Development and Evaluation of Sustained Release Matrix Tablet of Lamivudine

The study was obtained to develop oral controlled release matrix tablets of Lamivudine having different proportion of Guar gum (retardant polymer) and to study the effect of formulation factor such as polymer proportion on the invitro release. The prepared granules were evaluated such as angle of repose, loose bulk density, tapped bulk density and compressibility index and satisfactory results were obtained. Compressed tablets were also evaluated for uniformity of weight, content of active ingredient, thickness, friability, hardness, swelling, erosion behaviour and in-vitro dissolution studies. All the formulations showed good results which were compliance with Pharmacopoeial standards. In-vitro drug release studies were carried out using USP XXII dissolution apparatus type II at 50 rpm with 900 ml phosphate buffer solutions (PBS) of pH 6.8, maintained at 37±0.5C. The release kinetics was analyzed using the zero-order, first-order model equation, Higuchi’s squareroot equation, and the Korsmeyer-peppas model. In vitro release studies revealed that the release rate decreased with increases in polymer proportion. Matrix tablets containing 15% guar gum (Formulation F2) were found to show good initial release (21.34% in initial hour) and allowed sustained 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 sustained release characteristics might be able to minimise the demerits of conventional therapy having lamivudine.