Formulation and In Vitro Evaluation of Bilayered Matrix Tablets of Pioglitazone for Immediate Release and Glimepiride for Extended Release

Abstract

Bi-layer tablets are novel drug delivery systems where a combination of two or more drugs in a single unit having different release profiles which improves patient compliance and prolongs the drug action. The study was performed to design bilayer matrix tablets of pioglitazone for immediate release and glimepiride for extended release delivery system. Bilayered matrix tablets composed of two layers, one is immediate release and a second layer is extended release layers. The immediate release layer comprised sodium starch glycolate, and croscarmellose sodium as super disintegrates and extended release layer comprised ethyl cellulose and HPMC K4M as release retardant polymers. Direct compression method was employed for the formulation of bilayer tablets. In vitro studies have shown more than 80% of pioglitazone was released within 60 min. Ethyl cellulose and HPMC K4M retarded the release of glimepiride from the controlled release layer for 12 h. Drug release mechanism exponent (n) was determined for all formulations (0.689-0.789). The release of pioglitazone was found to follow a first order release and the release of glimepiride was followed zero order release model.