Ethanolic solutions\\u000a of ethylcellulose (EC), Eudragit RL-100, Eudragit RS-100, and polyvinylpyrrolidone were used as granulating agents along with\\u000a hydrophilic matrix materials like hydroxypropyl methylcellulose (HPMC), sodium carboxymethylcellulose,

K. Raghuram Reddy; Srinivas Mutalik; Srinivas Reddy

2003-01-01

48

Matrix tablets of carrageenans. I. A compaction study.  

PubMed

Carrageenans can be used as excipients for controlled-release tablets. The aim of this study was to determine their compaction and consolidation behavior to prove their usefulness for tableting. The Carr indices of the three carrangeenans, two kappa-carrageenans(Gelcarin GP-812 NF and GP-911 NF) and one tau-carrageenan (Gelcarin GP-379 NF), indicate that the materials are free flowing. They are polymers in the rubbery state. Their glass transition-temperature is about 0 degree C analyzed by differential scanning calorimetry (DSC). The powders were analyzed regarding their compression behavior using an eccentric tableting machine. From data obtained during one compaction cycle, porosity-pressure and pressure-time plots were made. Compaction behavior is evaluated by fitting the pressure-time function to the pressure-time plot and by fitting the Heckel function to the porosity-pressure plot. The polymers show "viscoelastic" tableting behavior. Several additional tableting parameters were analyzed for strengthening the results obtained, namely, maximum work, maximum power, and the time between maximum upper punch force and maximum displacement of the upper punch. The crushing strength of the tablets is high; therefore, the carrageenans are able to form strong compacts. However, they remain in the rubbery state, as shown by thermomechanical analysis. In addition, elastic recovery is regarded at several times after ejection. Finally, after 10 days, it is about 30% as determined from the minimum of tablet height during the compression cycle. These results indicate that the carrageenans are suitable tableting excipients for controlled-release tablets. They show good compactibility and good consolidation behavior. Strong compacts with a high elastic recovery are formed; this means that the materials are able to embed drugs softly. Only a little stress and strain remains in the tablet. All three carrageenans show similar tableting behavior, and a flexible dosage form design is possible. PMID:10071826

Picker, K M

1999-03-01

49

In vitro aceclofenac release from IPN matrix tablets composed of chitosan-tamarind seed polysaccharide.  

PubMed

This communication describes the formulation and in vitro evaluation of IPN matrix tablets of aceclofenac. IPN microparticles using chitosan and tamarind seed polysaccharide blend was prepared using glutaraldehyde as cross-linker. The drug entrapment efficiency and average particle size of these microparticles was found to be 91.97±1.30% and 498.12±38.67 ?m, respectively. These IPN microparticles were characterized by scanning electron microscopy (SEM) and powder X-ray diffraction (P-XRD) study. These microparticles were compressed with tablet excipients through direct compression technique. These matrix tablets showed sustained aceclofenac release over 8 h. These matrix tablets might be helpful to minimize dosing frequency and reduction of various side effects during prolong period of treatment. PMID:24463265

Jana, Sougata; Sen, Kalyan Kumar; Basu, Sanat Kumar

2014-04-01

50

Formulation, evaluation and optimization of sustained release matrix tablets of captopril  

PubMed Central

Sustained release matrix tablet is a delivery system by which the drug can be delivered at a controlled rate for long period of time. The present study aims at formulation, evaluation and optimization of captopril matrix tablets. A 32 full factorial design was adopted and all 9 batches were prepared by wet granulation method. Prepared granules and tablets were evaluated for precompression and postcompression characteristics respectively. Check point analysis was applied to the observations and the formula of the tablet was optimized. Optimized formula, F6 showed zero order drug release kinetics for the time period of 24 hours i.e. 17.55% release at the end of 2 hours, 53.4% release at the end of 12 hours and 100.24% release at the end of 24 hours. The results revealed that concentration of matrix forming agent and solution of granulating agent significantly affected in vitro drug release profile. PMID:23066215

Pandya, V. Pandya; Patel, Vandana B.; Patel, Prajesh

2012-01-01

51

[Applicability of a natural swelling matrix as the propellant of osmotic pump tablets].  

PubMed

The purpose of this study is to investigate the applicability of a natural swelling matrix derived from boat-fruited sterculia seed (SMS) as the propellant of osmotic pump tablets. The sugar components, static swelling, water uptake and viscosity of SMS were determined and compared with that of polythylene oxide (WSR-N10 and WSR-303). Both ribavirin and glipizide were used as water-soluble and water-insoluble model drugs. Then, the monolayer osmotic pump tablets of ribavirin and the bilayer osmotic pump tablets of glipizide were prepared using SMS as the osmotically active substance and propellant. SMS was mainly composed of rhamnose, arabinose, xylose and galactose and exhibited relatively high swelling ability. The area of the disintegrated matrix tablet was 20.1 times as that at initial after swelling for 600 s. SMS swelled rapidly and was fully swelled (0.5%) in aqueous solution with relative low viscosity (3.66 +/- 0.03) mPa x s at 25 degrees C. The monolayer osmotic pump tablets of ribavirin and the bilayer osmotic pump tablets of glipizide using SMS as propellant exhibited typical drug release features of osmotic pumps. In conclusion, the swelling matrix derived from boat-fruited sterculia seed, with low viscosity and high swelling, is a potential propellant in the application of osmotic pump tablets. PMID:24187843

Wu, Li; Li, Hai-Yan; Yin, Xian-Zhen; Li, Ying; Chen, Jian-Xiu; Hu, Rong-feng; Zhang, Ji-Wen

2013-08-01

52

Evaluation of floating and sticking extended release delivery systems: an unconventional dissolution test  

Microsoft Academic Search

The extent to which hydrophilic matrix tablets with a propensity to stick to the dissolution apparatus and\\/or float are susceptible to variations in hydrodynamic conditions during dissolution testing was investigated. Furthermore the usefulness of simple alternatives to the current compendial tests is examined. Swellable hydrocolloid (guar) matrix tablets containing verapamil HCl were evaluated using USP dissolution apparatus I and II.

Thomas Dürig; Reza Fassihi

2000-01-01

53

Bilayer Matrix Tablets for Prolonged Actions of Metformin Hydrochloride and Repaglinide.  

PubMed

A combination therapy of metformin hydrochloride (MH) and repaglinide (RG) achieves a perfect glycemic control; however, the combination formulation of immediate release must be taken several times a day, compromising the therapeutic benefits and causing inconveniences to the patients. Herein, a bilayer matrix tablet that aimed at continuously releasing both MH and RG over time was developed, in which the two drugs were formulated into two separated layers. The tablets were prepared by wet granulation method, and the optimized formulation was obtained by evaluating the factors that affected the drug release. The bilayer tablets simultaneously released the two drugs over 12 h; and a better in vivo performance with a steady plasma concentration, markedly lower C max, prolonged T max, and perfect absorption was obtained. Summarily, the bilayer matrix tablets sustained both MH and RG release over time, thereby prolonging the actions for diabetic therapy and producing better health outcomes. PMID:25319054

He, Wei; Huang, Shijing; Zhou, Chunyan; Cao, Lin; Yao, Jing; Zhou, Jianping; Wang, Guangji; Yin, Lifang

2014-10-16

54

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

Microsoft Academic Search

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

Walid Sakr; Fars Alanazi; Adel Sakr

2011-01-01

55

EFFECT OF CHANNELING AGENTS ON THE RELEASE PATTERN OF THEOPHYLLINE FROM KOLLIDON SR BASED MATRIX TABLETS  

Microsoft Academic Search

The purpose of the present study was to investigate the effect of channeling agent on the release profile of theophylline from Kollidon SR based matrix systems. Matrix tablets of theophylline using Kollidon SR which is plastic in nature were prepared by direct compression process. NaCl and PEG 1500 were used as channeling agents. Drug release study was evaluated for eight

MILLAT IBN RAZZAK; FERDOUS KHAN; MASUMA HOSSAIN

56

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

Microsoft Academic Search

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

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

2009-01-01

57

Formulation and evaluation of Ficus glomerata mucilage sustained release matrix tablets of gliclazide.  

PubMed

The main aim of present investigation was to develop sustained release matrix tablets of Gliclazide using fruit mucilage from the plant Ficus glomerata. Varying ratios of drug and polymer viz. 1:0.25, 1:0.5, 1:0.75, 1:1.0 and 1:1.25 were selected for the study. The flow properties of powdered mucilage and physical properties of matrix tablets were performed. The swelling behavior and release rate characteristics were studied. The in vitro drug release data was analyzed by zero order, first order, Higuchi plot, Peppas plot and Hixon-Crowell Models. It was observed that as the proportion of mucilage increased the release of drug from the matrix tablets was retarded. Stability studies were conducted at 40±2ºC and RH 75±5% for 3 months indicates that Gliclazide was stable in the matrix tablets. The Differential Scanning Calorimetric (DSC) and Fourier Transform Infrared (FTIR) study revealed that there was no negative chemical interaction between drug and the mucilage used. From the dissolution study, it was concluded that dried Ficus glomerata mucilage can be used as an excipient for making sustained release matrix tablets. PMID:21715275

Kumar, Chitta Suresh; Reddy-Budideti, Kishore Kumar; Battula, Suma Padmaja; Ayyavala, Chandra Sekhar

2011-07-01

58

[Comparison of the characteristics of several polymer materials used in hydrophilic matrix tablets].  

PubMed

Pure and drug hydrophilic matrix tablets were prepared by direct compression method with theophylline as a model drug. The characteristics of four hydrophilic matrix polymers, hydroxypropylmethylcellulose (HPMC), polyethylene oxide (PEO), sodium alginate (NaAlg) and xanthan gum (XG), were compared by investigating the water absorption, swelling, erosion and gel layer strength. The sequence of water absorption rate was XG > NaAlg (H) > PEO > NaAlg (L) > HPMC; The sequence of swelling index was XG > PEO > HPMC > NaAlg; The sequence of erosion rate was NaAlg (L) > NaAlg (H) > PEO80 > PEO200 > PEO300 > XG approximately PEO400 approximately K4M > K15M > PEO600 approximately K100M; The sequence of the gel layer strength was PEO > HPMC > XG > NaAlg. For the PEO and HPMC matrix tablets, with the polymer molecular weight increased, the drug release mechanism was gradually transferred from mainly depending on the erosion to the diffusion; for SAL matrix tablets, the drug release mainly depends on erosion mechanism; and for XG matrix tablets, the drug release mainly depends on non-Fick diffusion mechanism. Comparison of the performance difference between the polymer materials will contribute to rational design and prediction of drug release behaviors from matrix tables and ultimately to achieve clinical needs. PMID:21626791

Nie, Shu-Fang; Liu, Hui; Liu, Yan-Li; Pan, Wei-San

2011-03-01

59

Development of extended release divalproex sodium tablets containing hypdrophobic and hydrophilic matrix.  

PubMed

Bilayered tablets of Divalproex sodium for once-a-day administration were prepared using a hydrophilic and hydrophobic polymer as release retarding agents. This technology was found to be more effective than a simple matrix tablet with a mixture of the above polymers in order to retard the drug release for a period of 24 h. The drug release profile was strongly dependent on the presence of wicking agent, pathlength of hydrophobic layer, and hardness of tablet. f(1) value of 6.92 and f(2) value of 76.72 indicated similarity between the release profiles of batch BT3 and reference tablet (Depakote((R)) ER) with the target release of over 55% within 12 h and over 85% within 18 h. Mathematical modeling using Korsmeyer-Peppas equation indicated that the release followed a combination of diffusion and erosion mechanism. PMID:19604143

Chakraborty, S; Pandit, J K; Srinatha, A

2009-07-01

60

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

PubMed Central

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

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

2012-01-01

61

Inter-grade and inter-batch variability of sodium alginate used in alginate-based matrix tablets.  

PubMed

The purpose of this study is to characterize the inter-grade and inter-batch variability of sodium alginate used in the formulation of matrix tablets. Four different grades and three batches of one grade of sodium alginate were used to prepare matrix tablets. Swelling, erosion, and drug release tests of sodium alginate matrix tablets were conducted in a USP dissolution apparatus. Substantial differences in swelling and erosion behavior of sodium alginate matrix tablets were evident among different viscosity grades. Even different batches of the same grade exhibit substantial differences in the swelling and erosion behavior of their matrix tablets. The erosion behavior of sodium alginate matrix tablets can be partly explained by their rheological properties (both apparent viscosity and viscoelasticity) in solution. Sodium alginate with higher apparent viscosity and viscoelasticity in solution show slower erosion rate and higher swelling rate. Compacts prepared from grades or batches with higher viscosity and higher viscoelasticity show slower drug release. For grades or batches with similar apparent viscosities, apparent viscosities of sodium alginate solution at low concentration alone are not sufficient to predict the functionality of sodium alginate in matrix tablets. Viscoelastic properties of sodium alginate solutions at one high concentration corresponding to the polymer gel state, may be suitable indicia of the extended release behavior of sodium alginate matrix tablets. PMID:24889735

Fu, Shao; Buckner, Ira S; Block, Lawrence H

2014-10-01

62

Use of response surface methodology in the formulation and optimization of bisoprolol fumarate matrix tablets for sustained drug release.  

PubMed

The aim of this investigation was to develop and optimize bisoprolol fumarate matrix tablets for sustained release application by response surface methodology based on 2(3) 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

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

2012-01-01

63

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

PubMed Central

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

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

2012-01-01

64

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...

65

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

PubMed Central

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 f2 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

Sakr, Walid; Alanazi, Fars; Sakr, Adel

2010-01-01

66

Formulation and evaluation of sustained release matrix tablet of rabeprazole using wet granulation technique  

PubMed Central

Introduction: Rabeprazole, a member of substituted benzimidazoles, inhibits the final step in gastric acid secretions. This drug claims to cause fastest acid separation (due to higher pKa), and more rapidly converts to the active species to aid gastric mucin synthesis. The most significant pharmacological action of Rabeprazole is dose dependent suppression of gastric acid secretion; without anticholinergic or H2-blocking action. It completely abolishes the hydrochloric acid secretion as it is powerful inhibitor of gastric acid. Rabeprazole is acid labile and hence commonly formulated as an enteric coated tablet. The absorption of rabeprazole occurs rapidly as soon as tablet leaves the stomach. Aim: In the present study an attempt was made to formulate and evaluate Rabeprazole sustained release matrix tablet using wet granulation technique incorporating various polymers like HPMC-E15, Carbopol934, and sodium carboxymethyl cellulose (CMC). Materials and Methods: The Formulated tablets were evaluated for different physicochemical properties like rheological properties, weight variation, thickness, hardness, % friability, in vitro release studies and drug content. Results: Studies revealed that all the physicochemical parameters comply with the official standards. The in vitro release studies exhibits the release up to 90%, over a prolonged period of time which confirms the extended release profile of formulation, having better bioavailability as well as decreased dosing frequency with reduced doses. Conclusion: The sustained release matrix tablets of rabiprazole shown better bioavailability, efficacy and potency, when compared with official standards. PMID:25035637

Khan, Ruqaiyah; Ashraf, Md Shamim; Afzal, Muhammad; Kazmi, Imran; Jahangir, Mohammed Asadullah; Singh, Rajbala; Chandra, Ramesh; Anwar, Firoz

2014-01-01

67

Design of Controlled Release Non-erodible Polymeric Matrix Tablet Using Microwave Oven-assisted Sintering Technique.  

PubMed

The objective of the present study was to evaluate the effect of sintering condition on matrix formation and subsequent drug release from polymer matrix tablet for controlled release. The present study highlights the use of a microwave oven for the sintering process in order to achieve more uniform heat distribution with reduction in time required for sintering. We could achieve effective sintering within 8 min which is very less compared to conventional hot air oven sintering. The tablets containing the drug (propranolol hydrochloride) and sintering polymer (eudragit S-100) were prepared and kept in a microwave oven at 540 watt, 720 watt and 900 watt power for different time periods for sintering. The sintered tablets were evaluated for various tablet characteristics including dissolution study. Tablets sintered at 900 watt power for 8 min gave better dissolution profile compared to others. We conclude that microwave oven sintering is better than conventional hot air oven sintering process in preparation of controlled release tablets. PMID:21897655

Patel, Dm; Patel, Bk; Patel, Ha; Patel, Cn

2011-07-01

68

Use of hydrophilic natural gums in formulation of sustained-release matrix tablets of tramadol hydrochloride  

Microsoft Academic Search

The objective of this work was to develop matrix sustained-release tablets of highly water-soluble tramadol HCl using natural\\u000a gums (xanthan [X gum] and guar [G gum]) as cost-effective, nontoxic, easily available, and suitable hydrophilic matrix systems\\u000a compared with the extensively investigated hydrophilic matrices (ie, hydroxypropyl methylcellulose [HPMC]\\/carboxymethyl cellulose\\u000a [CMC] with respect to in vitro drug release rate) and hydration rate

Jaleh Varshosaz; Naser Tavakoli; Fatemeh Kheirolahi

2006-01-01

69

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

PubMed Central

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

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

2014-01-01

70

Study of formulation variables influencing the drug release rate from matrix tablets by experimental design.  

PubMed

Experimental design was utilized to simultaneously investigate the effect of varying the type of diluent (insoluble Calcium phosphate or water-soluble arabic gum) and the diluent/matrix ratio on the drug release behaviour from both lipophilic (glyceryl behenate, Compritol) or hydrophilic (hydroxypropylmethylcellulose) matrix tablets. Ketoprofen, theophylline and sodium sulphadiazine were selected as model drugs on the basis of their respectively very low, medium and high water-solubility, in order to evaluate the influence of this parameter as well. The selected response variables were the dissolution efficiency (i.e. the area under the dissolution curve) after one and six hours and the time necessary to dissolve 10% drug. Tablets obtained by direct compression of drug-diluent-matrix ternary mixtures prepared according to the experimental plan provided for by an asymmetric screening matrix, were tested for drug release properties using a USP paddle apparatus. Graphic analysis of the effects allowed identification, for each examined drug, of the formulation factors active on the selected responses and determination of the proper level of the variables to be selected for the response improvement. The different results obtained with the three examined drugs pointed out the role of the drug solubility in determining the influence of formulation parameters on drug release rate from matrix tablets. PMID:16154333

Furlanetto, Sandra; Cirri, Marzia; Maestrelli, Francesca; Corti, Giovanna; Mura, Paola

2006-01-01

71

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

PubMed Central

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

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

2009-01-01

72

Effect of two hydrophobic polymers on the release of gliclazide from their matrix tablets.  

PubMed

Gliclazide is an oral hypoglycemic agent, indicated in non insulin dependent diabetes mellitus and in patients with diabetic retinopathy. It has good tolerability and is a short acting sulfonyl urea that requires large dose to maintain the blood glucose level. So development of a sustained release formulation of gliclazide (GLZ) is required for better patient compliance. This study was conducted to assess the effects of different drug polymer ratios on the release profile of gliclazide from the matrix. Oral matrix tablets of gliclazide were prepared by hot melt method, using pure and blended mixture of glyceryl monostearate (GMS) and stearic acid (SA) in different ratios. In vitro release pattern was studied for 8 h in phosphate buffer media (pH 7.4). Different kinetic models including zero order, first order, Higuchi and Peppas were applied to evaluate drug release behavior. Drug excipient compatibility was evaluated by scanning with DSC and FTIR. Higuchi model was found the most appropriate model for describing the release profile of GLZ and non-Fickian release was found predominant mechanism of drug release. The release of drug from the matrix was greatly controlled by GMS while SA appeared to facilitate the release of drug from matrix tablets. FTIR results showed no chemical interaction between drug and the polymers, and DSC results indicated amorphous state of GLZ and polymers without significant complex formation. The results indicate that matrix tablets of gliclazide using glyceryl monostearate and stearic acid showed marked sustained release properties. PMID:23923399

Hussain, Talib; Saeed, Tariq; Mumtaz, Ahmad M; Javaid, Zeeshan; Abbas, Khizar; Awais, Azeema; Idrees, Hafiz Arfat

2013-01-01

73

Comparative release profile of sustained release matrix tablets of verapamil HCl  

PubMed Central

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

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

2013-01-01

74

Effect of solvents on physical properties and release characteristics of monolithic hydroxypropylmethylcellulose matrix granules and tablets  

Microsoft Academic Search

Effect of solvents on physical characteristics and release characteristics of monolithic acetaminophen (APAP) hydroxypropylmethylcellulose\\u000a (HPMC) matrix granules and tablets were examined. Various types and amounts of solvents were employed for granulation and\\u000a coating. APAP and other excipients were mixed and were then wet-granulated in a high-speed mixer. The dried granules were\\u000a then directly compressed and film-coated with low viscosity grade

Qing-Ri Cao; Yun-Woong Choi; Jing-Hao Cui; Beom-Jin Lee

2005-01-01

75

The Influence of the Compression Force on Zidovudine Release from Matrix Tablets  

Microsoft Academic Search

The aim of the present work is the study of different zidovudine (AZT) formulations containing polymers (both cellulosic and\\u000a acrylic), in order to evaluate the influence of the compression force on the antiviral release from the matrix tablets. The\\u000a results evidenced that the formulations compressed at 500 and 1,000 MPa exhibit a higher hardness than those prepared at 100 MPa.\\u000a The effect

Jucimary V. Santos; Luís A. E. Batista de Carvalho; Maria Eugénia Tavares Pina

2010-01-01

76

Designing an extended release waxy matrix tablet containing nicardipine–hydroxy propyl ? cyclodextrin complex  

PubMed Central

Aim The current study aimed to prepare a sustained release tablet for a drug which has poor solubility in alkaline medium using complexation with cyclodextrin. Nicardipine hydrochloride (NC) a weak basic drug was chosen as a model drug for this study. Method Firstly the most suitable binary system NC-HP?CD was selected in order to improve drug solubility in the intestinal media and then embedding the complexed drug into a plastic matrix, by fusion method, consists of glycerol monostearate (GMS) as an inert waxy substance and polyethylene glycol 4000 (PEG4000) as a channeling agent, after that the final solid dispersion [(NC:HP?CD):GMS:PEG4000] which was prepared at different ratios was mixed with other excipients, avicel PH101, lactose, and talc, to get a tablet owning dissolution profile complying with the FDA and USP requirements for the extended release solid dosage forms. Results Infrared spectroscopy (IR), differential scanning colorimetry (DSC), polarized microscopy and X-ray diffractometry proved that the coevaporation technique was effective in preparing amorphous cyclodextrin complexes with NC and trapping of NC within the HP?CD cavity by dissolving both in ethanol and evaporate the solvent using a rotavapor at 65 °C. Dissolution profile of NC enhanced significantly in pH 6.8 from NC:HP?CD inclusion complex prepared by the rotavapor (t-test Student p < 0.05). The release of NC from tablet containing [(NC:HP?CD):GMS:PEG4000] [(1):0.75:0.5] (w/w/w) solid dispersion (F8) was complying with the FDA dissolution requirements for extended release dosage forms, and studying the kinetics of the release showed that the diffusional contribution is the major factor controlling the drug release from that formula. Conclusion The prepared waxy matrix tablet containing NC complexes with CD shows promising results as extended release tablets. PMID:23960765

Al-Zein, Hind; Sakeer, Khalil; Alanazi, Fars K.

2011-01-01

77

Model drug release from matrix tablets composed of HPMC with different substituent heterogeneity.  

PubMed

The release of a model drug substance, methylparaben, was studied in matrix tablets composed of hydroxypropyl methylcellulose (HPMC) batches of the USP 2208 grade that had different chemical compositions. It was found that chemically heterogeneous HPMC batches with longer sections of low substituted regions and lower hydroxypropoxy content facilitated the formation of reversible gel structures at a temperature as low as 37°C. Most importantly, these structures were shown to affect the release of the drug from matrix tablets, where the drug release decreased with increased heterogeneity and a difference in T80 values of 7h was observed between the compositions. This could be explained by the much lower erosion rate of the heterogeneous HPMC batches, which decreased the drug release rate and also released the drug with a more diffusion based release mechanism compared to the less heterogeneous batches. It can therefore be concluded that the drug release from matrix tablets is very sensitive to variations in the chemical heterogeneity of HPMC. PMID:20883761

Viridén, Anna; Larsson, Anette; Schagerlöf, Herje; Wittgren, Bengt

2010-11-30

78

Formulation and in vitro, in vivo evaluation of extended- release matrix tablet of Zidovudine: Influence of combination of hydrophilic and hydrophobic matrix formers  

Microsoft Academic Search

The aim of the present study was to prepare and characterize extended-release matrix tablets of zidovudine using hydrophilic\\u000a Eudragit RLPO and RSPO alone or their combination with hydrophobic ethyl cellulose. Release kinetics was evaluated by using\\u000a United States Pharmacopeia (USP)-22 type I dissolution apparatus. Scanning electron microscopy was used to visualize the effect of dissolution medium on matrix\\u000a tablet surface.

Atul Kuksal; Ashok K. Tiwary; Narendra K. Jain; Subheet Jain

2006-01-01

79

Strategies for the design of hydrophilic matrix tablets with controlled microenvironmental pH.  

PubMed

Incorporation of weak acids as pH modifiers enhances the release of weakly basic drugs in higher pH environments by reducing the microenvironmental pH (pHM). The objectives of this study were: (a) to investigate the relationship between pHM, drug release, and pH modifier release and (b) to achieve simultaneous release of the drug and the pH modifier over the entire dissolution time (6 h, phosphate buffer, pH 6.8). Using dipyridamole as a model drug, we investigated drug and acid release and determined the average pHM potentiometrically using tablet cryosections. The first approach was based on incorporating different concentrations of pH modifiers in conventional matrix tablets based on hydroxypropylmethylcellulose. Owing to its high acidic strength and low aqueous solubility, fumaric acid resulted in simultaneous release and maintained a constant acidic pHM. Secondly, press-coated matrix tablets, comprising an acidic reservoir, were found to be a valuable approach for retarding the diffusion of more water-soluble acids. Using the power law expression (Mt/Minfinity = ktn) it became evident that the inclusion of acids increased drug release. Higher acid concentrations tended to decrease n standing for the slope, whereas the release constant k increased. Furthermore, the medial check term parameters depended on the type of pH modifier used. PMID:16551495

Siepe, Stefanie; Lueckel, Barbara; Kramer, Andrea; Ries, Angelika; Gurny, Robert

2006-06-19

80

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

PubMed

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

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

2013-12-01

81

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

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

82

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

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

83

Statistical Optimization of Sustained Release Venlafaxine HCI Wax Matrix Tablet.  

PubMed

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

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

2008-01-01

84

Evaluation of Solubilizers in the Drug Release Testing of Hydrophilic Matrix Extended-Release Tablets of Felodipine  

Microsoft Academic Search

The drug release of felodipine, a water-insoluble drug, was tested by using sodium lauryl sulphate (SLS), polyoxyethylene 20 sorbitan monooleate (Tween) or cetyltrimethylammonium bromide (CTAB) in the test medium as solubilizers. Three slightly different felodipine extended-release (ER) tablets 10 mg based on the gel matrix principle were evaluated under different solubilizer concentrations, agitation intensities and pH. These tablets were also

Bertil Abrahamsson; Dick Johansson; Arne Torstensson; Karin Wingstrand

1994-01-01

85

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

PubMed Central

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

Gönüllü, Ümit; Üner, Melike; Yener, Gülgün; Alt?nkurt, Turan

2006-01-01

86

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

PubMed

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

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

2008-02-01

87

Didanosine extended-release matrix tablets: optimization of formulation variables using statistical experimental design.  

PubMed

Statistical experimental design was applied to evaluate the influence of some process and formulation variables and possible interactions among such variables, on didanosine release from directly-compressed matrix tablets based on blends of two insoluble polymers, Eudragit RS-PM and Ethocel 100, with the final goal of drug release behavior optimization. The considered responses were the percent of drug released at three determined times, the dissolution efficiency at 6 h and the time to dissolve 10% of drug. Four independent variables were considered: tablet compression force, ratio between the polymers and their particle size, and drug content. The preliminary screening step, carried out by means of a 12-run asymmetric screening matrix according to a D-optimal design strategy, allowed evaluation of the effects of different levels of each variable. The drug content and the polymers ratio had the most important effect on drug release, which, moreover, was favored by greater polymers particle size; on the contrary the compression force did not have a significant effect. The Doehlert design was then applied for a response-surface study, in order to study in depth the effects of the most important variables. The desirability function was used to simultaneously optimize the five considered responses, each having a different target. This procedure allowed selection, in the studied experimental domain, of the best formulation conditions to optimize drug release rate. The experimental values obtained from the optimized formulation highly agreed with the predicted values. The results demonstrated the reliability of the model in the preparation of extended-release matrix tablets with predictable drug release profiles. PMID:11955809

Sánchez-Lafuente, Carla; Furlanetto, Sandra; Fernández-Arévalo, Mercedes; Alvarez-Fuentes, Josefa; Rabasco, Antonio M; Faucci, M Teresa; Pinzauti, Sergio; Mura, Paola

2002-04-26

88

Modulation of drug release kinetics from hydroxypropyl methyl cellulose matrix tablets using polyvinyl pyrrolidone.  

PubMed

Hydrophilic matrix tablets are widely used to extend the release of a broad range of pharmaceutically active materials. The mechanism and kinetics of drug release are dependent on the solubility of the active moiety and the swelling and erosion properties of the polymer, with water soluble compounds released predominantly by diffusion. The swelling and erosion properties of hydroxypropyl methyl cellulose (HPMC), typically lead to a first order release rate for water soluble compounds as opposed to the more desirable zero-order kinetics. In addition, for compounds with differences in regional absorption within the gastrointestinal tract a dosage form with a bi-modal release profile may be required, which is difficult to achieve with a simple dosage form. The following paper presents a simple, cost effective and elegant solution for achieving a range of predictable release profiles from linear to bi-modal for a water soluble drug (caffeine) from HPMC matrices, through the inclusion of polyvinyl pyrrolidone (PVP). Mechanistic studies using gel rheology, excipient dissolution and near-infrared microscopy (NIR) microscopy are presented which show that the modulation of drug release kinetics is mediated through a reduction in HPMC viscosity in the presence of a critical concentration of PVP, which leads to a break-up of the extended release tablet. A validated mathematical model is also presented which allows drug release profiles to be reliably predicted based on the initial HPMC and PVP content in the tablet. PMID:17306477

Hardy, Ian J; Windberg-Baarup, Anne; Neri, Claudia; Byway, Paul V; Booth, Steven W; Fitzpatrick, Shaun

2007-06-01

89

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

PubMed Central

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

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

2003-01-01

90

Optimization of sustained release matrix tablet of metoprolol succinate using central composite design.  

PubMed

The present study was performed to optimize the formulation of metoprolol succinate (MS) sustained release tablets using hydroxypropyl methylcellulose (HPMC) and sodium alginate (SA) as the matrix combination. After investigating the effects of various parameters on drug release, a 2-factor, 5-level central composite design was employed, using the amount of HPMC K4M (A) and SA (318 cP) (B) as the independent variables and the drug percentage released at 1h, 4h, 8h, 20h (Q1, Q4, Q8, Q20) as the responses. Response surfaces were established to obtain the matrix ranges and the main factors affecting four responses. In order to validate the optimization study, six confirmatory runs were performed; indicating high predictability of response surface methodology for MS sustained release tablets. Data fitting to Peppas equation indicated that the mechanism of drug release could be diffusion along with erosion. This matrix combination can be used as a good alternative to the commercially pellet technology, which was complicated, time-consuming and energy-intensive. PMID:24035948

Li, Li; Sun, Huijuan; Gao, Jing; Jiang, Tao; Gao, Yuan; Zhang, Jianjun

2013-09-01

91

Matrix tablets of carrageenans. II. Release behavior and effect of added cations.  

