Twenty-one day administration of dienogest reversibly suppresses gonadotropins and testosterone in normal men

Androgen-progestin combinations are promising male contraceptive regimens. Optimization of these regimens includes the development of new progestins with more favorable biological properties. In this context we tested the effects of the progestin dienogest (DNG) on reproductive hormones and metabolic parameters in men. After a 3-wk control period, 25 men were randomly assigned to receive daily doses of 2, 5, or 10 mg DNG or placebo and 10 mg cyproterone acetate for 21 d (n = 5 subjects/group). Subjects were followed for 2 wk after cessation of hormone administration. Weekly blood samples, physical examinations, hormone and chemistry measurements, semen analysis, and sexual/behavioral assessments were performed. These parameters were compared among study groups and within each group at different time points throughout the study periods. DNG and cyproterone acetate administration resulted in profound suppression of gonadotropins and T with no change in SHBG levels. No adverse effects were detected in any subject. Hormone levels returned to baseline after stopping hormone intake. DNG is a potent suppressor of gonadotropins and T in men and does not induce adverse effects over a 21-d administration. DNG is a promising progestin to be used in clinical trials for male contraception.