Ovulation-inhibiting effects of dienogest in a randomized, dose-controlled pharmacodynamic trial of healthy women.

Dienogest offers pharmacological advantages for the effective treatment of endometriosis and for use in contraception and hormone replacement therapy. This pharmacodynamic study investigated the ovulation-inhibiting effects of dienogest monotherapy in healthy women. Dienogest was administered at 0.5, 1, 2, or 3 mg daily for up to 72 days to women aged 18 to 35 years (n = 102). Ovarian activity was assessed pretreatment and during 2 treatment periods (days 0-36 and days 37-72) by the Hoogland score, based on follicle size and serum estradiol and progesterone levels. Additional hormonal parameters and endometrial thickness were assessed. Hoogland scoring indicated ovulation in all women pretreatment, decreasing to 3 of 21, 1 of 23, 0 of 20, and 0 of 23 women in the 0.5-, 1-, 2-, and 3-mg groups, respectively (per-protocol set). Maximum serum estradiol concentrations were similar to pretreatment levels in the 0.5- or 1-mg group and decreased moderately (within physiologic levels) in the 2- or 3-mg group. Endometrial thickness was reduced by all dienogest doses. Hormonal changes during follow-up indicated resumption of ovulation in most women, shortly after treatment cessation. Dienogest ≥2 mg daily provides moderate suppression of estradiol production and reliable ovulation inhibition, which reverses rapidly after treatment cessation.