Design and Evaluation of Sustained Release Matrix Tablet of Metformin Hydrochloride

The present study was based on direct-compressed matrix tablets consisting of a combination of Metformin HCl with the hydrophilic polymers HPMC K 100M and hydrophobic polymers Ethylcellulose 7cps. The resulting formulation produced monolithic tablets with optimum hardness, uniform thickness, consistent weight uniformity low friability, drug content. In vitro release studies were carried out in 0.1N HCl for first 2h and followed by phosphate buffer at 6.8 over a period of 12hrs using USP type II dissolution apparatus. Applying different kinetic models, the mechanism of drug release from formulations was found to be followed Higuchi model. The swelling and gelling properties of hydrophilic polymer matrix like HPMC form protective barrier to influx of water and efflux of drug solution along with ethylcellulose which controls diffusion of drug towards surface of matrices. Due to these properties the combination of hydrophilic HPMC K 100M and hydrophobic EC in matrix have better retarding property to give desire dissolution profile.