PubMed

Carrageenans are hydrocolloids in the rubbery state at standard conditions. They are useful excipients for controlled-release tablets. Three carrageenans, two kappa-carrageenans (Gelcarin GP-812 NF and GP-911 NF) and one iota-carrageenan (Gelcarin GP-379 NF), are analyzed regarding their release behavior in combination with sorption, swelling, and rheology. The iota-carrageenan has a higher substitution by sulfate groups. The kappa-carrageenan Gelcarin GP-812 NF contains a small amount of potassium chloride left over from processing. Water sorption of the pure materials was studied gravimetrically, and the rheology of different solutions (2% and 5% w/w) was studied by cup-cylinder rotation viscosimetry. Swelling was determined as the vertical expansion of the tablets with a specially designed swelling apparatus. Drug release from the tablets was performed by the USP paddle method for 8 hr. The data indicate that drug release increases when water sorption and swelling extent decrease and as viscosity increases. The order of release is nearly zero-order kinetics for theophylline monohydrate, a nonionic drug. Diffusion of the anionic drug diclofenac sodium is anomalous. In addition, the influence of the added salts potassium and calcium chloride on swelling and release was studied. Before tableting, physical mixtures of these salts with and without theophylline monohydrate were prepared. Swelling and release change in the same order, but this is only valid when the ionic interactions responsible for this are strong enough. Besides this, physical mixing of salts with the carrageenans can result in an increased release of drug caused by decreased cohesion of the matrix during drug release, mainly for calcium chloride. PMID:10071827

Picker, K M

1999-03-01

92

Formulation and in vitro evaluation of Eudragit S-100 coated naproxen matrix tablets for colon-targeted drug delivery system  

PubMed Central

The purpose of the present investigation was to prepare matrix tablets of naproxen using a hydrophobic polymer, i.e., Eudragit RLPO, RSPO, and combination of both, by wet granulation method. The tablets were further coated with different concentrations of Eudragit S-100, a pH-sensitive polymer, by dip immerse method. In vitro drug release studies of tablets were carried out in different dissolution media, i.e., 0.1 N HCl (pH 1.2), phosphate buffers pH 6.8 and 7.4, with or without rat cecal content. The swelling studies of the optimized formulation were carried out. The physicochemical parameters of all the formulations were found to be in compliance with the pharmacopoeial standards. The effect of dissolution medium on the surface of matrix tablet was determined by using Scanning Electron Microscopy technique. The stability studies of all formulations were performed as per ICH guidelines. The results demonstrated that the tablets coated with Eudragit S-100 (2% w/v) showed a sustained release of 94.67% for 24 h, but drug release increased to about 98.60% for 24 h in the presence of rat cecal content while the uncoated tablets released the drug within 5 h. With regard to release kinetics, the data were best fitted with the Higuchi model with non-Fickian drug release kinetics mechanism. The stability studies of tablets showed less degradation during accelerated and room temperature storage conditions for 6 months. The enteric-coated Eudragit S-100 coated matrix tablets of naproxen showed promising site-specific drug delivery in the colon region. PMID:23662280

Mehta, Rohit; Chawla, Anuj; Sharma, Pooja; Pawar, Pravin

2013-01-01

93

Formulation and in vitro evaluation of Eudragit S-100 coated naproxen matrix tablets for colon-targeted drug delivery system.  

PubMed

The purpose of the present investigation was to prepare matrix tablets of naproxen using a hydrophobic polymer, i.e., Eudragit RLPO, RSPO, and combination of both, by wet granulation method. The tablets were further coated with different concentrations of Eudragit S-100, a pH-sensitive polymer, by dip immerse method. In vitro drug release studies of tablets were carried out in different dissolution media, i.e., 0.1 N HCl (pH 1.2), phosphate buffers pH 6.8 and 7.4, with or without rat cecal content. The swelling studies of the optimized formulation were carried out. The physicochemical parameters of all the formulations were found to be in compliance with the pharmacopoeial standards. The effect of dissolution medium on the surface of matrix tablet was determined by using Scanning Electron Microscopy technique. The stability studies of all formulations were performed as per ICH guidelines. The results demonstrated that the tablets coated with Eudragit S-100 (2% w/v) showed a sustained release of 94.67% for 24 h, but drug release increased to about 98.60% for 24 h in the presence of rat cecal content while the uncoated tablets released the drug within 5 h. With regard to release kinetics, the data were best fitted with the Higuchi model with non-Fickian drug release kinetics mechanism. The stability studies of tablets showed less degradation during accelerated and room temperature storage conditions for 6 months. The enteric-coated Eudragit S-100 coated matrix tablets of naproxen showed promising site-specific drug delivery in the colon region. PMID:23662280

Mehta, Rohit; Chawla, Anuj; Sharma, Pooja; Pawar, Pravin

2013-01-01

94

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

PubMed

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

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

2013-11-01

95

Design and in vitro/in vivo evaluation of extended release matrix tablets of nateglinide  

PubMed Central

Aim Nateglinide is a quick acting anti-diabetic medication whose potent activity lasts for a short duration. One of the dangerous side effects of nateglinide administration is rapid hypoglycemia, a condition that needs to be monitored carefully to prevent unnecessary fatalities. The aim of the study was to develop a longer lasting and slower releasing formulation of nateglinide that could be administered just once daily. Methods Matrix tablets of nateglinide were prepared in combination with the polymers hydroxypropylmethylcellulose (HPMC), eudragits, ethyl cellulose and polyethylene oxide and the formulated drug release patterns were evaluated using in vitro and in vivo studies. Conclusion Of the seventeen formulated matrix tablets tested, only one formulation labelled HA-2 that contained 15% HPMC K4M demonstrated release profile we had aimed for. Further, swelling studies and scanning electron microscopic analysis confirmed the drug release mechanism of HA-2. The optimized formulation HA-2 was found to be stable at accelerated storage conditions for 3 months with respect to drug content and physical appearance. Mathematical analysis of the release kinetics of HA-2 indicated a coupling of diffusion and erosion mechanisms. In-vitro release studies and pharmacokinetic in vivo studies of HA-2 in rabbits confirmed the sustained drug release profile we had aimed for. PMID:24563597

Sharma, Pushkar R.; Lewis, Shaila A.

2013-01-01

96

The influence of crystallization inhibition of HPMC and HPMCAS on model substance dissolution and release in swellable matrix tablets.  

PubMed

One of the drawbacks with solid solution systems is their thermodynamic instability in solution. Considering the release of these systems from extended-release formulations, in particular swellable matrix tablets, a successful tablet formulation can be regarded as a composition able to maintain the molecular state of the poorly soluble crystalline drug through diffusion in the matrix. This may in turn provide molecular rather than particulate delivery of the substance from the matrix. In this study, the solid state and dissolution behavior of amorphous solid dispersions of a model crystalline substance, butyl paraben in HPMC and HPMCAS, was investigated. In addition, the suitability of HPMCAS as both effective solid solution carrier and as extended-release matrix forming polymer was examined. The release from all systems investigated showed extended-release capacity with a release rate similar to the rate of matrix erosion. However, a detailed study of the factors affecting the release mechanism revealed that upon hydration, the model substance crystallized in the gel layer of the HPMC-based formulation, whereas it remained in amorphous form in the HPMCAS tablets. In the case of HPMCAS formulation, this effect was attributed to (i) the ability of this polymer to keep the model substance in a supersaturated state and (ii) the very slow matrix hydration, resulting in a steep concentration gradient of the drug substance and a short diffusion path through the matrix into the dissolution bulk. PMID:21168491

Tajarobi, Farhad; Larsson, Anette; Matic, Hanna; Abrahmsén-Alami, Susanna

2011-05-01

97

Formulation development and stability studies of norfloxacin extended-release matrix tablets.  

PubMed

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

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

2013-01-01

98

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

PubMed Central

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

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

2013-01-01

99

Effect of Channeling Agents on the Release Profile of Theophylline from METHOCEL K4M Based Matrix tablets  

Microsoft Academic Search

The present study was undertaken to investigate the effect of channeling agents on the release profile of Theophylline from METHOCEL K4M based matrix systems. Matrix tablets of Theophylline using METHOCEL K4M were prepared by direct compression process. METHOCEL K4M polymer is hydrophilic in nature. NaCl and PEG 1500 were used as channeling agents. Drug release study was evaluated for eight

Ferdous Khan; Kanij Fatema; Muhammed Shahidul Islam

2008-01-01

100

Application of mixture experimental design in the formulation and optimization of matrix tablets containing carbomer and hydroxy-propylmethylcellulose.  

PubMed

Using mixture experimental design, the effect of carbomer (Carbopol((R)) 971P NF) and hydroxypropylmethylcellulose (Methocel((R)) K100M or Methocel((R)) K4M) combination on the release profile and on the mechanism of drug liberation from matrix tablet was investigated. The numerical optimization procedure was also applied to establish and obtain formulation with desired drug release. The amount of TP released, release rate and mechanism varied with carbomer ratio in total matrix and HPMC viscosity. Increasing carbomer fractions led to a decrease in drug release. Anomalous diffusion was found in all matrices containing carbomer, while Case - II transport was predominant for tablet based on HPMC only. The predicted and obtained profiles for optimized formulations showed similarity. Those results indicate that Simplex Lattice Mixture experimental design and numerical optimization procedure can be applied during development to obtain sustained release matrix formulation with desired release profile. PMID:20162406

Petrovic, Aleksandra; Cvetkovic, Nebojsa; Ibric, Svetlana; Trajkovic, Svetlana; Djuric, Zorica; Popadic, Dragica; Popovic, Radmila

2009-12-01

101

Formulation of sustained - release lithium carbonate matrix tablets: influence of hydrophilic materials on the release rate and in vitro-in vivo evaluation  

Microsoft Academic Search

Purpose: Conventional lithium carbon- ate (LC) tablets not only produce rapid and relatively high peak blood levels resulting in adverse effects but also should be administered 3 to 4 times daily. These drawbacks can be overcome by designing a suitable sustained-release LC preparation. Methods: Sustained- release matrix tablets containing 450 mg LC were developed using different types and ratios of

Jaber Emami; Naser Tavakoli

102

Conceptuation, formulation and evaluation of sustained release floating tablets of captopril compression coated with gastric dispersible hydrochlorothiazide using 23 factorial design  

PubMed Central

Ambulatory blood pressure monitoring is regarded as the gold standard for hypertensive therapy in non-dipping hypertension patients. A novel compression coated formulation of captopril and hydrochlorothiazide (HCTZ) was developed in order to improve the efficacy of antihypertensive therapy considering the half-life of both drugs. The synergistic action using combination therapy can be effectively achieved by sustained release captopril (t1/2= 2.5 h) and fast releasing HCTZ (average t1/2= 9.5 h). The sustained release floating tablets of captopril were prepared by using 23 factorial design by employing three polymers i.e., ethyl cellulose (EC), carbopol and xanthan gum at two levels. The formulations (CF1-CF8) were optimized using analysis of variance for two response variables, buoyancy and T50%. Among the three polymers employed, the coefficients and P values for the response variable buoyancy and T50% using EC were found to be 3.824, 0.028 and 0.0196, 0.046 respectively. From the coefficients and P values for the two response variables, formulation CF2 was optimized, which contains EC polymer alone at a high level. The CF2 formulation was further compression coated with optimized gastric dispersible HCTZ layer (HF9). The compression coated tablet was further evaluated using drug release kinetics. The Q value of HCTZ layer is achieved within 20 min following first order release whereas the Q value of captopril was obtained at 6.5 h following Higuchi model, from which it is proved that rapid release HCTZ and slow release of captopril is achieved. The mechanism of drug release was analyzed using Peppas equation, which showed an n >0.90 confirming case II transportation mechanism for drug release. PMID:25006552

Sirisha, Pathuri Lakshmi; Babu, Govada Kishore; Babu, Puttagunta Srinivasa

2014-01-01

103

Conceptuation, formulation and evaluation of sustained release floating tablets of captopril compression coated with gastric dispersible hydrochlorothiazide using 2(3) factorial design.  

PubMed

Ambulatory blood pressure monitoring is regarded as the gold standard for hypertensive therapy in non-dipping hypertension patients. A novel compression coated formulation of captopril and hydrochlorothiazide (HCTZ) was developed in order to improve the efficacy of antihypertensive therapy considering the half-life of both drugs. The synergistic action using combination therapy can be effectively achieved by sustained release captopril (t1/2= 2.5 h) and fast releasing HCTZ (average t1/2= 9.5 h). The sustained release floating tablets of captopril were prepared by using 2(3) factorial design by employing three polymers i.e., ethyl cellulose (EC), carbopol and xanthan gum at two levels. The formulations (CF1-CF8) were optimized using analysis of variance for two response variables, buoyancy and T50%. Among the three polymers employed, the coefficients and P values for the response variable buoyancy and T50% using EC were found to be 3.824, 0.028 and 0.0196, 0.046 respectively. From the coefficients and P values for the two response variables, formulation CF2 was optimized, which contains EC polymer alone at a high level. The CF2 formulation was further compression coated with optimized gastric dispersible HCTZ layer (HF9). The compression coated tablet was further evaluated using drug release kinetics. The Q value of HCTZ layer is achieved within 20 min following first order release whereas the Q value of captopril was obtained at 6.5 h following Higuchi model, from which it is proved that rapid release HCTZ and slow release of captopril is achieved. The mechanism of drug release was analyzed using Peppas equation, which showed an n >0.90 confirming case II transportation mechanism for drug release. PMID:25006552

Sirisha, Pathuri Lakshmi; Babu, Govada Kishore; Babu, Puttagunta Srinivasa

2014-04-01

104

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

PubMed

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

Bagchi, Saumitra; Li, Weiyong; Plakogiannis, Fotios

2012-01-01

105

Drug release phenomena within a hydrophobic starch acetate matrix: FTIR mapping of tablets after in vitro dissolution testing.  

PubMed

The aim of this study was to assess the utility of Fourier transform infrared mapping to study the drug release phenomena within a hydrophobic matrix tablet. Starch acetate with a degree of substitution (2.7) was used as a hydrophobic matrix former. Anhydrous caffeine and riboflavin sodium phosphate were used as water soluble model drugs. The USP (XXVIII) paddle-method was selected as an in vitro dissolution test. Mapping of the diluted tablets' cross-section was performed by attenuated total reflection mode. Fourier transform infrared mapping can distinguish drug particles from the bulk matrix and it can be considered as a valuable method for obtaining both quantitative and qualitative information on drug release processes. The physicochemical properties of the drug compound strongly contribute to its release behavior when the USP paddle in vitro dissolution test is used. Mapping of the riboflavin product revealed a more homogenous matrix distribution due to its smaller particle size. Consequently, its dissolution release profile was more uniform than caffeine which possessed a wider particle size distribution and lower solubility. Mapping showed that caffeine became localized in the lower part of the tablet unlike riboflavin. The hydrodynamic conditions during the in vitro release test might contribute to this differentiation. PMID:18085712

Pajander, Jari; Soikkeli, Anne-Marie; Korhonen, Ossi; Forbes, Robert T; Ketolainen, Jarkko

2008-08-01

106

Compressed matrix core tablet as a quick\\/slow dual-component delivery system containing ibuprofen  

Microsoft Academic Search

The purpose of the present research was to produce a quick\\/slow biphasic delivery system for ibuprofen. A dual-component tablet\\u000a made of a sustained release tableted core and an immediate release tableted coat was prepared by direct compression. Both\\u000a the core and the coat contained a model drug (ibuprofen). The sustained release effect was achieved with a polymer (hydroxypropyl\\u000a methylcellulose [HPMC

Carla Martins Lopes; José M. Sousa Lobo; João F. Pinto; Paulo C. Costa

2007-01-01

107

The application of generalized regression neural network in the modeling and optimization of aspirin extended release tablets with Eudragit ® RS PO as matrix substance  

Microsoft Academic Search

The objective of this work is to use a generalized regression neural network (GRNN) in the design of extended-release aspirin tablets. As model formulations, 10 kinds of aspirin matrix tablets were prepared. Eudragit® RS PO was used as matrix substance. The amount of Eudragit® RS PO and compression pressure were selected as causal factors. In-vitro dissolution–time profiles at four different

Svetlana Ibri?; Milica Jovanovi?; Zorica Djuri?; Jelena Paroj?i?; Ljiljana Solomun

2002-01-01

108

Sustained Release of a Water-Soluble Drug from Alginate Matrix Tablets Prepared by Wet Granulation Method  

Microsoft Academic Search

Alginate matrix tablet of diltiazem hydrochloride (DTZ), a water-soluble drug, was prepared using sodium alginate (SAL) and\\u000a calcium gluconate (CG) by the conventional wet granulation method for sustained release of the drug. The effect of formulation\\u000a variables like SAL\\/CG ratio, drug load, microenvironmental pH modulator, and processing variable like compression force on\\u000a the extent of drug release was examined. The

Sanchita Mandal; Sanat Kumar Basu; Biswanath Sa

2009-01-01

109

Influence of formulation and process variables on in vitro release of theophylline from directly-compressed Eudragit matrix tablets  

Microsoft Academic Search

Extended-release theophylline (TP) matrix tablets were prepared by direct compression of drug and different pH-dependent (Eudragit L100, S100 and L100-55) and pH-independent (Eudragit RLPO and RSPO) polymer combinations. The influence of varying the polymer\\/polymer (w\\/w) ratio and the drug incorporation method (simple blend or solid dispersion) was also evaluated. Drug release, monitored using the Through Flow Cell system, markedly depended

A. Ceballos; M. Cirri; F. Maestrelli; G. Corti; P. Mura

2005-01-01

110

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

PubMed Central

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

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

2013-01-01

111

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

PubMed

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

Pongjanyakul, Thaned; Kanjanabat, Sopaphan

2012-06-01

112

Sucrose esters with various hydrophilic-lipophilic properties: novel controlled release agents for oral drug delivery matrix tablets prepared by direct compaction.  

PubMed

Sucrose esters (SE) are esters of sucrose and fatty acids with various hydrophilic-lipophilic properties which have attracted interest from being used in pharmaceutical applications. This study aimed to gain insight into the use of SE as controlled release agents for direct compacted matrix tablets. The study focused on the effect of hydrophilic-lipophilic properties on tableting properties and drug release. Sucrose stearate with hydrophilic-lipophilic balance (HLB) values ranging from 0 to 16 was systematically tested. Tablet formulations contained SE, metoprolol tartrate as a highly soluble model drug and dibasic calcium phosphate dihydrate as a tablet formulation filler in the ratio 1:1:2. The compaction behaviour of matrix tablets was compared with the compacts of individual starting materials as reference. SE incorporation improved the plasticity, compressibility and lubricating property of powder mixtures. The hydrophilic-lipophilic properties of SE affected tableting properties, drug release rate and release mechanism. Increasing hydrophilicity corresponding to the increased monoesters in SE composition increased the relative porosity, elastic recovery and tensile strength of the tablets due to the increased hydrogen bonding between the monoesters. This also facilitated the swelling behaviour of SE, which sustained the drug release rate. A sustained release effect prevailed in tablets containing SE with HLB values of 3-16. The ability to improve the tableting properties as well as sustain the drug release rate of the highly soluble model drug via gelation of SE highlights SE as promising controlled release regulators for direct compacted matrix tablets comprising drugs with various solubilities according to the Biopharmaceutics Classification System. PMID:20132913

Chansanroj, K; Betz, G

2010-08-01

113

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

PubMed Central

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 (f2) determination. The formulation P8 (10% HPMC K4M, 15% HPMC 15cps) with a similarity factor (f2) 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

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

2012-01-01

114

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

PubMed

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

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

2012-01-01

115

Response Surface Optimization of Sustained Release Metformin-Hydrochloride Matrix Tablets: Influence of Some Hydrophillic Polymers on the Release  

PubMed Central

The aim of the present work was designed to develop a model-sustained release matrix tablet formulation for Metformin hydrochloride using wet granulation technique. In the present study the formulation design was employed to statistically optimize different parameters of Metformin hydrochloride tablets at different drug-to-polymer ratios employing polymers Hydroxypropyl methylcellulose of two grades K4M and K100M as two independent variables whereas the dependent variables studied were X60, X120, T50, T90, n, and b values obtained from dissolution kinetics data. The in vitro drug release studies were carried out at simulated intestinal fluids, and the release showed a non-Fickian anomalous transport mechanism. The drug release was found to reveal zero order kinetics. The granules and the tablets were tested for their normal physical, morphological, and analytical parameters and were found to be within the satisfactory levels. There were no significant drug-polymer interactions as revealed by infrared spectra. It has been found out that on an optimum increased Hydroxypropyl methylcellulose K100M concentration and decreased Hydroxypropyl methylcellulose K4M concentration the formulations were elegant in terms of their release profiles and were found to be statistically significant and generable. PMID:22988527

Roy, Amitava; Roy, Kalpana; Roy, Sarbani; Deb, Jyotirmoy; Ghosh, Amitava; Ali, Kazi Asraf

2012-01-01

116

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

PubMed

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

Saurí, J; Millán, D; Suñé-Negre, J M; Colom, H; Ticó, J R; Miñarro, M; Pérez-Lozano, P; García-Montoya, E

2014-12-30

117

Magnetic Resonance Imaging and Image Analysis for Assessment of HPMC Matrix Tablets Structural Evolution in USP Apparatus 4  

Microsoft Academic Search

Purpose  The purpose of the study was to present a methodology for the processing of Magnetic Resonance Imaging (MRI) data for the\\u000a quantification of the dosage form matrix evolution during drug dissolution. The results of the study were verified by comparison\\u000a with other approaches presented in literature.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  A commercially available, HPMC-based quetiapine fumarate tablet was studied with a 4.7T MR system.

Piotr Kulinowski; Przemys?aw Doro?y?ski; Anna M?ynarczyk; W?adys?aw P. W?glarz

2011-01-01

118

Formulation and In-vitro Characterization of Sustained Release Matrix Type Ocular Timolol Maleate Mini-Tablet  

PubMed Central

The purpose of this study was preparation and evaluation of sustained release matrix type ocular mini-tablets of timolol maleate, as a potential formulation for the treatment of glaucoma. Following the initial studies on timolol maleate powder, it was formulated into ocular mini-tablets. The polymers investigated in this study included cellulose derivatives (HEC, CMC, EC) and Carbopol 971P. Mannitol was used as the solubilizing agent and magnesium stearate as the lubricant. Mini-tablets were prepared by through mixing of the ingredients, followed by direct compression. All the prepared formulations were evaluated in terms of physicochemical tests, including uniformity of weight, thickness, crushing strength, friability and in-vitro drug release. Four groups of formulations were prepared. The presence of different amounts of cellulose derivatives or Carbopol 971P, alone, was studied in group A formulations. In group B formulations, the effect of adding Carbopol 971P alongside different cellulose derivatives was investigated. Group C formulations were made by including mannitol as the solubilizing agent, alongside Carbopol 971P and a cellulose derivative. In group D formulations, mini-tablets were made using Carbopol 971P, alongside two different cellulose derivative. The selected formulation (C1) contained ethyl cellulose, Carbopol 971P, mannitol and magnesium stearate, which showed almost 100% drug release over 5 h. Based on kinetic studies, this formulation was found to best fit the zero-order model of drug release. However, the Higuchi and Hixson -Crowell models also showed a good fit. Hence, overall, formulation C1 was chosen as the best formulation. PMID:24734053

Mortazavi, Seyed Alireza; Jafariazar, Zahra; Ghadjahani, Yasaman; Mahmoodi, Hoda; Mehtarpour, Farzaneh

2014-01-01

119

Controlled Release Matrix Tablets of Olanzapine: Influence of Polymers on the In Vitro Release and Bioavailability  

Microsoft Academic Search

Controlled-release (CR) tablet formulation of olanzapine was developed using a binary mixture of Methocel® K100 LV-CR and\\u000a Ethocel® standard 7FP premium by the dry granulation slugging method. Drug release kinetics of CR tablet formulations F1,\\u000a F2, and F3, each one suitably compressed for 9-, 12-, and 15-kg hardness, were determined in a dissolution media of 0.1 N\\u000a HCl (pH 1.5) and phosphate

Amir Badshah; Fazal Subhan; Khalid Rauf

2010-01-01

120

Paroxetine hydrochloride controlled release POLYOX matrix tablets: screening of formulation variables using Plackett-Burman screening design.  

PubMed

The aim of the present study was to screen the effects of the formulation variables - POLYOX molecular weight (X1), the ratio of POLYOX/Avicel PH102 (X2) and the amount of POLYOX and Avicel PH102 (X3), hardness (X4), HPMCP amount (X5), Eudragit L100 amount (X6), and citric acid amount (X7) - on the paroxetine hydrochloride release from POLYOX matrix tablet using the Plackett-Burman screening design. Paroxetine hydrochloride matrix tablets were prepared according to a 7-factor-12-run statistical model and subjected to a 8-h dissolution study in Tris buffer at pH 7.5. The regression results showed that POLYOX molecular weight (X1) and POLYOX/Avicel PH102 ratio (X2) had significantly influence on the drug release mechanism and drug release rate as main effects. Hardness (X4) had an insignificant effect on the drug release mechanism but a significant effect on the drug release rate. On the other hand, HPMCP, Eudragit L100 and citric acid had an insignificant effect on the both responses. The information obtained by screening design study can be expected to be useful for further formulation studies. PMID:18409056

Jin, Shun-Ji; Yoo, Yeon-Hee; Kim, Min-Soo; Kim, Jeong-Soo; Park, Jeong-Sook; Hwang, Sung-Joo

2008-03-01

121

Study on sustained-release metformin hydrochloride from matrix tablet: Influence of hydrophilic polymers and in vitro evaluation  

PubMed Central

The overall objective of the present work was to develop an oral sustained-release (SR) metformin tablet prepared by the direct compression method, using hydrophilic hydroxylpropylmethylcellulose (HPMC) and Guar gum polymer alone and in combination at different concentrations. Metformin hydrochloride (HCl), a biguanide, has a relatively short plasma half-life and low absolute bioavailability. All the batches were evaluated for thickness, weight variation, hardness and drug content uniformity and in vitro drug release. Mean dissolution time is used to characterize the drug release rate from a dosage form, and indicates the drug release-retarding efficiency of the polymer. The hydrophilic matrix of HPMC alone could not control the Metformin release effectively for 12 h whereas when combined with Guar gum, it could slow down the release of drug and, thus, can be successfully employed for formulating SR matrix tablets. Fitting the data to the Korsmeyer equation indicated that diffusion along with erosion could be the mechanism of drug release. Similarity factor ƒ2 values suggest that the test and reference profiles are identical. PMID:23071938

Wadher, Kamlesh J; Kakde, Rajendra B; Umekar, Milind J

2011-01-01

122

Controlled release matrix uncoated tablets of enalapril maleate using hpmc alone.  

PubMed

Hydroxy propyl methyl cellulose (HPMC) is generally combined with hydrophobic polymers in fabricating oral controlled solid dosage forms. This study evaluated the utility of diverse grades of HPMC in developing a controlled release formulation for a hydrophilic drug, enalapril maleate. Controlled release uncoated tablets were prepared by direct compression technique. Two grades of HPMC (K100 and K4M) in different proportions were used to prepare the tablets, and were evaluated for physical properties, drug content, in vitro drug release and drug release kinetics as well. All the formulations demonstrated good physical integrity and the drug content were in the official limits. The formulation with HPMC K100 (25 mg/tablet) and K4M (15 mg/tablet) have been found to release the required amount of drug (2.97 mg/h) through out the study period (14 h). The calculated regression coefficients showed higher r(2) value with Higuchi model and zero order kinetics. Given the excellent release profile, the study concluded that HPMC in different grades with low concentration alone can control the enalapril maleate release over a period of time (14 h). PMID:24825968

Nair, Anroop B; Vyas, Hiral; Kumar, Ashok

2010-03-01

123

CONTROLLED RELEASE MATRIX UNCOATED TABLETS OF ENALAPRIL MALEATE USING HPMC ALONE  

PubMed Central

Hydroxy propyl methyl cellulose (HPMC) is generally combined with hydrophobic polymers in fabricating oral controlled solid dosage forms. This study evaluated the utility of diverse grades of HPMC in developing a controlled release formulation for a hydrophilic drug, enalapril maleate. Controlled release uncoated tablets were prepared by direct compression technique. Two grades of HPMC (K100 and K4M) in different proportions were used to prepare the tablets, and were evaluated for physical properties, drug content, in vitro drug release and drug release kinetics as well. All the formulations demonstrated good physical integrity and the drug content were in the official limits. The formulation with HPMC K100 (25 mg/tablet) and K4M (15 mg/tablet) have been found to release the required amount of drug (2.97 mg/h) through out the study period (14 h). The calculated regression coefficients showed higher r2 value with Higuchi model and zero order kinetics. Given the excellent release profile, the study concluded that HPMC in different grades with low concentration alone can control the enalapril maleate release over a period of time (14 h). PMID:24825968

Nair, Anroop B.; Vyas, Hiral; Kumar, Ashok

2010-01-01

124

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

PubMed

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

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

2013-04-01

125

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

PubMed

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

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

2015-01-01

126

Gum Ghatti--a pharmaceutical excipient: development, evaluation and optimization of sustained release mucoadhesive matrix tablets of domperidone.  

PubMed

The objective of this study was to extend the GI residence time of the dosage form and to control the release of domperidone using directly compressible sustained release mucoadhesive matrix (SRMM) tablets. A 2-factor centre composite design (CCD) was employed to study the influence of independent variables like gum ghatti (GG) (X1) and hydroxylpropylmethyl cellulose K 15M (HPMC K 15M) (X2) on dependent variable like mucoadhesive strength, tensile strength, release exponent (n), t50 (time for 50% drug release), rel(10 h) (release after 10 h) and rel(18 h) (release after 18 h). Tablets were prepared by direct compression technology and evaluated for tablet parametric test (drug assay, diameter, thickness, hardness and tensile strength), mucoadhesive strength (using texture analyzer) and in vitro drug release studies. The tensile strength and mucoadhesive strength were found to be increased from 0.665 +/- 0.1 to 1.591 +/- 0.1 MN/cm2 (Z1 to Z9) and 10.789 +/- 0.985 to 50.924 +/- 1.150 N (Z1 to Z9), respectively. The release kinetics follows first order and Hixson Crowell equation indicating drug release following combination of diffusion and erosion. The n varies between 0.834 and 1.273, indicating release mechanism shifts from non fickian (anomalous release) to super case II, which depict that drug follows multiple drug release mechanism. The t50 time was found to increase from 5 +/- 0.12 to 11.4 +/- 0.14 h (Z1 to Z9) and release after 10 and 18 h decreases with increasing concentration of both polymers concluding with release controlling potential of polymers. The accelerated stability studies were performed on optimized formulation as per ICH guideline and the result showed that there was no significant change in tensile strength, mucoadhesive strength and drug assay. PMID:22876617

Gurpreetarora; Malik, Karan; Rana, Vikas; Singh, Inderbir

2012-01-01

127

The consequence of the chemical composition of HPMC in matrix tablets on the release behaviour of model drug substances having different solubility  

Microsoft Academic Search

This study investigates the effect of the chemical heterogeneity of hydroxypropyl methylcellulose (HPMC) on the release of model drug substances from hydrophilic matrix tablets. The hypothesis was that the release of drug substances could be influenced by possible interactions with HPMC batches having different chemical heterogeneity. The cloud point of the most heterogeneous batch was more affected by the model

Anna Viridén; Bengt Wittgren; Anette Larsson

2011-01-01

128

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

PubMed

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

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

2011-08-01

129

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

PubMed

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

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

2013-07-01

130

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

PubMed

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

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

1997-05-01

131

In vitro release of sodium diclofenac from a central core matrix tablet aimed for colonic drug delivery.  

