Methocel K4M Research Articles

Preparation and Evaluation of Carbamazepine Sustained Release Tablets

The purpose of the present studies was to develop and characterize sustained release tablets of Carbamazepine, an antiepileptic drug. Tablets were prepared by direct compression method. In the formulation, the active drug was taken 200 mg in every formulation. Methocel K4M, Methocel K15M CR, Methocel K100LV CR, Eudragit RSPO and Eudragit RLPO polymers were used as rate retarding agents in twenty four formulations (F-1 to F-24). The effect of hydrophilic polymer PEG 6000 as channeling agent with Methocel K4M was observed in four formulations (F-5 to F-8). The granules were evaluated for angle of repose, bulk density, tapped density. The tablets were subjected to average weight, diameter, thickness, weight variation, hardness, friability and in vitro dissolution studies. The granules showed satisfactory flow properties, compressibility and drug content. The in vitro dissolution study was carried using USP Apparatus-I (Rotating basket method apparatus) for 6 to 12 hours in distilled water with 1% sodium lauryl sulphate as the dissolution medium. The release mechanisms were explored and explained by Zero order, First order, Higuchi, Korsmeyer-Peppas and Hixson-Crowell equations. Primarily twelve formulations were prepared by using four variable amount of three polymers; Methocel K4M (50, 100, 150 and 200 mg) in the formulations from F-1 to F-4, Methocel K15M CR (50, 100, 150 and 200 mg) in the formulations from F-9 to F-12 and Methocel K100LV CR (50, 100, 150 and 200 mg) in the formulations from F-13 to F-16. Then four formulations were prepared where Methocel K4M amount was same but using variable amount of hydrophilic polymer PEG 6000 (50, 100, 150 and 200 mg). After that another eight formulations were prepared by using polymer Eudragit RSPO and Eudragit RLPO by using variable amount. In F-17 to F-20 the use of Eudragit RSPO was in variable amount (50, 100, 150 and 200 mg) and in F-21 to F-24 the use of Eudragit RLPO was in variable amount (50, 100, 150 and 200 mg). Other excipients remained same in the formulations. Among these twenty four formulations’ sustainability was studied and compared with three market product of 200 mg tablet. It was found that effect of PEG 6000 as channeling agent subsequently decreased the sustaining action (Formulation F5-F8). DOI: http://dx.doi.org/10.3329/dujps.v11i2.14577 Dhaka Univ. J. Pharm. Sci. 11(2): 173-180, 2012 (December)

Design and Development of Sustained Release Microspheres of Ibuprofen by Emulsification Solvent Evaporation Method Using Polymeric Blend

Ibuprofen, a non-steroidal anti-inflammatory drug was formulated as microspheres by using Methocel K4M & Eudragit RSPO. These microspheres were prepared by emulsification solvent evaporation method to provide sustained action and to minimize local side effect of Ibuprofen by avoiding the drug release in the upper gastrointestinal tract. The prepared microspheres were subjected to various evaluation and in-vitro release studies. In-vitro drug release was studied in a paddle type dissolution apparatus (USP Type II Dissolution Apparatus) using Phosphate buffer (pH 7.4) as the dissolution medium at 37.5oC for 6 hours (paddle speed 50 RPM). The release mechanisms were explored and explained with Zero Order, First Order, Higuchi and Korsmeyer-Peppas equations. The correlation coefficients values of the trend lines of the graphs showed that the formulations best fit with Korsmeyer-Peppas release pattern. Microspheres’ morphology and chemical integrity were studied by a scanning electron microscope (SEM) and Fourier transforms infrared spectroscopy (FTIR) respectively. DOI: http://dx.doi.org/10.3329/bpj.v16i1.14489 Bangladesh Pharmaceutical Journal 16(1): 39-44, 2013

Development and evaluation of Methocel K15M based Theophylline floating tablets

Effect of Self-Microemulsifying Lipid Formulations on the Dissolution and Compaction Profiles of Tablets Containing Theophylline; A BCS Class I CompoundNaser M.Y. Hasan, Mohammad A. Khaleel, Abdullah S. Altwairqi, Abdulmajeed G. Alqurashi, Abduallah H. Altwairqi

An Improvement of Efficacy of Moxifloxacin HCl for the Treatment of Bacterial Keratitis by Formulation of Ocular Mucoadhesive Microspheres

