Methocel K100 Research Articles

Effect of coating material on dissolution profile of BCS class 1 anti-epileptic extended-release tablets

The coating is one of the crucial phases in the production of the tablet dosage form with extended-release profiles. Tablet coating has numerous benefits, including disguising the medicine's odor, taste, physicochemical protection, and safeguarding the drug from the stomach environment. The aim to conduct this study was to determine the effect of varying concentrations of coating solutions on dissolution profiles. Extended-release tablet dosage form of antiepileptic drug as a prototype was developed to ensure minimize fluctuation in drug plasma levels. Tablets were prepared using two grades of HPMC methocel K100 and methocel K15 H, along with anhydrous lactose and microcrystalline cellulose followed by film coating using different concentrations of opadry white via spraying method, and results were compared with the marketed formulation.

Controlled Release Formulation of Tofacitinib Citrate Tablets Evaluated Using Quality by Design (QBD) Approach

The goal of the project is to use the quality-by-design (QbD) method to create and optimise Tofacitinib citrate matrix tablets with controlled release excipients. The drug's physicochemical parameters, reference product characterisation, QTPP (Quality Target Product Profile), and CQAs were used to start product development (Critical Quality Attributes). Hypromellose (Methocel K100 premium LV CR), Polyethylene Oxide (SentryPolyox WSR N80 LEO), and Magnesium Stearate were used as formulation variables and were optimised together. The complete factorial design of experiment (DOE) with three centre points was used to investigate traditional monolithic controlled release matrix tablets. Using Design-expert12 programme, dissolution was assessed as CQA. At acidic pH, hypromellose with a higher viscosity grade provides a regulated release pattern by retaining the integrity of the medication and preventing rapid drug release. Due to the nonionic nature of the polymer, drug release from the polymer matrices is pH independent. Present monolithic controlled release matrix system the extensive degradation of Tofacitinib Citrate in the acidic condition can be avoided with desired in-vitro drug release.

Towards functional characterization of excipients for oral solid dosage forms using UV–vis imaging. Liberation, release and dissolution

The purpose of this study was to investigate whole-dosage form UV–vis imaging as a potential tool for functional characterization of excipients used in solid oral dosage forms. To this end, tablets (average mass 260.0 mg, 224.5 mg and 222.1 mg) containing theophylline anhydrate (20 % w/w), 1% (w/w) magnesium stearate, and 79 % (w/w) of either microcrystalline cellulose (MCC, Avicel PH 101) or hydroxypropyl methylcellulose (HPMC, Methocel K15 M or K100 M) were prepared as model systems. Drug liberation from tablets was studied in 0.01 M HCl at 37 °C using a Sirius SDi2 equipped with a USP IV type flow cell comprising a UV–vis imaging detector operating at 255 nm and 520 nm. The effluent from the flow cell was passed through a downstream spectrophotometer, and UV–vis spectra in the wavelength range 200–800 nm were recorded every 2 min. The erosion and swelling behavior of the MCC tablets and HPMC K15 M and K100 M tablets were visualized in real time. The swelling of HPMC K15 M and K100 M containing tablets was assessed quantitatively as changes in tablet diameter measured at 520 nm, and was clearly distinguished from the swelling of the MCC tablets. Namely, an increment of 2.5 mm in diameter was determined for the HPMC tablets while the MCC tablets increased by 0.5–1 mm in diameter. Gel layers of variable thickness were observed only for the HPMC K15 M and K100 M tablets. In addition, a relatively high initial liberation rate of theophylline was found for the MCC tablets as compared to the HPMC tablets. UV–vis imaging revealed features of liberation not revealed by simply measuring drug concentration in the dissolution media or by visual assessment. It may be sufficiently sensitive to be further developed for functional characterization of excipients and provide insights into drug-excipient interactions likely to be useful in formulation development.

