[Description of the release of sodium ferulate from hydroxypropyl methylcellulose based matrix tablets in vitro]

To elucidate the mechanism and to present suitable models for the release of sodium ferulate (SF) from hydroxypropyl methylcellulose (HPMC) based matrix tablets.

The characteristics and mechanisms of drug release were analyzed from the point of thermodynamic, swelling and diffusion effect. Despite the classical equation of Higuchi, the semi-empirical power law and quadratic curve were also adopted to analogize the release of SF from HPMC based tablets in vitro.

The first release stage of SF was mainly controlled by Fick diffusion, and the rest SF released mainly according to case II transport process caused by the swelling effect of HPMC. The decreased Tg of HPMC, resulted from the entered water, enhanced the release of SF. The power law was possible for the first released 60% SF, but unfit for the last 40% SF. The quadratic curve expressed equation can illuminate the release of SF.

For the HPMC system, drug release undertakes the Fick diffusion process followed by the extend of polymer chain. The nonlinear quadratic equation might be valuable to explain the entire drug release from HPMC-based delivery system.