FORMULATION AND IN-VITRO EVALUATION OF CONTROLLED RELEASE FLOATING TABLETS OF LAMIVUDINE

The aim of the present work is to increase the gastric residence time of Lamivudine by preparing it into gastro retentive floating tablets whereby making it available at its site of absorption and to achieve an extended action for a time period of 24hrs and to reduce the dosing frequency to once a day, using release retardant polymers METHOCEL, POLYOX and CARBOPOL. The compatibility of the drug with excipients was confirmed by DSC study. The gastro retentive floating tablets were prepared by direct compression method and were evaluated for physicochemical characteristics and in-vitro dissolution studies. The optimized formulation was subjected to stability studies. The prepared tablets exhibited satisfactory physicochemical characteristics. The in-vitro drug release studies revealed that the drug release was sustained up to 24hrs for formulation F5 containing drug and POLYOX as release retardant polymer at a concentration of 1:0.75. Using Higuchi’s Model and the Korsmeyer equation, the drug release mechanism from the floating sustained release tablets was found to be Anomalous (non-Fickian) diffusion. Optimized formulations showed no significant change in physical appearance, pre and post compression parameters and drug dissolution studies after storage at 40° C ± 2° C and 75% ± 5% RH in a humidity chamber for 1 month. And hence the current investigation was successful in its intended aim.