Formulation and In vitro Evaluation of Unfolding Type Expandable Gastroretentive Film of Enalapril Maleate

The present work was based on the development and characterization of unfolding type gastroretentive dosage form appropriate for controlled release of enalapril maleate. Drug loaded films were prepared by solid dispersion technique using methocel K15 and eudragit RSPO and eudragit RLPO as polymers and polyethylene glycol 400 (PEG 400) as the plasticizer. The film folded in a capsule shell was shown to unfold in the gastric juice and provide drug release up to 12 h in the acidic medium. Formulations provided satisfactory unfolding characteristics allowing expansion to remain in the stomach. Formulation containing above 60% content of eudragit RSPO and eudgrait RLPO combination of total polymer content provided satisfactory film integrity over 12 hours. The result revealed that formulation F1 showed a minimum percentage of drug release of 63.41% followed by formulation F2, F3, F4 and F5 with 66.76%, 80.21%, 83.26% and 86.92% release in 8 hour respectively. Formulation with high proportion of eudragit RLPO and RSPO combination in total polymer content was found to be slow in drug release and lower the release from the polymeric film over time. As the concentration of HPMC K 15 in total polymer content increased the release rate of enalapril maleate as well as % release from the polymeric film also increased over time. Most of the formulation followed Higuchi release kinetics followed by Korsmeyer release kinetics. The drug release mechanism from the film follows Fickian and Non Fickian release kinetics. The films were evaluated for mechanical properties, in vitro drug release and unfolding behavior based on the mechanical shape memory of polymers. Absence of drug polymer interaction and uniform drug dispersion in the polymeric layers was revealed by DSC, FT-IR and SEM studies.Bangladesh Pharmaceutical Journal 20(2): 148-154, 2017

A novel co-processed directly compressible release-retarding polymer: In vitro, solid state and in vivo evaluation

Directly compressible (DC) co-processed excipient capable of providing nearly zero order release with improved functionality was developed without any chemical modification by employed various techniques such as physical mixing, high shear mixer granulation and spray drying. Co-processed excipient was developed by using release retarding polymer Eudragit RSPO, separately, in combination with different concentration of hydroxyl propyl methyl cellulose 100 cps (Methocel K100 LV, HPMC), ethyl cellulose (Ethocel N50, EC) and hydroxyl propyl cellulose (Klucel EF, HPC). All co-processed excipients were evaluated for their flow properties in terms of angle of repose, bulk density, tapped density, compressibility index and Hausner's ratio. Out of eighteen combinations, the nine co-processed excipients exhibited promising flow properties were found suitable for direct compression and formulated as tablets. Metoprolol succinate, a BCS Class I drug, was selected as a model drug and the formulation was developed employing direct compression approach. The developed tablets were evaluated for physical parameters like uniformity of weight, thickness, hardness, friability and assay. In vitro dissolution study confirms that formulation prepared using co-processed excipient showed sustained drug release. The optimized tablet formulation was characterized by DSC, FTIR and PXRD which confirms the absence of any chemical change during co-processing. The optimized formulation was kept for stability study for six months as per ICH guidelines and found to be stable. In vivo pharmacokinetic study of optimized formulation in rats showed similar pharmacokinetic behaviour as was observed with the marketed brand. Study revealed that co-processed excipient has advantage over polymers with single property and can be utilised for sustained release formulation.

Formulation and in vitro Evaluation of Glimepiride Sustained Release Tablets: Comparison with Immediate Release Tablets

This work aims at the design of a sustained release formulation of glimepiride which is currently available in the treatment of type 2 diabetes mellitus and to investigate the effect of polymers on the release profile of glimepiride. Glimepiride sustained release tablets were prepared by direct compression method using different ratios of various release retarding polymers such as carbopol, ethyl cellulose, methocel K4 MCR, methocel K15 MCR, methocel K100 MCR and xanthum gum. These formulations were also compared with glimepiride immediate release tablets. The prepared tablets were subjected to various physical parameter tests including weight variation, friability, hardness, thickness, diameter, etc. In vitro dissolution studies of the formulations were done at pH 6.8 in phosphate buffer using USP apparatus 2 (paddle method) at 50 rpm. The percent releases of all the formulations (30) were 73.11%- 98.76% after 8 hours. The release pattern followed zero order kinetics and the release of the drug was hindered by the polymers used in the study. On the other hand, 100% drug was released within 1 hour from the immediate release tablet of glimepiride. The study reveals that the polymers used have the capacity to retard the release of the drug from the sustained release tablets and the more is the amount of the polymer in the formulation the less is the release of drug showing more retardation of drug release.Bangladesh Pharmaceutical Journal 18(2): 157-162, 2015

