Inhibition of ovulation by a triphasic gestodene-containing oral contraceptive.

The minimal effective dose of gestodene for inhibition of ovulation was studied in 30 female volunteers. Daily doses of 10 micrograms to 50 micrograms gestodene were given orally for 21 days. A control cycle prior to treatment and a treatment cycle were monitored for LH, FSH, estradiol, progesterone and cervical score. At a daily dose of 40 micrograms of gestodene, 6/7 volunteers exhibited inhibition of ovulation and 1/7 had a cycle with luteal insufficiency. Ovulation was inhibited in all volunteers on 50 micrograms gestodene, suggesting that the minimum dose required to inhibit ovulation was 40 micrograms gestodene. Cervical score was blunted even at 10 micrograms gestodene. Similarly, 20 volunteers were treated with coated tablets containing ethinylestradiol/gestodene at 30/50 micrograms for 6 days, 40/70 micrograms for 5 days and 30/100 micrograms for 10 days. This triphasic gestodene-containing preparation inhibited ovulation in all 20 females. In one cycle in which follicle development was observed only 43 pg estradiol/ml was secreted. Data from this investigation suggest that this triphasic gestodene-containing OC has a high contraceptive efficacy.