The aim of this study was to prepare novel ocular mucoadhesive microspheres of Moxifloxacin HCl to increase its residence time on the ocular surface and to enhance its therapeutic efficacy in ocular bacterial keratitis. Microspheres were fabricated with different grades of Methocel and Sodium CMC as polymers. Microspheres were evaluated for their particle size, morphology, encapsulation efficiency, mucoadhesion, antimicrobial efficacy, and in vitro drug release studies. In vivo studies were carried out for the promising formulation on eyes of albino rabbits by inducing bacterial keratitis. A sterile microspheres suspension in light mineral oil was applied to infected eyes twice a day. A marketed conventional eye drop was used as a positive control. Eyes were examined daily for improvement of clinical signs of bacterial keratitis by an ophthalmologist. The average particle size of microspheres was found to be less than 80 μm. Methocel microspheres were found to have a smoother surface than Sodium CMC. Entrapment efficiency was enhanced with an increased polymer concentration and viscosity. The formulation containing Methocel K100M with a drug: polymer ratio of 1:2 exerted longer corneal and conjunctival mucoadhesion time of 8.45±0.15 h and 9.40±0.53 h respectively. In vitro release of Moxifloxacin HCl from microspheres was retarded with increased viscosity and concentration of polymers, and was controlled by diffusion as well as polymer relaxation. All formulations showed comparable antimicrobial activity in comparison with conventional marketed eye drops. The formulation containing Methocel K100M with a drug: polymer ratio of 1:2 was found to be a promising formulation and was used for the in vivo studies. The in vivo studies revealed that microspheres demonstrated significantly lower clinical scores and reduced the total duration of therapy than the marketed Moxifloxacin HCl eye drops. In vitro and in vivo studies showed that ocular mucoadhesive microspheres of Moxifloxacin HCl were found to have an improved efficacy in the treatment of ocular bacterial keratitis in comparison with the marketed formulation.

Formulation and Evaluation of Gastro Retentive Floating Tablets of Simvastatin using Hydrophilic Rate Retardant

Gastro retentive floating tablet of Simvastatin was prepared by direct compression technique using Methocel K4M as the rate controlling polymer. The hydrophilic cellulose derivative, Methocel K4M was evaluated for its gel forming and release controlling properties. Sodium bicarbonate and citric acid were incorporated as gas generating agents. The effects of soluble components (sodium bicarbonate and citric acid) and gel forming agents on drug release profile and floating properties were investigated. The tablets from all formulations were evaluated for thickness, diameter, weight variation, hardness, and friability. The tablets were also tested for the buoyancy studies and in vitro drug release studies. The drug release study was evaluated for eight hours using USP XXII paddle-type dissolution apparatus using 0.1N HCl with 1% Sodium Lauryl Sulphate as dissolution medium. The release mechanisms were explored and explained with zero order, first order, Higuchi, Hixon Crowell and Korsmeyer equations. The release rate, extent and mechanisms were found to be governed by the polymer content. It was found that the mean dissolution time, percentage drug release, release rate constant and diffusion exponent were influenced significantly by the amount of polymer incorporation. DOI: http://dx.doi.org/10.3329/bpj.v15i2.12575 Bangladesh Pharmaceutical Journal 15(2): 119-126, 2012

Formulation Development and in vitro Evaluation of Drug Release Kinetics from Sustained Release Aceclofenac Matrix Tablets using Hydroxypropyl Methyl Cellulose

The objective of the present study was to develop a once-daily sustained release matrix tablet of Aceclofenac using hydroxypropyl methyl cellulose (Methocel K 100M CR) as release controlling factor and to evaluate drug release parameters as per various release kinetic models. The tablets were prepared by direct compression method. The powder blends were evaluated for angle of repose, loose bulk density, tapped bulk density, compressibility index, total porosity and drug content etc. The tablets were subjected to thickness, weight variation test, drug content, hardness, friability and in vitro release studies. The in vitro dissolution study was carried out for 24 hours using United States Pharmacopoeia (USP) 22 paddle-type dissolution apparatus in phosphate buffer (pH 7.4). The powder blends showed satisfactory flow properties, compressibility index and drug content etc. All the tablet formulations showed acceptable pharmacotechnical properties and complied with pharmacopoeial specifications. The results of dissolution studies indicated that the formulation F-3 (40% Methocel K100M CR of total weight of tablet) could extend the drug release up to 24 hours and the total release pattern was very close to the theoretical release profile. By comparing the dissolution profiles with the originator brand of Arrestin SR, the formulation F-3 exhibited drug release profile like originator brand. From this study, a decrease in release kinetics of the drug was observed by increasing the polymer concentration. Kinetic modeling of in vitro dissolution profiles revealed the drug release mechanism ranges from diffusion controlled or Fickian transport to anomalous type or non-Fickian transport, which was only dependent on the type and amount of polymer used. The drug release followed both diffusion and erosion mechanism in all cases. The drug release from the formulation (F-3) was satisfactory after 3 months storage in 400C and 75% RH. Besides, this study explored both of the optimum concentration and effect of polymer(s) on Aceclofenac release pattern from the tablet matrix for 24 hour period. The matrix tablet of Aceclofenac using HPMC with molecular weight of K100M controlled the drug release effectively for 24 hours; hence the formulation can be considered as a once daily sustained release tablet of Aceclofenac in order to improve patient compliance. DOI: http://dx.doi.org/10.3329/dujps.v11i1.12485 Dhaka Univ. J. Pharm. Sci. 11(1): 37-43, 2012 (June)