Effect of Channeling Agents on Release Kinetics of Stavudine from Methocel K100 LVCR and Ethocel 20 cps Based Matrix Tablets

The study was performed to investigate the effect of channeling agent on the release profile of Stavudine from Methocel K100 LVCR and Ethocel 20 cps based matrix systems. Stavudine, a nucleoside analog drug, is used in the treatment of acquired immune deficiency syndrome (AIDS). Stavudine matrix tablet was prepared using Methocel K100 LVCR and Ethocel 20 cps as polymer and also using PEG 3350 and PEG 6000 as channeling agents. The drug release mechanisms from different matrix tablets were explored and explained by zero order, first order, Higuchi, Korsmeyer and Hixson-Crowell equations. The release rate, extent and mechanisms were found to be governed by polymer type used and the content of the channeling agent. It was found that the release of drug from the matrix tablet was increased with the increasing concentration of channeling agent. However, PEG 6000 enhanced the release of drug greater than PEG 3350 from the matrix. On the other hand, Stavudine matrix containing Ethocel 20 cps showed a strong tendency to retard the drug release to 51-56% after 8 hours of dissolution, whereas the release was found to be increased for the Methocel containing matrix to 90-100%. Kinetic modeling of dissolution profiles revealed drug release mechanism ranged from diffusion controlled or Fickian transport to anomalous type or non- Fickian transport, which was mainly dependent on the presence of relative amount of channeling agent and type of polymer. These studies indicate that the proper balance between a matrix forming agent and a channeling agent can produce optimum drug dissolution kinetics from Stavudine matrix tablet. The mechanism was also revealed by Scanning Electron Microscope (SEM) pictures taken at various intervals of dissolution which showed that the extent of pore formation in the matrix increases with the increasing amount of channeling agent and also the hydrophilic nature of the polymer used in the formulation.Dhaka Univ. J. Pharm. Sci. 14(1): 91-101, 2015 (June)

Effect of solubility enhancers on the release of Carbamazepine from Hydrophilic Polymer based matrix tablet

In the present study, an attempt has been taken to evaluate the effect of sodium lauryl sulphate (SLS) and glyceryl mono stearate (GMS) as solubility enhancers on the release profile of a poorly soluble drug, carbamazepine. Matrix tablets of carbamazepine were prepared by wet granulation technique using hydrophilic polymers (10% of Methocel K15 MCR and 10% of Methocel K100LV CR) as release controlling agents. Varying amounts of SLS and GMS were used in six different formulations to observe the impact on the release rate and mechanism of drug release. The dissolution study of carbamazepine from these extended release matrix tablets was conducted for 24 hours using basket method in 900 ml distilled water as dissolution medium. The data obtained from the dissolution studies were explored and explained with the help of zero order, Higuchi, first order, Korsmeyer- Peppas and Hixson-Crowell equations. It was found that the dissolution rate of carbamazepine with the formulation containing SLS was higher than GMS containing formulation and increased concentration of SLS increasing the release rate. Where there was no SLS or smaller amount of SLS or GMS release rate was decreased. Formulation having equal ratio of SLS and GMS did not show the desire release profile. The drug release mechanism followed mainly super case II transport. These results clearly demonstrated that the dissolution rate, extent and mechanism of carbamazepine release could be changed by optimizing the amount of SLS and GMS in the tablet formulation. DOI: http://dx.doi.org/10.3329/dujps.v13i2.21894 Dhaka Univ. J. Pharm. Sci. 13(2): 167-173, 2014 (December)

