FORMULATION AND IN VITRO EVALUATION OF CONTROLLED RELEASE MATRIX TABLET OF LAMIVUDINE

The objective of this study was to design oral controlled release matrix tablets of Lamivudine using different proportion of Guar gum as the retardant polymer and to study the effect of formulation factor such as polymer proportion on the in vitro release of drug. The granules were evaluated for angle of repose, loose bulk density, tapped bulk density and compressibility index, shows satisfactory results. Compressed tablets were evaluated for uniformity of weight, content of active ingredient, thickness, friability, hardness, swelling, erosion behavior and In vitro dissolution studies. All the formulation showed compliance with Pharmacopoeial standards. In vitro drug release studies were carried out using USP XXII dissolution apparatus type II at 50 rpm. The dissolution medium consisted of 900 ml of pH 6.8 phosphate buffer, maintained at 37+ 0.50C.The release kinetics were analyzed using the zero-order, first-order model equation, Higuchi’s square-root equation, and the Korsmeyer-peppas model. In vitro release studies revealed that the release rate decreased with increase in polymer proportion. Matrix tablets containing 15% guar gum (Formulation F2) were found to show good initial release (21.34% in first hour) and extended the release up to 12 hours. Mathematical analysis of the release kinetics indicated that the nature of drug release from the matrix tablets was dependent on polymer concentration and it was found to be diffusion coupled with erosion. The developed controlled release matrix tablets of lamivudine, with good initial release (21.34% in first hour) and extension of release for more than 12 hrs, can overcome the disadvantages of conventional tablets of lamivudine.