Clinical Re-evaluation on Bioequivalence and Relative Bioavailability of Micronized Progesterone Hard Capsule (Yimaxin) and Micronized Progesterone Soft Capsule (Utrogestan) under Vaginal and Oral Administration Routes

Background and Objective: To clinically re-evaluate relative bioavailability and bioequivalence of micronized progesterone (hard capsule) Yimaxin and micronized progesterone (soft capsule) Utrogestan under vaginal and oral administration routes.

Methods: From December 2017 to June 2018, a total of 16 postmenopausal healthy women were recruited and received a total of four rounds of drug treatment with cross-over design, respectively Yimaxin and Utrogestan under vaginal and oral administration routes. Changes in the subjects’ hormone levels after medication were monitored and an endometrial biopsy after a course of treatment was performed in our hospital.

Result: The Geomeans of AUC0-t of Yimaxin and Utrogestan under vaginal administration route were 252.15 and 115.46, respectively, with a ratio of 2.19, and under oral administration route were 244.64 and 413.68, respectively, with a ratio of 0.59. The Geomeans of Cmax of Yimaxin and Utrogestan under vaginal administration route were 28.11 and 12.21, respectively, with a ratio of 2.30, and under oral administration route were 53.12 and 129.85, respectively, with a ratio of 0.41.

Conclusion: Yimaxin was not bioequivalent to Utrogestan. Yimaxin had higher exposure to the drug in vivo at the same dose when administered vaginally, and Utrogestan had higher exposure to the drug in vivo at the same dose when administered orally.