目的研制米非司酮壳型阴道环，并考察其体外释放度。方法首先将药物制备成以PVP_K-30为载体的固体分散体，采用差式扫描量热法和X-射线衍射法进行表征。然后以硅橡胶为载体，采用热压硫化法制备米非司酮壳型阴道环，环内层为空白硅橡胶骨架，中间为含药部分，最外层为无活性的硅橡胶薄膜。以200mL（pH4.0）磷酸盐缓冲液为释放介质，采用紫外-可见分光光度法考察米非司酮阴壳型道环的体外释放度。结果米非司酮壳型阴道环释药更为平稳，每日平均释放药物1mg，持续释放时间至少达21d，且批间差异小。结论采用米非司酮固体分散体制备的壳型阴道环具有良好的缓控释特性，制备工艺稳定。采用紫外-可见分光光度法考察阴道环的体外释放度更方便、快速和准确。

OBJECTIVE To prepare and in vitro evaluate the shell vaginal ring（VR）containing mifepristone. METHODS The solid dispersion of mifepristone with PVP _K30 as a carrier was prepared and characterized by the methods of differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). The shell vaginal ring containing mifepristone was prepared by the method of mold molding process,the inner layer of vaginal ring is the blank silastic skeleton, the middle layer of vaginal ring is the part containing drug, the outermost layer is a non-active silicon rubber membrane. In vitro drug release test was conducted in a dissolution apparatus, release medium was 200 mL PBS (pH 4.0) meeting with sink conditions, and release samples were determined by the UV-vis spectrophotometry. RESULTS The shell vaginal ring containing mifepristone had a steady drug release rate in vitro during 21 d. The daily release of mifeprisotne was about 1 mg, which sustained two weeks at least at this release rate, and the variance intra- batch was very small. CONCLUSION The shell vaginal ring containing mifepristone exhibits the sustained and controlled release characteristics in vitro,and the preparation method is stable. The developed UV-vis method is rapid, accurate and convenient.