Formulation and Evaluation of Bilayer Tablets: Glimepiride in Floating Drug Delivery and Metformin in Sustained Release

The Glimepiride floating tablet is prepared with various polymer of guar gum; xanthan gum and carbopol with excipients talc, magnesium stearate, and sodium bicarbonate are compressed and taken as first layer. The Metformin sustained release is also prepared by different polymer ratio of HPMC, methyl cellulose and PVP with excipients microcrystalline cellulose, talc, magnesium stearate are compressed and taken as second layer of tablet. The first and second layer of tablet is combined as bilayer tables. Evaluation of bilayer tablet such as weight variation, thickness, hardness, friability, disintegration and floating lag time and floating capacity is carried out and shown that all the formulation are within the limit. Among all formulations F2 was selected based on invitro dissolution study with drug release up to 15 hours for metformin sustained release layer and 8 hours for glimepiride floating layer in the bilayer tablets. The release kinetics study was done for best formulation F2 and follows first order for Glimepiride and zero order for Metformin. Which was studied for release mechanism; Higuchi shows higher linear with regression value of 0.993 for glimepiride and 0.981 for metformin respectively, which indicates drug release from the both layer is by diffusion principle (r2 is more than 0.98) and further it is confirmed by peppas n-value 0.982 for glimepiride and 0.989 for metformin, so it is considered as non-fickian type of drug release