Design and development of bilayer tablet for immediate and extended release of acarbose and metformin HCl

The present investigation studied a novel Bilayer tablet having extended release (ER) system of metformin HCl (M.HCl) with Eudragit RS 100 and RL 100 and immediate release (IR) system of Acarbose with PVP K30 and PEG 6000 in different ratios using solvent evaporation technique. Solid dispersions (SDs) were characterized by Fourier Transform-Infra Red spectroscopy, Diffrential Scanning Calorimetry, X-Ray Diffractometry and Scanning Electron Microscopy. Selected SD system was subjected to Bilayer tablet preparation by direct compression. Compressed tablets were evaluated for physical parameters, drug release and stability. SEM studies suggested the homogenous dispersion of the drug in polymers. FT-IR studies confirmed the formation of hydrogen bonding between the drug and polymer. XRD and DSC suggested the amorphous nature of the drug in SDs. All tablet formulations showed compliance with pharmacopoeial standards. In-vitro dissolution kinetics followed the Higuchi model via a non-fickian diffusion controlled release mechanism after the initial burst release. Stability studies conducted for optimized formulation did not show any change in the physical properties, drug content and drug release. Bilayer tablets showed an IR effect to provide the loading dose of the drug, followed by ER effect for 12 h, indicating a promising potential of the M.HCl and Acarbose Bilayer tablet as an alternative to the conventional dosage form