Preparation and Evaluation of Gastro Retentive Floating Tablets of Atorvastatin Calcium

This investigation describes the preparation and in vitro evaluation of gastro retentive floating tablets of atorvastatin calcium. Two hydrophilic cellulose derivatives, Methocel K4M and Methocel K15M CR were used in floating tablets as gel forming agents to control drug release. Sodium bicarbonate and citric acid were incorporated as gas generating agents. The tablets prepared by direct compression technique were evaluated by various quality parameters including weight variation, hardness and buoyancy studies. In vitro drug release was determined for eight hours using USP XXII paddle-type dissolution apparatus in 0.1N HCl solution containing 1% sodium lauryl sulphate. The release mechanisms were explored and explained with zero order, first order, Higuchi and Korsmeyer equations. The release rates, extent and mechanisms, were found to be governed by polymer loading. It was also found that the polymer content significantly affected the mean dissolution time, percentage of drug release, release rate constant and diffusion exponent. Based on the dissolution data and floating time, formulation F-3 containing Methocel K4M and F-9 containing Methocel K15M CR may be considered as the best formulation. So an effective floating tablet of atorvastatin calcium can be prepared by using both the grades of HPMC. DOI: http://dx.doi.org/10.3329/dujps.v10i2.11784 Dhaka Univ. J. Pharm. Sci. 10(2): 79-85, 2011 (December)

Formulation and in vitro Evaluation of Betahistine Dihydrochloride Twice Daily Controlled Release Matrix Tablet

In order to reduce dosing frequency, a sustained release dosage form of betahistine dihydrochloride was developed as a twice daily controlled release tablet formulation that could be used to decrease vertigo resulted in Meniere's disease for a prolonged time. Six formulations were developed by using Methocel K4M CR, Methocel K15M CR and Methocel K 100 LVCR as single and combinations in different percentage. The tablets were prepared by wet granulation method. Physical properties of betahistine dihydrochloride granules and betahistine dihydrochloride matrix tablets were evaluated. The tablets were characterized for Betahistine Dihydrochloride release in both gastric simulated fluid (0.1 N HCl, pH 1.3) and simulated intestinal fluid (buffer solution pH 6.8). The data were subjected to different models in order to evaluate their release kinetics and mechanisms. The results of the in vitro dissolution study indicate that most of the formulations showed above 80% of drug release in 12 hours but formulations (F-2 and F-4) met the official specification of release profile. Dissolution data were fitted to zero order equation, Higuchi square root law, Korsmeyer-Peppas model and Hixson-Crowell cube root law as these plots showed the highest value of linearity to evaluate kinetic data. The release of betahistine dihydrochloride was prolonged for 12 hours indicating the usefulness of the formulations for twice daily dosage forms, leading to improve efficacy, controlling the release and better patient compliance. DOI: http://dx.doi.org/10.3329/dujps.v10i2.11786 Dhaka Univ. J. Pharm. Sci. 10(2): 93-100, 2011 (December)

Formulation and Evaluation of Extended Release Solid Dispersions Conatining Simvastatin

The purpose of this research was to formulate and characterize solid dispersion (SD) of Simvastatin using Polyethylene glycol 4000 as the hydrophilic carrier and Methocel K15M as the release retardant by the solvent evaporation and co-grinding method. The influence of drug polymer ratio on drug release was studied by dissolution testing. Characterization was performed by Fourier Transform Infrared Spectroscopy (FTIR), and Ultraviolet Spectroscopy. Release data were examined kinetically. SD with 1:2 and 1:3 ratio of drug to polymer obtained by solvent evaporation and co-grinding were selected as the best candidates suitable for prolonged-release oral dosage form of Simvastatin. KEYWORDS: Co-grinding, Simvastatin, Methocel, Solid dispersion, Solvent evaporation.