PubMed

The present study was aimed at developing a novel sodium diclofenac formulation for colonic release. The proposed delivery system consisted in a polymeric matrix tablet containing a drug central core purposely designed for obtaining a time-controlled release profile characterized by an initial phase of lag-time followed by a controlled release phase, according to zero order kinetics. The spheric central core was formed by a solid dispersion of the drug into the hydrophilic polymer PEG 4000, which enabled an improvement of drug dissolution properties with respect to other carriers such as lactose. Eudragit RS100 was used as inert polymeric matrix for the core coating, mixed (50:50, w/w) with sodium chloride and Emdex as channeling agents. Tablets containing the drug central core were prepared by direct compression, without any other excipient, and tested for dissolution properties according to the USP paddle method, under pH-gradient conditions. For both series of formulations, lag times increased with decreasing the channeling agent particle size, as a consequence of the smaller pores formed by its dissolution. However, formulations containing sodium chloride always showed longer lag times than the corresponding with Emdex and were more effective in providing prolonged zero-order release periods. This was mainly attributed to the plastic deformation properties under compression shown by sodium chloride, leading to a less porous, more compact network which more strictly controlled solvent penetration and drug dissolution and release rates. By varying the sodium chloride/Eudragit w/w ratio, it was possible to suitably modulate the length of both the lag time (for achieving colonic targeting) and zero-order release phases. PMID:13678801

González-Rodríguez, María Luisa; Maestrelli, Francesca; Mura, Paola; Rabasco, Antonio María

2003-09-01

132

Formulation and design of sustained release matrix tablets of metformin hydrochloride: Influence of hypromellose and polyacrylate polymers  

PubMed Central

Aim: The current paper was an attempt to design a sustained release dosage form using various grades of hydrophilic polymers, Hypromellose (hydroxyl-propyl methylcellulose [HPMC] K15M, HPMC K100M and HPMC K200M) and Polyacrylate polymers, Eudragit RL100 and Eudragit RS100 with or without incorporating ethyl cellulose on a matrix-controlled drug delivery system of Metformin hydrochloride. Materials and Methods: Laboratory scale batches of nine tablet formulations were prepared by wet granulation technique (Low shear). Micromeritic properties of the granules were evaluated prior to compression. Tablets were characterized as crushing strength, friability, weight variation, thickness, drug content or assay and evaluated for in-vitro release pattern for 12 h using Phosphate buffer of pH 6.8 at 37 ± 0.5°C. The in-vitro release mechanism was evaluated by kinetic modeling. Results and Discussion: The results obtained revealed that HPMC K200M at a concentration of 26% in formulation (F6) was able to sustain the drug release for 12 h and followed the Higuchi pattern quasi-Fickian diffusion. With that, combined effect of HPMC K15M as an extragranular section and Eudragit RS100 displayed a significant role in drug release. Dissolution data were compared with innovator for similarity factor (f2), and exhibited an acceptable value of ?50 Three production validation scale batches were designed based on lab scale best batch and charged for stability testing, parameters were within the limit of acceptance. There was no chemical interaction found between the drug and excipients during Fourier Transform Infrared Spectroscopy (FTIR) and Differential scanning calorimetry study. Conclusion: Hence, combinely HPMC K200M and Eudragit RS100 at a suitable concentration can effectively be used to sustain drug release. PMID:23776841

Roy, Harekrishna; Brahma, Chandan K; Nandi, Sisir; Parida, Kirti R

2013-01-01

133

Controlled-release matrix tablets of ibuprofen using cellulose ethers and carrageenans: effect of formulation factors on dissolution rates.  

PubMed

The study was conducted to investigate the effects of carrageenans, and cellulose ethers on the drug release rates of ibuprofen controlled-release tablet matrices prepared by direct compression. Polymer blends containing carrageenans or cellulose ethers were used for the formulation and the effect of varying the polymer concentration on the release of the drug was studied. Other factors such as changes in surface topography of the matrices due to hydration were observed using a cryogenic scanning electron microscopy technique. Multiple regression analysis was used to predict the time for 50% release (t50) as a function of the concentration of the polymers used. Most of the formulations showed linear release profiles (r(2)>or=0.96-0.99) and sustained the release of ibuprofen over 12-16 h. The highest t50 (9.3 h) was for the formulation that contained a blend of 1:2 ratio of Viscarin and HPMC, while the lowest (3 h) was for the matrices that contained a 2:1 ratio of methylcellulose and Gelcarin. The majority of the matrix tablets that contained 10% polymer disintegrated prematurely. Of all the polymer blends that were investigated, the combination of Viscarin and HPMC gave almost linear release profiles over the entire range of concentration that was studied. The least effective combination was methylcellulose in combination with HPMC. Most of the formulations released ibuprofen by an anomalous (non-Fickian) transport mechanism, except those matrices that contained methylcellulose and Gelcarin (in a 1:1 and 1:2 ratio), which showed zero-order release. PMID:15893919

Nerurkar, Jayanti; Jun, H W; Price, J C; Park, M O

2005-09-01

134

The effect of citric acid added to hydroxypropyl methylcellulose (HPMC) matrix tablets on the release profile of vinpocetine.  

PubMed

Vinpocetine is a pH-dependent experimental drug with a short half-life. The sustained-release matrix tablets of vinpocetine were prepared by direct compression using hydroxypropyl methylcellulose (HPMC) and different amounts of citric acid to set up a system bringing about gradual release of this drug. In order to investigate the influence of citric acid and the pH value of medium on the drug release from HPMC matrix tablets, an in vitro release test was carried out in either phosphate buffer pH 6.8 [0.5% sodium dodecyl sulfate (SDS)] for 12 hr or in 0.1 N HCl (0.5% SDS) (0-2 hr) and phosphate buffer pH 6.8 (0.5% SDS) (2-12 hr). Dissolution curves were described by the Peppas equation: M(t)/M(inf)=ktn, and the influence of citric acid on the dissolution mechanism was estimated according to the regression parameter-n and k values. The addition of citric acid and the pH value of medium could notably influence the dissolution behavior and mechanism of drug-release from matrices. Increasing the amounts of citric acid produced an increase in drug release rate, which showed a good linear relationship between contents of citric acid and drug accumulate release (%) in phosphate buffer pH 6.8 (0.5% SDS) (r>0.99). Moreover, a higher drug release rate could be found in 0.1 N HCl (0.5% SDS) than that in phosphate buffer pH 6.8 (0.5% SDS) during the first two hours when the content of citric acid added to matrices was lower than 45 mg/tab., but no significant difference could be found when the content of citric acid was above that value. Increasing amounts of citric acid produced decreasing values of n and increasing values of k, in a linear relationship, which indicated there was a trend favoring the mechanism of diffusion with the addition of increasing quantities of citric acid. PMID:15285336

Nie, Shufang; Pan, Weisan; Li, Xiaodong; Wu, Xueming

2004-07-01

135

Extended release of a large amount of highly water-soluble diltiazem hydrochloride by utilizing counter polymer in polyethylene oxides (PEO)\\/polyethylene glycol (PEG) matrix tablets  

Microsoft Academic Search

The purpose of this study was to evaluate the feasibility of using a counter polymer in polyethylene oxide (PEO)\\/polyethylene glycol (PEG) polymeric matrices for the sustained release of a large amount of highly water-soluble drug. PEO\\/PEG matrix tablets (CR-A) containing four drugs with different water solubilities were prepared to investigate the effect of drug solubility on the drug-release and diffusion

Hiroyuki Kojima; Keiichi Yoshihara; Toyohiro Sawada; Hiromu Kondo; Kazuhiro Sako

2008-01-01

136

Effects of coformers on phase transformation and release profiles of carbamazepine cocrystals in hydroxypropyl methylcellulose based matrix tablets.  

PubMed

The aim of this study was to investigate the effects of coformers on phase transformation and release profiles of carbamazepine (CBZ) cocrystals in hydroxypropyl methylcellulose (HPMC) based matrix tablets. It has been found that selection of different coformers of saccharin (SAC) and cinnamic acid (CIN) can affect the stability of CBZ cocrystals in solution, resulting in significant differences in the apparent solubility of CBZ. The dissolution advantage of CBZ-SAC cocrystals can only be shown for a short period during dissolution because of the fast conversion to its dihydrate form (DH). HPMC can partially inhibit the crystallisation of CBZ DH during dissolution of CBZ-SAC cocrystal. However, the increased viscosity of HPMC dissolution medium reduced the dissolution rate of CBZ-SAC cocrystals. Therefore the CBZ-SAC cocrystal formulation did not show any significant advantage in CBZ release rate. In contrast the improved CBZ dissolution rate of CBZ-CIN cocrystal can be realised in both solution and formulation due to its high stability. In conclusion, exploring and understanding the mechanisms of the phase transformation of pharmaceutical cocrystals in aqueous medium for selection of lead cocrystals is the key for success of product development. PMID:25542989

Qiu, Shi; Li, Mingzhong

2015-02-01

137

A novel pH-responsive interpolyelectrolyte hydrogel complex for the oral delivery of levodopa. Part II: Characterization and formulation of an IPEC-based tablet matrix.  

PubMed

This study was undertaken in order to apply a synthesized interpolyelectrolyte complex (IPEC) of polymethacrylate and carboxymethylcellulose as a controlled release oral tablet matrix for the delivery of the model neuroactive drug levodopa. The IPEC (synthesized in Part I of this work) was characterized by techniques such as Fourier Transform Infra-Red (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), Advanced DSC (ADSC), and Scanning Electron Microscopy (SEM). The tablet matrices were formulated and characterized for their drug delivery properties and in vitro drug release. FTIR confirmed the interaction between the two polymers. The IPEC composite generated tablet matrices with a hardness ranging from 19.152-27.590 N/mm and a matrix resilience ranging between 42 and 46%. An IPEC of polymethacrylate and carboxymethylcellulose was indeed an improvement on the inherent properties of the native polymers providing a biomaterial with the ability to release poorly soluble drugs such as levodopa at a constant rate over a prolonged period of time. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1085-1094, 2015. PMID:24909309

Ngwuluka, Ndidi C; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Khan, Riaz A; Pillay, Viness

2015-03-01

138

The consequence of the chemical composition of HPMC in matrix tablets on the release behaviour of model drug substances having different solubility.  

PubMed

This study investigates the effect of the chemical heterogeneity of hydroxypropyl methylcellulose (HPMC) on the release of model drug substances from hydrophilic matrix tablets. The hypothesis was that the release of drug substances could be influenced by possible interactions with HPMC batches having different chemical heterogeneity. The cloud point of the most heterogeneous batch was more affected by the model drug substances, methylparaben and butylparaben, and most by butylparaben with the lowest solubility. The different clouding behaviour was explained by the heterogeneously substituted batches being more associative and the more lipophilic butylparaben being able to interact more efficiently with the hydrophobic HPMC transient crosslinks that formed. Interestingly, tablet compositions of the heterogeneously substituted HPMC batches released the more soluble methylparaben at lower rates than butylparaben. The explanation is that the hydrophobic HPMC interactions with butylparaben made the gel of the tablet less hydrated and more fragile and therefore more affected by erosional stresses. In contrast, drug release from compositions consisting of the more homogeneously substituted batches was affected to a minor extent by the drugs and was very robust within the experimental variations. The present study thus reveals that there can be variability in drug release depending on the lipophilicity of the drug and the substituent heterogeneity of the HPMC used. PMID:21081160

Viridén, Anna; Wittgren, Bengt; Larsson, Anette

2011-01-01

139

Studies on drug release kinetics from ibuprofen-carbomer hydrophilic matrix tablets: influence of co-excipients on release rate of the drug.  

PubMed

Controlled-release (CR) matrix tablets of ibuprofen (IBF) and Carbopol(R) 934P, and blended mixture of Carbopol(R) 934P and 971P resins, at different drug to polymers ratios, were prepared by the direct compression method. The investigation focuses on the influence of the proportion of the matrix material, and several co-excipients (lactose, microcrystalline cellulose (MCC), and starch) on the mechanism and release rate of the drug from the tablets. In vitro drug release in pH 7.2 phosphate buffer solution appears to occur both by diffusion and a swelling-controlled mechanism, exhibiting either anomalous or Case II type transport. The release process could be described by plotting the fraction released versus time and fitting data to the simple exponential model: Mt/Minfinity=ktn. The release kinetics were modified when the blended mixtures of Carbopol(R) 934P and 971P resins were used as the matrix materials. In general, all of the co-excipients, used in this study, enhanced the release rate of IBF. However, lactose demonstrated slower and more linear release behavior as compared to microcrystalline cellulose or starch. The dissolution T50 and T90 values for the three co-excipients were in the order of lactose>microcrystalline cellulose>starch. PMID:9971903

Khan, G M; Zhu, J B

1999-02-01

140

Development of Controlled-Release Matrix Tablet of Risperidone: Influence of Methocel®- and Ethocel®Based Novel Polymeric Blend on In Vitro Drug Release and Bioavailability  

Microsoft Academic Search

Controlled-release (CR) matrix tablet of 4 mg risperidone was developed using flow bound dry granulation–slugging method to\\u000a improve its safety profile and compliance. Model formulations F1, F2, and F3, consisting of distinct blends of Methocel® K100\\u000a LV-CR and Ethocel® standard 7FP premium, were slugged. Each batch of granules (250–1,000 ?m), obtained by crushing the slugs,\\u000a was divided into three portions after lubrication

Amir Badshah; Fazal Subhan; Khalid Rauf; Nadeem Irfan Bukhari; Kifayatullah Shah; Samiullah Khan; Zia Ahmed; Ihsanullah Khan

2011-01-01

141

Preparation of controlled release tablets of TA-5707F with wax matrix type and their in vivo evaluation in beagle dogs.  

PubMed

Studies on controlled release dosage forms were conducted by using waxy materials for a newly developed anti-allergy drug, 6-methyl-N-(1H-tetrazol-5-yl)-2-pyridinecarboxamide (TA-5707F), which is not maintained at an effective level in blood for a long duration. Four kinds of tablets were prepared by changing the amount of hydrogenated oil (K3 wax) and polyethyleneglycol-6000 in the tablets. Then, they were administered orally to beagle dogs, and the TA-5707F concentration in the plasma was determined by a HPLC method. The pharmacokinetic parameters were estimated and compared with the results of the in vitro dissolution test determined by the JP paddle method and by the disintegration method. The linearity between the in vivo mean dissolution time (MDT) and in vitro MDT was good in both in vitro dissolution methods. However, the MDTs obtained by the disintegration method were one-third of the in vivo MDT, while those obtained by the paddle methods were 3 times higher. This suggests that both the diffusion of TA-5707F through the waxy matrix and the erosion of the wax matrix caused by the gastrointestinal (GI) tract mobility contributed to the in vivo dissolution mechanism. The blood levels were very low when the tablet was administered after giving food. The prolongation of resident time in the stomach and the low solubility of TA-5707F in an acidic medium seemed to be related to the phenomena. By the depression of GI motility using propantheline bromide, the blood levels could be markedly prolonged and the area under the plasma concentration-time curve (AUC) increased 1.3 times. PMID:7581255

Yamakita, H; Maejima, T; Osawa, T

1995-07-01

142

Studies in preparation and evaluation of pH-independent sustained-release matrix tablets of verapamil HCl using directly compressible Eudragits.  

PubMed

The objective of the present study was to investigate the impact of formulation factors on the properties of a 12h modified-release formulation of verapamil HCl. A 2(3) full factorial design was employed to investigate the influence of amount of Eudragit RS PO/RL PO (X1, a matrixing agent), HPMC K4M (X2, an auxiliary matrixing agent cum binder) and PEG 4000 (X3, channelling agent cum plasticizer). The tablets were prepared by direct compression and they were evaluated for in vitro dissolution studies in 0.1 N HCl. The time required for 90% of the drug release (t90) and similarity factor (f2) were used as responses for the selection of most appropriate batches. Swelling and fluid penetration studies were carried out in 0.1 N HCl. Time required for 90% of the drug release (t90) was calculated by using an appropriate kinetic model for each batch. An ideal drug release profile (i.e., 25% in the first hour and a constant drug release thereafter) was considered as a reference release profile for calculation of f2. Multiple regression analysis was adopted to evolve refined models for t90. The required release pattern was shown by batches containing a low level of Eudragit RS PO/RL PO (30% w/w), low level of HPMC K4M (10% w/w), and high level of PEG 4000 (15% w/w). Response surface plots are shown for t90. These formulations showed slower drug release in alkaline medium (pH 7.2). Succinic acid and KH2PO4 were incorporated in the matrix in order to obtain pH-independent drug release. Swelling of tablets and fluid penetration in the matrix were found to be influenced by the selected independent variables. This study demonstrates that the desired drug release pattern can be obtained by adopting a systematic formulation approach. PMID:14601957

Gohel, Mukesh C; Patel, Tejas P; Bariya, Shital H

2003-01-01

143

Graft copolymers of ethyl methacrylate on waxy maize starch derivatives as novel excipients for matrix tablets: drug release and fronts movement kinetics.  

PubMed

A previous paper deals with the physicochemical and technological characterization of novel graft copolymers of ethyl methacrylate (EMA) on waxy maize starch (MS) and hydroxypropylstarch (MHS). The results obtained suggested the potential application of these copolymers as excipients for compressed non-disintegrating matrix tablets. Therefore, the purpose of the present study was to investigate the mechanism governing drug release from matrix systems prepared with the new copolymers and anhydrous theophylline or diltiazem HCl as model drugs with different solubility. The influence of the carbohydrate nature, drying procedure and initial pore network on drug release kinetics was also evaluated. Drug release experiments were performed from free tablets. Radial drug release and fronts movement kinetics were also analysed, and several mathematical models were employed to ascertain the drug release mechanisms. The drug release markedly depends on the drug solubility and the carbohydrate nature but is practically not affected by the drying process and the initial matrix porosity. A faster drug release is observed for matrices containing diltiazem HCl compared with those containing anhydrous theophylline, in accordance with the higher drug solubility and the higher friability of diltiazem matrices. In fact, although diffusion is the prevailing drug release mechanism for all matrices, the erosion mechanism seems to have some contribution in several formulations containing diltiazem. A reduction in the surface exposed to the dissolution medium (radial release studies) leads to a decrease in the drug release rate, but the release mechanism is not essentially modified. The nearly constant erosion front movement confirms the behaviour of these systems as inert matrices where the drugs are released mainly by diffusion through the porous structure. PMID:22210473

Marinich, J A; Ferrero, C; Jiménez-Castellanos, M R

2012-04-01

144

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

PubMed Central

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

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

2010-01-01

145

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

PubMed Central

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

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

2011-01-01

146

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

PubMed

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

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

2011-10-01

147

Tablet Weaving  

ERIC Educational Resources Information Center

Article described a weaving technique called tablet weaving, an ancient textile process that provides opportunity for making a variety of items, such as guitar straps, belts, and decorative bands. (Author/RK)

Kren, Margo

1976-01-01

148

On floats and float tests  

NASA Technical Reports Server (NTRS)

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.

Seewald, Friedrich

1931-01-01

149

Preparation and in-vitro in-vivo evaluation of sustained release matrix diclofenac sodium tablets using PVP-K90 and natural gums.  

PubMed

Conventional dosage form is nowadays mostly replaced by sustained release formulation in order to increase drug efficacy and patient compliance. The sustained release properties of the PVP K90 alone and in combination with guar gum, xanthan gum and gum tragacanth were evaluated using diclofenac sodium (100 mg/tablet) as a model drug. Tablets were processed using wet granulation method and evaluated for sustained drug release properties. The drug release from the formulations was studied in relationship with Commercially available Diclofenac Sodium SR, used as a reference tablets and results were expressed as similarity (f1) and differential factor (f2). The tablets prepared using PVP K90 160 mg/tablet sustained the release of diclofenac sodium for 12 hours. Formulations where the PVP K90 was partially replaced with different gums also sustained the release of drug for 12 hours. The release of the drug from these formulations mainly followed Higuchi model and super case-II and Non-Fickian diffusion. The in-vivo drug release was studied in healthy human volunteers using non-blinded cross over, two period design using Diclofenac Sodium SR Tablets as a reference drug. The relative bioavailability of the formulation containing PVP K90 and gum tragacanth was 0.91. The studies showed that the use of the PVP K90 in combination with gum tragacanth both in-vitro and in-vivo sustained the release of the drug. PMID:21959802

Iqbal, Zafar; Khan, Raza; Nasir, Fazli; Khan, Jamshaid Ali; Rashid, Abdur; Khan, Abbas; Khan, Abad

2011-10-01

150

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

PubMed Central

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

Dey, Sanjay; Chattopadhyay, Sankha; Mazumder, Bhaskar

2014-01-01

151

Relationship between diffusivity of water molecules inside hydrating tablets and their drug release behavior elucidated by magnetic resonance imaging.  

PubMed

We reported previously that sustained release matrix tablets showed zero-order drug release without being affected by pH change. To understand drug release mechanisms more fully, we monitored the swelling and erosion of hydrating tablets using magnetic resonance imaging (MRI). Three different types of tablets comprised of polyion complex-forming materials and a hydroxypropyl methylcellulose (HPMC) were used. Proton density- and diffusion-weighted images of the hydrating tablets were acquired at intervals. Furthermore, apparent self-diffusion coefficient maps were generated from diffusion-weighted imaging to evaluate the state of hydrating tablets. Our findings indicated that water penetration into polyion complex tablets was faster than that into HPMC matrix tablets. In polyion complex tablets, water molecules were dispersed homogeneously and their diffusivity was relatively high, whereas in HPMC matrix tablets, water molecule movement was tightly restricted within the gel. An optimal tablet formulation determined in a previous study had water molecule penetration and diffusivity properties that appeared intermediate to those of polyion complex and HPMC matrix tablets; water molecules were capable of penetrating throughout the tablets and relatively high diffusivity was similar to that in the polyion complex tablet, whereas like the HPMC matrix tablet, it was well swollen. This study succeeded in characterizing the tablet hydration process. MRI provides profound insight into the state of water molecules in hydrating tablets; thus, it is a useful tool for understanding drug release mechanisms at a molecular level. PMID:22466738

Kikuchi, Shingo; Onuki, Yoshinori; Kuribayashi, Hideto; Takayama, Kozo

2012-01-01

152

Floating layer recovery apparatus  

SciTech Connect

This patent describes an apparatus for recovery of a layer of a first underground liquid floating on a second underground liquid in a well. It comprises: first float means disposed in the well in the first liquid, the float means having an effective buoyancy such that it floats in the first liquid; second float means disposed in the well in the first liquid, the float means having an effective buoyancy such that it floats near the bottom of the first liquid, the second float means having top, side and bottom surfaces; an inlet means disposed on the second float surface for permitting entry of the first liquid; conduit means coupled to the inlet means and extending below the second float means; third float means disposed in the second liquid and having an effective buoyancy such that the third float means will remain submerged in the second liquid, the conduit means being coupled to the third float; the guide means for slidably connecting the second float between the first and third float means.

Newcomer, K.; Richter, S.

1991-03-12

153

Preparation and Characterization of a Gastric Floating Dosage Form of Capecitabine  

PubMed Central

Gastrointestinal disturbances, such as nausea and vomiting, are considered amongst the main adverse effects associated with oral anticancer drugs due to their fast release in the gastrointestinal tract (GIT). Sustained release formulations with proper release profiles can overcome some side effects of conventional formulations. The current study was designed to prepare sustained release tablets of Capecitabine, which is approved by the Food and Drug Administration (FDA) for the treatment of advanced breast cancer, using hydroxypropyl methylcellulose (HPMC), carbomer934P, sodium alginate, and sodium bicarbonate. Tablets were prepared using the wet granulation method and characterized such that floating lag time, total floating time, hardness, friability, drug content, weight uniformity, and in vitro drug release were investigated. The sustained release tablets showed good hardness and passed the friability test. The tablets' floating lag time was determined to be 30–200 seconds, and it floated more than 24 hours and released the drug for 24 hours. Then, the stability test was done and compared with the initial samples. In conclusion, by adjusting the right ratios of the excipients including release-retarding gel-forming polymers like HPMC K4M, Na alginate, carbomer934P, and sodium bicarbonate, sustained release Capecitabine floating tablet was formulated. PMID:24288681

Taghizadeh Davoudi, Ehsan; Ibrahim Noordin, Mohamed; Kadivar, Ali; Kamalidehghan, Behnam; Farjam, Abdoreza Soleimani; Akbari Javar, Hamid

2013-01-01

154

Preparation and characterization of a gastric floating dosage form of capecitabine.  

PubMed

Gastrointestinal disturbances, such as nausea and vomiting, are considered amongst the main adverse effects associated with oral anticancer drugs due to their fast release in the gastrointestinal tract (GIT). Sustained release formulations with proper release profiles can overcome some side effects of conventional formulations. The current study was designed to prepare sustained release tablets of Capecitabine, which is approved by the Food and Drug Administration (FDA) for the treatment of advanced breast cancer, using hydroxypropyl methylcellulose (HPMC), carbomer934P, sodium alginate, and sodium bicarbonate. Tablets were prepared using the wet granulation method and characterized such that floating lag time, total floating time, hardness, friability, drug content, weight uniformity, and in vitro drug release were investigated. The sustained release tablets showed good hardness and passed the friability test. The tablets' floating lag time was determined to be 30-200 seconds, and it floated more than 24 hours and released the drug for 24 hours. Then, the stability test was done and compared with the initial samples. In conclusion, by adjusting the right ratios of the excipients including release-retarding gel-forming polymers like HPMC K4M, Na alginate, carbomer934P, and sodium bicarbonate, sustained release Capecitabine floating tablet was formulated. PMID:24288681

Taghizadeh Davoudi, Ehsan; Ibrahim Noordin, Mohamed; Kadivar, Ali; Kamalidehghan, Behnam; Farjam, Abdoreza Soleimani; Akbari Javar, Hamid

2013-01-01

155

Direct analysis of 18 flavonol glycosides, aglycones and terpene trilactones in Ginkgo biloba tablets by matrix solid phase dispersion coupled with ultra-high performance liquid chromatography tandem triple quadrupole mass spectrometry.  

PubMed

Analysis and quality control of Ginkgo biloba have been comprehensively studied. However, little attention has been devoted to the simultaneous extraction and analysis of flavonols and terpene trilactones, especially for direct quantification of flavonol glycosides. This work described a rapid strategy for one-step extraction and quantification of the components. A matrix solid phase dispersion (MSPD) method was designed for the extraction of ginkgo ingredients and compared with the heat-reflux and ultrasonic extraction methods. An ultra-high performance liquid chromatography (UHPLC)-tandem-triple-quadrupole-mass spectrometry (QQQ-MS) method was developed for detection of the 18 components, including 10 original flavonol glycosides, 3 aglycones, and 5 lactones. Subsequently, the proposed strategy was used for the analysis of 12 G. biloba tablets. Results showed that MSPD produced comparable extraction efficiency but consumed less time and required lower solvent volumes compared with conventional methods. Without hydrolysis, the concentration detected was much closer to the original in the sample. The total flavonol glycoside contents in ginkgo tablets ranged from 3.59 to 125.21?gmg(-1), and the terpene trilactone varied from 3.45 to 57.8?gmg(-1) among different manufacturers. In conclusion, the proposed MSPD and UHPLC-QQQ-MS is rapid and sensitive in providing comprehensive profile of chemical constituents especially the genuine flavonol glycosides for improved quality control of ginkgo products. PMID:24876067

Liu, Xin-Guang; Yang, Hua; Cheng, Xiao-Lan; Liu, Lei; Qin, Yong; Wang, Qi; Qi, Lian-Wen; Li, Ping

2014-08-01

156

Terahertz Technology: A Boon to Tablet Analysis  

PubMed Central

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

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

2009-01-01

157

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

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

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

2011-04-01

158

Design of Sustained Release Tablet Containing Fucoidan.  

PubMed

The study introduced a new therapeutic agent,fucoidan, which can offer potential medical treatments including anti-inflammatory and anti-coagulant activities, as well as anti-proliferative effects on cancer cells. Fucoidan was included in sustained release formulations expected for aneffective plasma drug concentration for approximately 24 h. The matrices based on the two polymers hydroxypropylmethycellulose (HPMC) and polyethylene oxide (PEO) were prepared with various ratios between the polymers and fucoidan. The dissolution profiles of various matrix tablets performed in enzyme-free simulated intestinal fluid (pH 6.8) for 24 h indicated a higher potential of PEO-based matrix tablets in sustaining release of fucoidan. The swelling and erosion of the tablets were also characterized to elucidate the difference among those dissolution profiles. PMID:25382179

Tran, Thao Truong-Dinh; Ngo, Dai Kieu-Phuong; Vo, Toi Van; Tran, Phuong Ha-Lien

2014-11-01

159

Clinical evaluation of sodium flouride chewable tablets in dental caries.  

PubMed

Chewable tablets containing low dosage flouride content were prepared using two varities of celluloses and their in vitro parameters were evaluated. An eighteen month clinical trial revealed that both these formulations were effective in controlling the caries. However, ethyl cellulose is proved to be superior to methylcellulose as a controlled release matrix material in controlling caries. Thus this study recommends ethylcellulose matrix tablets containing low flouride content is an efficacious and cost effective drug device in controlling dental caries. PMID:10865398

Maddi, S S; Tandon, S; Aithal, K S

1999-01-01

160

Floating portable pump  

SciTech Connect

A floating portable pump is constructed of a float defining a well for containing water, a centrifugal pump supported on the float with its impeller shaft extending vertically and with its suction inlet submerged in water in the well, and an internal combustion engine arranged to drive the pump impeller. The pump and engine are secured together on the float in an arrangement such that the engine causes rotation of the pump impeller to cause the pump to draw water from the well through its suction inlet and discharge water from the pump discharge.

Eberhardt, H. A.

1985-11-19

161

Formulation and in vitro Evaluation of Floating Capsules of Theophylline  

PubMed Central

Sustained release floating capsules for theophylline were fabricated using drug:polymer ratio of 30:70. The hydrocolloids were used in different proportions and four formulations were prepared. These formulations were optimized on the basis of buoyancy, matrix integrity, duration of floating and in vitro drug release. All the four formulations showed good buoyancy and matrix integrity. The duration of floating was more than 12 h for all formulations. In vitro drug release study of these formulations indicated controlled release of theophylline and about 76 percent drug was released at the end of 12 h. PMID:20046717

Bhise, S. B.; Aloorkar, N. H.

2008-01-01

162

Charge retention characteristics of silicide-induced crystallized polycrystalline silicon floating gate thin-film transistors for active matrix organic light-emitting diode.  

PubMed

In this work, non-volatile memory thin-film transistor (NVM-TFT) was fabricated by nickel silicide-induced laterally crystallized (SILC) polycrystalline silicon (poly-Si) as the active layer. The nickel seed silicide-induced crystallized (SIC) poly-Si was used as storage layer which is embedded in the gate insulator. The novel unit pixel of active matrix organic light-emitting diode (AMOLED) using NVM-TFT is proposed and investigated the electrical and optical performance. The threshold voltage shift showed 17.2 V and the high reliability of retention characteristic was demonstrated until 10 years. The retention time can modulate the recharge refresh time of the unit pixel of AMOLED up to 5000 sec. PMID:24245194

Park, Jae Hyo; Son, Se Wan; Byun, Chang Woo; Kim, Hyung Yoon; Joo, So Na; Lee, Yong Woo; Yun, Seung Jae; Joo, Seung Ki

2013-10-01

163

The influence of particles of a minor component on the matrix strength of sodium chloride.  

PubMed

This paper deals with the matrix strength of sodium chloride particles in pure sodium chloride tablets and in tablets compressed from binary mixtures of sodium chloride with low concentrations of pregelatinised starch. Because this study concerns the strength of the sodium chloride matrix, the tablet strength is reflected as a function of the sodium chloride volume fraction in the tablet. Starch particles in the mixture tablets decrease the sodium chloride volume fraction-tensile strength relationship compared with that of pure sodium chloride tablets. To determine the contribution of the sodium chloride matrix to the tablet strength, the starch particles were removed from the mixture tablets by heat treatment. Determination of the strengths of these heat-treated tablets reveals that the sodium chloride matrix strength determines the tablet strength of mixture tablets containing a single matrix of sodium chloride particles. The decrease of the sodium chloride matrix density in the three different tablets (pure sodium chloride tablets, mixture tablets and heat-treated tablets) is reflected by an increase of the median pore size. The matrix in sodium chloride tablets shows a higher tensile strength to median pore size relation than the matrices in the mixture and heat-treated tablets. Based on calculations according to the theory of elastic-brittle fracture, it is suggested that the initial presence of starch particles during tablet compaction causes the pores in the matrices of the mixtures and heat-treated tablets to be relatively more flat and longer. These pores weaken the sodium chloride matrix in the mixture and heat-treated tablets to a larger extent than the shorter, more spherical pores formed during compaction of pure sodium chloride. PMID:12208452

van Veen, B; van der Voort Maarschalk, K; Bolhuis, G K; Gons, M; Zuurman, K; Frijlink, H W

2002-09-01

164

Micromechanisms with floating pivot  

DOEpatents

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.

