To improve the pharmacological activity, a multi-stage controlled-release oral dosage form (MSCR system) was developed. The MSCR system consisted of granules containing drug, granules embedded swellable matrix, and coating layer. Through this system, zero-order release pattern was basically achieved and coating layer could control initial lag-time. The in-vitro release profiles of various drugs from MSCR system were verified by the amount of release-controlling agents and swellable polymeric matrix material. Oxybutynin hydrochloride was incorporated into the system as a model drug and its in-vitro and in-vivo release profiles were compared with Ditropan XL. The zero-order release pattern after initial lag-time was obtained and it was similar with Ditropan XL. The plasma concentration of oxyburynin was maintained within the therapeutic level for 24 hours and the AUC of N-desethyl-oxyburynin was similar with Ditropan XL in human body. It could be concluded that MSCR system was feasible system for a long acting pharmaceutical dosage form and showed the possibility of customized release as a once-a-day treatment.
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