Contraceptive potential of a mifepristone-nomegestrol acetate sequential regimen in women

The effectiveness of a sequential regimen consisting of mifepristone, 10 mg /day for 15 days, followed by nomegestrol acetate (NOMA), 5 mg/day for the next 13 days, for inhibiting ovulation and maintaining regular bleeding cyc les was assessed in 10 surgically sterilized volunteers who were followed f or one pretreatment and three treated cycles. Hormonal determinations in bl ood and urine, ovarian ultrasonography, bleeding records in all cycles and an endometrial biopsy taken on day 22-25 of the third treatment cycle were used to monitor the effects of treatment. During treatment, 24 monophasic ( no sustained progesterone rise above 12 nmol/l) and six biphasic cycles wer e recorded. Nine follicular ruptures were detected echographically in these 30 treated cycles, five of which occurred in monophasic cycles, All follic ular ruptures occurred on days 1-7 of NOMA treatment. Echographic and endoc rine features of ovulatory cycles were both present in only four treated cy cles (13.3%:). Development of a secretory endometrium was achieved in all c ases, but it was always irregular. Regular withdrawal bleeding occurred in all subjects and no adverse reactions were recorded. The ovarian and endome trial effects of this regimen justify testing its contraceptive effectivene ss in phase 2 clinical trials.