Garcia, Ernest J. (Albuquerque, NM)

2001-03-06

165

Floating Squares (GCMP)  

NSDL National Science Digital Library

Floating Squares: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will coat a piece of notecard with graphite (from pencil lead). We then will float the piece in two beakers containing water and a second solvent. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

166

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

PubMed Central

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

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

2014-01-01

167

Ketorolac tromethamine floating beads for oral application: Characterization and in vitro/in vivo evaluation  

PubMed Central

The floating beads have been employed to make a sustained release of the drug in the stomach and to decrease the dose of the drug and hence overcome its side effects. The common benefits of the floating beads were it is easy preparation, without the need of a high temperature, and high percentage of the drug entrapment. In the present work, the Ketorolac tromethamine (KT) floating beads were prepared by extrusion congealing method utilizing calcium carbonate as a gas forming agent. The physical characters of the produced beads were investigated such as KT yield, KT loading, and entrapment efficiency of the drug. In addition, floating behavior, swelling, particle size, morphology and KT stability were also evaluated. In vitro drug release study was carried out, and the kinetics of the release was evaluated using the linear regression method. Furthermore, the in vivo analgesic effect of KT after oral administration of the selected formula of floating beads (F10) was carried out using hot plate and tail flick methods. Oral commercial KT tablets and KT solution were used for the comparison. The prepared beads remained floated for more than 8 h. The optimized formulation (F10) exhibited prolonged drug release (more than 8 h) and the drug release follows the Higuchi kinetic model, with a Fickian diffusion mechanism according to Korsmeyer-Peppas (n = 0.466). Moreover, F10 showed a sustained analgesic effect as compared to the commercial tablet. PMID:25161380

Abou el Ela, Amal El Sayeh F.; Hassan, Maha A.; El- Maraghy, Dalia A.

2013-01-01

168

The influence of hydroxypropyl methylcellulose (HPMC) molecular weight, concentration and effect of food on in vivo erosion behavior of HPMC matrix tablets.  

PubMed

Four different hydrophilic matrix formulations based on hydroxypropyl methylcellulose (HPMC) were investigated for erosion properties in vivo. Three formulations contained a fixed amount of HPMC (40%) with varying proportions of two HPMC grades with different molecular weights (Methocel K100LV and K4M), and a fourth formulation contained a lower amount of the HPMC of lower molecular weight (20%). The effect of food on the in vivo erosion behavior was investigated on two formulations containing different contents of the same HPMC grade. The in vivo erosion behavior and gastrointestinal transit were investigated using magnetic marker monitoring (MMM). The in vitro and in vivo erosion-time profiles show that the erosion was strongly dependent on the composition of the formulation. The formulations containing a larger proportion of high molecular weight HPMC or higher content of HPMC exhibit relatively slower erosion rate and vice versa. In vivo erosion rates were significantly higher under postprandial administration as compared to fasted state administration. No rapid disintegration of any of the formulations (i.e. formulation failure that can potentially cause dose dumping) was observed. PMID:24818771

Jain, Arun Kumar; Söderlind, Erik; Viridén, Anna; Schug, Barbara; Abrahamsson, Bertil; Knopke, Christian; Tajarobi, Farhad; Blume, Henning; Anschütz, Maria; Welinder, Anette; Richardson, Sara; Nagel, Stefan; Abrahmsén-Alami, Susanna; Weitschies, Werner

2014-08-10

169

What Floats Your Boat?  

NSDL National Science Digital Library

Students use modeling clay, a material that is denser than water and thus ordinarily sinks in water, to discover the principle of buoyancy. They begin by designing and building boats out of clay that will float in water, and then refine their designs so that their boats will carry as great a load (metal washers) as possible. Building a clay boat to hold as much weight as possible is an engineering design problem. Next, they compare amount of water displaced by a lump of clay that sinks to the amount of water displaced by the same lump of clay when it is shaped so as to float. Determining the masses of the displaced water allows them to arrive at Archimedes' principle, whereby the mass of the displaced water equals the mass of the floating clay boat.

Engineering K-Phd Program

170

Can flexibility help you float?  

E-print Network

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 ...

Burton, Lisa Janelle

171

Sink or Float? Inquiry Investigation  

NSDL National Science Digital Library

Students explore and experiment with various objects to find which materials will float or sink. They record predictions and results, and generate ideas about the properties of materials that float or sink.

172

Microstructural investigation of tablet compaction and tablet pharmacological properties  

E-print Network

In current tablet manufacturing processes, there is a knowledge gap concerning material transformation and the subsequent impact on tablet properties; this gap presents a barrier to rational formulation / process design. ...

Mao, Kangyi

2010-01-01

173

Effect of ionic crosslink on the release of metronidazole from partially carboxymethylated guar gum tablet.  

PubMed

Partially carboxymethylated guar gum (PCMGG) was crosslinked in situ by Ca(2+) ions during wet massing step of tablet preparation. The resulting tablets were evaluated for the effect of the extent of crosslinking on drug release and matrix swelling. Increase in the concentration of Ca(2+) ions increased the viscosity of gel layer and reduced the water penetration velocity into the matrix with subsequent decrease in swelling of the tablets and drug release. Beyond a certain concentration of Ca(2+) ions, the viscosity of the gel layer decreased and the drug release rate increased primarily due to erosion of the matrix. The mechanism of drug release appeared to be non-Fickian or anomalous transport. The release data also best fitted in zero order equation. The model drug, metronidazole, was compatible with the matrix materials as evident from instrumental analyses. Such formulation may provide flexibility in achieving the desired drug release rate from crosslinked matrix tablets. PMID:24721097

Singh, Rakesh; Maity, Siddhartha; Sa, Biswanath

2014-06-15

174

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

Microsoft Academic Search

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

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

2011-01-01

175

Desktop 3D printing of controlled release pharmaceutical bilayer tablets.  

PubMed

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

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

2014-01-30

176

Floating In Air  

NSDL National Science Digital Library

Float a ping-pong ball with a hairdryer, as a demonstration of Bernoulli's principle. This classic physics activity includes a twist with the addition of a toilet paper tube that allows learners to explore air pressure in a different way.

2014-05-28

177

A robust floating nanoammeter  

E-print Network

A circuit capable of measuring nanoampere currents while floating at voltages up to at least 25kV is described. The circuit relays its output to ground potential via an optical fiber. We particularly emphasize the design and construction techniques which allow robust operation in the presence of high voltage spikes and discharges.

Sauer, B E; Hudson, J J; Tarbutt, M R; Hinds, E A

2008-01-01

178

Corona from floating electrodes  

Microsoft Academic Search

It is not unusual to have insulated conducting objects located close to the conductors of a Lightning Protection System. However, the separation of these objects from the Lightning Protection System could vary from a few millimetres to some centimetres. When the system is exposed to thunderstorm electric fields, discharge could be initiated between the Lightning Protection System and the floating

Francisco Roman; Vernon Cooray; Viktor Scuka

1996-01-01

179

Compound floating pivot micromechanisms  

DOEpatents

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.

Garcia, Ernest J. (Albuquerque, NM)

2001-04-24

180

Floating Paper Clip  

NSDL National Science Digital Library

In this activity, challenge learners to float a paper clip in a cup of water. Learners discover that a paper clip will sink in a cup of water, except when it is placed on a piece of paper towel. Use this activity to demonstrate the principles of surface tension, adhesion/cohesion, and gravity.

Boston, Wgbh

2002-01-01

181

Root Beer Float  

NSDL National Science Digital Library

In this quick activity/demonstration about density, learners examine what happens when two cans of root beer--one diet and one regular--are placed in a large container of water. Do they sink or float? Use this activity to introduce learners to the importance of density as well as the nutritional content of soft drinks.

2012-06-26

182

Advanced formulation design of venlafaxine hydrochloride coated and triple-layer tablets containing hypromellose.  

PubMed

The purpose of this research work was to develop venlafaxine hydrochloride-coated and layered matrix tablets using hypromellose adopting wet granulation technique. The granules and the tablets were characterized. The monolithic tablets were coated with different ratios of ethyl cellulose and hypromellose. The in vitro dissolution study was performed in distilled water. In the layered tablets, the middle layer containing drug was covered with barrier layers containing high viscosity grade hypromellose. Simplex lattice design was used for formulating the layered tablets. The dissolution study of the optimized batches and a reference product was carried out in 0.1 N HCl, phosphate buffer and hydroalcoholic solution. Burst drug release was exhibited by the uncoated tablets, probably due to high aqueous solubility of venlafaxine HCl. The coated tablets showed sustained drug release without burst effect. The drug release was best explained by Weibull model. A unified Weibull equation was evolved to express drug release from the coated tablets. The layered tablets also exhibited sustained release without burst effect due to effective area reduction. The optimized batches showed identical drug release in 0.1 N HCl, phosphate buffer and 10% v/v aqueous alcohol. Layered tablets may well be adopted by the industry due to the possibility of achieving a high production rate. PMID:19883254

Gohel, Mukesh; Bariya, Shital H

2009-01-01

183

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

PubMed

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

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

2014-12-01

184

WindFloat: A floating foundation for offshore wind turbines  

Microsoft Academic Search

This manuscript summarizes the feasibility study conducted for the WindFloat technology. The WindFloat is a three-legged floating foundation for multimegawatt offshore wind turbines. It is designed to accommodate a wind turbine, 5 MW or larger, on one of the columns of the hull with minimal modifications to the nacelle and rotor. Potential redesign of the tower and of the turbine

Dominique Roddier; Christian Cermelli; Alexia Aubault; Alla Weinstein

2010-01-01

185

Sugar End-Capped Poly d , l -lactides as Excipients in Oral Sustained Release Tablets  

Microsoft Academic Search

Sugar end-capped poly-d,l-lactide (SPDLA) polymers were investigated as a potential release controlling excipient in oral sustained release matrix\\u000a tablets. The SPDLA polymers were obtained by a catalytic ring-opening polymerization technique using methyl ?-d-gluco-pyranoside as a multifunctional initiator in the polymerization. Polymers of different molecular weights were synthesized\\u000a by varying molar ratios of monomer\\/catalyst. The matrix tablets were prepared by direct

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

2009-01-01

186

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

PubMed Central

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.

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

2014-01-01

187

Imperatorin sustained-release tablets: In vitro and pharmacokinetic studies.  

PubMed

We prepared and evaluated imperatorin (IMP) sustained-release tablets. IMP is an active compound in Angelica dahuricae, a Chinese herbal medicine. We used different polymers, such as hydroxypropyl methylcellulose (HPMC K4M, K15M, and K100M), carbopol 934P, sodium carboxymethyl cellulose (CMC-Na), and their combinations to prepare the matrix tablets and achieve the desired sustained release profile. The in vitro release profiles of these formulations were examined and fit to various kinetic release models. We also tested the effects of polymer combination ratios on the in vitro release rate. In vivo studies were performed for the optimized formulation in six beagle dogs, and pharmacokinetic parameters were compared with plain IMP tablets. IMP sustained-release tablets exhibited a more sustained plasma concentration than the plain tablets, with a relative bioavailability of 127.25%. The in vitro releases rates and in vivo absorption correlated for the initial 8 hours. These results demonstrate that the sustained-release tablet system can effectively control the release of IMP. PMID:20803124

Pan, Jingjing; Lu, Wen; Li, Changhui; Wang, Sicen; He, Langchong

2010-08-01

188

CES 2011: Tablet Crazy  

ERIC Educational Resources Information Center

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…

Rapp, David

2011-01-01

189

Modifying drug release and tablet properties of starch acetate tablets by dry powder agglomeration.  

PubMed

In this study three model drugs (N-acetyl-D-glucosamine (NAG), anhydrous caffeine, and propranolol hydrochloride) were agglomerated with starch acetate (SA) by mixing the binary powders on a stainless steel (SS) plate. Agglomeration was induced by triboelectrification of the particles during mixing, and it was evaluated as a method to achieve controlled drug release rate. These agglomerates, mixed with different amounts of a disintegrant, were compressed into tablets whose dissolution characteristics were determined. Triboelectric measurements showed that when the drugs were in contact with SS, charges of the opposite polarity were generated to SA (+) and caffeine and NAG (-) promoting adhesion. Instead, propranolol HCl was charged with the same polarity as SA. SEM micrographs showed that smaller caffeine particles, in spite of their larger negative charge, agglomerated less efficiently with SA than larger NAG particles. This emphasizes the importance of particle size in the agglomeration process. Propranolol HCl did not form agglomerates with SA since their particle sizes and charges were identical. As a result, agglomeration of powders prior to tablet compression allows for modification and control of the release rate of the drugs from the SA matrix tablets as well as the tensile strength of the tablets. PMID:17075868

Mäki, Riikka; Suihko, Eero; Rost, Susanne; Heiskanen, Minna; Murtomaa, Matti; Lehto, Vesa-Pekka; Ketolainen, Jarkko

2007-02-01

190

The floating water bridge The floating water bridge  

E-print Network

properties and is also the reason why water must not be treated as a simple liquid [1,2]. The interactionThe floating water bridge The floating water bridge Elmar C. Fuchs1 , Jakob Woisetschläger2 , Karl ____________________________________________ Abstract When high voltage is applied to distilled water filled into two glass beakers which are in contact

Podgornik, Rudolf

191

21 CFR 520.581 - Dichlorophene tablets.  

Code of Federal Regulations, 2010 CFR

... § 520.581 Dichlorophene tablets. (a) Specifications. Each tablet contains 1 gram of dichlorophene...Amount. Single dose of 1 tablet (1 gram of dichlorophene...foods and milk for at least 12 hours prior to medication...

2010-04-01

192

21 CFR 520.812 - Enrofloxacin tablets.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Enrofloxacin tablets. 520.812 Section 520... § 520.812 Enrofloxacin tablets. (a) Specifications. Each tablet contains either 22.7, 68...divided into 2 equal doses at 12 hour intervals,...

2010-04-01

193

21 CFR 520.455 - Clomipramine tablets.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Clomipramine tablets. 520.455 Section 520... § 520.455 Clomipramine tablets. (a) Specifications. Each tablet contains 5, 20, 40, or 80...veterinarian. [64 FR 1762, Jan. 12, 1999, as amended at 72...

2010-04-01

194

Formulation and Evaluation of Floating Oral In Situ Gelling System of Amoxicillin  

PubMed Central

Purpose. Effective Helicobacter pylori eradication requires delivery of the antibiotic locally in the stomach. High dose of amoxicillin (750 to 1000?mg) is difficult to incorporate in floating tablets but can easily be given in liquid dosage form. Keeping the above facts in mind, we made an attempt to develop a new floating in situ gelling system of amoxicillin with increased residence time using sodium alginate as gelling polymer to eradicate H. pylori. Methods. Floating in situ gelling formulations were prepared using sodium alginate, calcium chloride, sodium citrate, hydroxypropyl methyl cellulose K100, and sodium bicarbonate. The prepared formulations were evaluated for solution viscosity, floating lag time, total floating time, and in vitro drug release. The formulation was optimized using a 32 full factorial design. Dissolution data were fitted to various models to ascertain kinetic of drug release. Regression analysis and analysis of variance were performed for dependent variables. Results. All formulations (F1–F9) showed floating within 30?s and had total floating time of more than 24?h. All the formulations showed good pourability. It was observed that concentration of sodium alginate and HPMC K100 had significant influence on floating lag time, cumulative percentage drug release in 6?h and 10?h. The batch F8 was considered optimum since it showed more similarity in drug release (f2 = 74.38) to the theoretical release profile. Conclusion. Floating in situ gelling system of amoxicillin can be formulated using sodium alginate as a gelling polymer to sustain the drug release for 10 to 12?h with zero-order release kinetics. PMID:22389849

Patel, Dasharath M.; Patel, Divyesh K.; Patel, Chhagan N.

2011-01-01

195

Floating natural gas liquefaction plant  

Microsoft Academic Search

Floating LNG plants offer a technically feasible and economical method to produce natural gas from marginal offshore fields and are under certain circumstances an economical alternative to land-based LNG plants. The presented floating, semisubmersible plant can keep up production under northern North Sea conditions all the year round.

Meyer-Detring

1977-01-01

196

Mirage of Floating Exchange Rates  

Microsoft Academic Search

This note summarizes some of the highlights of my longer paper with Guillermo Calvo”Fear of Floating.” Many emerging market countries have suffered financial crises. One view blames soft pegs for these crises. Adherents to that view suggest that countries move to corner solutions--hard pegs or floating exchange rates. We analyze the behavior of exchange rates, reserves, and interest rates to

Carmen M. Reinhart

2000-01-01

197

What Makes a Boat Float?  

NSDL National Science Digital Library

Whether or not a boat floats is determined by its shape and density. In this activity, students discover how and why boats float by designing different hull shapes and finding which design holds the most weight. Students record, calculate, and interpret data as they learn about buoyancy in this hands-on activity.

Eichinger, John

2009-05-01

198

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

PubMed

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

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

2013-01-01

199

Application of Design of Experiment for Floating Drug Delivery of Tapentadol Hydrochloride  

PubMed Central

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 32 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

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

2013-01-01

200

Floating treatment wetlands for domestic wastewater treatment.  

PubMed

Floating islands are a form of treatment wetland characterized by a mat of synthetic matrix at the water surface into which macrophytes can be planted and through which water passes. We evaluated two matrix materials for treating domestic wastewater, recycled plastic and recycled carpet fibers, for chemical oxygen demand (COD) and nitrogen removal. These materials were compared to pea gravel or open water (control). Experiments were conducted in laboratory scale columns fed with synthetic wastewater containing COD, organic and inorganic nitrogen, and mineral salts. Columns were unplanted, naturally inoculated, and operated in batch mode with continuous recirculation and aeration. COD was efficiently removed in all systems examined (>90% removal). Ammonia was efficiently removed by nitrification. Removal of total dissolved N was ?50% by day 28, by which time most remaining nitrogen was present as NO(3)-N. Complete removal of NO(3)-N by denitrification was accomplished by dosing columns with molasses. Microbial communities of interest were visualized with denaturing gradient gel electrophoresis (DGGE) by targeting specific functional genes. Shifts in the denitrifying community were observed post-molasses addition, when nitrate levels decreased. The conditioning time for reliable nitrification was determined to be approximately three months. These results suggest that floating treatment wetlands are a viable alternative for domestic wastewater treatment. PMID:22105133

Faulwetter, J L; Burr, M D; Cunningham, A B; Stewart, F M; Camper, A K; Stein, O R

2011-01-01

201

Floating production systems  

SciTech Connect

The paper reviews the different types of floating production systems available to the petroleum industry and addresses why these platforms presently represent attractive candidates for future worldwide offshore Field developments. Attention is focused on tension leg platforms monohull production vessels and semisubmersible production platforms. The potential of new concepts such as the Spar platform are mentioned. Further, the paper focuses on important design features and engineering challenges for the various platform types. In order to highlight the global design aspects, both topside facilities and support structures as well as mooring systems, risers, subsea facilities and motion behavior are addressed, References to recent designs are made to illustrate the present state-of-the-art technology.

Moksnes, J.; Naess, T.; Eriksen, K.; Fjeld, S.

1995-12-31

202

Floating Silicon Method  

SciTech Connect

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.

Kellerman, Peter

2013-12-21

203

Floating on oil.  

PubMed

We demonstrate that disk-shaped steel meshes coated with a superamphiphobic layer are able to float on water and on organic liquids. A coated disk-shaped steel mesh of 1 cm radius has a loading capacity of 17 mN in water and still remarkable 9 mN in n-hexadecane. Experimentally measured supporting forces and loading capacities agree well with theoretical predictions. Inspired by the giant water lily, pan-shaped "oil lilies" with even higher loading capacity and artificial oil striders carrying more than 10 times their own weight are designed. Even after the artificial devices are fully immersed into different liquids, they show self-draining properties due to capillary forces. PMID:25109826

Zhang, Jihua; Deng, Xu; Butt, Hans-Jürgen; Vollmer, Doris

2014-09-01

204

Floating into Deep Space  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

205

Tablet PCs: The Write Approach  

ERIC Educational Resources Information Center

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…

Milner, Jacob

2006-01-01

206

Mucoadhesive bilayered tablets for buccal sustained release of flurbiprofen.  

PubMed

The aim of this work was the design of sustained-release mucoadhesive bilayered tablets, using mixtures of mucoadhesive polymers and an inorganic matrix (hydrotalcite), for the topical administration of flurbiprofen in the oral cavity. The first layer, responsible for the tablet retention on the mucosa, was prepared by compression of a cellulose derivative and polyacrylic derivative blend. The second layer, responsible for buccal drug delivery, was obtained by compression of a mixture of the same (first layer) mucoadhesive polymers and hydrotalcite containing flurbiprofen. Nonmedicated tablets were evaluated in terms of swelling, mucosal adhesion, and organoleptic characteristics; in vitro and in vivo release studies of flurbiprofen-loaded tablets were performed as well. The best results were obtained from the tablets containing 20 mg of flurbiprofen, which allowed a good anti-inflammatory sustained release in the buccal cavity for 12 hours, ensuring efficacious salivary concentrations, and led to no irritation. This mucoadhesive formulation offers many advantages over buccal lozenges because it allows for reduction in daily administrations and daily drug dosage and is suitable for the treatment of irritation, pain, and discomfort associated with gingivitis, sore throats, laryngopharyngitis, cold, and periodontal surgery. Moreover, it adheres well to the gum and is simple to apply, which means that patient compliance is improved. PMID:17915804

Perioli, Luana; Ambrogi, Valeria; Giovagnoli, Stefano; Ricci, Maurizio; Blasi, Paolo; Rossi, Carlo

2007-01-01

207

Control development for floating wind  

NASA Astrophysics Data System (ADS)

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.

Savenije, Feike; Peeringa, Johan

2014-06-01

208

Electrically floating, near vertical incidence, skywave antenna  

SciTech Connect

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.

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

2014-07-08

209

Bioadhesive mini-tablets for vaginal drug delivery.  

PubMed

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

Hiorth, Marianne; Nilsen, Susanne; Tho, Ingunn

2014-01-01

210

Skylab floating ice experiment  

NASA Technical Reports Server (NTRS)

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.

Campbell, W. J. (principal investigator); Ramseier, R. O.; Weaver, R. J.; Weeks, W. F.

1975-01-01

211

Floating wind turbine system  

NASA Technical Reports Server (NTRS)

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.

Viterna, Larry A. (Inventor)

2009-01-01

212

Vardenafil orodispersible tablet.  

PubMed

Vardenafil orodispersible tablet (ODT) is a supralingual formulation of vardenafil that is available for the on-demand treatment of erectile dysfunction. The pharmacokinetics of vardenafil ODT are not equivalent to those of the vardenafil film-coated tablet in that the ODT formulation provides consistently greater vardenafil systemic exposure. Therefore, the two formulations are not interchangeable. The efficacy of on-demand vardenafil ODT 10 mg was established in the POTENT I and II studies, which were 6-week, randomized, double-blind, multinational trials in men with erectile dysfunction of at least 6 months duration. In both trials, vardenafil ODT improved erectile function significantly more than placebo, as indicated by International Index of Erectile Function-Erectile Function subscale scores at week 12 and overall erection success rates during treatment according to responses to questions 2 and 3 of the Sexual Encounter Profile (coprimary endpoints). In a pooled analysis of both trials, vardenafil ODT improved erectile function regardless of age, severity of erectile dysfunction at baseline or the presence or absence of underlying medical conditions. Vardenafil ODT was generally well tolerated in clinical trials, including in men aged ?65 years, and adverse events were mostly mild or moderate in severity. PMID:22191797

Sanford, Mark

2012-01-01

213

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

PubMed

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

Jagdale, Swati C; Pawar, Chandrakala R

2014-01-01

214

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

PubMed Central

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

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

2013-01-01

215

Design and evaluation of hydrophobic coated buoyant core as floating drug delivery system for sustained release of cisapride.  

PubMed

An inert hydrophobic buoyant coated-core was developed as floating drug delivery system (FDDS) for sustained release of cisapride using direct compression technology. Core contained low density, porous ethyl cellulose, which was coated with an impermeable, insoluble hydrophobic coating polymer such as rosin. It was further seal coated with low viscosity hydroxypropyl methyl cellulose (HPMC E15) to minimize moisture permeation and better adhesion with an outer drug layer. It was found that stable buoyant core was sufficient to float the tablet more than 8 h without the aid of sodium bicarbonate and citric acid. Sustained release of cisapride was achieved with HPMC K4M in the outer drug layer. The floating lag time required for these novel FDDS was found to be zero, however it is likely that the porosity or density of the core is critical for floatability of these tablets. The in vitro release pattern of these tablets in simulated gastric fluid showed the constant and controlled release for prolonged time. It can be concluded that the hydrophobic coated buoyant core could be used as FDDS for gastroretentive delivery system of cisapride or other suitable drugs. PMID:24825997

Jacob, Shery; Nair, Anroop B; Patil, Pandurang N

2010-12-01

216

Formulation of biphasic release tablets containing slightly soluble drugs  

Microsoft Academic Search

A new biphasic release system for slightly soluble drugs has been proposed. To enhance the dissolution rate, the drug was milled with a superdisintegrant. Then, double-layer tablets were prepared. One layer was formulated to release the drug in a very short time (fast-release). The other consisted of an extended-release hydroxypropylmethylcellulose (HPMC) matrix. Different HPMC concentrations (10, 16 and 22%) and

Lauretta Maggi; Evelyn Ochoa Machiste; Maria Luisa Torre; Ubaldo Conte

1999-01-01

217

Oral bioavailability of mesna tablets  

Microsoft Academic Search

To test the feasibility of uroprotection with sodium 2-mercaptoethane-sulfonate (mesna) in tablet form the bioavailability of mesna tablets was determined in healthy volunteers by HPLC. The area under the plasma concentration-time curve (AUC) of free mesna was significantly lower following oral (110 µmol.l-1.h-1; 95% CI 98–122) than following i.v. administration of 1.2 g of mesna (201 µmol.l-1.h-1; 95% CI 158–244).

Brigitte Stofer-Vogell; Thomas Cerny; Markus Borner; Bernhard H. Lauterburgl

1993-01-01

218

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2012 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2012-01-01

219

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2013 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2013-01-01

220

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2014 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2014-01-01

221

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2011 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2011-01-01

222

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2010 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2010-01-01

223

Development and in vitro characterization of mebendazole delayed release tablet for colonic drug delivery.  

PubMed

The main objective behind this study was to formulate delayed release colon targeted tablet of Mebendazole by using different polymers. The precompressional parameters of powder blend were studied. The wet granulation method was used for the preparation of tablets. The tablets of all formulation were subjected for different physicochemical evaluation. The drug-excipient interaction study was carried out by using Fourier transforms Infrared spectroscopy (FTIR). The in vitro evaluation was carried out at different pH ranges (0.1M HCl, 6.8 and 7.4 Phosphate buffer) for the prepared tablets. From the stability, Fourier transform infra-red spectroscopy studies Mebendazole tablet does not show any interaction between drug and polymer. The prepared tablets were complied all the physicochemical test as per official limit. The formulated (M3) batch shows better sustained release 99.89% over a period of 12 hours and the data was fitted into Korsemeyer-Peppas kinetic equation. The result indicates that Mebendazole colon targeted matrix tablet remain stable in the stomach and shows better release into the colon with the help of pH dependent synthetic polymers. PMID:24577910

Baviskar, Dheeraj; Rajput, Amarjit; Bare, Kapil; Biranwar, Yogeshkumar; Chaudhari, Hiralal; Narkhede, Deepak; Jain, Dinesh

2014-03-01

224

Floating ports: Design and construction practices  

SciTech Connect

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.

Tsinker, G.P.

1986-01-01

225

The fluid mechanics of floating and sinking  

E-print Network

objects can float at an interface between two fluids. We obtain the conditions on density and size for various objects to float and show that being ‘super-hydrophobic’ does not generally help small, dense objects to float. Super-hydrophobicity does...

Vella, Dominic Joseph Robert

2007-10-02

226

E-Books and the Tablet PC.  

ERIC Educational Resources Information Center

Highlights the emerging technologies of e-books, electronic versions of texts, and the Tablet PC, a new hybrid laptop computer and personal digital assistant that features a writing tablet and stylus-based input/navigation. (Author/VWL)

Goodwin-Jones, Bob

2003-01-01

227

21 CFR 520.1310 - Marbofloxacin tablets.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Marbofloxacin tablets. 520.1310 Section 520...FORM NEW ANIMAL DRUGS § 520.1310 Marbofloxacin tablets. (a) Specifications ...50, 100, or 200 milligrams (mg) marbofloxacin. (b) Sponsor. See No....

2010-04-01

228

21 CFR 520.1380 - Methocarbamol tablets.  

Code of Federal Regulations, 2014 CFR

...DRUGS § 520.1380 Methocarbamol tablets. (a) Chemical name. 3-(O-Methoxyphenoxy)-1,2-propanediol 1-carbamate. (b) Specifications. Each tablet contains 500 milligrams of methocarbamol. (c) Sponsor. See No. 000856...

2014-04-01

229

21 CFR 520.1380 - Methocarbamol tablets.  

Code of Federal Regulations, 2010 CFR

...DRUGS § 520.1380 Methocarbamol tablets. (a) Chemical name. 3-(O-Methoxyphenoxy)-1,2-propanediol 1-carbamate. (b) Specifications. Each tablet contains 500 milligrams of methocarbamol. (c) Sponsor. See No. 000856...

2010-04-01

230

21 CFR 520.1380 - Methocarbamol tablets.  

Code of Federal Regulations, 2013 CFR

...DRUGS § 520.1380 Methocarbamol tablets. (a) Chemical name. 3-(O-Methoxyphenoxy)-1,2-propanediol 1-carbamate. (b) Specifications. Each tablet contains 500 milligrams of methocarbamol. (c) Sponsor. See No. 000856...

2013-04-01

231

21 CFR 520.1380 - Methocarbamol tablets.  

Code of Federal Regulations, 2011 CFR

...DRUGS § 520.1380 Methocarbamol tablets. (a) Chemical name. 3-(O-Methoxyphenoxy)-1,2-propanediol 1-carbamate. (b) Specifications. Each tablet contains 500 milligrams of methocarbamol. (c) Sponsor. See No. 000856...

2011-04-01

232

21 CFR 520.1380 - Methocarbamol tablets.  

Code of Federal Regulations, 2012 CFR

...DRUGS § 520.1380 Methocarbamol tablets. (a) Chemical name. 3-(O-Methoxyphenoxy)-1,2-propanediol 1-carbamate. (b) Specifications. Each tablet contains 500 milligrams of methocarbamol. (c) Sponsor. See No. 000856...

2012-04-01

233

21 CFR 520.312 - Carnidazole tablets.  

Code of Federal Regulations, 2010 CFR

...Conditions of use —(1) Amount. Adult pigeons: 1 tablet (10 milligrams); newly weaned pigeons: 1/2 tablet (5 milligrams). (2...trichomoniasis (canker) in ornamental and homing pigeons. (3) Limitations. Not for...

2010-04-01

234

21 CFR 520.312 - Carnidazole tablets.  

Code of Federal Regulations, 2011 CFR

...Conditions of use —(1) Amount. Adult pigeons: 1 tablet (10 milligrams); newly weaned pigeons: 1/2 tablet (5 milligrams). (2...trichomoniasis (canker) in ornamental and homing pigeons. (3) Limitations. Not for...

2011-04-01

235

21 CFR 520.2088 - Roxarsone tablets.  

Code of Federal Regulations, 2012 CFR

...Conditions of use —(i) Growing chickens and growing turkeys—(a ) Amount. Dissolve 2 tablets in each gallon of... (4) Conditions of use in growing chickens and growing turkeys —(i) Amount . 1 tablet in each gallon of drinking...

2012-04-01

236

21 CFR 520.2088 - Roxarsone tablets.  

Code of Federal Regulations, 2010 CFR

...Conditions of use —(i) Growing chickens and growing turkeys—(a ) Amount. Dissolve 2 tablets in each gallon of... (4) Conditions of use in growing chickens and growing turkeys —(i) Amount . 1 tablet in each gallon of drinking...

2010-04-01

237

21 CFR 520.2088 - Roxarsone tablets.  

Code of Federal Regulations, 2013 CFR

...Conditions of use —(i) Growing chickens and growing turkeys—(a ) Amount. Dissolve 2 tablets in each gallon of... (4) Conditions of use in growing chickens and growing turkeys —(i) Amount . 1 tablet in each gallon of drinking...

2013-04-01

238

21 CFR 520.2088 - Roxarsone tablets.  

Code of Federal Regulations, 2011 CFR

...Conditions of use —(i) Growing chickens and growing turkeys—(a ) Amount. Dissolve 2 tablets in each gallon of... (4) Conditions of use in growing chickens and growing turkeys —(i) Amount . 1 tablet in each gallon of drinking...

2011-04-01

239

Flinking: Neither Floating nor Sinking.  

