Design and Evaluation of Lamivudine Sustained Released Matrix Tablets

Abstract

The objective of this study was to design oral Sustained release matrix tablets of lamivudine using hydroxypropyl methylcellulose (HPMC) as the retardant polymer and to study the effect of various formulation factors such as polymer proportion, polymer viscosity, and compression force on the in vitro release of drug. In vitro release studies were performed using 900 ml of  0.1 N HCL and phosphate buffer pH 7.4 as dissolution medium using a USP dissolution paddle assembly at 50 rpm and 37^o ± 0.5^o C.. The release kinetics was analyzed using the zero-order model equation, Higuchi’s square-root equation, and the Ritger-Peppas empirical equation. Compatibility of the drug with various excipients was studied. In vitro release studies revealed that the release rate decreased with increase in polymer proportion and viscosity grade. Increase in compression force was found to decrease the rate of drug release. Matrix tablets containing Low viscosity of HPMC (E15LV) of F1 formulation extended up to 16 hrs, with maximum release of 98.28%.By increasing the viscosity of HPMC (E50LV) of   F2 formulation goes on increase the duration up to 18 hrs, with maximum release of 97.62%. Mathematical analysis of the release kinetics indicated that the nature of drug release from the matrix tablets was dependent on drug diffusion and polymer relaxation and therefore followed non-Fickian or anomalous release. No incompatibility was observed between the drug and excipients used in the formulation of matrix tablets. The developed controlled release matrix tablets of lamivudine, with good initial release and extension of release up to 20 to 24 hours, can overcome the disadvantages of conventional tablets of lamivudine.