EFFECTS OF A SEQUENTIAL REGIMEN OF MIFEPRISTONE-MEDROXYPROGESTERONE ACETATE ON OVARIAN-FUNCTION, ENDOMETRIAL DEVELOPMENT AND HORMONAL PARAMETERS

The efficacy of a low dose of mifepristone, 5 mg/day for the first 15 days of the menstrual cycle, followed by medroxyprogesterone acetate ( MPA), 10 mg/day for the next 13 days, for inhibiting ovulation was ass essed in ten volunteers who were treated for three successive cycles. Hormonal determinations in blood and urine samples, ovarian ultrasonog raphy and an endometrial biopsy taken on day 21-24 of the third treatm ent cycle were used to monitor the cycles. Ovulation was confirmed in 11 of the 30 treated cycles and, in these 11, the LH peak and follicul ar rupture occurred during MPA treatment periods. Out of 19 anovulator y cycles, 16 had no increase in progesterone levels and another 3 deve loped a luteinized unruptured follicle. Progestin administration induc ed secretory changes in the endometrium, but irregular or delayed deve lopment was found. Regular withdrawal bleeding occurred in all subject s. These data indicate that the sequential regimen can suppress ovulat ion while maintaining regular bleeding but increased efficacy is neede d for phase II clinical trials.