Instant Powder of Malabar Tamarind Fruit Extract Prepared by Foam-Mat Method

Garcinia cambogia (Malabar tamarind) is a native plant of Southeast Asia which its dried rind has been extensively employed as an ingredient of the traditional food seasoning and dietary supplements for weight loss. This study aims to prepare the malabar tamarind fruit extract in form of stable foam mat. The development was performed using 1% w/v hydroxypropyl methylcellulose (Methocel K15M) and maltodextrin as foaming agent and foam carrier respectively. The contents of foaming agent were varied: 10, 20, 30, 40 and 50 percent and the contents of foam carrier were also varied: 20, 30, 40 and 50 percent. Highest content of foamed powder received when 50 percent of foaming agent was used and the content of foamed powder was much higher when maltodextrin was added. However, maltodextrin higher than 20 % can cause the disruption of foam formation and resulting in lower yield of foamed powder. Thus malabar tamarind instant powder could be prepared by foam-mat method using 50 percent of 1% methocel and 20 percent of maltodextrin as foaming agent and foam carrier, respectively. Foamed powder of malabar tamarind extract obtained after drying with hot air oven at 70 °C was bulky and stable.

Formulation and evaluation of delayed-onset extended-release tablets of metoprolol tartrate using hydrophilic-swellable polymers

In view of the circadian rhythm of cardiovascular diseases, a delayed-onset extended-release (DOER) formulation of metoprolol tartrate (MT) was prepared. This was achieved through dissolution-guided optimization of the proportion of Methocel K4M and Methocel K15M. Core erosion ratio was greater than 50 %, thereby showing steady release of the drug after the lag time until complete dissolution. Optimized formulation produced a lag phase of 6 h followed by complete release of 98.7 ± 2.1 % in 24 h. Water uptake study revealed that Methocel K15M has lower water uptake (30 ± 1 %) than Methocel K4M (40 ± 2 %) after 24 h. Axial swelling of polymers was higher than swelling in the radial direction. Drug-polymer interaction study precludes any interaction between drug and polymer. Such a drug delivery system may provide a viable alternative for effective management of hypertension and other related disorders. This work also proposes an approach to attain DOER for a hydrophilic drug by using a hydrophilic swellable polymer in press coat.

Preparation and Evaluation of Gastroretentive Floating Pellets of Metronidazole Using Na-alginate and Hydroxyl Propyl Methyl Cellulose Polymers

Gastroretentive floating pellets of metronidazole were formulated to prolong the gastric residence time in order to obtain controlled release characteristics of the drug. Nine formulations of metronidazole floating pellets such as AX, BX, CX, AY, BY, CY, AZ, BZ and CZ were prepared by extrusion method using different quantities of hydroxyl propyl methyl cellulose (HPMC) polymers such as methocel K4M premium and methocel K100LV premium in the ratio of 2:1, 1:2 and 1.5:1.5 while the amount of Na-alginate used in the formulations was 3.50, 5.25 and 7.0 g, respectively. The in vitro dissolution studies were carried out in 900 mL of phosphate buffer (pH 1.2) at 37 +/- 0.5 degrees C and 50 rpm for 6 h using USP XXIV paddle method and the content of drug release was done by UV spectrophotometer at 277 nm. It was found that the percent release of metronidazole from different formulations was different with passing of time. The drug release profile of the formulation (AX) having Na-alginate 3.50 g methocel K4M premium and methocel K100LV premium in the ratio of 2:1 showed best fit to Higuchi release kinetics with R2 value of 0.994. Finally, it might be concluded that the polymers had significant effect on drug release kinetics of metronidazole from floating pellets. The selection and use of suitable polymers in appropriate ratio might be very important in designing floating pellets and using the capabilities of these polymers, suitable floating pellets of metronidazole with desirable release rate could be formulated. Thus, in vivo research studies by the future researchers will confirm the appropriateness of these formulated metronidazole floating pellets.