ERIC Educational Resources Information Center

Describes an activity that challenges students to make an object that, when released under water, does not float up or sink down. The main concept this activity investigates is the density of ordinary objects in comparison to the density of water. (PR)

Wilson, Roger B.

1993-01-01

240

A study on maize proteins as a potential new tablet excipient.  

PubMed

This investigation has examined the use of zein proteins from maize as the major component in oral controlled-release tablets, such formulations often being required to improve patient compliance. Tablets containing ground zein proteins, calcium hydrogen orthophosphate, polyvinyl pyrrolidone, theophylline and magnesium stearate were produced by wet granulation and compression on a single station tablet press and were compared to directly compressed tablets based on zein proteins, calcium hydrogen orthophosphate and theophylline. Non invasive techniques such as Fourier Transform infrared spectroscopy and Fourier Transform Raman spectroscopy were employed to investigate any changes in the secondary structure of zein proteins during tablet production. Random coils, alpha helices and beta sheets predominated and their relative content remained unaffected during grinding, wet granulation and compression, indicating that formulations based on zeins will be robust, i.e. insensitive to minor changes in the production conditions. Drug release from the tablets was studied using a standard pharmacopoeial dissolution test. Dissolution profiles in water, 0.1M HCl (pH=1) and phosphate buffer (pH=6.8) show that only a limited amount of theophylline was released after 4.5h, suggesting that zein proteins could act as a potential vehicle for oral controlled drug release. Analysis of the theophylline release profiles using the Peppas and Sahlin model reveals that diffusion and polymer relaxation occurred in acidic (pH=1) and buffered (pH=6.8) conditions for wet granulated tablets, whereas diffusion was predominant in directly compressed tablets. In conclusion, the present study has shown that zeins can be successfully used as a pharmaceutical excipient, and in particular as a matrix in monolithic controlled release tablets. PMID:18294824

Georget, Dominique M R; Barker, Susan A; Belton, Peter S

2008-06-01

241

Double-Layered Mucoadhesive Tablets Containing Nystatin  

Microsoft Academic Search

The objective of this work was to design a mucoadhesive tablet with a potential use in the treatment of oral candidosis. A 2-layered tablet containing nystatin was formulated. Lactose CD (direct compression), carbomer (CB), and hydroxypropylmethylcellulose (HPMC) were used as excipients. Tablets were obtained through direct compression. Properties such as in vitro mucoadhesion, water uptake, front movements, and drug release

Juan Manuel Llabot; Ruben Hilario Manzo; Alberto allemandi

2002-01-01

242

21 CFR 520.816 - Epsiprantel tablets.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Epsiprantel tablets. 520.816 Section 520.816 Food...ANIMAL DRUGS § 520.816 Epsiprantel tablets. (a) Specifications . Each tablet contains either 12.5, 25, 50, or 100 milligrams of...

2010-04-01

243

Scaffolding Equals Success in Teaching Tablet PCs  

ERIC Educational Resources Information Center

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…

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

2009-01-01

244

Onsite Wastewater Treatment Systems: Tablet Chlorination  

E-print Network

the basin. As that tablet dissolves and/or erodes, the tablet above it falls by gravity to replace it. A tablet can dissolve quickly or slowly, depending on the amount of wastewater coming into contact Richard Weaver and Bruce Lesikar Professor in Soil...

Lesikar, Bruce J.

2008-10-23

245

Balloons and Other Things That Sometimes Float  

NSDL National Science Digital Library

Hot air balloons float--sometimes. Regular old balloons that you get at a party float--sometimes. Boats float--sometimes. What makes them float and what makes them sink? How can a boat made of steel float but a solid chunk of steel sink to the bottom of the ocean? Part of the answer has to do with something called density, which will be discussed in this chapter. And yes, the concepts addressed in this chapter do have a lot to do with weather.

2005-01-01

246

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

PubMed Central

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

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

2011-01-01

247

Evaluation of the potential use of poly(ethylene oxide) as tablet- and extrudate-forming material  

Microsoft Academic Search

The purpose of this study was to assess the potential use of poly(ethylene oxide) (PEO) as matrix-forming mate-rial for tablets\\u000a and extrudates. Raw materials were characterized for size, size distribution, and shape. Tablets with 2- and 10-mm diameter\\u000a were prepared by direct compression at both 13 and 38 MPa from mixtures with poly(ethylene oxide)s, a model drug (propranolol\\u000a hydrochloride) and

João F. Pinto; Kathrin F. Wunder; Andrea Okoloekwe

2004-01-01

248

Utilization of poly( dl-lactide-co-glycolide) nanoparticles for preparation of mini-depot tablets by direct compression  

Microsoft Academic Search

Purpose: The objectives of this study were to prepare the long-acting matrix tablets by direct compression of the mixture of drug and poly(dl-lactide-co-glycolide) (PLGA) nanoparticles and to clarify the effects of such factors as polymer species, mixing ratio of nanoparticles with different molecular weights, and the tablet weight on the drug release and to discuss the mechanism of drug release

Hideki Murakami; Masao Kobayashi; Hirofumi Takeuchi; Yoshiaki Kawashima

2000-01-01

249

Can flexibility help you float?  

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

250

Float Zone Experiments in Space  

NASA Technical Reports Server (NTRS)

The objective of this work has been to evaluate whether or not Marangoni flow could be suppressed in molten metals by the presence of very thin oxide films. Experimental work has been carried out on molten Sn under UHV conditions. A disk floating zone arrangement was developed to allow in situ Auger examination of molten surfaces. An electron energy loss technique was developed which allows detection of continuous tin oxide films of 6 A or greater. Experiments were planned to detect the effects of oxide formation upon Marangoni flow by measuring: (1) temperature profiles, (2) solid liquid interface shapes, (3) macrosegregation, and (4) the onset of oscillatory Marangoni flow by detecting oscillating temperature variations. Work on (4) showed that oscillatory temperature variations of frequency or = 10 Hz were not present in the disk float zone geometry under conditions of Ma = 4300 with an oxide free molten surface. The disk float zone geometry was modeled with a finite element analysis and temperature and velocity profiles were determined.

Verhoeven, J. D.

1985-01-01

251

Float zone experiments in space  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

252

Crystallization of excipients in tablets.  

PubMed

Whisker-like crystals appeared on the surface of tablets that contained lactose or mannitol, a hygroscopic material such as docusate sodium, magnesium chloride, or potassium acetate, and other ingredients stored in an atmosphere of high relative humidity. The crystals were observed under a scanning electron microscope and were measured using differential scanning calorimetry and TLC. The crystals contained lactose or mannitol. PMID:3921688

Ando, H; Watanabe, S; Ohwaki, T; Miyake, Y

1985-02-01

253

Technology of dispensing check based-on tablet features  

Microsoft Academic Search

This paper designs and realizes a bagged tablets checking system. First, according to tablet characteristics, color feature library and shape feature library are created. Second, the tablet image is clustered by K-means algorithm. And threshold segmentation for the tablet image use Ostu method. Finally, the recognition result of sorts of tablets in bag will compare with prescription in database written

Dong Yin; Jun Xu; Song Wang

2011-01-01

254

Pharmaceutical and analytical evaluation of triphalaguggulkalpa tablets  

PubMed Central

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

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

2011-01-01

255

Tank Tests of Twin Seaplane Floats  

NASA Technical Reports Server (NTRS)

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.

Herrman, H; Kempf, G; Kloess, H

1928-01-01

256

Modeling International Space Station (ISS) Floating Potentials  

NASA Technical Reports Server (NTRS)

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.

Ferguson, Dale C.; Gardner, Barbara

2002-01-01

257

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

PubMed Central

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

Jagdale, Swati C.; Pawar, Chandrakala R.

2014-01-01

258

21 CFR 520.2158b - Dihydrostreptomycin tablets.  

Code of Federal Regulations, 2010 CFR

...false Dihydrostreptomycin tablets. 520.2158b Section...AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.2158b Dihydrostreptomycin tablets. (a) Specifications. Each tablet contains 37.5...

2010-04-01

259

21 CFR 520.1696d - Penicillin V potassium tablets.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Penicillin V potassium tablets. 520.1696d...ANIMAL DRUGS § 520.1696d Penicillin V potassium tablets. (a) Specifications. Each tablet contains penicillin V potassium equivalent to...

2011-04-01

260

21 CFR 520.1696d - Penicillin V potassium tablets.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Penicillin V potassium tablets. 520.1696d...ANIMAL DRUGS § 520.1696d Penicillin V potassium tablets. (a) Specifications. Each tablet contains penicillin V potassium equivalent to...

2012-04-01

261

21 CFR 520.1696d - Penicillin V tablets.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Penicillin V tablets. 520.1696d Section...NEW ANIMAL DRUGS § 520.1696d Penicillin V tablets. (a) Specifications. Each tablet contains penicillin V potassium equivalent to 125...

2013-04-01

262

21 CFR 520.1696d - Penicillin V tablets.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Penicillin V tablets. 520.1696d Section...NEW ANIMAL DRUGS § 520.1696d Penicillin V tablets. (a) Specifications. Each tablet contains penicillin V potassium equivalent to 125...

2014-04-01

263

21 CFR 520.1696d - Penicillin V potassium tablets.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Penicillin V potassium tablets. 520.1696d...ANIMAL DRUGS § 520.1696d Penicillin V potassium tablets. (a) Specifications. Each tablet contains penicillin V potassium equivalent to...

2010-04-01

264

21 CFR 520.82a - Aminopropazine fumarate tablets.  

Code of Federal Regulations, 2010 CFR

... § 520.82a Aminopropazine fumarate tablets. (a) Specifications. The drug is in tablet form. Each tablet contains aminopropazine fumarate equivalent...weight. The dosage can be repeated every 12 hours, as indicated.1 (3)...

2010-04-01

265

21 CFR 520.1284 - Sodium liothyronine tablets.  

Code of Federal Regulations, 2010 CFR

...Specifications. Sodium liothyronine tablets consist of tablets intended for oral administration...liothyronine at 60 or 120 micrograms per tablet, as the sodium salt. (b...orally to dogs at levels up to 12.8 micrograms per...

2010-04-01

266

21 CFR 520.434 - Chlorphenesin carbamate tablets.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Chlorphenesin carbamate tablets. 520.434 ...FORM NEW ANIMAL DRUGS § 520.434 Chlorphenesin carbamate tablets. (a) Specifications...Each tablet contains 400 milligrams of chlorphenesin carbamate. (b) Sponsor....

2012-04-01

267

21 CFR 520.434 - Chlorphenesin carbamate tablets.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Chlorphenesin carbamate tablets. 520.434 ...FORM NEW ANIMAL DRUGS § 520.434 Chlorphenesin carbamate tablets. (a) Specifications...Each tablet contains 400 milligrams of chlorphenesin carbamate. (b) Sponsor....

2011-04-01

268

21 CFR 520.434 - Chlorphenesin carbamate tablets.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Chlorphenesin carbamate tablets. 520.434 ...FORM NEW ANIMAL DRUGS § 520.434 Chlorphenesin carbamate tablets. (a) Specifications...Each tablet contains 400 milligrams of chlorphenesin carbamate. (b) Sponsor....

2013-04-01

269

21 CFR 520.434 - Chlorphenesin carbamate tablets.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Chlorphenesin carbamate tablets. 520.434 ...FORM NEW ANIMAL DRUGS § 520.434 Chlorphenesin carbamate tablets. (a) Specifications...Each tablet contains 400 milligrams of chlorphenesin carbamate. (b) Sponsor....

2010-04-01

270

21 CFR 520.434 - Chlorphenesin carbamate tablets.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Chlorphenesin carbamate tablets. 520.434 ...FORM NEW ANIMAL DRUGS § 520.434 Chlorphenesin carbamate tablets. (a) Specifications...Each tablet contains 400 milligrams of chlorphenesin carbamate. (b) Sponsor....

2014-04-01

271

Wave drag on floating bodies  

PubMed Central

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

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

2011-01-01

272

14 CFR 29.757 - Hull and auxiliary float strength.  

Code of Federal Regulations, 2010 CFR

...float strength. The hull, and auxiliary floats if used, must withstand the water loads prescribed by § 29.519 with a rational and conservative distribution of local and distributed water pressures over the hull and float bottom. [Amdt....

2010-01-01

273

14 CFR 29.757 - Hull and auxiliary float strength.  

Code of Federal Regulations, 2012 CFR

...float strength. The hull, and auxiliary floats if used, must withstand the water loads prescribed by § 29.519 with a rational and conservative distribution of local and distributed water pressures over the hull and float bottom. [Amdt....

2012-01-01

274

14 CFR 29.757 - Hull and auxiliary float strength.  

Code of Federal Regulations, 2011 CFR

...float strength. The hull, and auxiliary floats if used, must withstand the water loads prescribed by § 29.519 with a rational and conservative distribution of local and distributed water pressures over the hull and float bottom. [Amdt....

2011-01-01

275

Double-layered mucoadhesive tablets containing nystatin  

Microsoft Academic Search

The objective of this work was to design a mucoadhesive tablet with a potential use in the treatment of oral candidosis. A\\u000a 2-layered tablet containing nystain was formulated. Lactose CD (direct compression), carbomer (CB), and hydroxypropylmethylcellulose\\u000a (HPMC) were used as excipients. Tablets were obtained through direct compression. Properties such as in vitro mucoadhesion,\\u000a water uptake, front movements, and drug release

Juan Manuel Llabot; Ruben Hilario Manzo; Alberto allemandi

2002-01-01

276

1H-NMR microscopy of tablets.  

PubMed

A 1H-nuclear magnetic resonance (NMR) microscopy method was utilized for the first time to determine the porosity distribution of physically intact tablets. The main advantage of this newly developed method was that porosity cross sections through whole tablets or specific locations could be obtained without mechanically destroying the tested tablet. This was achieved by filling tablet cavities with silicone oil under vacuum. The amount of silicone oil locally within the tablet was then determined by 1H-NMR microscopy, revealing the inverse inner structure. To reduce the measuring time, a paramagnetic gadolinium complex was added to the silicone oil. The cross sectional signals produced by 1H-NMR microscopy through the tablet were transformed into a color image by a specially designed computer graphic program. To improve the signal-noise ratio an algorithm of 3D-filtering was introduced. The maximal spatial resolution achieved with this method was about 95 microns for a cube's edge length corresponding to some 380,000 positions in a 9-mm-diameter compression-coated tablet. Uneven porosity distributions within tablets, cracks, or cavities could be visualized with this newly developed method. Different compaction mechanisms were observed with plastic- or brittle-type tablets. The different states of densification during compaction of powders could be detected. The integrity of compression coatings was determined to be dependent on the pressure load and the location of the core within the coat. PMID:7616364

Nebgen, G; Gross, D; Lehmann, V; Müller, F

1995-03-01

277

Evaluation of named binders in Rauwolfia vomitoria root tablets.  

PubMed

Some physical properties of Rauwolfia vomitoria root tablets were studied. Tablet characteristics studied were: weight uniformity, tensile strength, friability, disintegration time and content uniformity. Tablet property varied depending on the type and concentration of the binder. The tablets had type and concentration of the binder. The tablets had acceptable hardness and friability profiles. Although tablets containing 150 mg R. vomitoria root had lower tensile strength values. All the tablets passed the B.P. disintegration time test of 15 min. Moreover tablets containing 150 mg R. vomitoria root disintegrated under 1 min. at 4% w/w binder concentration. PMID:10961024

Onunkwo, G C

2000-01-01

278

IEEE Standard unifies arithmetic model Floating points  

E-print Network

years use IEEE floating-point arithmetic. This doesn't mean that they all get exactly the same resultsIEEE Standard unifies arithmetic model Floating points by Cleve Moler C l e v e ' s C o r n e r I f you look carefully at the definition of fundamental arithmetic operations like addition

Beron-Vera, Francisco Javier

279

Multiplications of floating point expansions Marc Daumas  

E-print Network

of overflow or underflow, the process is error free and possibly more efficient than its integer based counterMultiplications of floating point expansions Marc Daumas CNRS - Lab LIP - UMR 8512 - ENS de Lyon computers, the floating point unit is the part of the processor delivering the highest computing power

California at Davis, University of

280

Future float zone development in industry  

NASA Technical Reports Server (NTRS)

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.

Sandfort, R. M.

1980-01-01

281

Floating Entanglement Witness Measure and Genetic Algorithm  

E-print Network

In this paper based on the notion of entanglement witness, a new measure of entanglement called floating entanglement witness measure is introduced which satisfies some of the usual properties of a good entanglement measure. By exploiting genetic algorithm, we introduce a classical algorithm that computes floating entanglement witness measure. This algorithm also provides a method for finding entanglement witness for a given entangled state.

A. Baghbanpourasl; G. Najarbashi; M. Seyedkazemi

2007-08-27

282

Interval Arithmetic Implementations using Floating Point Arithmetic  

Microsoft Academic Search

This paper presents some algorithms implementing interval arithmetic using floating point arithmetic. The algorithms apply to almost any digital computer supporting normalized floating point arithmetic and provide better performance than conventional interval arithmetic program libraries. For reasons of generality and machine independence, algorithms are presented in a high-level language. They are intended to be used as an implementation guide for

Michael Clemmesen

1984-01-01

283

Interval arithmetic implementations: using floating point arithmetic  

Microsoft Academic Search

This paper presents some algorithms implementing interval arithmetic using floating point arithmetic. The algorithms apply to almost any digital computer supporting normalized floating point arithmetic and provide better performance than conventional interval arithmetic program libraries. For reasons of generality and machine independence, algorithms are presented in a high-level language. They are intended to be used as an implementation guide for

Michael Clemmesen

1984-01-01

284

Formulation and optimization of mucoadhesive bilayer buccal tablets of atenolol using simplex design method  

PubMed Central

Introduction: In the present study, mucoadhesive buccal bilayer tablets of atenolol were fabricated with the objective of avoiding first pass metabolism and to improve its bioavailability with reduction in dosing frequency. Hence, the aim of this work was to design oral controlled release mucoadhesive tablets of atenolol and to optimize the drug release profile and bioadhesion. Materials and Methods: Bilayer buccal tablets of atenolol were prepared by direct compression method using simplex method of optimization to investigate the combined effect of hydroxypropyl methylcellulose 15 cps (X1), Carbopol (X2) and mannitol (X3); the in vitro drug release (Y1) and mucoadhesive strength (Y2) were taken as responses. The designed tablets were evaluated for various physical and biological parameters like drug content uniformity, in vitro drug release, short-term stability, and drug- excipient interactions (FTIR). Results: The formulation C containing hydroxypropyl methylcellulose 15 cps (10% w/w of matrix layer), Carbopol 934p (10% w/w of matrix layer) and mannitol (channeling agent, 40% w/w of matrix layer) was found to be promising. This formulation exhibited an in vitro drug release of 89.43% in 9 h along with satisfactory bioadhesion strength (7.20 g). Short-term stability studies on the promising formulation indicated that there are no significant changes in drug content and in vitro dissolution characteristics (P<0.05). IR spectroscopic studies indicated that there are no drug-excipient interactions. PMID:23071958

Shirsand, SB; Suresh, Sarasija; Keshavshetti, GG; Swamy, PV; Reddy, P Vijay Prakash

2012-01-01

285

Condition and Error Estimates in Numerical Matrix Computations  

SciTech Connect

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.

Konstantinov, M. M. [University of Architecture, Civil Engineering and Geodesy, 1046 Sofia (Bulgaria); Petkov, P. H. [Technical University of Sofia, 1000 Sofia (Bulgaria)

2008-10-30

286

Floating-Point Matrix Multiplication in a Polymorphic Processor  

E-print Network

and of the applications using it. In this paper, we address a reconfigurable coprocessor extension of a General Purpose, proposed in [1], with the major difference that we consider a tightly coupled co-processor architectural multiplier with 9 process- ing elements, organized in a CCU running at 100 MHz on an XC2VP30­6 FPGA. Our

Kuzmanov, Georgi

287

Investigation of excipient type and level on drug release from controlled release tablets containing HPMC.  

PubMed

The purpose of this study was to investigate the influence of excipient type and level on the release of alprazolam formulated in controlled release matrix tablets containing hydroxypropyl methylcellulose (HPMC). Each tablet formulation contained alprazolam, HPMC (Methocel K4MP), excipients, and magnesium stearate. The soluble excipients investigated were lactose monohydrate, sucrose, and dextrose, and the insoluble excipients included dicalcium phosphate dihydrate, dicalcium phosphate anhydrous, and calcium sulfate dihydrate. The similarity factor (f2 factor) was used to compare the dissolution profile of each formulation. The insoluble excipients, especially dicalcium phosphate dihydrate, caused the drug to be released at a slower rate and to a lesser extent than the soluble excipients. Soluble excipients created a more permeable hydrated gel layer for drug release, increased the porosity resulting in faster diffusion of drug, and increased the rate of tablet erosion. Use of binary mixtures of lactose monohydrate and dicalcium phosphate dihydrate produced release profiles of intermediate duration. Rapid drug dissolution was obtained when only 9.1% w/w of lactose monohydrate was present in the tablet formulation. Only when the dicalcium phosphate dihydrate level was sufficiently high (36.5% w/w) was the release rate and extent decreased. It was demonstrated that the type and level of excipient influenced the rate and extent of drug release from controlled release tablets containing HPMC. The release mechanism of alprazolam from each tablet formulation was described by either the Hixson-Crowell cube root kinetics equation or Peppas's equation. However, the different excipient types investigated did not influence the release mechanism of alprazolam from the final tablets. PMID:12066573

Williams, Robert O; Reynolds, Thomas D; Cabelka, Tim D; Sykora, Matthew A; Mahaguna, Vorapann

2002-05-01

288

Multiprocessing system for performing floating point arithmetic operations  

SciTech Connect

This patent describes a data processing system. It comprises: a fixed point arithmetic processor means for performing fixed point arithmetic operations and including control means for decoding a floating point arithmetic instruction specifying a floating point arithmetic operation, and an addressing means for computing addresses for floating point data for the floating point operation from a memory means. The memory means for storing data and including means for receiving the addresses from the fixed point arithmetic processor means and providing the floating point data to a floating point arithmetic processor means; and the floating point arithmetic processor means for performing floating point arithmetic operations and including control means for decoding the floating point instruction and performing the specified floating point arithmetic operation upon the floating point data from the memory means.

Nguyenphu, M.; Thatcher, L.E.

1990-10-02

289

[Calorimetric evaluation of directly compressed tablets].  

PubMed

The paper studies the effect of the type of the disintegrating substance and the lubricant on the destruction heat of tablet materials and tablets. Destruction heat was determined by means of isoperibolic calorimetry. Tablet materials and tablets contained Avicel PH 101 as the dry binder, 10% of Primojel, Ac-Di-Sol, or Polyplasdone XL as disintegrating substances, and 5% of magnesium strearate or sodium laurylsulfate as the lubricants. The sum of destruction heats of the individual auxiliary substances equalled the found values in tablet materials and tablets. In tablets, in contrast to tablet materials, values of destruction heat higher by 57.9% were found. In the disintegrating substances and lubricants tested, the found values of destruction heats were dependent on the values of destruction heats of the individual auxiliary substances. In the disintegrating substances, a linear dependence of the total destruction heat (CDT) on the destruction heat of the disintegrating substances (DTR) was found, given by the relationship CDT = 0.797.DTR + 17.666 with the correlation coefficient r = 0.986. PMID:11242832

Rehula, M; Lavická, J; Musilová, M

2001-01-01

290

Photostability of extended-release matrix formulations  

Microsoft Academic Search

The photostability of drugs has been widely studied while less attention is devoted to the possible modifications that UV light may induce on the excipients of a dosage form, in particular, on the functional polymers used to modulate drug delivery. In this work we have evaluated the effect of UV light on the release characteristics of extended-release matrix tablets containing

L. Maggi; E. Ochoa Machiste; E. Fasani; A. Albini; L. Segale; U. Conte

2003-01-01

291

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

PubMed

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

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

2003-01-01

292

Inulin-based tablet in capsule device for variable multipulse delivery of aceclofenac: optimization and in vivo roentgenography.  

PubMed

The aim of the study was to develop single-unit tablet in capsule system of aceclofenac for the treatment of late night pain and morning stiffness associated with rheumatoid arthritis. The system was conceptualized as a three-component design (1) a hard gelatin enteric-coated capsule (for carrying two pulses), (2) first-pulse granules (for rapid release in intestine), and (2) second-pulse matrix tablet (for slow release in colon). An appropriate integration of pH-sensitive (Eudragit S100) and bacteria-responsive (inulin) functions, on the basis of 3(2) factorial design, led to formulation of TICS 1-9 that were screened for in vitro release. TICS 2 with biphasic drug release of 98.64% from first-pulse granules in simulated intestinal fluid (12 h) and 97.82% from second-pulse matrix tablet in simulated colonic fluid (24 h) was the optimized formulation that exhibited Fickian diffusion of drug (n=0.363). In vivo fluoroscopy in rats traced the intact tablet to colon in 7.5 h that got eroded at the tenth hour. This demonstrated the colon-specific delivery of the matrix tablet affirming the potential of the system to obviate the need for two-time administration of drug at odd hours. The experimental design was validated by extra design check point, and diffuse reflectance spectroscopy and DSC revealed absence of chemical interaction between the formulation excipients. PMID:23615771

Sharma, Puja; Pathak, Kamla

2013-06-01

293

WindWaveFloat Final Report  

SciTech Connect

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.

Alla Weinstein, Dominique Roddier, Kevin Banister

2012-03-30

294

Smartphones and tablets: Reshaping radiation oncologists’ lives  

PubMed Central

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

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

2012-01-01

295

Floating point arithmetic in future supercomputers  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

296

Preparation of multiple-unit floating-bioadhesive cooperative minitablets for improving the oral bioavailability of famotidine in rats.  

PubMed

Abstract The aims of this study were to prepare fine famotidine-containing floating-bioadhesive cooperative minitablets and to investigate the possibility of using those minitablets as a delivery system for promoting the oral bioavailability of famotidine. Nine minitablet formulations were designed using hydroxypropylmethylcellulose (HPMC K4M) as release-retarding polymers, Carbopol 971P as bioadhesive materials and sodium bicarbonate (NaHCO3) as gas formers. The prepared 3?±?0.02?mm minitablets were evaluated in terms of their swelling ability, floating behavior, bioadhesion test and in vitro release. The optimized minitablets (F6) containing HPMC K4M (50.00%, w/w), Carbopol 971P (10.00%, w/w) and NaHCO3 (10.00%, w/w) were found to float in 1?min and remain lastingly buoyant over a period of 8?h in vitro, with excellent bioadhesive properties (20.81?g) and sustained drug release characteristics (T50%?=?46.54%) followed one-order model. In addition, plasma concentration-time profiles from pharmacokinetic studies in rats dosed with minitablets showed 1.62-fold (p?tablets XinFaDing®. These studies demonstrated that the multiple-unit floating-bioadhesive cooperative minitablets may be a promising gastro-retentive delivery system for drugs that play a therapeutic role in the stomach. PMID:24456044

Zhu, Xuehua; Qi, Xiaole; Wu, Zhenghong; Zhang, Ziwei; Xing, Jiayu; Li, Xiangbo

2014-09-01

297

The effect of HPMC particle size on the drug release rate and the percolation threshold in extended-release mini-tablets.  

PubMed

Abstract The particle size of HPMC is a critical factor that can influence drug release rate from hydrophilic matrix systems. Percolation theory is a statistical tool which is used to study the disorder of particles in a lattice of a sample. The percolation threshold is the point at which a component is dominant in a cluster resulting in significant changes in drug release rates. Mini-tablets are compact dosage forms of 1.5-4?mm diameter, which have potential benefits in the delivery of drug to some patient groups such as pediatrics. In this study, the effect of HPMC particle size on hydrocortisone release and its associated percolation threshold for mini-tablets and tablets was assessed. For both mini-tablets and tablets, large polymer particles reduced tensile strength, but increased the drug release rate and the percolation threshold. Upon hydration, compacts with 45-125??m HPMC particles formed a strong gel layer with low porosity, reducing hydrocortisone release rates. In comparison, faster drug release rates were obtained when 125-355?µm HPMC particles were used, due to the greater pore sizes that resulted in the formation of a weaker gel. Using 125-355?µm HPMC particles increased the percolation threshold for tablets and to a greater extent for mini-tablets. This work has demonstrated the importance of HPMC particle size in ER matrices, the effects of which are even more obvious for mini-tablets. PMID:24134563

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

2015-01-01

298

Phase transformation in thiamine hydrochloride tablets: Influence on tablet microstructure, physical properties, and performance.  

PubMed

The objective of this article was to monitor phase transformation in thiamine hydrochloride, from a nonstoichiometric hydrate (NSH) to a hemihydrate (HH), in stored tablets, prepared both by direct compression and wet granulation, and to relate the storage-induced phase transformation with changes in tablet microstructure, physical properties, and performance. Raman spectroscopy revealed complete NSH ? HH transformation in tablets, within 30 h of storage at 40°C/75% relative humidity. When the tablets were prepared by wet granulation of NSH alone, there was a marked increase in both tablet volume and hardness on storage. However, when microcrystalline cellulose (MCC) was included in granulation, the resulting stored tablets also exhibited a pronounced increase in disintegration time. In contrast, tablets prepared by dry processing via compression of a NSH-MCC physical mixture did not exhibit any changes in properties, despite the in situ solid form conversion. Scanning electron microscopy revealed growth of needle-like HH crystals in all stored tablets and mercury porosimetry revealed considerable changes in the pore size distribution during storage. Longer storage led to crystal growth (Ostwald ripening), causing further gradual but less dramatic changes in properties. The phase transformation and the complex interparticulate associations in the tablet influenced the changes in tablet microstructure, compact physical properties, and product behavior. PMID:22213350

Chakravarty, Paroma; Suryanarayanan, Raj; Govindarajan, Ramprakash

2012-04-01

299

Program Converts VAX Floating-Point Data To UNIX  

NASA Technical Reports Server (NTRS)

VAX Floating Point to Host Floating Point Conversion (VAXFC) software converts non-ASCII files to unformatted floating-point representation of UNIX machine. This is done by reading bytes bit by bit, converting them to floating-point numbers, then writing results to another file. Useful when data files created by VAX computer must be used on other machines. Written in C language.

Alves, Marcos; Chapman, Bruce; Chu, Eugene

1996-01-01

300

Preparation and in vitro Characterization of Porous Carrier–Based Glipizide Floating Microspheres for Gastric Delivery  

PubMed Central

Floating microspheres have been utilized to obtain prolonged and uniform release of drug in the stomach for development of once-daily formulations. A controlled-release system designed to increase residence time in the stomach without contact with the mucosa was achieved through the preparation of floating microspheres by the emulsion solvent diffusion technique, using (i) calcium silicate (CS) as porous carrier; (ii) glipizide, an oral hypoglycemic agent; and (iii) Eudragit® S as polymer. The effects of various formulations and process variables on the internal and external particle morphology, micromeritic properties, in vitro floating behavior, drug loading, and in vitro drug release were studied. The microspheres were found to be regular in shape and highly porous. The prepared microspheres exhibited prolonged drug release (~8 h) and remained buoyant for >10 h. The mean particle size increased and the drug release rate decreased at higher polymer concentrations. No significant effect of the stirring rate during preparation on drug release was observed. In vitro studies demonstrated diffusion-controlled drug release from the microspheres. Microsphere formulation CS4, containing 200 mg calcium silicate, showed the best floating ability (88% buoyancy) in simulated gastric fluid. The release pattern of glipizide in simulated gastric fluid from all floating microspheres followed the Higuchi matrix model and the Peppas-Korsmeyer model. PMID:21731353

Pandya, N; Pandya, M; Bhaskar, V H

2011-01-01

301

Lagrangian floats as sea floor imaging platforms  

NASA Astrophysics Data System (ADS)

There is a persistent need for high resolution photographic images of the sea floor and associated biota for marine habitat classification and fisheries stock assessment. This paper presents a novel low cost Lagrangian imaging platform that offers high quality images with reduced operational demands in comparison to existing methodologies such as diver surveys, drop cameras, ship towed systems and dedicated remote or autonomous underwater vehicles. The platform consists of a recently developed bottom following Lagrangian float fit with down looking stereo cameras and strobe lighting. The float can use active ballasting to perform constant altitude photographic drift surveys in coastal waters over varying bathymetry. Images from the float can be used to create large photomosaics, stereographic bathymetry estimates and image-derived current measurements. Test data are presented to demonstrate the operation of the Lagrangian float and summarize the data products.

