Gastric Floating Matrix Tablets of Metformin Hcl: Design and Optimization Using Combination of Polymers

The objective of this study was to develop a floating drug delivery system (FDDS) from metformin hydrochloride to enhance gastro residence time (GRT), with floating properties which remain in the stomach more than gastric empting time (GET). Eight batches were prepared using hydrophilic polymers as release-retarding, and sodium bicarbonate as a gas former by direct compression technique. The effects of effervescent agent (sodium bicarbonate) and a binary combination of hydroxypropyl methylcellulose (HPMC) K4M with polyvinylpyrrolidone (PVP) or carbopol934 on floating properties and drug release profile were investigated. Drug release study was evaluated for 12 hours using USP paddle-type dissolution apparatus using 0.1N HCl in 37±0.5˚C as dissolution medium. The swelling index, floating behavior and kinetic parameter were found to be regulated by polymers and CO2 generating agent content. The results of powder ingredients and compressed tablets showed acceptable physicochemical properties. It was found that polymer content affected in the release rate constant and diffusion exponent. Statistical analyses of formulations data exhibited that F7 formulation was promising systems revealing excellent floating properties and sustained drug release characteristics. The MDT and DE12h of F7 formulation were calculated to be 5.26h and 49.88%, respectively. Drug release profile of F7 formulation followed non-Fickian diffusion with Hixson-crowell model.