Formulation and Evaluation of Bilayer Floating Matrix Tablets For Captopril

The importance of the present investigation was to formulate a bilayer-floating tablet (BFT) for captopril using direct compression technology. The release layer contained captopril and various polymers such as HPMC-K15M, PVP-K30 and Carbopol 934p, alone or in combination with the drug. HPMC, K-grade and effervescent mixture of citric acid and sodium bicarbonate formed the floating layer. The floating mechanism and in vitro dissolution studies were carried out in a USP 23 apparatus 2 in simulated gastric fluid (without enzyme, pH 1.2). Final formulation released approximately 95% drug in 12 hrs in vitro, while the floating lag time was 10 min and the tablet remained floatable throughout all studies. Final formulation followed the Higuchi release model and showed no significant change in physical appearance, drug content, floatability or in vitro dissolution pattern after storage at 45 °C / 75% RH for three months. Thus, it seems that an increase in gastric retention time may increase the extent of absorption and bioavailability of the drug. In the present study, we have attempted to formulate a floating system of captopril.