Objective:To develop an etonogestrel (ENG)/ethinyl estradiol (EE) compound vaginal ring with good sustained-release properties, studying its in vitro release assay methodology, and establishing an accelerated release method with good correlation with real-time release methods. Methods:Ethylene-vinyl acetate copolymer (EVA) was used as the matrix to prepare ENG/EE compound vaginal ring by hot melt extrusion method, and an in vitro real-time release assay method and an accelerated release assay method based on shake flask method were established. The in vitro release behavior and release mechanism of ENG/EE compound vaginal ring were investigated, and the correlation between real-time release and accelerated release over time was analyzed. Results:The obtained vaginal ring had a round appearance and a smooth surface, and the drug was slowly released under the optimal real-time release conditions in vitro (release medium: 200 mL of pure water, shaking at 60 r/min in a constant temperature water bath shaker at 37 ℃), and the cumulative release of ENG and EE on the 21st day were 54.39% and 46.80%, respectively. The correlation coefficients of drug release and its mechanism under the optimized in vitro accelerated conditions (release medium: 200 mL of 0.6% sodium dodecyl sulfate aqueous solution, shaking at 60 r/min at 55 ℃) with the results under real-time release conditions were all greater than 0.99. Conclusion:The ENG/EE compound vaginal ring obtained in this study has a significant in vitro sustained-release effect, and the established accelerated release conditions have a good correlation with real-time release conditions, which can provide a useful reference for the quality evaluation research of such vaginal ring products and the formulation of guidelines for in vitro release research methods.

Objective:To develop an etonogestrel (ENG)/ethinyl estradiol (EE) compound vaginal ring with good sustained-release properties, studying its in vitro release assay methodology, and establishing an accelerated release method with good correlation with real-time release methods. Methods:Ethylene-vinyl acetate copolymer (EVA) was used as the matrix to prepare ENG/EE compound vaginal ring by hot melt extrusion method, and an in vitro real-time release assay method and an accelerated release assay method based on shake flask method were established. The in vitro release behavior and release mechanism of ENG/EE compound vaginal ring were investigated, and the correlation between real-time release and accelerated release over time was analyzed. Results:The obtained vaginal ring had a round appearance and a smooth surface, and the drug was slowly released under the optimal real-time release conditions in vitro (release medium: 200 mL of pure water, shaking at 60 r/min in a constant temperature water bath shaker at 37 ℃), and the cumulative release of ENG and EE on the 21st day were 54.39% and 46.80%, respectively. The correlation coefficients of drug release and its mechanism under the optimized in vitro accelerated conditions (release medium: 200 mL of 0.6% sodium dodecyl sulfate aqueous solution, shaking at 60 r/min at 55 ℃) with the results under real-time release conditions were all greater than 0.99. Conclusion:The ENG/EE compound vaginal ring obtained in this study has a significant in vitro sustained-release effect, and the established accelerated release conditions have a good correlation with real-time release conditions, which can provide a useful reference for the quality evaluation research of such vaginal ring products and the formulation of guidelines for in vitro release research methods.