In Vitro – In Vivo Evaluation of Floating Tablet Containing Anti Retroviral Agent Lamivudine

This study aimed to develop hydrophilic matrix based controlled release  gastroretentive drug delivery system of Lamivudine floating matrix tablets, which after oral administration are designed to prolong the gastric residence time, increase the drug bioavailability and diminish the side effects of irritating drugs. FTIR studies revealed that there is no interaction between the drug and polymers used for the formulation. Among all the formulations F21 containing HPMC K100M, Carbopol 934P, Polyox WSR 303 and sodium bicarbonate, as gas generating agent was selected as optimized formulation based on physico chemical properties, floating lag time (34 sec) and total floating time (>24 h). From in vitro dissolution studies, the optimized formulation F21 showed drug release of 99.36±5.36%, whereas 92.36±5.02% of the drug was released from the marketed product within 24h. From in vivo bioavailability studies, after oral administration of floating tablet containing 100 mg Lamivudine, the Cmax, Tmax, and AUC0–∞ of optimized gastroretentive formulation were found to be 32.11±3.16 µg/mL, 8.00±1.26 h and 225±28.14 µg*h/ml, respectively. Cmax and AUC values of optimized formulation were found to be significantly higher than of marketed product, where longer gastric residence time is an important condition for prolonged or controlled drug release and also for improved bioavailability. Hence, gastro retention can be a promising approach to enhance bioavaiilability of Lamivudine with narrow absorption window in upper GIT.