Microencapsulation of Verapamil Hydrochloride: A Novel Approach for Gastric Retention Using Different Polymers

The aim of the present investigation was to prepare and evaluate gastroretentive floating microspheres of Verapamil hydrochloride that would retain the drug in stomach and continuously release the drug in controlled manner up to a predetermined time. Floating microspheres were prepared by emulsion solvent evaporation technique. In the present investigation three polymers were used in various concentrations; Methocel K4M, Methocel K15M and Methocel K100M. In vitro performance was evaluated by the usual pharmacopoeial and other tests such as particle size analysis, drug entrapment efficiency, flow properties, in vitro floatability studies, in vivo floatability studies in dog, in vitro drug release studies, stability studies etc. Results showed that the mixing ratio of components in the organic phase affected the size, size distribution, yield, drug content, floating time and drug release of microspheres. In most cases good in vitro floating behavior was observed and a broad variety of drug release pattern could be achieved by variation of the drug, polymer and solvent ratio.

Isolation and characterization of jackfruit mucilage and its comparative evaluation as a mucoadhesive and controlled release component in buccal tablets.

Background:The purpose of the present research work was to extract jackfruit mucilage, use it as a mucoadhesive agent, and to develop extended release buccoadhesive tablets with an intention to avoid hepatic first-pass metabolism, by enhancing residence time in the buccal cavity.Materials and Methods:The mucilage was isolated from the jackfruit pulp by the aqueous extraction method and characterized for various physiochemical parameters as well as for its adhesive properties. Three batches of tablets were prepared (wet granulation method) and evaluated containing three mucoadhesive components: Methocel K4M, Carbopol 974P, and isolated jackfruit mucilage using chlorpheniramine maleate (CPM) as a model drug and changing the proportion of the mucoadhesive component (1:2:3), resulting in nine different formulations.Results:The results of the study indicate that the isolated mucilage had good physicochemical and morphological characteristics, granules and tablets conformed to the Pharmacopoeial specifications, and in vitro release studies showed the sustained action of drug with increasing concentration of the isolated natural mucoadhesive agent in the formulations. Permeability studies indicated that changing the mucoadhesive component, permeability behavior was not statistically different (P > 0.05). FTIR and UV spectroscopy studies between mucilage and CPM suggested the absence of a chemical interaction between CPM and jackfruit mucilage.Conclusion:The developed mucoadhesive tablets for buccal administration containing natural mucilage (MF3) have a potential for the sustained action of drug release. Thus, mucoadhesive tablets for controlled release were successfully developed using natural jackfruit mucilage.

Systematic formulation development of once-a-day gastroretentive controlled release tablets of rivastigmine using optimized polymer blends

Abstract Rivastigmine is a drug extensively prescribed for the treatment of Alzheimer’s disease. On therapeutic fronts, severe gastrointestinal (GI) adverse effects owing to a rapid rise and fall in drug plasma levels, and the high frequency of its dosing, tend to limit its usage. The present investigation, therefore, aimed at developing a gastroretentive floating-bioadhesive CR formulation for delivering rivastigmine in a sustained manner at the desired site of absorption. Employing 7-factor Taguchi design, the influential factors were embarked upon as Carbopol 971P and Methocel K15M CR. Effervescent floating-bioadhesive hydrophilic matrices were systematically formulated using a face-centered cube design (FCCD) and evaluated for in vitro drug release, floatation and ex vivo bioadhesive strength. Optimal composition of polymer blends systematically chosen using brute-force methodology, overlay plots and desirability function exhibited excellent bioadhesive and floatational characteristics besides possessing adequate drug release control (T 60 > 5 h). Pharmacokinetic studies carried out in rabbits showed the absence of any sharp peaks or troughs in the plasma drug levels, and various levels of in vitro/in vivo correlation (IVIVC) were successfully established. In vivo gamma scintigraphic studies in human volunteers ratified the gastroretentive characteristics of the optimized formulation with retention time of 6 h or more. Thus, besides unraveling the polymer synergism, the study helped in developing an optimal once-a-day gastroretentive drug delivery system exhibiting excellent swelling, floating, and bioadhesive characteristics.

