Development and in Vitro Evaluation of Sustained Release Floating Matrix Tablets of Metformin Hydrochloride

Floating matrix tablets of metformin hydrochloride were developed and evaluated for increase bioavailability by increasing gastric residence time and sustained release of drug on the upper part of gastrointestinal tract thereby diminishing side effects and enhanced patient compliance. Metformin hydrochloride, an oral antidiabetic having narrow absorption window in the upper part of gastrointestinal tract, was formulated as floating matrix tablet using gas generating agent (potassium bicarbonate) and hydrophilic gelling polymer hydroxyl propyl methyl cellulose (hypromellose) by wet granulation technique. The prepared formulations were evaluated for floating time and in vitro drug release characteristics using modified dissolution method. All formulations possessed good floating properties with total floating time more than 12 hours. Optimization study included 2 factorial design with t50% and t80% as the kinetic parameters. Matrix characterization included photomicrograph, which showed definite entrapment of the drug in the matrix. Formulations with high amount of hypromellose were found to float for longer duration and provide more sustained release of drug. The formulated drug delivery system was found to be independent of pH. Release kinetics of formulations followed Higuchi model with anomalous non fickian diffusion. Hence it is evident from this study that effervescent floating matrix tablet could be a promising delivery system for metformin hydrochloride with sustained release action and improved drug availability.