IN VITRO AND IN VIVO CHARACTERIZATION OF GLIMEPIRIDE MICROPARTICLES

In the present investigation, controlled release microparticles of Glimepiride were prepared by emulsion solvent evaporation technique using cellulose acetate as release retardant polymer. The microparticles were evaluated for In-Vitro release study and In-Vivo evaluation. The microparticles were subjected to In-vitro release studies by employing 7.8 pH phosphate buffer as dissolution medium. The rate of drug release from these microparticles followed zero order kinetics and the mechanism of drug release was governed by peppas mechanism. The exponential coefficient (n) value indicating that drug release followed non fickian mechanism. The in vivo performance of pure drug and optimized Glimepiride microparticles were evaluated in rabbits in a randomized cross-over design. The estimation of glimepiride in serum was carried out by HPLC method. The parameters such as maximum plasma concentration (Cmax), time for peak plasma concentration (tmax), mean residence time (MRT) and area under curve (AUC_{0 – α}) were significantly (P< 0.001) differed following glimepiride microparticles compared to pure drug administration. The relative bioavailability of glimepiride was increased about five fold after microparticles administration as compared to pure drug. This may be due to the slow controlled release of Glimepiride. In the case of optimized Glimepiride microparticles administration, percentage blood  glucose reduction was observed after 4.0 hrs and was prolonged over a period of 16 hrs. It was concluded that the Glimepiride microparticles administration, resulted in increased relative bioavailability and reduced frequency of administration.