AN INVESTIGATION OF OVULATION INHIBITION WITH A LOW-DOSE COMBINED ORAL-CONTRACEPTIVE CONTAINING 75 MU-G GESTODENE AND 20 MU-G ETHINYLESTRADIOL

This open-label, single-center study investigated the efficacy of a 21 -day monophasic oral contraceptive containing 75 mu g gestodene and 20 mu g ethinylestradiol with respect to its effects on the hypothalamic -pituitary-ovarian axis and ovulation inhibition. A total of 38 health y women between the ages of 21 and 34 years entered the study, which c onsisted of two control cycles (cycles 1 and 5) and three treatment cy cles (cycles 2, 3 and 4). During treatment, each subject received the contraceptive preparation once a day for 21 days followed by 7 days of placebo. Ovulation was inhibited in all 79 treatment cycles, as defin ed by ultrasound measurements of follicle size greater than or equal t o 16 mm diameter and by serum levels of progesterone > 5 ng/ml in a si ngle cycle. Luteinizing hormone, follicle stimulating hormone and 17 b eta-estradiol were also suppressed by the treatment. The greatest supp ressive effect on ovarian follicular activity was observed in cycle 2, where treatment with gestodene/ethinylestradiol began on day 1 of the menstrual cycle. There were no serious adverse events. Results from t his study demonstrate that this low-dose combined oral contraceptive i s effective as an inhibitor of ovulation, by suppressing the activity of the hypothalamic-pituitary-ovarian axis.