Gastroretentive inorganic–organic hybrids to improve class IV drug absorption

Therapeutic efficacy of some orally administered molecules is often conditioned by their solubility in physiological fluids as well as their absorption. The last aspect becomes more limitative and conditioning drug plasmatic profiles when the active ingredient is preferentially absorbed in a specific region of the gastrointestinal tract. A case is represented by furosemide (FURO) preferentially absorbed in the stomach, site in which, because of its acidic nature, is poorly soluble. To solve this problem new oral solid formulations have been developed. The inorganic–organic hybrid MgAl-HTlc-FURO has been formulated in tablet in which floating and mucoadhesion properties have been combined. Swellable (Methocel K4, Methocel K15, Methocel K100 M, hydroxypropyl methyl cellulose) or swellable/erodible polymers (Methocel E50 LV, Methocel K100 LV), used to obtain the floating, were combined to Carbopol® (971P or 974P) to confer mucoadhesion capacity. Prepared tablets were deeply characterized in terms of hydration capacity, erosion %, buoyancy lag time/floating time and mucoadhesion. The most suitable tablets selected from these preliminary tests, submitted to in vitro release studies, showed a sustained release of FURO. This is useful to maintain the therapeutic concentrations for a long time, in comparison to conventional dosage forms, thanking to the enhancement of formulation residence time in the stomach.

Preparation of Metformin Hydrochloride Extended Release Matrix Tablets by Direct Compression Method and Its In vitro Evaluation

Aims: Metformin Hydrochloride, a biguanide, is an orally active antihyperglycemic agent, used in the treatment of non-insulin dependent diabetes mellitus (NIDDM). It has relatively short plasma half life, low absolute bioavailability. Extended release formulation of Metformin Hydrochloride by direct compression method has significant challenges due to its poor inherent compressibility and high dose. The aim of this study was to develop extended release tablets of Metformin Hydrochloride by direct compression method and In vitro evaluation.Study Design: Nine different formulations were made by varying drug-polymer ratio and were subjected to different physical property tests of the powder blend as well as prepared tablets, followed by dissolution test.Place and Duration of Study: Department of Pharmacy, State University of Bangladesh, Dhaka, Bangladesh, between January 2013 and July 2013.Methodology: Nine formulations of Metformin Hydrochloride matrix tablets - F-1, F-2, F-3, F-4, F-5, F-6, F-7, F-8 and F-9 - were prepared by direct compression method using release retarding materials, Methocel K100 MCR Premium (derivative of hydroxypropyl methylcellulose - HPMC) and Xanthan gum. The drug and polymer ratio were 1:0.41, 1:0.45, 1:0.49, 1:0.59, 1:0.63, 1:0.67, 1:0.77, 1:0.81 & 1:0.85 respectively. The micromeritic behavior of the powder blends were evaluated for bulk density, angle of repose, compressibility index along with post compressional attributes of the tablets such as thickness, hardness, friability, weight variation and content of Metformin Hydrochloride in the tablets. The in-vitro drug release study was carried out in 1000 mL phosphate buffer medium (pH 6.8) at 37±0.5°C at 100 rpm for 10 hours using USP Apparatus Type-II (paddle) method.Results: FT-IR study showed drug-excipient compatibility and DSC analysis showed no solid state interaction between components. The physical properties of the powder blend and the tablets were within the acceptable limits. Maximum and minimum drug release were found in formulation F-1 and F-9 respectively which indicate that release rate is inversely proportional to the concentration of Methocel K100 MCR Premium and Xanthan gum in combination. Dissolution study also showed that, formulations F-7, F-8 & F-9 do not comply with drug release specification of USP and among the rest six formulations F-3, F-4 & F-5 comply better with drug release specification of USP. After fitting the data to Korsmeyer-Peppas equation we found that diffusion along with erosion could be the mechanism of drug release.Considering the micromeritic behaviour of the powder blend, physical attributes of the compressed tablets, and dissolution, formulation F-4 seemed most suitable.Conclusion: Extended release Metformin Hydrochloride tablets can be produced to overcome frequent dosing related problems. However, Further study on formulation optimization and scale up, stability and bioequivalence is needed to confirm the appropriateness of these formulated extended release tablets.

