Dose finding in a low-dose 21-day combined oral contraceptive containing gestodene

An open label, non-comparative study was carried out in 22 women over a total of five cycles. After an untreated cycle, oral administration of 20 μg ethinyl estradiol (EE) with 50 μg gestodene (GST) (tablets taken daily for 21 days with a break of 7 days) was commenced, and three treatment cycles were followed by an untreated follow-up control cycle. The ability of this formulation to inhibit ovulation and suppress ovarian activity was assessed by using hormonal parameters and ultrasound. One ovulation occurred during treatment. Luteinized unruptured follicles were observed in three cases in the second treatment cycle and in one case during the third treatment cycle. Follicle-like structures larger than 13 mm associated with a serum estradiol level of more than 30 pg/mL were noted in 19% of the women in the first treatment cycle. The rate of active follicle-like structures was 43% in the second treatment cycle and 28% in the third treatment cycle. The results were compared with previously reported findings of a preparation containing 20 μg EE and 75 μg GST. With regard to ovarian grading and endogenous hormone secretion, considerably more residual ovarian activity, with all parameters examined, was found in the 20 μg EE and 50 μg GST preparation compared to the 20 μg EE and 75 μg GST preparation. It was concluded that the 20 μg EE and 50 μg GST preparation administered for 21 days does not meet the requirements of a combined oral contraceptive with respect to ovulation inhibition.