Drug release from HPMC matrices in milk and fat‐rich emulsions

"Biorelevant" media for the fed stomach, including fat emulsions, are routinely used during in vitro testing of solid dosage forms. However, their complexity undoubtedly creates difficulties in identifying factors which affect drug release. Here, we show fats can directly influence drug release from hydroxypropyl methylcellulose (HPMC; Methocel K4M) matrices which are often subjected to biorelevant testing. Model fat systems included milk (0.1%-3.5% fat) and the parenteral emulsion Intralipid® (20%-30% fat). The matrix showed good extended-release properties for at least 12 h in these media (USP-1/USP-4), but at the highest fat concentration, release was retarded and shifted towards zero-order release. Confocal imaging studies using a water-soluble (fluorescein) and fat-soluble (Nile red) fluorophore provided evidence of phase separation of Intralipid® at the surface of the emerging gel. Combined magnetic resonance imaging-USP-4 drug release testing provided further evidence for deposition of fat on the tablets. We propose that the aqueous portion of the emulsion is removed by the hydrating matrix, causing coalescence and deposition of a fat layer at the surface, and these deposits cause slower drug release by reducing the matrix surface area available for release. Therefore, there is a risk of a direct interaction between fat emulsions and HPMC tablets, with resultant effects on drug release in vitro.

Effect of Media on the Dissolution Profiles of Propranolol Hydrochloride from Matrices Containing Different Substitution Types of Methocel

The effects of media on the dissolution properties of matrices containing propranolol hydrochloride and two quantities (50 mg or 150 mg) of different substitution types of Methocel were studied. Tukey's multiple comparison test was used to assess the effect of water, 0.1M hydrochloric acid and phoshate buffer (pH 7.4), or the substitution type, on the square root time dissolution rates and the release exponents. The low content (50 mg) Methocel E4M failed to control release in the three media used. Matrices containing Methocel A4M (50 mg) showed burst release in 0.1 M hydrochloric acid and matrices containing either 50 or 150mg Methocel A4M showed burst release in phosphate buffer, pH 7.4. Methocel grades F4M and K4M achieved better control of drug release. The ranking of the Methocels based on square root time dissolution rates or the release exponents depended on the dissolution media. The ranking of the square root time rates was: water > hydrochloric acid > phosphate buffer irrespective of the substitution type of the Methocel used in the matrices. The release exponents indicated that there was a higher contribution of erosion to release in 0.1M hydrochloric acid than in water or phosphate buffer.

Preparation and evaluation of mucoadhesive hydrophilic hydroxy propyl methyl cellulose based extended release matrix tablets of Niacin (Nicotinic acid)

The aim of this study is to develop a once-daily extended release matrix tablet of Niacin using Hydroxy Propyl Methyl Cellulose i.e. Methocel K4M CR as release controlling factor and to evaluate drug release parameters as per various release kinetic models and also to find the best fitted extended release matrix formulation of Niacin. In order to achieve required extended release profile, tablets were prepared by wet granulation technique using different formulations (F-1, F-2, F-3, F-4, F-5 and F-6) with different amount of Methocel K4M CR. The formulated tablets were also characterized by physical and chemical parameters and results were found in acceptable limits. Different release kinetic models were applied in order to evaluate release of Niacin from the prepared matrix tablets. Criteria for selecting the most appropriate model were based on linearity (coefficient of correlation) and diffusion exponent of the respective kinetic model. Among all the formulations, F-5 was found as the best fitted matrix tablet for extended release of Niacin. Drug release mechanism was found as a complex mixture of diffusion, swelling and erosion.

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

Comparison Between the Effect of Strongly and Weakly Cationic Exchange Resins on Matrix Physical Properties and the Controlled Release of Diphenhydramine Hydrochloride from Matrices

This study focused on investigating and comparing between the effect of the strongly cationic exchange resin, Dowex 88 (Dow88), and the weakly cationic exchange resin, Amberlite IRP64 (Am64), on the physical properties of matrices and their drug release profiles. The matrices were prepared by direct compression of Methocel K4M (HPMC) or Ethocel 7FP (EC) polymeric matrix formers and contained diphenhydramine hydrochloride as a model drug. The addition of Dow88 to the matrices decreased matrix hardness and increased thickness, diameter, and friability. In contrast, the addition of Am64 increased matrix hardness and maintained the original thickness, diameter, and friability. In deionized water, both resins lowered drug release from HPMC-based matrices by virtue of the gelation property of matrix former and the drug exchange property of embedded resin, in other words in situ resinate formation. Dow88 strongly dissociated and lowered the drug release to a greater extent than Am64, which was weakly dissociated. However, Am64 could retard drug release under simulated gastrointestinal conditions. EC-based matrices containing either resin displayed a propensity for disintegration caused by swelling and wicking (water adsorption) actions by the resin. The results of this study provided useful information on the utilization of ion exchange resins as release modifiers in matrix systems.