The effect of hydrophilic and hydrophobic polymers on release profiles of diclofenac sodium from matrix tablets

Objective: The current study aimed to develop a matrix type sustained release Diclofenac tablet, using hydrophilic hydroxypropyl methylcellulose (HPMC) and hydrophobic polymer cetyl alcohol (CA). Materials and Methods: Two different polymers, that is, Methocel K15MCR ® and CA were used in various proportions as release controlling factor. Matrix tablets were prepared by wet granulation technique. The physicochemical properties of the granules and tablets were evaluated. In vitro dissolution studies of prepared matrix tablet and patent product Voltaren SR ® tablet (VSR) were performed at pH 7.4 phosphate buffer at 100 rpm, and at 37 ± 0.5°C, and subjected to in vitro bioequivalence study in terms of similarity and difference factors. Stability studies were conducted for 6 months using optimized formulation for extended period of time, both at room temperature and accelerated conditions. The dissolution data were fit to Zero‑order, First‑order, Higuchi, and Korsmeyer‑Peppas’ equations. Results: The formulated tablets showed acceptable weight variation, hardness, drug content uniformity with sustained release matrix characteristics. Hydrophilic Methocel K15 MCR ® matrices‑based tablets showed zero‑order and hydrophobic CA matrices‑based tablets followed first‑order kinetics except for formulation six (F6 showed zero‑order profile). It was found that formulations containing CA showed better dissolution properties with respect to formulations containing Methocel K15 MCR ® in terms of similarity and difference factor. Furthermore, the formulations F4, F5, and F6 exhibited similar drug release profile as compared with VSR tablet, which indicated that these formulations could be bioequivalent with VSR tablet in vitro. Tablets were stable both at room temperature and as well as at accelerated conditions. Conclusion: The present study demonstrated that Diclofenac could be successfully prepared using an appropriate amount of Methocel K15 MCR ® and CA in the form of matrix tablets with similar dissolution profile of patent product Voltaren SR ® . The type of polymers used was found to induce a profound effect on release rate and mechanism.

Formulation and characterization of gastroretentive drug delivery system of losartan potassium

Floating matrix tablets of losartan potassium were developed with an aim to prolong its gastric residence time and increase the bioavailability of drug. Rapid gastrointestinal transit could result in incomplete drug release from the drug delivery system above the absorption zone leading to diminished efficacy of the administered dose. The tablets were prepared by wet granulation technique, using polymers Methocel K15 and Methocel K100 in combination with other standard excipients. Sodium bicarbonate was incorporated as gas generating agent. The effects of sodium bicarbonate and polymers on drug release profile and floating properties were investigated. It was found that viscosity of Methocel K15 and Methocel K100 along with sodium bicarbonate had significant impact on the release and floating properties of the delivery system. The decrease in the release rate was observed with an increase in the viscosity of the polymeric system. Polymer with high viscosity Methocel K100 was shown to be beneficial than low viscosity polymer Methocel K15 in improving the floating properties of gastric floating drug delivery system (GFDDS). The observed difference in the drug release and floating properties of GFDDS could be attributed to the difference in the basic properties of two polymers, Methocel K15 and Methocel K100 due to their water uptake potential and functional group substitution. The release mechanism were explored and described with zero-order, first-order and Korsmeyer-Peppas equations. The drug release profiles and buoyancy of the floating tablets were stable when stored at 40°C/75% RH for 6 months.DOI: http://dx.doi.org/10.3329/icpj.v2i1.12872 International Current Pharmaceutical Journal 2012, 2(1): 11-17

Development and in vitro Evaluation of Sustained Release Matrix Tablets of Indapamide from Methocel® K15 MCR and K100 LVCR

Indapamide, a low-dose thiazide-type diuretic, is used for the treatment of essential hypertension. In this study, we developed an indapamide sustained release formulation using Methocel K15 MCR (a modified hydroxypropyl methylcellulose), Methocel K100 LVCR (a modified hydroxypropyl methylcellulose), magnesium stearate, talc and starch 1500 by direct compression. The powders for tableting were evaluated for angle of repose, loose bulk density, tapped bulk density, compressibility index, total porosity etc. The tablets were subjected to thickness, weight variation test, hardness, friability and in vitro release studies. The in vitro dissolution study was carried out in the gastric medium (pH 1.3) for first two hours and then in the intestinal medium (pH 6.8) for 22 hours using United States Pharmacopoeia (USP) 22 paddle-type dissolution apparatus. The granules showed satisfactory flow properties, compressibility index etc. All the tablets complied with pharmacopoeial specifications. The results of dissolution studies indicated that the formulation F-5 and F-7 (up to 75.36 % drug release in 12 hours) could extend the drug release up to 12 hours. The drug release patterns were simulated in different kinetic orders such as Zero Order release kinetics, First Order release kinetics, Higuchi release kinetics, Korsmeyer-Peppas release kinetics and Hixson-Crowell release kinetics to assess the release mechanism. From the study we observed that Higuchi release kinetics was the predominant release mechanism than Zero Order and First Order kinetics. The drug release mechanism from the matrix tablets was found to be non Fickian mechanism. DOI: http://dx.doi.org/10.3329/dujps.v10i2.11785 Dhaka Univ. J. Pharm. Sci. 10(2): 87-92, 2011 (December)