Roman, Chris; Inglis, Gabrielle; McGilvray, Bryan

2011-10-01

302

Exploring Floating Concrete and Beam Design.  

ERIC Educational Resources Information Center

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)

Snell, Billie G.; Snell, Luke M.

2002-01-01

303

Genetics Home Reference: Floating-Harbor syndrome  

MedlinePLUS

... syndrome? Floating-Harbor syndrome is a disorder involving short stature, slowing of the mineralization of the bones (delayed ... deficiency ; disability ; gene ; inherited ; motor ; mutation ; philtrum ; protein ; short stature ; stature ; syndrome ; testes You may find definitions for ...

304

Advanced controls for floating wind turbines  

E-print Network

Floating Offshore Wind Turbines (FOWT) is a technology that stands to spearhead the rapid growth of the offshore wind energy sector and allow the exploration of vast high quality wind resources over coastal and offshore ...

Casanovas, Carlos (Casanovas Bermejo)

2014-01-01

305

Parametric design of floating wind turbines  

E-print Network

As the price of energy increases and wind turbine technology matures, it is evident that cost effective designs for floating wind turbines are needed. The next frontier for wind power is the ocean, yet development in near ...

Tracy, Christopher (Christopher Henry)

2007-01-01

306

Gas transfer in floating-leaved plants  

Microsoft Academic Search

Pressurized gas transport with flow rates of 1.1 to 1.81 gas h-1 plant-1 have been detected in the floating-leaved aquatic macrophyte Euryale ferox on sunny days. The younger leaves gave the highest pressurization, but the gas flow was initiated mainly by the middle-aged leaves of the plants. The gas through-flow was shown to be highly beneficial for floating-leaved plants. It

W. Große; C. Bauch

1991-01-01

307

Floating assembly of diatom Coscinodiscus sp. microshells.  

PubMed

Diatoms have silica frustules with transparent and delicate micro/nano scale structures, two dimensional pore arrays, and large surface areas. Although, the diatom cells of Coscinodiscus sp. live underwater, we found that their valves can float on water and assemble together. Experiments show that the convex shape and the 40 nm sieve pores of the valves allow them to float on water, and that the buoyancy and the micro-range attractive forces cause the valves to assemble together at the highest point of water. As measured by AFM calibrated glass needles fixed in manipulator, the buoyancy force on a single floating valve may reach up to 10 ?N in water. Turning the valves over, enlarging the sieve pores, reducing the surface tension of water, or vacuum pumping may cause the floating valves to sink. After the water has evaporated, the floating valves remained in their assembled state and formed a monolayer film. The bonded diatom monolayer may be valuable in studies on diatom based optical devices, biosensors, solar cells, and batteries, to better use the optical and adsorption properties of frustules. The floating assembly phenomenon can also be used as a self-assembly method for fabricating monolayer of circular plates. PMID:22387476

Wang, Yu; Pan, Junfeng; Cai, Jun; Zhang, Deyuan

2012-03-30

308

Floating intake reduces pump damage  

SciTech Connect

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.)

Kronig, A.

1993-12-31

309

DESIGN AND EVALUATION OF A METRONIDAZOLE CENTRAL CORE MATRIX TABLET  

PubMed Central

In this paper, a study of different concentration of HPMC K 15 M exerts influence on the drug release process from a new controlled drug delivery system has been realized in order to obtain a constant release rate during a prolonged period of time, for a programmed drug release. The drug release profiles obtained for the different batches have shown an interesting relationship between the particle size of the channeling agent used and the length of different operational periods. PMID:22247836

Nagaich, Upendra; Chaudhary, Vandana; Tonpay, S.D.; Karki, Roopa

2010-01-01

310

The Sea Peoples, from cuneiform tablets to carbon dating.  

PubMed

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

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

311

Preparation and evaluation of once-daily sustained-release coated tablets of tolterodine-L-tartrate.  

PubMed

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

Pradhan, Roshan; Kim, Yong-Il; Chang, Sun Woo; Kim, Jong Oh

2014-01-01

312

Comparative evaluation of drug release from aged prolonged polyethylene oxide tablet matrices: effect of excipient and drug type.  

PubMed

Abstract 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

Shojaee, Saeed; Kaialy, Waseem; Cumming, Kenneth Iain; Nokhodchi, Ali

2014-11-20

313

The origin of tablet boudinage: Results from experiments using power-law rock analogs  

NASA Astrophysics Data System (ADS)

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.

Zulauf, J.; Zulauf, G.; Kraus, R.; Gutiérrez-Alonso, G.; Zanella, F.

2011-10-01

314

Suitability of ?-carrageenan pellets for the formulation of multiparticulate tablets with modified release.  

PubMed

?-Carrageenan is a novel pelletisation aid with high formulation robustness and quick disintegration leading to fast drug release unlike the matrix-like release from non-disintegrating microcrystalline cellulose pellets. Compression of pellets into tablets is cost effective. The feasibility of formulating multiparticulate tablets with coated ?-carrageenan pellets was investigated. Pellets containing a highly soluble drug in acid, namely bisacodyl and ?-carrageenan or MCC as pelletisation aid were prepared, enteric coated with a mixture of Kollicoat(®) MAE 30 DP and Eudragit(®) NE 30 D and compressed using silicified microcrystalline cellulose as embedding powder. The effect of coating level, type of pellet core, compression force and punch configurations on drug release were studied. A sufficient coating thickness for ?-carrageenan pellets was necessary to obtain multiparticulate tablets with adequate resistance in the acid stage regardless of the compression pressure used. While ?-carrageenan pellets and their tablets released over 80% of the drug during the neutral stage only about 20-24% was released from MCC pellets and their tablets. The type of punches used (oblong or round) did not significantly influence the drug release from the prepared tablets. Moreover, sufficient prolonged release properties were obtained with ?-carrageenan pellets containing theophylline as a model drug and coated with Kollicoat(®) SR 30 D using Kollicoat(®) IR as pore former. A lower coating level and higher amount of pore former were needed in case of theophylline pellets formulated with MCC as pelletisation aid. The sustained release properties of both coated pellet formulations were maintained after compression at different compression pressures. PMID:21335073

Ghanam, Dima; Kleinebudde, Peter

2011-05-16

315

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

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

Chen, Ying-Chen; Ho, Hsiu-O; Liu, Der-Zen; Siow, Wen-Shian; Sheu, Ming-Thau

2015-01-01

316

Airship-floated wind turbine  

SciTech Connect

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.

Watson, W. K.

1985-01-01

317

21 CFR 520.1310 - Marbofloxacin tablets.  

Code of Federal Regulations, 2012 CFR

...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1310 Marbofloxacin tablets...Indications for use . For the treatment of infections in dogs and cats associated with bacteria susceptible to marbofloxacin....

2012-04-01

318

Pharmaceutical tablet compaction : product and process design  

E-print Network

This thesis explores how tablet performance is affected by microstructure, and how microstructure can be controlled by selection of excipients and compaction parameters. A systematic strategy for formulation and process ...

Pore, Mridula

2009-01-01

319

Tablets for Timely Design Documentation  

NSDL National Science Digital Library

One of the biggest challenges we have experienced in supervising digital systems senior design projects is the quality and completeness of the individual lab notebooks. Of the five outcomes we continuously track for this capstone course, the lab notebooks have consistently received the lowest quantitative scores. A significant improvement was achieved three years ago when we transitioned from carbon paper and pen notebooks to on-line (HTML) notebooks. Many teams took advantage of (and put to good use) the ability to post digital pictures of prototyping setups, provide hyperlinks to all their device datasheets, post their latest schematics and software listings for evaluation, and post video clips of their project in action (as verification of their project success criteria). The primary drawback has been the need for students to be in front of a networked computer to make lab notebook entries; consequently, the notebook updates still tended to be done in spurts (typically after the fact) rather than in real time. Project work (and inspiration), in fact, does not always occur in a lab setting, where networked computers are readily available, nor does it occur when all team members are working in the same physical location. Our hypothesis is that equipping each project team with wireless Tablet PCs should not only significantly improve the spontaneity (and regularity) with which the on-line lab notebooks are updated, but also facilitate collaboration among team members working on the design project at different locations. An HP Technology for Teaching Grant has provided a critical mass of Tablet PCs to test this hypothesis. A description of how the equipment provided is being utilized, along with a discussion of the preliminary results obtained, is presented in this paper.

Brown, Cordelia; Johnson, Mark; Meyer, David

2009-08-25

320

Development and characterization of buccoadhesive nifedipine tablets  

Microsoft Academic Search

The buccoadhesive controlled-release tablets for delivery of nifedipine were prepared by direct compression of carboxymethyl cellulose (CMC) with carbomer (CP), which showed superior bioadhesion properties compared to polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), hydroxypropylmethyl cellulose (HPMC), and acacia in a modified tensiometry method in vitro. The tablets containing 30mg of nifedipine and various amounts of CMC and CP showed a zero-order

J. Varshosaz; Z. Dehghan

2002-01-01

321

Formulation and optimization of potassium iodide tablets  

PubMed Central

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.

Al-Achi, Antoine; Patel, Binit

2014-01-01

322

A new brittleness index for compacted tablets.  

PubMed

A dimensionless index that quantifies the brittle or ductile character of tablets is presented. The work of failure (WOF) of crushed or broken flat tablets is calculated by numerical integration of the force-displacement measurement in a flexure tester. The ratio between WOF and the crushing force (F) corrected for the diameter of the tablet (D) is proposed to express the brittle/ductile index (BDI). [Formula: see text] This dimensionless index quantitatively denotes the brittle/ductile character of the compacted material as the normalized deformation in percentage of a cylindrical tablet at the breaking point. For ideal brittle materials, the BDI value will be 0 and for complete plastic deformation, that is, a total compression of the tablet without fracture, BDI will be 100. The validity and discriminative power is demonstrated on mixtures of microcrystalline cellulose and lactose. The robust measure of brittleness with an acceptable accuracy is obtained with only a minor influence of the tablet diameter and the speed of platen. PMID:24258281

Sonnergaard, Jørn M

2013-12-01

323

Application of chemometric algorithms to MALDI mass spectrometry imaging of pharmaceutical tablets.  

PubMed

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

Gut, Yoann; Boiret, Mathieu; Bultel, Laurent; Renaud, Tristan; Chetouani, Aladine; Hafiane, Adel; Ginot, Yves-Michel; Jennane, Rachid

2015-02-01

324

On the electrostatic behavior of floating nanoconductors  

NASA Astrophysics Data System (ADS)

In this work, the electrostatic behaviour of nanometer-sized metallic floating conductors embedded in a dielectric medium has been investigated. First of all, we present a semi-analytical approach based on Green functions and show its excellent quantitative agreement with well known finite element methods concerning electrostatic computations. Then, we compare floating potential values obtained by numerical simulation with an approach based on an equivalent capacitor circuit. We show that the latter is inappropriate for sub-100 nm wide floating electrodes when the parallel plates approximation (PPA) is used to estimate the coupling capacitance values because of lateral coupling effects. Nevertheless, we finally show that these coupling capacitances can be easily extracted to predict the electrostatic potential of metallic nano-dots with the same accuracy than with a direct numerical computation. We finally propose a figure of merit to estimate the validity of the PPA. These results are useful to predict the floating potential of future generations of non-volatile-memories using metallic dots. Moreover they can be used to give a first estimation of the floating potential in a self consistent Poisson-Schrödinger resolution when considering semiconductor nanocrystals.

Deleruyelle, D.; Micolau, G.

2008-01-01

325

Floating seal system for rotary devices  

DOEpatents

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.

Banasiuk, H.A.

1983-08-23

326

Vibration characteristics of floating slab track  

NASA Astrophysics Data System (ADS)

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.

Kuo, Chen-Ming; Huang, Cheng-Hao; Chen, Yi-Yi

2008-11-01

327

Floating zone melting of cadmium telluride  

NASA Technical Reports Server (NTRS)

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.

Chang, Wen-Ming; Regel, L. L.; Wilcox, W. R.

1992-01-01

328

Hydroxypropylated starches of varying amylose contents as sustained release matrices in tablets.  

PubMed

Waxy corn, Hylon VII, and common corn starches were hydroxypropylated to low and high levels, and their sustained release properties and matrix characteristics were studied. Hydroxypropylation had a stronger impact on Hylon VII and common corn starch matrices than on waxy corn ones, suggesting that the behavior of starch tablet was dominated by its amylose content. The introduction of hydroxypropyl groups increased the water holding capacity of all starches and resulted in more fluid-like and softer matrices with increased chain mobility for amylose-containing starches. There was a decrease in the tablet porosity and in the storage modulus of swollen tablets of Hylon VII and common corn starches after hydroxypropylation. Microscopic analyses revealed smoother and less porous tablet structure upon hydroxypropylation of all starches. Hydroxypropylation improved the sustained release ability of amylose-containing starch matrices, and conferred additional resistance to the hydrolytic action of pancreatin under simulated gastrointestinal conditions. However, hydroxypropylation had a detrimental impact on drug release from waxy corn starch matrices. PMID:19879935

Onofre, F O; Wang, Y-J

2010-01-29

329

Development of novel floating delivery system based on psyllium: application on metformin hydrochloride.  

PubMed

psyllium, a medicinally active gel forming natural polysaccharide and a dietary fiber has been used as a medicine in myriad of conditions such as constipation and inflammatory bowel syndrome. One of its more recent uses that have received attention has been its ability to reduce blood sugar levels in diabetics. Therefore present work is an attempt to formulate anti diabetic drug Metformin as a controlled release floating delivery making use of pysllium as release retardant and to assist the drug in stabilizing blood sugar level in type II diabetics. Drug and excipients compatibility studies were monitored by thermal analysis using differential scanning calorimeter (DSC) and Fourier transform infra red (FTIR). The DSC thermogram and FTIR of drug and drug-polymer mixture did not reveal any incompatibility. psyllium was tried in different concentrations along with other polymers like HPMC K15M and carbopol 940 to achieve the desired release profile. The total drug: polymer ratio was kept between 1:0.4 to 1:0.5, and different polymer combinations were tried to achieve desired drug release for 12 hours. The prepared tablets were evaluated for in vitro release studies and floating behavior. Our conclusion from the present study indicated that pysllium could potentially be used in conjunction with other polymers to formulate controlled release formulations of anti-diabetic drugs to provide better control over blood glucose levels. PMID:23410070

Rathnanand, Mahalaxmi; Narkhede, Rajkiran; Udupa, N; Kalra, Atin

2013-06-01

330

Angular circulation speed of tablets in a vibratory tablet coating pan.  

PubMed

In this work, a single tablet model and a discrete element method (DEM) computer simulation are developed to obtain the angular circulation speed of tablets in a vibratory tablet coating pan for range of vibration frequencies and amplitudes. The models identify three important dimensionless parameters that influence the speed of the tablets: the dimensionless amplitude ratio (a/R), the Froude number (a?2/g), and the tablet-wall friction coefficient, where a is the peak vibration amplitude at the drum center, ? is the vibration angular frequency, R is the drum radius, and g is the acceleration due to gravity. The models predict that the angular circulation speed of tablets increases with an increase in each of these parameters. The rate of increase in the angular circulation speed is observed to decrease for larger values of a/R. The angular circulation speed reaches an asymptote beyond a tablet-wall friction coefficient value of about 0.4. Furthermore, it is found that the Froude number should be greater than one for the tablets to start circulating. The angular circulation speed increases as Froude number increases but then does not change significantly at larger values of the Froude number. Period doubling, where the motion of the bed is repeated every two cycles, occurs at a Froude number larger than five. The single tablet model, although much simpler than the DEM model, is able to predict the maximum circulation speed (the limiting case for a large value of tablet-wall friction coefficient) as well as the transition to period doubling. PMID:23325382

Kumar, Rahul; Wassgren, Carl

2013-03-01

331

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2013 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2013-10-01

332

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2011 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2011-10-01

333

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2012 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2012-10-01

334

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2010 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2010-10-01

335

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2014 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2014-10-01

336

Effect of repeated compaction of tablets on tablet properties and work of compaction using an instrumented laboratory tablet press.  

PubMed

Abstract The repeated compaction of Avicel PH101, dicalcium phosphate dihydrate (DCP) powder, 50:50 DCP/Avicel PH101 and Starch 1500 was studied using an instrumented laboratory tablet press which measures upper punch force, punch displacement and ejection force and operates using a V-shaped compression profile. The measurement of work compaction was demonstrated, and the test materials were ranked in order of compaction behaviour Avicel PH101?>?DCP/Avicel PH101?>?Starch?>?DCP. The behaviour of the DCP/Avicel PH101 mixture was distinctly non-linear compared with the pure components. Repeated compaction and precompression had no effect on the tensile fracture strength of Avicel PH101 tablets, although small effects on friability and disintegration time were seen. Repeated compaction and precompression reduced the tensile strength and the increased disintegration time of the DCP tablets, but improved the strength and friability of Starch 1500 tablets. Based on the data reported, routine laboratory measurement of tablet work of compaction may have potential as a critical quality attribute of a powder blend for compression. The instrumented press was suitable for student use with minimal supervisor input. PMID:24171692

Gamlen, Michael John Desmond; Martini, Luigi G; Al Obaidy, Kais G

2015-01-01

337

The syntactic and semantic roots of floating quantification  

E-print Network

Through the study of floating quantifiers in a variety of languages, I demonstrate that floating quantification is not a uniform phenomenon and outline a series of puzzles that force us to adopt a two-part analysis. I argue ...

Fitzpatrick, Justin Michael

2006-01-01

338

14 CFR 27.521 - Float landing conditions.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 false Float landing conditions. 27.521 Section...Water Loads § 27.521 Float landing conditions. If certification...equal to that determined for wheel landing gear): (a) Up-load conditions...

2011-01-01

339

14 CFR 27.521 - Float landing conditions.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 false Float landing conditions. 27.521 Section...Water Loads § 27.521 Float landing conditions. If certification...equal to that determined for wheel landing gear): (a) Up-load conditions...

2010-01-01

340

Improvements in floating point addition/subtraction operations  

DOEpatents

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.

Farmwald, P.M.

1984-02-24

341

Design and Evaluation of a Novel Matrix Type Multiple Units as Biphasic Gastroretentive Drug Delivery Systems  

Microsoft Academic Search

A biphasic gastroretentive floating drug delivery system with multiple-unit mini-tablets based on gas formation technique\\u000a was developed to maintain constant plasma level of a drug concentration within the therapeutic window. The system consists\\u000a of loading dose as uncoated core units, and prolonged-release core units are prepared by direct compression process; the latter\\u000a were coated with three successive layers, one of

Meka Lingam; Thadisetty Ashok; Vobalaboina Venkateswarlu; Yamsani Madhusudan Rao

2008-01-01

342

Formulation Optimization of Hydrodynamically Balanced Oral Controlled Release Bioadhesive Tablets of Tramadol Hydrochloride  

PubMed Central

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

Singh, Bhupinder; Rani, Ashu; Babita; Ahuja, Naveen; Kapil, Rishi

2010-01-01

343

Tablets and E-Readers May Disrupt Your Sleep  

MedlinePLUS

... on this page, please enable JavaScript. Tablets and E-readers May Disrupt Your Sleep Light from these ... HealthDay News) -- People who receive a tablet or e-book reader for the holidays might wind up ...

344

21 CFR 529.400 - Chlorhexidine tablets and suspension.  

Code of Federal Regulations, 2014 CFR

... —(1) Amount. Place 1 or 2 tablets deep in each uterine horn; or infuse a solution of 1 tablet disolved in an appropriate amount of clean boiled water; or infuse one syringe of suspension into the uterus. (2) Indications for...

2014-04-01

345

SANCTUARY : asymmetric interfaces for game-based tablet learning  

E-print Network

This thesis describes the production of Sanctuary, a multiplayer learning game to be played on two tablet computers. Sanctuary's principle innovation is the splitting of the user interface onto two tablets, separating ...

Haas, Jason M. (Jason Matthew)

2013-01-01

346

In vitro-in vivo evaluation of xanthan gum and eudragit inter polyelectrolyte complex based sustained release tablets  

PubMed Central

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

Deb, Tamal Krishna; Ramireddy, B.; Moin, Afrasim; Shivakumar, H.G.

2015-01-01

347

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2014 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2014-01-01

348

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2012 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2012-01-01

349

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2014 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2014-01-01

350

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2012 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2012-01-01

351

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2013 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2013-01-01

352

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2013 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2013-01-01

353

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2011 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2011-01-01

354

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2011 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2011-01-01

355

Novel approach of aceclofenac fast dissolving tablet.  

PubMed

Fast disintegrating tablets (FDTs) have received ever increasing demand during the last decade, and the ?eld 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

Dave, Vivek; Yadav, Sachdev; Sharma, Swapnil; Vishwakarma, Pushpendra; Ali, Nasir

2015-01-01

356

Submerged floating tunnels (SFTs) for Norwegian fjords  

Microsoft Academic Search

Submerged floating tunnels (SFTs) weigh roughly the same as the surrounding water. The loads on the tunnel depend on the variation of the forces on the tunnel. The forces come from variation in traffic, current, temperature, waves, weight of water, weight of concrete, growth on the tunnel, wear of asphalt, dust and debris, relaxation of prestress and shrinkage and creep

Per Tveit

2010-01-01

357

Floating hydrometer with energy dissipating baffle  

Microsoft Academic Search

This patent describes a floating hydrometer employable for purposes of obtaining measurements of the presence of suspended solids in a fluid substance contained in a receptacle comprising: a. a probe portion operative as an instrument-bearing housing; b. an elongated tubular element having a hollow interior and at least one open end so as to enable the flow into the hollow

Kownurko

1987-01-01

358

Daphnia (zoomed on floating blood cells)  

NSDL National Science Digital Library

These pin drops are the clearly defined blood cells of the Daphnia. We are only able to see the cells with use of a microscope. Keep in mind that the cells are not confined in any blood vessel (called an open circulatory system) and freely float throughout the body.

Katie Hale (CSUF; Biological Sciences)

2007-07-18

359

Dealing with Human Death: The Floating Perspective.  

ERIC Educational Resources Information Center

Explores approach to dealing with human death. Describes floating perspective, based on insights from Choron and Jaspers, as suggesting it is possible to deal with human death by refraining from taking ultimate position on the problem. Position encourages openness to death. Examines role of anxiety and describes possible meaningful outcomes of…

Kenyon, Gary M.

1991-01-01

360

Floating--A Key to Survival.  

ERIC Educational Resources Information Center

Described are several activities to be used to help students grasp the concept of floating. The activities include the use of a spring scale to measure the weight of the objects in air, in water, and in salt water, and a discussion of why there are differences in these weights. (DS)

Anderson, Norman

1980-01-01

361

[Formulation of calcium carbonate tablets with various binding substances].  

PubMed

The test results of calcium carbonate tablets, made of different binding substances (microcrystal cellulose, gelatin, 7pp sodium carboxymethylcellulose and starch) were presented. The content of calcium-carbonate in tablets as well as varying, solidity, prodigality and aptness to decay was determined. The best properties were observed in tablets made with starch. PMID:9214090

Gazikalovi?, E; Obrenovi?, D; Nidzovi?, Z; Toski?-Radojici?, M

1996-01-01

362

21 CFR 520.1720a - Phenylbutazone tablets and boluses.  

Code of Federal Regulations, 2010 CFR

...055246 for use of 100-mg tablets in dogs. (5) No. 000143 for use of 1-g tablets in horses. (6) No. 058829 for use of 100-mg or 1-g tablets in dogs and horses, or 1-g...amended at 74 FR 1146, Jan. 12,...

2010-04-01

363

Influence of ethanol on swelling and release behaviors of Carbopol(®)-based tablets.  

PubMed

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

Rahim, Safwan Abdel; Al-Ghazawi, Mutasim; Al-Zoubi, Nizar

2013-01-01

364

Water hyacinth: a possible alternative rate retarding natural polymer used in sustained release tablet design  

PubMed Central

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

Khatun, Sabera; Sutradhar, Kumar B.

2014-01-01

365

Pulse release of doxazosin from hydroxyethylcellulose compression coated tablet: Mechanistic and in vivo study.  

PubMed

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%=46min) after an initial lag of 243min. 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

Biswas, Nikhil; Guha, Arijit; Sahoo, Ranjan Kumar; Kuotsu, Ketousetuo

2015-01-01

366

Fast disintegrating crystalline solid dispersions of simvastatin for incorporation into orodispersible tablets  

PubMed Central

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

Pabari, Ritesh M; Jamil, Asha; Kelly, John G; Ramtoola, Zebunnissa

2014-01-01

367

Formulation and Evaluation of Chondroitin Sulphate Tablets of Aceclofenac for Colon Targeted Drug Delivery  

PubMed Central

The aim of the present study was to develop a single unit, site-specific matrix tablets of aceclofenac allowing targeted drug release in the colon with a microbially degradable polymeric carrier, chondroitin suphate (CS) and to coat the optimized batches with a pH dependent polymeric. The tablets were prepared by wet granulation method using starch mucilage as a binding agent and HPMC K-100 as a swellable polymer. Chondroitin Sulphate and drug and physical mixture were characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The tablets were tested for their in-vitro dissolution characteristics in various simulated gastric fluids for their suitability as a colon-specific drug delivery system and also the tablets were evaluated for physicochemical properties, drug content, water percentage swelling and erosion characteristics. The dissolution data demonstrates that the 10% w/w increase in coating level of the pH dependent polymer (Eudragit L-100 and Eudragit S-100 in a ratio of 1 : 4 prevented the drug release in the simulated gastric fluid (pH 1.2-SGF) and the simulated intestinal fluid (pH 7.4-SIF). The dissolution rate of the tablet is dependent upon the concentration of Chondroitin sulphate in the simulated colonic fluid (SCF). The rapid increase in release of aceclofenac in SCF was revealed as due to the degradation of the Chondroitin sulphate membrane by bacterial enzymes. The studies confirmed that, the designed system could be used potentially as a carrier for colon delivery of aceclofenac by regulating drug release in stomach and the small intestine. PMID:24250470

Ramasamy, Thiruganesh; Subbaih Khandasamy, Umadevi; Shanmugam, Suresh; Ruttala, Himabindhu

2012-01-01

368

Formulation and evaluation of chondroitin sulphate tablets of aceclofenac for colon targeted drug delivery.  

PubMed

The aim of the present study was to develop a single unit, site-specific matrix tablets of aceclofenac allowing targeted drug release in the colon with a microbially degradable polymeric carrier, chondroitin suphate (CS) and to coat the optimized batches with a pH dependent polymeric. The tablets were prepared by wet granulation method using starch mucilage as a binding agent and HPMC K-100 as a swellable polymer. Chondroitin Sulphate and drug and physical mixture were characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The tablets were tested for their in-vitro dissolution characteristics in various simulated gastric fluids for their suitability as a colon-specific drug delivery system and also the tablets were evaluated for physicochemical properties, drug content, water percentage swelling and erosion characteristics. The dissolution data demonstrates that the 10% w/w increase in coating level of the pH dependent polymer (Eudragit L-100 and Eudragit S-100 in a ratio of 1 : 4 prevented the drug release in the simulated gastric fluid (pH 1.2-SGF) and the simulated intestinal fluid (pH 7.4-SIF). The dissolution rate of the tablet is dependent upon the concentration of Chondroitin sulphate in the simulated colonic fluid (SCF). The rapid increase in release of aceclofenac in SCF was revealed as due to the degradation of the Chondroitin sulphate membrane by bacterial enzymes. The studies confirmed that, the designed system could be used potentially as a carrier for colon delivery of aceclofenac by regulating drug release in stomach and the small intestine. PMID:24250470

Ramasamy, Thiruganesh; Subbaih Khandasamy, Umadevi; Shanmugam, Suresh; Ruttala, Himabindhu

2012-01-01

369

Formulation, development, and performance evaluation of metoclopramide HCl oro-dispersible sustained release tablet.  

PubMed

The present study was undertaken to develop and evaluate an oro-dispersible, sustained release tablet of metoclopramide HCl. The technology was comprised of developing sustained release microparticles, and compression of resultant microspheres into a fast dispersible tablet by direct compression. The microspheres of metoclopramide HCl were prepared by an emulsification-solvent evaporation method using ethylcellulose as the matrix polymer. The prepared microspheres were evaluated for morphology, particle size, entrapment efficiency, and in vitro drug release characteristics. Scanning electron microscopy demonstrated spherical particles with a mean diameter of 81.27 ± 5.87 ?m and the drug encapsulation efficiency was found to be 70.15 ± 3.06%. The process and formulation variables such as rotation speed, polymer concentration, and drug concentration influenced the drug encapsulation efficiency and in vitro drug release. Optimized microspheres were compressed into tablets which were comprised of metoclopramide HCl microspheres, 53% (w/v) of D-mannitol granules, 7% (w/w) of Polyplasdone XL 10, and 0.5% (w/w) of calcium stearate. The tablets demonstrated a hardness of 59 ± 3 N, friability of 0.21% and disintegration time of 27 ± 3 sec. The formulations were subjected to stability studies as per ICH guidelines and were found to be stable after a 6 month study. In vivo experiments conducted in rats demonstrated that a constant level of metoclopramide HCl in plasma could be maintained for up to 20 h at a suitable concentration for antiemetic activity. An appropriate combination of excipients made it possible to obtain orally disintegrating sustained release tablets of metoclopramide HCl using simple and conventional techniques. PMID:22076769

Kasliwal, Nikhil; Negi, Jeetendra Singh; Jugran, Vandana; Jain, Rahul

2011-10-01

370

Evaluation of the performance characteristics of bilayer tablets: Part II. Impact of environmental conditions on the strength of bilayer tablets.  

PubMed

Ambient air humidity and temperature are known to influence the mechanical strength of tablets. The objective of this work is to understand the influence of processing parameters and environmental conditions (humidity and temperature) on the strength of bilayer tablets. As part of this study, bilayer tablets were compressed with different layer ratios, dwell times, layer sequences, material properties (plastic and brittle), first and second layer forces, and lubricant concentrations. Compressed tablets were stored in stability chambers controlled at predetermined conditions (40C/45%RH, 40C/75%RH) for 1, 3, and 5 days. The axial strength of the stored tablets was measured and a statistical model was developed to determine the effects of the aforementioned factors on the strength of bilayer tablets. As part of this endeavor, a full 3?×?2(4) factorial design was executed. Responses of the experiments were analyzed using PROC GLM of SAS (SAS Institute Inc, Cary, North Carolina, USA). A model was fit using all the responses to determine the significant interactions (p?tablets. For Avicel-lactose and lactose-Avicel tablets, tablet strength decreased with the increasing humidity and storage time. But for lactose-lactose tablets, due to the formation of solid bridges upon storage, an increase in tablet strength was observed. Significant interactions were observed between processing parameters and storage conditions on the strength of bilayer tablets. PMID:22965660

Kottala, Niranjan; Abebe, Admassu; Sprockel, Omar; Bergum, James; Nikfar, Faranak; Cuitiño, Alberto M

2012-12-01

371

Potential of carnuba wax in ameliorating brittle fracture during tableting.  

PubMed

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

Uhumwangho, M U; Okor, R S; Adogah, J T

2009-01-01

372

Miconazole mucoadhesive tablet for oropharyngeal candidiasis  

PubMed Central

Oropharyngeal candidiasis is a commonly encountered problem in daily clinical practice. Topical therapies for oropharyngeal candidiasis are considered preferable to systemic therapies in most patient populations. However, traditional topical therapies have limitations including short contact time with the oral mucosa and the need for multiple doses each day. Miconazole mucoadhesive tablet has recently been approved in Europe (Loramyc®) and the USA (Oravig™) for the treatment of oropharyngeal candidiasis. This tablet adheres to the oral mucosa and provides sustained local release of miconazole over a period of several hours with just one daily application. This article reviews the pharmacology, safety and efficacy of this novel agent. PMID:21171872

Lalla, Rajesh V; Bensadoun, René-Jean

2011-01-01

373

New Spectrophotometric Method for Simultaneous determination of Metoprolol Tartarate and Hydrochlorthiazide in Tablets  

PubMed Central

The present work describes a two-wavelength method for simultaneous determination of metoprolol and hydrochlorthiazide in fixed dose combination tablet. The wavelengths selected for method were 257.8 nm, 282.9 nm and 315.0 nm. The absorbance difference at first two wavelengths was used for determination of metoprolol and the latter was used for determination of hydrochlorthiazide. The recovery value for the drugs from the tablet matrix was found to be 100.55% (metoprolol) and 99.97% (comparison with standard) and 98.09% (E1%, 1cm) for hydrochlorthiazide. The method has an advantage that hydrochlorthiazide can be estimated in combination, as there is no interference of metoprolol at 315.0 nm. The method was evaluated statistically for its accuracy and precision. PMID:20046783

Gupta, K. R.; Tajne, M. R.; Wadodkar, S. G.

