Preparation and optimization of oxybutynin hydrochloride microporous membrane osmotic pump tablets

Objective: To develop a microporous-controlled delivery system for oxybutynin hydrochloride, to investigate the drug release in vitro, and to determine the best formulation eventually. Methods: The cumulative release was used as an evaluating index, the amount of penetration enhancer and pore-forming agents as well as thickness of coating were assessed to study the impacts on the drug release in vitro. The response surface methodology was employed to optimize formulations in terms of three variables. Results: The drug release was driven by the osmotic pressure, and the three variables mentioned above had a significant effect on the release rate. Conclusion: The release rate of controlled-release tablets prepared by the optimized formulations fulfilled the requirements; furthermore, the release profile matched the zero-order release characteristics well.