Optimization of metoprolol tartrate modified- release matrix tablet formulation using Eudragit NE as binder for metoprolol fluid bed granulation

The aim of this experimental work was to investigate the possibility of obtaining hydroxypropyl methylcellulose (HPMC) hydrophilic matrix extended-release dosage forms with metoprolol by using aqueous dispersions of Eudragit NE, as binders in fluid bed granulation. To evaluate the influence of formulation variables (levels of HPMC—Methocel K100 M and Surelease E7 19010) on drug release during a period of time of 12 hours, and on the kinetic release, a full factorial experimental design with two factors and three levels was used. The formulation factors were the granulation polymer concentration and the matrix-forming polymer concentration. The obtained results have shown that the percentage of the drug released during the 12 hours is influenced both by the Methocel ratio and the Eudragit NE ratio; increasing the ratios of Eudragit and Methocel leads to the decrease of the percentage of the released drug.The influence of Eudragit NE percentage is maximum at four and six hours, but the influence of Methocel K100 M concentration is almost the same at all sampling times; all studied formulations showed a kinetic release that fitted best with the Peppas model.

An Emerging Trend in Tablet Technology:- Floating Tablets of Ranitidine HCl .

The rationale of this research was to prepare a gastroretentive drug delivery system of Ranitidine HCL. Floating Drug delivery system used to target drug release in the stomach or to the upper part of the intestine. The oral delivery of Ranitidine is tested by preparing a non-disintegrating floating dosage form, which increase its absorption in the stomach by increasing the drug’s gastric residence time. The polymer PVC and Sodium bicarbonate was used as the gas–generating agents. Sodium bicarbonate causes the tablets to floats for more then 24hr. The prepared tablets were evaluated on their physicochemical properties and drug release characters. In-vitro release studies indicate that the Ranitidine release form the floating dosage form was uniform followed zero order release. A combination of sodium bicarbonate (70mg) and citric acid (15mg) was found to achieve Optimum in vitro buoyancy. The tablets with methocel K100 were found to float for longer duration of time as compared to formulations containing methocel K15M. The drug release from the tablets was sufficiently sustained. Keywords: Ranitidine; Floating tablets; Methocel

In-vitro Studies of Pentoxifylline Controlled-Release from Hydrophilic Matrices

Methocel K15 MCR (a modified hydroxypropylmethylcellulose) matrix tablets of pentoxifylline using microcrystalline cellulose (MCC), starch and lactose were prepared by wet granulation process. There was no significant difference in drug release between the hydrophilic matrices when the Methocel K15 MCR concentration was modified in low percentage. The release of pentoxifylline was influenced by the presence of microcrystalline cellulose, and by the different concentrations of starch and lactose. The data obtained proved that the formulation with 12.5% Methocel K15 MCR and 20% lactose is more useful for a controlled release pentoxifylline, due to the percentage released after 8 hours is nearly to 65%. There was no significant change on release profile after three months storage of tablets. The best-fit release kinetics was achieved with the Higuchi model, followed by the first-order plot.Keywords: Pentoxifylline; Controlled release; Methocel K15 MCR.© 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v1i2.1080

Formulation and Evaluation of Famotidine Floating Tablets

The purpose of this investigation was to prepare a gastroretentive drug delivery system of famotidine. Floating tablets of famotidine were prepared employing two different grades of methocel K100 and methocel K15M by effervescent technique; these grades of methocel were evaluated for their gel forming properties. Sodium bicarbonate was incorporated as a gas-generating agent. The floating tablets were evaluated for uniformity of weight, hardness, friability, drug content, in vitro buoyancy and dissolution studies. The effect of citric acid on drug release profile and floating properties was investigated. The prepared tablets exhibited satisfactory physico-chemical characteristics. All the prepared batches showed good in vitro buoyancy. The tablet swelled radially and axially during in vitro buoyancy studies. It was observed that the tablet remained buoyant for 6-10 hours. Decrease in the citric acid level increased the floating lag time but tablets floated for longer duration. A combination of sodium bicarbonate (130mg) and citric acid (10mg) was found to achieve optimum in vitro buoyancy. The tablets with methocel K100 were found to float for longer duration as compared with formulations containing methocel K15M. The drug release from the tablets was sufficiently sustained and non-Fickian transport of the drug from tablets was confirmed.