2008-01-01

374

[Fast-disintegration oral tablets having sustained release property].  

PubMed

Fast-disintegrating (FD) tablets containing nicorandil-loaded dry emulsions were prepared and their controlled-release properties were examined and compared with the plain FD tablets (FD tablets without dry emulsions) and commercial tablets. The dry emulsions were prepared with myristyl alcohol and stearyl alcohol and their property was modified by mixing the ratio of the two alcohols. Disintegration time of the prepared FD tablets was sufficiently fast (i.e., 12 to 23 s). In vitro release of nicorandil from the FD tablets containing the dry emulsions was sustained over 6 h, while that from plain FD and commercial tablets was complete within 5 min. In vivo absorption of nicorandil from the tablets was evaluated by oral administration in beagle dogs. FD tablets containing dry emulsions showed a similar AUC, lower Cmax, and delayed Tmax compared to the plain FD and commercial tablets. These results suggest that the dry emulsion-loaded FD tablets can be utilized to improve the sustained-release property of active drugs. PMID:12440156

Jin, Yi; Ohkuma, Hideki; Wang, Hua; Natsume, Hideshi; Sugibayashi, Kenji; Morimoto, Yasunori

2002-11-01

375

Pharmacokinetics of metformin gastric-retentive tablets in healthy volunteers.  

PubMed

The single-dose pharmacokinetics of two gastric-retentive, extended-release tablet formulations of metformin hydrochloride in fed, healthy volunteers were compared with those of the currently marketed immediate-release metformin hydrochloride product. The plasma concentration-time profiles demonstrated extended-release characteristics from the gastric-retentive tablets. The mean bioavailability from each gastric-retentive tablet was approximately 115%, relative to the immediate-release (IR) product. Cmax values were lower and tmax values were greater for the gastric-retentive tablets compared with the IR product. In contrast to conventional extended-release metformin tablets reported in the literature, these gastric-retentive tablets showed extended-release plasma concentration profiles of metformin hydrochloride and increased bioavailability compared with the immediate-release tablet. PMID:11402634

Gusler, G; Gorsline, J; Levy, G; Zhang, S Z; Weston, I E; Naret, D; Berner, B

2001-06-01

376

Development of theophylline floating microballoons using cellulose acetate butyrate and/or Eudragit RL 100 polymers with different permeability characteristics  

PubMed Central

The objective of the present investigation was to design a sustained release floating microcapsules of theophylline using two polymers of different permeability characteristics; Eudragit RL 100 (Eu RL) and cellulose acetate butyrate (CAB) using the oil-in-oil emulsion solvent evaporation method. Polymers were used separately and in combination to prepare different microcapsules. The effect of drug-polymer interaction was studied for each of the polymers and for their combination. Encapsulation efficiency, the yield, particle size, floating capability, morphology of microspheres, powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC) were evaluated. The in vitro release studies were performed in PH 1.2 and 7.4. The optimized drug to polymer ratios was found to be 4:1 (F2) and 0.75:1 (F'2) with Eu RL and CAB, respectively. The best drug to polymer ratio in mix formulation was 4:1:1 (theophylline: Eu RL: CAB ratio). Production yield, loading efficiencies, and particle size of F2 and F’2 were found to be 59.14% and 45.39%, 73.93% and 95.87%, 372 and 273 micron, respectively. Microsphere prepared with CAB showed the best floating ability (80.3 ± 4.02% buoyancy) in 0.1 M HCl for over 12 h. The XRD and DSC showed that theophylline in the drug loaded microspheres was stable and in crystaline form. Microparticles prepared using blend of Eu RL and CAB polymers indicated more sustained pattern than the commercial tablet (P<0.05). Drug loaded floating microballoons prepared of combination of Eu RL and CAB with 1:1 ratio were found to be a suitable delivery system for sustained release delivery of theophylline which contained lower amount of polymer contents in the microspheres. PMID:21589766

Jelvehgari, M.; Maghsoodi, M.; Nemati, H.

2010-01-01

377

Understanding and Predicting Drug Delivery from Hydrophilic Matrix  

E-print Network

boundary condi- tions, non-homogeneous polymer swelling, drug dissolution, and polymer dissolution. We- nomena (water, drug and polymer diffusion, polymer swell- ing, and drug and polymer dissolution) can phenomena which are involved in the swelling and drug release from hydrophilic matrix tablets using

Peppas, Nicholas A.

378

Dissolution of tablet-in-tablet formulations studied with ATR-FTIR spectroscopic imaging.  

PubMed

This work uses ATR-FTIR spectroscopic imaging to study the dissolution of delayed release and pH resistant compressed coating pharmaceutical tablets. Tablets with an inner core and outer shell were constructed using a custom designed compaction cell. The core of the delayed release tablets consisted of hydroxypropyl methylcellulose (HPMC) and caffeine. The shell consisted of microcrystalline cellulose (MCC) and glucose. The core of the pH resistant formulations was an ibuprofen and PEG melt and the shell was constructed from HPMC and a basic buffer. UV/vis spectroscopy was used to monitor the lag-time of drug release and visible optical video imaging was used as a complementary imaging technique with a larger field of view. Two delayed release mechanisms were established. For tablets with soluble shell sections, lag-time was dependent upon rapid shell dissolution. For tablets with less soluble shells, the lag-time was controlled by the rate of dissolution medium ingress through the shell and the subsequent expansion of the wet HPMC core. The pH resistant formulations prevented crystallization of the ibuprofen in the core during dissolution despite an acidic dissolution medium. FTIR imaging produced important information about the physical and chemical processes occurring at the interface between tablet sections during dissolution. PMID:23291036

Wray, Patrick S; Clarke, Graham S; Kazarian, Sergei G

2013-03-12

379

Morphological instability in a float zone  

NASA Technical Reports Server (NTRS)

This paper examines the morphological instability of the freezing interface of the float zone in a crystal sheet for which the height of the liquid zone L = Lf + Lm (where Lf and Lm are the planar positions of the solidifying and melting interfaces) is smaller than the width and the thickness of the sheet. The Lf and Lm positions are calculated, and basic state concentration profiles are determined for a planar interfacial system. A linear stability analysis of this system is performed showing that the growth rate of disturbances is a modified version of the growth rate for a directional solidification system. It was found that shorter melt zone configurations are less susceptible to long wavelength morphological instability, indicating that, to suppress morphological instability in a float zone system, it is necessary to decrease the liquid zone height.

Humphreys, Laura B.; Heminger, John A.; Young, Gerald W.

1990-01-01

380

Can Oil Float Completely Submerged in Water?  

E-print Network

Droplet formation in a system of two or more immiscible fluids is a celebrated topic of research in the fluid mechanics community. In this work, we propose an innovative phenomenon where oil when injected drop-wise into a pool of water moves towards the air-water interface where it floats in a fully submerged condition. The configuration, however, is not stable and a slight perturbation to the system causes the droplet to burst and float in partially submerged condition. The droplet contour is analyzed using edge detection. Temporal variation of a characteristic length of the droplet is analyzed using MATLAB image processing. The constraint of small Bond Number established the assumption of lubrication regime in the thin gap. A brief theoretical formulation also showed the temporal variation of the gap thickness

Nath, Saurabh; Chatterjee, Souvick

2013-01-01

381

OCD metrology by floating n/k  

NASA Astrophysics Data System (ADS)

In this paper, one of the major contributions to the OCD metrology error, resulting from within-wafer variation of the refractive index/extinction coefficient (n/k) of the substrate, is identified and quantified. To meet the required metrology accuracy for the 65-nm node and beyond, it is suggested that n/k should be floating when performing the regression for OCD modeling. A feasible way of performing such regression is proposed and verified. As shown in the presented example, the measured CDU (3?) with n/k fixed and n/k floating is 1.94 nm and 1.42 nm, respectively. That is, the metrology error of CDU committed by assuming n/k fixed is more than 35% of the total CDU.

Yu, Shinn-Sheng; Huang, Jacky; Ke, Chih-Ming; Gau, Tsai-Sheng; Lin, Burn J.; Yen, Anthony; Lane, Lawrence; Vuong, Vi; Chen, Yan

2007-03-01

382

Graphics Tablet for the BBC Microcomputer.  

ERIC Educational Resources Information Center

Describes an inexpensive solution to the problem of transferring pictures onto a television screen using the analog part of the Model "B" BBC Microcomputer. Instruction for building the graphics tablet (which can easily be constructed by secondary students), program listing for required software, and documentation are included. (JN)

Whale, R.

1984-01-01

383

MEASUREMENT OF BOUNDARIES USING A DIGITIZER TABLET  

EPA Science Inventory

The perimeter is the most error prone of the primary measurements (length, perimeter and area) made when using a device such as a digitizer tablet to trace profiles on micrographs. o allow for minimization of this error an expression is developed relating the error in the perimet...

384

Touch Tablet Surprises: A Preschool Teacher's Story  

ERIC Educational Resources Information Center

A year and a half ago, Rena, Cheri, and Cassandra were introduced to each other by a colleague because they shared an interest in exploring the impact newer technologies have on learning in early childhood classrooms. They meet regularly to share ideas and information on how to incorporate tablets using best practices. Cassandra's preschool…

Shifflet, Rena; Toledo, Cheri; Mattoon, Cassandra

2012-01-01

385

Form recognition from ink strokes on tablet  

Microsoft Academic Search

This paper proposes a method for form recognition from handwritten input captured as digital ink on a tablet. Form recognition is an important step of form processing to read the data on a filled form. This type of recognition is different from traditional image matching (searching and retrieving) because the query image (data ink) has but few common characteristics with

De Cao Tran; Patrick Franco; Jean-Marc Ogier

2010-01-01

386

You May Now Open Your Test Tablets...  

ERIC Educational Resources Information Center

Tony Alpert, chief operating officer for the Smarter Balanced Assessment Consortium (SBAC), ponders whether to allow tablet computers--and particularly iPads--to be used for summative testing online. As Alpert points out, not only would student cheating compromise the validity of the individual student's test event, "worse yet, it could expose…

Schaffhauser, Dian

2012-01-01

387

21 CFR 520.1616 - Orbifloxacin tablets.  

Code of Federal Regulations, 2011 CFR

...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1616 Orbifloxacin tablets...c) of this chapter. (c) Conditions of use in dogs and cats —(1) Amount . 2.5 to 7.5 mg per kilogram body...

2011-04-01

388

21 CFR 520.1900 - Primidone tablets.  

Code of Federal Regulations, 2011 CFR

...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1900 Primidone tablets...species, as primidone appears to have a specific neurotoxicity in cats. Federal law restricts this drug to use by or on the order...

2011-04-01

389

Free-floating atmospheric pressure ball plasmas  

Microsoft Academic Search

A long-lived (0.3 second, 10-20 cm diameter) ball plasma floating in the air above a water surface has been formed and studied in the laboratory. A 0.4 - 1 mF capacitor is charged to 4-5 kV, and subsequently discharged (30-60 Amps, 20-50 msec duration) into central copper cathode held fixed just below the surface of a bucket of water (with

G. A. Wurden; C. Ticos; Z. Wang; C. J. V. Wurden

2007-01-01

390

Floating Ice: Grades K-1: Illustrated Book  

NSDL National Science Digital Library

This informational text discusses the unique property of ice - that it floats in liquid water. Students focus on real-world examples and how ice is necessary for life in the polar regions. The text is written at a kindergarten through grade one reading level. This version is a full-color PDF that can be printed, cut and folded to form a book. Each book contains color photographs and illustrations.

Fries-Gaither, Jessica

391

Maintaining competency for float nursing staff.  

PubMed

Orienting staff to multiple areas is challenging, as is maintaining multiple competencies, which might be used infrequently. Creating a strategy to regularly assess needed competencies to maintain a highly skilled pool of nurses, prepared to float to multiple areas, is critical to supporting flexible staffing. A plan for how to achieve this complex analysis is described and can be translated to other complex environments. PMID:25036084

Overman, Kimberly; Hauver, Jeni; McKay, Jennifer; Aucoin, Julia

2014-01-01

392

Polymer Percolation Threshold in Multi-Component HPMC Matrices Tablets  

PubMed Central

Introduction:The percolation theory studies the critical points or percolation thresholds of the system, where one component of the system undergoes a geometrical phase transition, starting to connect the whole system.The application of this theory to study the release rate of hydrophilic matrices allows to explain the changes in release kinetics of swellable matrix type system and results in a clear improvement of the design of controlled release dosage forms. Methods: In this study, the percolation theory has been applied to multi-component hydroxypropylmethylcellulose (HPMC) hydrophilic matrices. Matrix tablets have been prepared using phenobarbital as drug, magnesium stearate as a lubricant employing different amount of lactose and HPMC K4M as a filler and matrix forming material, respectively. Ethylcelullose (EC) as a polymeric excipient was also examined. Dissolution studies were carried out using the paddle method.In order to estimate the percolation threshold, the behaviour of the kinetic parameters with respect to thevolumetric fraction of HPMC at time zero, was studied. Results: In both HPMC/lactose and HPMC/EC/lactose matrices, from the point of view of the percolation theory, the optimum concentration for HPMC, to obtain a hydrophilic matrix system for the controlled release of phenobarbital is higher than 18.1% (v/v) HPMC. Above 18.1% (v/v) HPMC, an infinite cluster of HPMC would be formed maintaining integrity of the system and controlling the drug release from the matrices. According to results, EC had no significant influence on the HPMC percolation threshold. Conclusion: This may be related to broad functionality of the swelling hydrophilic matrices. PMID:24312753

Maghsoodi, Maryam; Barghi, Leila

2011-01-01

393

FPP [Floating Potential Probe] Results, Final Report  

NASA Technical Reports Server (NTRS)

The Floating Potential Probe (FPP) operated on the International Space Station (ISS) from December 2000 to April 2001. During that time, it took many measurements of the ISS floating potential and the electron density and temperature. Those measurements were used as inputs to the Environments WorkBench (EWB) model of ISS potentials (originally developed by SAIC, but now sometimes called the Boeing model) that is used even today to predict charging levels for ISS. FPP is now completely defunct, having been removed and ejected from ISS. With the advent of the new Floating Potential Monitoring Unit (FPMU) on ISS, and the beginning of ISS operations with two large solar array panels instead of just one, a review of FPP measurements can offer comparisons with the new FPMU data and perhaps improve the accuracy of future ISS charging predictions. In particular, FPP measurements during times of low electron temperature and high electron density (the times of worst ISS charging) will be brought forward for comparison with the newly obtained FPMU data.

Ferguson, Dale C.

2007-01-01

394

Floating debris in the Mediterranean Sea.  

PubMed

Results from the first large-scale survey of floating natural (NMD) and anthropogenic (AMD) debris (>2 cm) in the central and western part of the Mediterranean Sea are reported. Floating debris was found throughout the entire study area with densities ranging from 0 to 194.6 items/km(2) and mean abundances of 24.9 AMD items/km(2) and 6.9 NMD items/km(2) across all surveyed locations. On the whole, 78% of all sighted objects were of anthropogenic origin, 95.6% of which were petrochemical derivatives (i.e. plastic and styrofoam). Maximum AMD densities (>52 items/km(2)) were found in the Adriatic Sea and in the Algerian basin, while the lowest densities (<6.3 items/km(2)) were observed in the Central Tyrrhenian and in the Sicilian Sea. All the other areas had mean densities ranging from 10.9 to 30.7 items/km(2). According to our calculations, more than 62 million macro-litter items are currently floating on the surface of the whole Mediterranean basin. PMID:25127501

Suaria, Giuseppe; Aliani, Stefano

2014-09-15

395

Capillary induced buckling of floating sheets  

NASA Astrophysics Data System (ADS)

When a water droplet is deposited over a thin floating sheet, radial wrinkles appear in the vicinity of the droplet as a result of capillary forces exerted at the contact line [1]. However, determining the stress state at the contact line is still challenging and limits the full description of the wrinkling pattern. In order to avoid this contact line ambiguities, we propose the experimental study of the buckling of a macroscopic annulus floating on the surface of water and submitted to a difference in surface tension between its inner and outer edges. This particular configuration allows to generate radial wrinkles on the membrane with well defined border conditions. The topography of the wrinkled patterns are precisely measured using a synthetic Schlieren technique. Based on the standard buckling theory, we develop scaling laws for the buckling threshold of the annulus as well as for the wave length and radial extension of the wrinkles, which are compared to our experimental results and numerical simulations. [4pt] [1] J. Huang, M. Juszkiewicz, W.H. de Jeu, E. Cerda, T. Emrick, N. Menon, and T.P. Russell. Capillary wrinkling of floating thin polymer films. Science, 317(5838):650-653, 2007.

Pineirua, Miguel; Bico, Jose; Roman, Benoit; Menon, Narayanan

2012-02-01

396

Developing a mapping tool for tablets  

NASA Astrophysics Data System (ADS)

Digital field mapping offers significant benefits when compared with traditional paper mapping techniques in that it provides closer integration with downstream geological modelling and analysis. It also provides the mapper with the ability to rapidly integrate new data with existing databases without the potential degradation caused by repeated manual transcription of numeric, graphical and meta-data. In order to achieve these benefits, a number of PC-based digital mapping tools are available which have been developed for specific communities, eg the BGS•SIGMA project, Midland Valley's FieldMove®, and a range of solutions based on ArcGIS® software, which can be combined with either traditional or digital orientation and data collection tools. However, with the now widespread availability of inexpensive tablets and smart phones, a user led demand for a fully integrated tablet mapping tool has arisen. This poster describes the development of a tablet-based mapping environment specifically designed for geologists. The challenge was to deliver a system that would feel sufficiently close to the flexibility of paper-based geological mapping while being implemented on a consumer communication and entertainment device. The first release of a tablet-based geological mapping system from this project is illustrated and will be shown as implemented on an iPad during the poster session. Midland Valley is pioneering tablet-based mapping and, along with its industrial and academic partners, will be using the application in field based projects throughout this year and will be integrating feedback in further developments of this technology.

Vaughan, Alan; Collins, Nathan; Krus, Mike

2014-05-01

397

Floating Oil-Spill Containment Device  

NASA Technical Reports Server (NTRS)

Previous oil containment booms have an open top that allows natural gas to escape, and have significant oil leakage due to wave action. Also, a subsea pyramid oil trap exists, but cannot move relative to moving oil plumes from deepsea oil leaks. The solution is to have large, moveable oil traps. One version floats on the sea surface and has a flexible tarp cover and a lower weighted skirt to completely entrap the floating oil and natural gas. The device must have at least three sides with boats pulling at each apex, and sonar or other system to track the slowly moving oil plume, so that the boats can properly locate the booms. The oil trap device must also have a means for removal of the oil and the natural gas. A second design version has a flexible pyramid cover that is attached by lines to ballast on the ocean floor. This is similar to fixed, metal pyramid oil capture devices in the Santa Barbara Channel off the coast of California. The ballast lines for the improved design, however, would have winches that can move the pyramid to always be located above the oil and gas plume. A third design is a combination of the first two. It uses a submerged pyramid to trap oil, but has no anchor and uses boats to locate the trap. It has ballast weights located along the bottom of the tarp and/or at the corners of the trap. The improved floating oil-spill containment device has a large floating boom and weighted skirt surrounding the oil and gas entrapment area. The device is triangular (or more than three sides) and has a flexible tarp cover with a raised gas vent area. Boats pull on the apex of the triangles to maintain tension and to allow the device to move to optimum locations to trap oil and gas. The gas is retrieved from a higher buoyant part of the tarp, and oil is retrieved from the floating oil layer contained in the device. These devices can be operated in relatively severe weather, since waves will break over the devices without causing oil leaking. Also, natural gas is entrapped and can be retrieved. All designs can use sonar to locate the moving oil plume, and then be relocated by using boats or winches to move the oil trapping devices. These devices can be constructed of treated, non-permeable DuPont Kevlar cloth (or similar material).

Jones, Jack A.

2012-01-01

398

Float processing of high-temperature complex silicate glasses and float baths used for same  

NASA Technical Reports Server (NTRS)

A float glass process for production of high melting temperature glasses utilizes a binary metal alloy bath having the combined properties of a low melting point, low reactivity with oxygen, low vapor pressure, and minimal reactivity with the silicate glasses being formed. The metal alloy of the float medium is exothermic with a solvent metal that does not readily form an oxide. The vapor pressure of both components in the alloy is low enough to prevent deleterious vapor deposition, and there is minimal chemical and interdiffusive interaction of either component with silicate glasses under the float processing conditions. Alloys having the desired combination of properties include compositions in which gold, silver or copper is the solvent metal and silicon, germanium or tin is the solute, preferably in eutectic or near-eutectic compositions.

Cooper, Reid Franklin (Inventor); Cook, Glen Bennett (Inventor)

2000-01-01

399

Compression-coated tablets of glipizide using hydroxypropylcellulose for zero-order release: in vitro and in vivo evaluation.  

PubMed

Compression coating, which presents some advantages like short manufacturing process and non-solvent residue over liquid coating, has been introduced to the oral administration systems for decades. The purpose of this study was to design a zero-order release of compression-coated tablets using hydroxypropylcellulose (HPC) as the coating layer and glipizide which was solubilized by manufacturing the inclusion complex of ?-cyclodextrin as a model drug. The effects of the weight ratio of drug and the viscosity of HPC on the release profile were investigated by "f2" factor with Glucotrol XL(®). The uptake and erosion study, the correlation coefficient (R) and the exponent (n) were used as indicators to justify drug release mechanism. Bioavailability in vivo was determined by administering the compression-coated tablets to rabbits in contrast with Glucotrol XL(®). It was found that the formulation presented a well zero-order behavior at the weight ratio of drug 11:14 (core:layer) and the combination of HPC-L (8.0 mPa s) and HPC-M (350 mPa s) (8:9), with the "f2" of 66.90. The mechanism for zero-order release of these compression-coated tablets was solvent penetration into the dosage form and drug dissolution from the erosion of the gelled HPC matrix. The parameter AUC0-? of the compression coated tablets and the market tablets were 37,255.93±1474.08 h ng/ml and 43265.40±1015.28 h ng/ml, while the relative bioavailability was 87.66±1.56%. These studies demonstrate that the designed compression-coated tablets may be a promising strategy for peroral controlled release delivery system of water-insoluble drugs. PMID:23370433

Huang, Haiqin; Wu, Zhenghong; Qi, Xiaole; Zhang, Huiting; Chen, Qin; Xing, Jiayu; Chen, Haiyan; Rui, Yao

2013-03-25

400

An Analysis of the Full-Floating Journal Bearing  

NASA Technical Reports Server (NTRS)

An analysis of the operating characteristics of a full-floating journal bearing, a bearing in which a floating sleeve is located between the journal and bearing surfaces, is presented together with charts from which the performance of such bearings may be predicted. Examples are presented to illustrate the use of these charts and a limited number of experiments conducted upon a glass full-floating bearing are reported to verify some results of the analysis.

Shaw, M C; Nussdorfer, T J , Jr

1947-01-01

401

Stability of Temperature and Conductivity Sensors of Argo Profiling Floats  

Microsoft Academic Search

After recalibration of the temperature and conductivity sensors of three Argo profiling floats recovered after operations\\u000a for four to nine months, the results indicate that the floats basically showed no significant drift, either in temperature\\u000a or salinity, and adequately fulfilled the accuracy requirement of the Argo project (0.005C for temperature and 0.01 psu for\\u000a salinity). Only the third float showed

Eitarou Oka; Kentaro Ando

2004-01-01

402

78 FR 47410 - Certain Wireless Devices, Including Mobile Phones and Tablets Institution of Investigation  

Federal Register 2010, 2011, 2012, 2013, 2014

...Certain Wireless Devices, Including Mobile Phones and Tablets Institution of Investigation...certain wireless devices, including mobile phones and tablets by reason of infringement...certain wireless devices, including mobile phones and tablets by reason of...

2013-08-05

403

78 FR 15956 - Guidance for Industry on Tablet Scoring: Nomenclature, Labeling, and Data for Evaluation...  

Federal Register 2010, 2011, 2012, 2013, 2014

...FDA-2011-D-0595] Guidance for Industry on Tablet Scoring: Nomenclature...availability of a guidance for industry entitled ``Tablet Scoring...availability of a guidance for industry entitled ``Tablet Scoring...Providing a harmonized approach to chemistry, manufacturing, and...

2013-03-13

404

78 FR 1247 - Certain Electronic Devices, Including Wireless Communication Devices, Tablet Computers, Media...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Tablet Computers, Media Players, and Televisions, and Components Thereof; Institution...tablet computers, media players, and televisions, and components thereof by reason of...tablet computers, media players, and televisions, and components thereof that...

2013-01-08

405

75 FR 39025 - Determination That ACTONEL (Risendronate Sodium) Tablets, 75 Milligrams, and ACTONEL WITH CALCIUM...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Tablets, 75 Milligrams, and ACTONEL WITH CALCIUM (Risendronate Sodium and Calcium Carbonate (Copackaged)) Tablets, 35 Milligrams...Tablets, 75 milligrams (mg), and ACTONEL WITH CALCIUM (risendronate sodium and calcium...

2010-07-07

406

75 FR 61503 - Determination That AZDONE (Hydrocodone Bitartrate and Aspirin) Tablet, 5 Milligrams/500...  

Federal Register 2010, 2011, 2012, 2013, 2014

...That AZDONE (Hydrocodone Bitartrate and Aspirin) Tablet, 5 Milligrams/500 Milligrams...that AZDONE (hydrocodone bitartrate and aspirin) Tablet, 5 milligrams (mg)/ 500 mg...ANDAs) for hydrocodone bitartrate and aspirin tablet, 5 mg/500 mg, if all...

2010-10-05

407

76 FR 24051 - In the Matter of Certain Electronic Devices, Including Mobile Phones, Mobile Tablets, Portable...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Mobile Phones, Mobile Tablets, Portable Music Players, and Computers, and Components...mobile phones, mobile tablets, portable music players, and computers, and components...mobile phones, mobile tablets, portable music players, and computers, and...

2011-04-29

408

Environment parameters and basic functions for floating-point computation  

NASA Technical Reports Server (NTRS)

A language-independent proposal for environment parameters and basic functions for floating-point computation is presented. Basic functions are proposed to analyze, synthesize, and scale floating-point numbers. The model provides a small set of parameters and a small set of axioms along with sharp measures of roundoff error. The parameters and functions can be used to write portable and robust codes that deal intimately with the floating-point representation. Subject to underflow and overflow constraints, a number can be scaled by a power of the floating-point radix inexpensively and without loss of precision. A specific representation for FORTRAN is included.

Brown, W. S.; Feldman, S. I.

1978-01-01

409

Floating Drug Delivery of Nevirapine as a Gastroretentive System  

PubMed Central

A multiple-unit floating drug delivery system based on gas formation technique was developed, in order to prolong the gastric residence time and to increase the overall bioavailability of the dosage form. The floating bead formulations were prepared by dispersing nevirapine together with calcium carbonate in a mixture of sodium alginate and hydroxypropyl methylcellulose solution and then dripping the dispersion into an acidified solution of calcium chloride. Calcium alginate beads were formed, as the alginate underwent ionotropic gelation by calcium ions, and carbon dioxide developed from the reaction of carbonate salts with acid. The obtained beads were able to float due to CO2-gas formation and the gas entrapment by the polymeric membrane. The prepared beads were evaluated for percent drug loading, drug entrapment efficiency, morphology, surface topography, buoyancy, in-vitro release, and release kinetics. The formulations were optimized for different weight ratios of the gas-forming agent and sodium alginate. The beads containing higher amounts of calcium carbonate demonstrated an instantaneous, complete, and excellent floating ability over a period of 24 hours. The increased amount of the gas forming agent did not affect the time to float, but increased the drug release from the floating beads, while increasing the coating level of the gas-entrapped membrane, increased the time to float, and slightly retarded the drug release. Good floating properties and sustained drug release were achieved. Finally, these floating beads seemed to be a promising gastroretentive drug delivery system. PMID:21264092

Vedha, Hari BN; Brahma, Reddy A; Samyuktha, Rani B

2010-01-01

410

Statistical analysis of the metrological properties of float glass  

NASA Astrophysics Data System (ADS)

The radius of curvature, slope error, surface roughness and associated height distribution and power spectral density of uncoated commercial float glass samples have been measured in our Canadian Light Source Optical Metrology Facility, using our Micromap-570 surface profiler and long trace profilometer. The statistical differences in these parameters have been investigated between the tin and air sides of float glass. The effect of soaking the float glass in sulfuric acid to try to dissolve the tin contamination has also been investigated, and untreated and post-treatment surface roughness measurements compared. We report the results of our studies on these float glass samples.

Yates, Brian W.; Duffy, Alan M.

2008-08-01

411

Mucoadhesive Microparticles in a Rapidly Dissolving Tablet for Sustained Drug Delivery to the Eye  

PubMed Central

Purpose. To test the hypothesis that mucoadhesive microparticles formulated in a rapidly dissolving tablet can achieve sustained drug delivery to the eye. Methods. Mucoadhesive microparticles, smaller than 5 ?m were fabricated with poly(lactic-co-glycolic acid) and poly(ethylene glycol) as a core material and mucoadhesion promoter, respectively, and encapsulated pilocarpine as a model drug. These microparticles were embedded in a poly(vinyl alcohol) matrix to form a dry tablet designed to reduce rapid clearance of the microparticles on initial application to the eye. Results. This in vitro drug release study exhibited that for all formulations, approximately 90% of pilocarpine was released during the first 10 minutes, and the remaining 10% was released slowly for 3 hours. In vivo mucoadhesion test on the rabbit eye indicated that mucoadhesive microparticles adhered significantly better to the preocular surface than other formulations. To assess the pharmacodynamics, the most prolonged pilocarpine-induced pupil constriction was observed in rabbit eyes in vivo using a tablet with mucoadhesive microparticles; it lasted up to 330 minutes. Conclusions. The authors conclude that mucoadhesive microparticles formulated into a dry dosage form is a promising system for sustained drug delivery to the eye. PMID:21245405

Choy, Young Bin; Patel, Samirkumar R.; Park, Jung-Hwan; McCarey, Bernard E.; Edelhauser, Henry F.

2011-01-01

412

The Variability of Ecstasy Tablets Composition in Brazil.  

PubMed

The content of ecstasy tablets has been changing over the years, and nowadays 3,4-methylenedioxymethamphetamine (MDMA) is not always present in the tablets. The aim of this study was to investigate the chemical composition in the seized tablets labeled as ecstasy. We analyzed samples from 150 different seizures made by Sao Paulo's State Police by gas chromatography-mass spectrometry. MDMA was present in 44.7% of the analyzed samples, and another twenty different active substances were identified in these tablets, such as caffeine, 2C-B, piperazines, amphetamines, phencyclidine, and others. Methamphetamine was present in 22% of these samples. The results demonstrate a huge shift in the pattern of trafficking of synthetic drugs, where MDMA has been replaced in tablets mostly by illicit psychoactive substances, in a clear attempt to bypass the law. The great variability in the tablets composition may lead to an increased risk of drug poisoning. PMID:25125149

Togni, Loraine R; Lanaro, Rafael; Resende, Rodrigo R; Costa, Jose L

2014-08-14

413

Biocidal Efficacy of a Flocculating Emergency Water Purification Tablet  

PubMed Central

Chlor-Floc (CF) emergency water purification tablets were tested for bactericidal, virucidal, and cysticidal efficacy in water at temperatures ranging from 5 to 25°C. The minimal required log reduction was achieved for bacteria, Giardia muris, and rotavirus, but CF did not achieve the required log reduction of poliovirus at any of the temperatures or times investigated. The biocidal properties of the CF tablet were equivalent to if not greater than those of the Globaline iodine tablet, and the CF tablet was a more rapid cysticide under several potential use conditions. Therefore, it is a suitable substitute for iodine tablets for emergency purification of drinking water. Clarification of turbid waters was effective, but filtration through a cloth is necessary to prevent flocculated sediment from entering the canteen. The CF tablets met military requirements for emergency water purification and are safe and acceptable for use by the military. PMID:16349318

Powers, Edmund M.; Hernandez, C.; Boutros, S. N.; Harper, B. G.

