Formulation And Evaluation of Once a Day Controlled Release Tablets of Verapamil Hydrochloride Using Binary Polymeric Systems

R.L.C. Sasidhar 1 *, S. Vidyadhara1and R.Nagaraju 2

Abstract: The objectives of the present investigation are to investigate the influence of polymer type and concentration on the release of verapamil hydrochloride from matrix tablets. The polymers used for the study are synthetic polymers like poly (ethylene oxides), water insoluble polymers like Eudragit L 100 and Eudragit S 100, gums like xanthan gum and guar gum and natural polysaccharide sodium alginate. The matrix tablets were prepared by direct compression process and evaluated for hardness, weight variation, friability and in-vitro release of the drug. The matrix tablets containing xanthan gum, guar gum and sodium alginate alone or in combination could not efficiently retard the drug release for prolonged period of time. The tablets containing the combination of natural polymers along with poly (ethylene oxides) and Eudragits exhibited controlled release of the drug for prolonged period of time. All the physical characteristics evaluated for the tablets were found to be within the acceptable limits. The release kinetics was found to be governed by the type and combination of the polymers used in the preparation of matrix tablets. The prepared tablets showed no significant change in drug release rate when stored at ambient room conditions for 6 months.

Introduction: Oral administration of drugs is most common and preferred route for delivery of most therapeutic agents. This is due to patient acceptance, ease of administration accurate dosing and cost effective manufacturing methods. Among various oral controlled release formulations, matrix tablet formulation is the simplest and most cost effective method to fabricate oral controlled release dosage form. Various factors will influence the drug release from matrix tablet, which may include choice of polymer, filler type and level, use of enteric polymers, use of hydrophobic materials, use of polysaccharides, etc( 1-5). In the preparation of matrix tablets when hydrophilic polymers and gums are mixed and when the tablet is exposed to the dissolution medium the polymers absorb the medium swells and they interact with each other. This may result in an increase in viscosity, which becomes greater than the viscosity of each solution individually which can be used for extending the drug release for prolonged period of time (6). Among the variety of hydrophilic polymers, polyethylene oxide (PEO) is one of the most important materials used in the preparation of matrix tablets because of its non-toxicity, high water-solubility and swellability. In a research work it was proved that polyethylene oxides can be used as alternative to HPMC for the preparation of matrix tablets.(7-8). Methacrylic polymers (Eudragits) also attracted researchers in fabricating controlled release dosage forms [9], due to their high chemical stability, good compatibility properties. Natural gums from natural sources hydrate and swell on contact with water and these have been used for the preparation of controlled release dosage forms(10) and also due to their cost effectiveness and regulatory acceptance.



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