Preparation and Evaluation of a Sustained-Release Formulation of Nifedipine HPMC Tablets

A nifedipine (NF) polyethylene glycol (PEG) solid dispersion was prepared. Using this solid dispersion, NF hydroxypropylmethylcellulose (HPMC) matrix tablets were prepared. Both the high-viscosity grade HPMC (Methocel K15M) and low-viscosity grade HPMC (Methocel K100) were applied in the tablets to form the matrix. The dissolution and absorption of NF from the tablet were evaluated as a formulation that had a sustained release over 24 hr. The Hixson-Crowell equation and Higuchi equation were used to investigate the dissolution mechanism, and the erosion and diffusion codependent mechanism was established. Adalat GITS 30 was used as a reference dosage form. Each beagle dog was also administered an intravenous injection to obtain the pharmacokinetics parameters. The Loo-Riegelman method was applied to study the in vitro/in vivo correlation of the tested tablets and Adalat GITS 30, and significant correlation was proved. Absolute bioavailability and comparative bioavailability of the tested tablet were studied. The results indicated that the NF HPMC tablet could be an ideal 24-hr sustained-release formulation.

Formulation of biphasic release tablets containing slightly soluble drugs

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 viscosity grades (Methocel K4, K15 and K100M) were used to obtain different release rates of the drug from the extended-release layer, ketoprofen and praziquantel were used as slightly soluble model drugs.The in vitro dissolution tests of the prepared double-layer systems, showed the desired biphasic behaviour: the drug contained in the fast releasing layer dissolved within the first 15 min, while the drug contained in the prolonged-release layer was released at different times, depending on the formulation of the hydrophilic matrix. In particular, an increase in the percentage and viscosity grade of HPMC, in the extended release layer, leads to a decrease in the drug delivery rate and produces a wide range of different release rates from only a few hours up to 24 h.

<i>In vitro</i> Release Kinetic Study of Esomeprazole Magnesium from Methocel K15M and Methocel K100 LVCR Matrix Tablets

In the present study esomeprazole sustained release tablet matrix was prepared by utilizing different grades of hydroxypropyl methylcellulose (HPMC) polymers such as Methocel K15M & Methocel K100 LVCR by direct compression method. Different amount of Methocel K15M was used to develop matrix builder in the seven proposed formulations (F1-F7) for the study of release rate retardant effect at 20%, 25%, 30%, 35%, 40%, 45% and 50% of total weight of tablet matrix respectively. The dissolution study of Methocel K15M based tablet matrices of those proposed formulations were carried out in the simulated gastric medium (pH 1.3) for first two hours and then in the simulated intestinal medium (pH 6.8) for 8 hours using USP dissolution apparatus II. The formulation F-5 (40%) and F-6 (45%) met the optimum release rate of esomeprazole for 10h period of in vitro dissolution study. The release kinetics of formulation F-5 and F-6 very closely followed Higuchi kinetic order than first order and zero order kinetics. Similarly Methocel K100 LVCR was used to develop matrix builder in another seven proposed formulations (F8-F14). It was found that formulations F-11 (35%), F-12 (40%) and F-13 (45%) met the desired release rate of esomeprazole for 10h period. The release kinetics of formulation F-11, F-12 and F-13 followed Higuchi kinetic order. Between these two polymers, Methocel K100 LVCR showed better release retardant effect than Methocel K15M. Key words: Esomeprazole, Direct compression, Controlled release, Methocel K15M and Methocel K100 LVCRDOI = 10.3329/dujps.v7i1.1216 Dhaka Univ. J. Pharm. Sci. 7(1): 39-45, 2008 (June) Â