Efficacy of low-dose oral contraceptives containing levonorgestrel, gestoden and cyproterone acetate

The efficacy of low-dose oral contraceptives containing 30 micrograms or 35 micrograms ethinyl estradiol in combination with Levonorgestrel, gestoden (delta 15-Levonorgestrel) and cyproterone acetate was studied. Borderline doses for inhibition of ovulation were found to be approximately 50 micrograms for Levonorgestrel, 40 micrograms for gestoden and 1 mg for cyproterone acetate. These results were derived from the assay of luteinizing hormone, follicle-stimulating hormone, 17 beta-estradiol and progesterone serum levels during the daily treatment of a total of 47 female volunteers from day 5 through day 25 of their cycles. A combination of 30 micrograms ethinyl estradiol plus 75 micrograms Levonorgestrel or 75 micrograms gestoden resulted in complete inhibition of ovulation in each of the 20 subjects studied. Monitoring of hormone serum levels in 6 female volunteers with normal cycles during the administration of 35 micrograms ethinyl estradiol plus 2 mg cyproterone acetate showed inhibition of ovulation in all subjects studied during the first and third therapy cycle. One subject exhibited follicular maturation during the third treatment cycle as judged from the patterns of 17 beta-estradiol serum levels. Present data suggest that low-dose oral contraceptives containing Levonorgestrel, gestoden and cyproterone acetate are highly efficient in providing great contraceptive safety and do not support the previous notion that the kind of progestagen used is relevant for the degree of central inhibition.