1994-01-01

414

Pharmaceutical equivalence of metformin tablets with various binders  

Microsoft Academic Search

Metformin hydrochloride is a high-dose drug widely used as an oral anti-hyperglycemic agent. As it is highly crystalline and has poor compaction properties, it is difficult to form tablets by direct compression. The aim of this study was to develop adequate metformin tablets, pharmaceutically equivalent to the reference product, Glucophage® (marketed as Glifage® in Brazil). Metformin 500mg tablets were produced

Tania Mari

415

Influence of plasticizers on tableting properties of polymers.  

PubMed

This study relates tablet formation with relaxation properties of two polymers on the basis of the stress-deformation curve. The mechanical properties of the polymers were varied by changing tableting temperature, adding varying amounts of plasticizer, and incorporating a monomer with plasticizer effect on the polymer chain. The crucial parameter appeared to be the difference between the glass transition temperature and the tableting temperature. This temperature difference was found to determine the amount of energy stored during densification. The energy is manifested as the stress relaxation propensity of the material. Large stress relaxation yields porous and consequently weak tablets. At a low temperature difference (i.e., tableting temperature is much lower than the glass transition temperature), the amount of stored energy is large. An increase in tableting temperature, or a decrease in glass transition temperature, yields a decrease in stored energy as a result of a decrease in yield strength. Consequently, production of less porous and stronger tablet is possible. However, if the tableting temperature is higher than the glass transition temperature, the stress relaxation propensity of the deformed polymers is extremely high because the elastic modulus of the materials is low under these circumstances. This results is porous and even capped tablets. From the data it is concluded that, independent of the type of polymer and the method of plasticizing, compaction at a temperature of about 20 K under the glass transition temperature yields circumstances for which the amount of stored energy has a minimum. Consequently, tablet porosity has a minimum and tablet strength has a maximum. These circumstances are created by changing both the tableting temperature and the glass transition temperature of the powder. PMID:9876583

Van der Voort Maarschalk, K; Vromans, H; Bolhuis, G K; Lerk, C F

1998-03-01

416

Safety evaluation of saffron ( Crocus sativus) tablets in healthy volunteers  

Microsoft Academic Search

Saffron (Crocus sativus) stigma tablets were evaluated for short-term safety and tolerability in healthy adult volunteers. The study was a double-blind, placebo-controlled design consisting of a 1 week treatment of saffron tablets. Volunteers were divided into 3 groups of 10 each (5 males and 5 females). Group I received placebo; groups 2 and 3 received 200 and 400mg saffron tablets,

Mohammad-Hadi Modaghegh; Masoud Shahabian; Habib-Allah Esmaeili; Omid Rajbai; Hossein Hosseinzadeh

2008-01-01

417

Evaluation and floating enhancement of levodopa sustained release floating minitablets coated with insoluble acrylic polymer.  

PubMed

This article describes the in vitro evaluation and the enhancement of the floating properties of coated sustained release (SR) minitablets (MTs). The evaluated system consisted of a 3-mm drug-containing gas-generating core prepared by melt granulation and subsequent compression, which was then coated with a flexible polymeric membrane. Eudragit RL30D and acetyl triethylcitrate were used as a film former and a plasticizer, respectively. The coating level was fixed at 20% (wt/wt). The optimally coated floating MTs floated within 10 min and remained buoyant for more than 13 h, regardless of the pH of the test medium. By evaluating the dissolution profiles of levodopa at different pH, it was found that the release of levodopa was sustained for more than 12 h regardless of the pH, even if the coating did not cancel the effect of the pH-dependent solubility of the active drug. Finally, the robustness of the coated floating MTs was assessed by testing the drug release variability in function of the stirring conditions during dissolution tests. PMID:18618310

Goole, J; Amighi, K; Vanderbist, F

2008-08-01

418

Evaluation of buccoadhesive metronidazole tablets: microbiological response.  

PubMed

Metronidazole has been found beneficial in a number of oro-dental infections namely dry socket, gingivitis, smelling tumours and periodontal diseases where anaerobes are implicated as pathogens. Buccoadhesive tablets of metronidazole were prepared by compressing the drug, bioadhesive polymers namely Carbopol-934P, a cellulose ether derivative, mannitol and suitable flavouring and sweetening agents. The tablet showed good release in vitro. It was subjected to in-situ release studies using bovine cheek pouch membrane in a flow through cell. The concentration was found to be above the MIC of the drug over the entire period of the release studies. The samples were tested against anaerobic strains commonly found in oro-dental infections. Since anaerobes are very slow growing microorganisms, a method for testing their susceptibility to metronidazole solutions was developed which can be used for other bioadhesive formulations which are active against anaerobes. PMID:9583086

Ahuja, A; Khar, R K; Chaudhry, R

1998-04-01

419

Research effort aims at floating production technology  

SciTech Connect

This paper reports that a 3 year research and development program on floating production systems (FPS), instigated by the Royal Norwegian Council for Scientific and Industrial Research (NTNF), has refined and qualified technologies for North Sea and arctic conditions. The FPS 2000 program, which cost 58 million kroner ($10 million), concentrated mainly on mooring systems and pipeline technology, along with new system concepts and cost reduction measures. More than 30 projects have been completed within the scheme. The anchoring and positioning project concentrates on developing methods for simulating behavior of mooring systems for large volume structures in deep water. It also seeks ways to determine efficiency of dynamic positioning thrusters under extreme conditions.

Not Available

1992-08-17

420

Illinois PER Interactive Examples: Floating Cylinders  

NSDL National Science Digital Library

This is an interactive homework problem for introductory physics students relating to fluids and buoyant force. It involves two differently shaped cylinders with the same mass density floating in a container of non-moving water. The student must determine the ratio of the height of Cylinder #2 above the water to the height of Cylinder #1 above the water. A user-activated "help" sequence is provided for each step of the problem-solving, from conceptual analysis through quantitative calculation. To promote critical thinking, immediate feedback is received for both correct and incorrect responses. This item is part of a larger collection of interactive homework problems for introductory physics.

Gladding, Gary

2008-09-10

421

Floating hydrometer with energy dissipating baffle  

SciTech Connect

This patent describes a floating hydrometer employable for purposes of obtaining measurements of the presence of suspended solids in a fluid substance contained in a receptacle comprising: a. a probe portion operative as an instrument-bearing housing; b. an elongated tubular element having a hollow interior and at least one open end so as to enable the flow into the hollow interior of the elongated tubular element through the open end; and c. energy dissipating baffle means having a first mode of action and a second mode of action and including a member having a hollow interior.

Kownurko, W.A.

1987-11-24

422

Floating production unit to work off Brazil  

SciTech Connect

This paper reports that Petroleo Brasileiro SA expects by early November to deploy its Petrobras XXIV floating production unit (FPU) in about 900 ft of water in Albacora field off Brazil. The FPU was scheduled to depart Galveston, Tex., this month, following completion of modifications and upgrades under a turnkey contract with Chiles Offshore International Inc. Chiles began modifying Petrobras XXIV about 1 year ago as part of a deal closed in October 1991 in which Chiles Offshore Corp. sold the vessel, then known as Intrepid, to Brasoil, the international subsidiary of Petrobras.

Not Available

1992-10-19

423

Tried and True: Whatever floats your boat  

NSDL National Science Digital Library

Ever since Archimedes ran down the streets of ancient Greece shouting, "Eureka!," scientists have understood that a submerged body displaces a volume of water equalto its own volume. Scientists also came to realize that if a body weighed less than the water it displaced, the body would float. Although this knowledge has been aroundfor nearly 2,500 years, many students still have difficulty explaining how a vessel made of a heavier-than-water material, such as steel, remains afloat. The following triedand true activity provides students with a hands-on experience that explains the principle of buoyancy.

Mcbride, Susan L.

2003-03-01

424

An integrated circuit floating point accumulator  

NASA Technical Reports Server (NTRS)

Goddard Space Flight Center has developed a large scale integrated circuit (type 623) which can perform pulse counting, storage, floating point compression, and serial transmission, using a single monolithic device. Counts of 27 or 19 bits can be converted to transmitted values of 12 or 8 bits respectively. Use of the 623 has resulted in substantial savaings in weight, volume, and dollar resources on at least 11 scientific instruments to be flown on 4 NASA spacecraft. The design, construction, and application of the 623 are described.

Goldsmith, T. C.

1977-01-01

425

Hordeum Vulgare Hull in the Design of Fast Disintegrating Tablets  

PubMed Central

In the present study, fast disintegrating tablets were designed with a view to enhance patient compliance. In this method, the hull of Hordeum vulgare, cross carmellose sodium, and sodium starch glycolate were used as superdisintegrants (4 and 6%), along with microcrystalline cellulose and mannitol, to enhance mouth feel. The prepared batches of tablets were evaluated for hardness, friability, drug content uniformity, wetting time, water absorption ratio and in vitro dispersion time. Based on the in vitro dispersion time, the formulations were tested for the in vitro drug release pattern. Tablets having H. vulgare hull showed the release profile comparable to those tablets having sodium starch glycolate and cross carmellose sodium. PMID:21897660

Rajpurohit, H; Sharma, P; Sharma, S; Purohit, S; Bhandari, A

2011-01-01

426

Analysis of fatty acids in ecstasy tablets.  

PubMed

Fatty acids are the basis of so-called stearates which are frequently used as lubricants in the production of ecstasy tablets. Being a product added at the initial tablet production step its composition does not change once the compression is performed. The analysis of fatty acids can therefore provide useful information for a drug intelligence purpose. In this context an appropriate analytical method was developed to improve results already obtained by routine analyses. Considering the small quantity of such fatty acids in ecstasy tablets (approximately 3%) the research focussed on their extraction and concentration. Two different procedures were tested: (1) liquid/liquid extraction using dichloromethane followed by derivatisation and (2) in situ transesterification using bortrifluoride. Analyses were performed by GC-MS. The two procedures were optimized and applied to eight ecstasy seizures, in order to choose one of the procedures for its application to a large ecstasy sample set. They were compared by considering the number of peaks detected and sample amount needed, reproducibility and other technical aspects. PMID:19395206

Baer, Ines; Margot, Pierre

2009-07-01

427

Chocolate tablet aspects of cytherean Meshkenet Tessera  

NASA Technical Reports Server (NTRS)

Meshkenet Tessera structures were mapped from Magellan data and several resemblances to chocolate tablet boudinage were found. The complex fault sets display polyphase tectonic sequences of a few main deformation phases. Shear and tension have contributed to the areal deformation. Main faults cut the 1600-km long Meshkenet Tessera highland into bar-like blocks which have ridge and groove pattern oriented along or at high angles to the faults. The first approach to the surface block deformation is an assumption of initial parallel shear faulting followed by a chocolate tablet boudinage. Major faults which cut Meshkenet Tessera into rectangular blocks have been active repetitively while two progressive or superposed boudinage set formations have taken place at high angles during the relaxational or flattening type deformation of the area. Chocolate tablet boudinage is caused by a layer-parallel two-dimensional extension resulting in fracturing of the competent layer. Such structures, defined by two sets of boudin neck lines at right angles to each other, have been described by a number of authors. They develop in a flattening type of bulk deformation or during superposed deformation where the rock is elongated in two dimensions parallel to the surface. This is an attempt to describe and understand the formation and development of structures of Meshkenet Tessera which has complicated fault structures.

Raitala, J.

1993-01-01

428

Chocolate tablet aspects of cytherean Meshkenet Tessera  

NASA Astrophysics Data System (ADS)

Meshkenet Tessera structures were mapped from Magellan data and several resemblances to chocolate tablet boudinage were found. The complex fault sets display polyphase tectonic sequences of a few main deformation phases. Shear and tension have contributed to the areal deformation. Main faults cut the 1600-km long Meshkenet Tessera highland into bar-like blocks which have ridge and groove pattern oriented along or at high angles to the faults. The first approach to the surface block deformation is an assumption of initial parallel shear faulting followed by a chocolate tablet boudinage. Major faults which cut Meshkenet Tessera into rectangular blocks have been active repetitively while two progressive or superposed boudinage set formations have taken place at high angles during the relaxational or flattening type deformation of the area. Chocolate tablet boudinage is caused by a layer-parallel two-dimensional extension resulting in fracturing of the competent layer. Such structures, defined by two sets of boudin neck lines at right angles to each other, have been described by a number of authors. They develop in a flattening type of bulk deformation or during superposed deformation where the rock is elongated in two dimensions parallel to the surface. This is an attempt to describe and understand the formation and development of structures of Meshkenet Tessera which has complicated fault structures.

Raitala, J.

1993-03-01

429

The Clinical Assessment and Remote Administration Tablet  

PubMed Central

Electronic data capture of case report forms, demographic, neuropsychiatric, or clinical assessments, can vary from scanning hand-written forms into databases to fully electronic systems. Web-based forms can be extremely useful for self-assessment; however, in the case of neuropsychiatric assessments, self-assessment is often not an option. The clinician often must be the person either summarizing or making their best judgment about the subject’s response in order to complete an assessment, and having the clinician turn away to type into a web browser may be disruptive to the flow of the interview. The Mind Research Network has developed a prototype for a software tool for the real-time acquisition and validation of clinical assessments in remote environments. We have developed the clinical assessment and remote administration tablet on a Microsoft Windows PC tablet system, which has been adapted to interact with various data models already in use in several large-scale databases of neuroimaging studies in clinical populations. The tablet has been used successfully to collect and administer clinical assessments in several large-scale studies, so that the correct clinical measures are integrated with the correct imaging and other data. It has proven to be incredibly valuable in confirming that data collection across multiple research groups is performed similarly, quickly, and with accountability for incomplete datasets. We present the overall architecture and an evaluation of its use. PMID:22207845

Turner, Jessica A.; Lane, Susan R.; Bockholt, H. Jeremy; Calhoun, Vince D.

2011-01-01

430

Exploring the possible relationship between the drug release of Compritol®-containing tablets and its polymorph forms using micro X-ray diffraction.  

PubMed

Lipid excipients are more and more commonly used in the pharmaceutical industry as sustained drug delivery agents. However, their development may still be hindered by the well-known polymorphism of lipids which is perceived as a disadvantage with possible impact on drug release upon storage. In order to explore the eventual link between drug release modification and lipid polymorphism, we used a synchrotron radiation-based micro X-ray diffraction that allows probing the crystalline structures of the lipid matrix-forming excipient at a local scale and scanning it across the whole tablet. This technique demonstrated that only one polymorph of Compritol® 888 ATO is present in each tablet. This polymorph is identical whatever the compression force applied during the manufacturing is, and stays the same after storage at 40°C for 45days, even if these tablets exhibit different drug release profiles. Hence modification of drug release observed after storage is not due to lipid polymorphism. Implementation of post-compression thermal treatments generates another lipid polymorph. Again drug release is not linked with polymorphism because two different polymorphs of Compritol® 888 ATO lead to exactly the same dissolution profile. Variation of drug release observed during storage in accelerated conditions could be attributed to an altered distribution of the lipid component within the matrix structure. The lipid may flow within the matrix structure and increase the hydrophobicity of tablets. PMID:25445699

Jannin, Vincent; Rosiaux, Yvonne; Doucet, Jean

2015-01-10

431

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2011 CFR

...false What are the requirements for lights on a floating hose string? 149...AND EQUIPMENT Aids to Navigation Lights on Floating Hose Strings § 149.550 What are the requirements for lights on a floating hose string?...

2011-07-01

432

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2012 CFR

...false What are the requirements for lights on a floating hose string? 149...AND EQUIPMENT Aids to Navigation Lights on Floating Hose Strings § 149.550 What are the requirements for lights on a floating hose string?...

2012-07-01

433

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2013 CFR

...false What are the requirements for lights on a floating hose string? 149...AND EQUIPMENT Aids to Navigation Lights on Floating Hose Strings § 149.550 What are the requirements for lights on a floating hose string?...

2013-07-01

434

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2014 CFR

...false What are the requirements for lights on a floating hose string? 149...AND EQUIPMENT Aids to Navigation Lights on Floating Hose Strings § 149.550 What are the requirements for lights on a floating hose string?...

2014-07-01

435

Free floating planets in stellar clusters?  

E-print Network

We have simulated encounters between planetary systems and single stars in various clustered environments. This allows us to estimate the fraction of systems liberated, the velocity distribution of the liberated planets, and the separation and eccentricity distributions of the surviving bound systems. Our results indicate that, for an initial distribution of orbits that is flat in log space and extends out to 50AU, 50% of the available planets can be liberated in a globular cluster, 25% in an open cluster, and less than 10% in a young cluster. These fractions are reduced to 25%, 12% and 2% if the initial population extends only to 20AU. Furthermore, these free-floating planets can be retained for longer than a crossing time only in a massive globular cluster. It is therefore difficult to see how planets, which by definition form in a disc around a young star, could be subsequently liberated to form a significant population of free floating substellar objects in a cluster.

Kester W. Smith; Ian A. Bonnell

2001-01-05

436

Thermal Performance of the LDX Floating Coil  

NASA Astrophysics Data System (ADS)

The Levitated Dipole Experiment (LDX) is an innovative facility to study plasma confinement in a dipole magnetic field, created by a superconducting solenoid (floating coil), which is magnetically levitated in the center of a 5 m diameter by 3 m tall vacuum chamber. The floating coil (F-coil) consists of a Nb3Sn magnet installed inside a strong vessel filled with high-pressure helium gas at room temperature. It is surrounded by a fiberglass-lead composite radiation shield and by a toroidal vacuum shell. The cryostat design provides the ability to operate the magnet for several hours of wanning while suspended in the middle of the vacuum chamber without electric and cryogenic connections to the coil. For this reason the magnet is charged/discharged inductively in a lower part of the vacuum chamber. The retractable cryogenic transfer lines serve to cool down the magnet to 4.5 K before it is lifted to the operating position. The F-coil can be re-cooled multiple times while maintaining its field and current. This paper describes the thermal performance of the F-coil.

Zhukovsky, A.; Garnier, D. T.; Radovinsky, A. L.

2006-04-01

437

What every computer scientist should know about floating-point arithmetic  

Microsoft Academic Search

Floating-point arithmetic is considered as esoteric subject by many people. This is rather surprising, because floating-point is ubiquitous in computer systems: Almost every language has a floating-point datatype; computers from PCs to supercomputers have floating-point accelerators; most compilers will be called upon to compile floating-point algorithms from time to time; and virtually every operating system must respond to floating-point exceptions

David Goldberg

1991-01-01

438

Medical Matrix  

NSDL National Science Digital Library

Medical Matrix is a Web resource that offers a database of Internet clinical medicine resources. Medical Matrix categorizes resources by disease, specialty, and other interest areas. It is designed as a "home page" for a physician's or healthworker's computer. Medical Matrix is a project of the Internet Working Group of the American Medical Informatics Association.

439

Development of sustained release antipsychotic tablets using novel polysaccharide isolated from Delonix regia seeds and its pharmacokinetic studies  

PubMed Central

A natural polysaccharide was isolated from the seeds of Delonix regia. The isolated polysaccharide could maintain aqueous equilibrium between the dosage form and the surrounding medium due to its massive competence of water absorption (80.72%) and swelling index (266.7%). The Scanning Electron Micrograph of a polysaccharide exhibits rough surface with pores and crevices, hence, the drug release will be retarded because of the drug particles entrapment in the pores and crevices. Further, the surface tension of polysaccharide is higher than that of water, which may facilitate sustained release of drugs from dosage forms. An antipsychotic drug, quetiapine fumarate has a short half-life of 6 h and administered multiple times per day. Hence the quetiapine fumarate oral sustained release tablets were formulated using this polysaccharide in the concentration of 5–30% to avoid the side effects and increase patient compliance. Dissolution of the developed tablets with 25% polysaccharide content showed a better release profile than the other batches (5–20%) at the end of 12 h. The strong matrix complex has low solubility in water, it does not dissolve rapidly and the drug continues to diffuse through the gel layer at a consistent rate. Drug release from the matrix tablets follows matrix type except F-4 and F-5 which follow first order and Hix.crow type. The bioavailability study was carried out using healthy male New Zealand white rabbits that show the AUC(0–inf) value for developed SR tablets is 1.44 times higher than the reference thus, indicating more efficient and sustained drug delivery capable of maintaining plasma drug levels better. PMID:24115903

Krishnaraj, Kaliaperumal; Chandrasekar, Mulla Joghi Nanjan; Nanjan, Mulla Joghi; Muralidharan, Selvadurai; Manikandan, Duraikannu

2011-01-01

440

Argo at PMEL: Intro http://floats.pmel.noaa.gov  

E-print Network

) ·End-to-end (Float providers involved in instrumentation development, preparation & testing, deployment at PMEL: Float Preparation ·Suite of tests developed with academic colleagues & manufacturers and data quality -Inspect exterior, seals, &components -Check weight -Test transmitter, oil pump, vacuum

441

Floating gate power supply of multilevel converters for circuit integration  

Microsoft Academic Search

There is the possibility of the intrinsic elimination of harmonics and electromagnetic interference (EMI) by introducing multilevel converters with a large number of levels. As the number of levels increases, the number of the main switching devices on their higher side increases, and their floating gate power supplies become larger scale circuits. Because it is necessary to integrate the floating

Masamu Kamaga; Kyungmin Sung; Jin Xu; Yukihiko Sato; Hiromichi Ohashi

2009-01-01

442

Apollo 9 spacecraft floats in Atlantic recovery area after splashdown  

NASA Technical Reports Server (NTRS)

Apollo 9 spacecraft floats in the Atlantic recovery area after splashdown to conclude a successful ten-day, earth-orbital space mission. Splashdown occurred at 12:00:53 p.m., March 13, 1969. Notice the spent parachutes floating on the water's surface near the capsule.

1969-01-01

443

22. Float located adjacent to entry stair in filtration bed. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. Float located adjacent to entry stair in filtration bed. The float actuates a valve that maintains water level over the bed. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

444

Submarine Floating Antenna Model for LORAN-C Signal  

E-print Network

Submarine Floating Antenna Model for LORAN-C Signal Processing A. MONIN LAAS-CNRS France An electromagnetic model of the floating antenna used by submarines for LORAN-C radionavigation and very low The antenna used by submarines, for LORAN-C radionavigation and very low frequency (VLF) communications

Monin, André

445

A FLOATING-FISH SNARE FOR CAPTURING BALD EAGLES  

Microsoft Academic Search

Bald Eagles (Haliaeetus leucocephalus) were captured using a system of 4 monofilament snares fixed on a small (20-24 cm) floating fish attached by monofilament and shock cord to a free- floating (or anchored) driftwood log. When an eagle strikes the bait and begins to fly away, the snare loops close around the bird's toes as the line tightens. Resistance of

STEVEN L. CAIN; JOHN I. HODGES

446

Role of various natural, synthetic and semi-synthetic polymers on drug release kinetics of losartan potassium oral controlled release tablets  

PubMed Central

Objective: The objective of the present work was to formulate and to characterize controlled release matrix tablets of losartan potassium in order to improve bioavailability and to minimize the frequency of administration and increase the patient compliance. Materials and Methods: Losartan potassium controlled release matrix tablets were prepared by direct compression technique by the use of different natural, synthetic and semisynthetic polymers such as gum copal, gum acacia, hydroxypropyl methyl cellulose K100 (HPMC K100), eudragit RL 100 and carboxy methyl ethyl cellulose (CMEC) individually and also in combination. Studies were carried out to study the influence of type of polymer on drug release rate. All the formulations were subjected to physiochemical characterization such as weight variation, hardness, thickness, friability, drug content, and swelling index. In vitro dissolution studies were carried out simulated gastric fluid (pH 1.2) for first 2 h and followed by simulated intestinal fluid (pH 6.8) up to 24 h, and obtained dissolution data were fitted to in vitro release kinetic equations in order to know the order of kinetics and mechanism of drug release. Results and Discussion: Results of physiochemical characterization of losartan potassium matrix tablets were within acceptable limits. Formulation containing HPMC K100 and CMEC achieved the desired drug release profile up to 24 h followed zero order kinetics, release pattern dominated by Korsmeyer — Peppas model and mechanism of drug release by nonfickian diffusion. The good correlation obtained from Hixson-Crowell model indicates that changes in surface area of the tablet also influences the drug release. Conclusion: Based on the results, losartan potassium controlled release matrix tablets prepared by employing HPMC K100 and CMEC can attain the desired drug release up to 24 h, which results in maintaining steady state concentration and improving bioavailability. PMID:25426439

Jayasree, J.; Sivaneswari, S.; Hemalatha, G.; Preethi, N.; Mounika, B.; Murthy, S. Vasudeva

2014-01-01

447

Effect of a floating electrode on a plasma jet  

SciTech Connect

Two kinds of floating electrode, floating dielectric barrier covered electrode (FDBCE) and floating pin electrode (FPE), which can enhance the performance of plasma jet are reported. The intense discharge between the floating electrode and power electrode decreased the voltage to trigger the plasma jet substantially. The transition of plasma bullet from ring shape to disk shape in the high helium concentration region happened when the floating electrode was totally inside the powered ring electrode. The enhanced electric field between propagating plasma bullet and ground electrode is the reason for this transition. The double plasma bullets happened when part of the FDBCE was outside the powered ring electrode, which is attributed to the structure and surface charge of FDBCE. As part of the FPE was outside the powered ring electrode, the return stroke resulted in a single intensified plasma channel between FPE and ground electrode.

Hu, J. T.; Wang, J. G.; Liu, X. Y.; Liu, D. W.; Lu, X. P. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China)] [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China); Shi, J. J. [College of Science, Donghua University, Shanghai 201620 (China)] [College of Science, Donghua University, Shanghai 201620 (China); Ostrikov, K. [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P. O. Box 218, Lindfield, New South Wales 2070 (Australia)] [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P. O. Box 218, Lindfield, New South Wales 2070 (Australia)

2013-08-15

448

Hydroelastic responses of pontoon type very large floating offshore structure  

SciTech Connect

The authors developed the estimating method of the hydroelastic response of a very large pontoon type floating structure. In this method, the pressure distribution method with shallow draft assumption was used to obtain the hydrodynamic forces considering the elastic motion of a floating body. The elastic responses of very large floating structure were estimated by using 1-D beam modeling. On the other hand, to observe the elastic response of a large pontoon type structure they carried out experiments in head sea and head-beam sea conditions. The experimental model was an elastic model of pontoon type large floating body. To validate numerical estimation method the authors compared the numerical results with experimental results. From these results, they found good agreement and confirmed the accuracy of this numerical estimation method of the hydroelasticity of a very large pontoon type floating structure.

Haeda, Hisaaki; Miyajima, Shyogo [Univ. of Tokyo (Japan). Inst. of Industrial Science; Masuda, Koich; Ikoma, Tomoki [Nihon Univ., Funabashi, Chiba (Japan)

1996-12-31

449

Development of monolithic osmotic pump tablet system for isosorbide-5-mononitrate delivery and evaluation of it in vitro and in vivo.  

PubMed

The objective of this study is to develop the monolithic osmotic pump tablet system (MOTS) containing isosorbide-5-mononitrate (5-ISMN), and to evaluate its in vitro and in vivo properties. The influences of tablet formulation variables, size and location of the delivery orifice, membrane variables, and pH value of the dissolution medium on 5-ISMN release from MOTS have been investigated. These results demonstrated that the tablet core played an important role in MOTS, and membrane variables could affect the 5-ISMN release rate. The optimal formulation of 5-ISMN MOTS was determined by uniform design. Furthermore, the dog pharmacokinetics and relative bioavailability of the test formulation (5-ISMN MOTS) have been compared with the reference formulation (Imdur: 60 mg/tablet, a sustained release, SR, tablet system) following an oral single dose of 60 mg given to each of six Beagle dogs. The mean drug fraction absorbed by the dog was calculated by the Wagner-Nelson technique. The results showed that drug concentration in plasma could be maintained more stable and longer after the administration of 5-ISMN MOTS compared with the matrix tablets of Imdur, and a level A "in vitro-in vivo correlation" was observed between the percentage released in vitro and percentage absorbed in vivo. It is concluded that 5-ISMN MOTS is more feasible for a long-acting preparation than 5-ISMN SR tablet system as once-a-day treatment, and it is very simple in preparation, and can release 5-ISMN at the rate of approximately zero order for the combination of hydroxypropylmethyl cellulose as retarder and NaCl as osmogent. PMID:18979308

Duan, Xueyan; Liu, Qingfei; Zhang, Yu; Bi, Kaishun; Chen, Xi; Wang, Yiming; Luo, Guoan

2009-04-01

450

Hot melt granulation: a facile approach for monolithic osmotic release tablets.  

PubMed

The aim of this work was to develop and evaluate an extended release matrix tablet of glipizide (GP), an oral hypoglycemic agent. Matrices of GP were prepared using microcrystalline cellulose Avicel(™) PH 112, sodium chloride (SC) and polyethylene glycol 6000 (PEG). The content of Kollidon SR (KR), hydroxypropyl methylcellulose K4M premium CR grade (HM) and polyethylene oxide WSR 303 (PO) and/or magnesium hydroxide (MH) was varied in different formulations. All the formulations were processed by hot melt granulation technique. GP release was observed to be influenced by the amount of SC and MH present in the core formulation. The matrix tablets were coated with a solution containing combination of cellulose acetate 398.10 (CA) and PEG. The release of GP was observed to be inversely proportional to the weight of the coating membrane. Matrices containing PO in combination with SC and MH (14.28:8.56) showed significantly higher degree of hydration and swelling that was evident in the surface texture as visualized by scanning electron microscopy (SEM). Results of SEM studies confirmed the presence of pores in the semi-permeable coating membrane from where the GP release would have occurred. The release of GP from this formulation was similar to that of the marketed extended release tablet as judged from similarity factor (f2) analysis, which yielded a value of 74.7. The optimized formulation was found to be stable when tested according to long term and accelerated storage conditions of ICH guidelines upto 3 months. PMID:21954892

Panda, Rashmi R; Tiwary, Ashok K

2012-04-01

451

[Optimization of the formulation of ranolazine hydrochloride sustained-release tablet and its pharmacokinetics in dogs].  

PubMed

Ranolazine hydrochloride sustained-release tablet (RH-ST) was prepared and its release behavior in vitro was studied. The pharmacokinetic characteristics and bioavailability in six Beagle dogs after oral administration of RH-ST and ranolazine hydrochloride common tablets (RH-CT) as reference were compared. Three kinds of matrix, hydroxypropylmethylcellulose (HPMC K4M), ethylcellulose (EC 100cp) and acrylic resins (Eudragit RL100) were selected as functional excipients to keep ranolazine hydrochloride (RH) release for 12 hours. Through orthogonal designs, the polymers were quantified and the optimized cumulative release profile was obtained. The single oral dose of RH-ST 500 mg and RH-CT 333.3 mg was given to six dogs using a two way crossover design. Plasma levels were determined by LC-MS and the absorption fractions were calculated according to Loo-Riegelman formula. The steady-state concentration of RH in plasma of six dogs and its pharmacokinetics behaviors after continuous oral administration of RH-ST and RH-CT at different time intervals were studied by LC-MS. The steady-state pharmacokinetic parameters were computed by software program BAPP2.0. With the increase of the amount of the matrix, the drug release was decreased. The most important factor influencing drug release is the quantity of HPMC K4M. Drug release within the period (from 0 h to 12 h) fitted well into Higuchi model. The correlation coefficient (r) between the dissolution in vitro in release media of the distilled water and the absorptin fraction in vivo was 0.9550. To compare with RH-CT, RH-ST in vivo has a steady and slow release behavior, Tmax was obviously delayed (3.00 +/- 0.50) h and the relative bioavailability was over 80 percentage. The combined use of multiple polymers can decrease the tablet weight effectively, and the drug release rate can be decreased both in vitro and in vivo. PMID:21351575

Li, Chang-jun; Yu, Yan-ling; Yang, Qing-min; Li, Ying; Zhang, Yu-hong; Wang, Jing-yi

2010-09-01

452

POTENTIAL OF CARNUBA WAX IN AMELIORATING BRITTLE FRACTURE DURING TABLETING  

Microsoft Academic Search

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

UHUMWANGHO MU; OKOR RS; ADOGAH JT