Formulation and Evaluation of Gastro retentive Bilayer Tablets - Glimepiride as Sustained Release and Lisinopril as Immediate Release

Abstract

The Bilayer tablets containing Glimepiride SR and Lisinopril IR were successfully prepared by Wet granulation and direct compression method respectively. Various formulations were prepared and evaluated with an aim of presenting Glimepiride as sustained release and Lisinopril as immediate release for improving the patient’s compliance. The physiochemical evaluation results for the blends of all trials pass the official limits in all tests including Angle of repose, Bulk density, Tapped density, Compressibility index, and Hausner’s ratio. The prepared blend for SR layer tablets and IR layer tablets were also maintained the physiochemical properties of tablets such as weight variation, hardness, thickness, friability. The optimized formulation F9 in IR formulations contains the average thickness of 2.4 mm, average hardness of 4.9 kg/cm2, average weight of 150 mg, friability of 0.46% and disintegration time of 2 minutes. The optimized formulation F7 in SR formulations contains the average thickness of 2.64mm, average hardness of 5.9kg/cm2, average weight of 250 mg, friability of 0.52%, and optimum mucoadhesive strength. The F7 formulation of Glimepiride Sustained Release Layer releases 10.5% in 1st  hour but the remaining drug release was sustained up to 24 hours and F9 formulation of Lisinopril Immediate Release showed 99.92% drug release with in 30min. With the data of kinetic analysis, F7 formulation showed best linearity in zero order plot indicating that the release of drug is independent upon concentration and the mechanism from mucoadhesive layer follows Higuchi diffusion mechanism. The dissolution study was carried out for optimized bilayer tablet and it correlates with the drug release of individual release layer formulations. Stability studies were carried out for 6 months. All physical and chemical parameters were found to be satisfactory based on the stability data.