FORMULATION AND EVALUATION OF QUINAPRIL EXTENDED-RELEASE TRILAYERED MATRIX TABLETS BY DESIGN OF EXPERIMENT

Objective: The present research was focused on designing, formulate and evaluate the trilayer matrix tablets incorporated with quinapril for extending drug release. Methods: Quinapril trilayer matrix tablets were formulated using response surface methodology wherein initially 27 formulations (QF1-QF27) were designed for active layer from which one best formulation was chosen based on drug content, swelling index, and in-vitro release studies. The chosen formulation was formulated into extended-release trilayed matrix tablet by varying proportions of polymers by direct compression technique and was evaluated for various physicochemical parameters, drug release and the drug release data were fitted into the various kinetic model to know the mechanism of drug release. The best-optimized formulation was further characterized by FTIR and stability studies. Results: 27 active layer formulations were evaluated for various physicochemical properties and drug release, out of which the highest drug release was exhibited by QF16 (98.85%). Thus, QF16 was used for formulation into trilayer matrix tablets (AQF16-HQF16). All the formulations were evaluated for drug content, swelling index, and percentage drug release in which EQF16 was found to exhibit the highest values with 98.42% swelling index, 99.56 % drug content, and 99.72 % drug release in 24h. The drug release data was fitted into kinetic models, which showed zero-order release kinetics for all quinapril trilayer formulations and the first order for a marketed product. The optimized formulation EQF 16 was further characterized by FTIR studies and found to exhibit no interaction with excipients, and no significant changes were observed in drug content, swelling index, and drug release after loading under accelerated stability conditions. Hence quinapril was successfully formulated into trilayer matrix tablet and found to be stable.