Preparation and Study on Release Rate in Vitro for Sustained-release Tablets of Simvastatin

OBJECTIVE To prepare gel matrix sustained-release tablets of simvastatin and examine the factors affecting drug release rates. METHODS Assay the release rates in vitro by UV spectrophotometry, prepare the sustained-release tablets by wet granulation squash method with hydroxypropyl methyl cellulose (HPMC) as matrix material, examine the impact on the release rates with the specification and quantity of HPMC and other excipients, optimize the formulation with orthogonal test method and validate the preparation method. RESULTS The specification and quantity of HPMC and the kind of adhesive can impact on the release rates in vitro. When the proportion of HPMC (K15M) as matrix material to simvastatin is 1.5∶1, the release of the sustained-release tablets can stably last 12 hours, and the release rates in batches have good reproducibility. CONCLUSION The formulation is appropriate, the preparation method is feasible, and the sustained-release tablets has good and stable release rate.