A combined regimen of cyproterone acetate and testosterone enanthate as a potentially highly effective male contraceptive

Abstract

In this study we tested the effectiveness of the combined administration of cyproterone acetate (CPA) and testosterone enanthate (TE) in suppressing spermatogenesis. After a control phase of 3 months, 15 normal men were randomized to receive TE (100 mg/week) plus CPA at a dose of 100 mg/day (CPA-100; n = 5) or 50 mg/day (CPA-50; n = 5) or TE (100 mg/week) alone (n = 5) for 16 weeks. Semen analysis was performed every 2 weeks. Every 4 weeks, fasting blood samples were drawn for the measurement of LH, FSH, testosterone, estradiol, and biochemical and hematological parameters; subjects underwent a physical examination; and they and their partners filled in a sexual and behavioral questionnaire. Regardless of the dose, each of the 10 subjects receiving CPA plus TE became azoospermic, whereas only 3 of 5 subjects treated with TE alone achieved azoospermia. Times to azoospermia were 6.8 +/- 0.5, 8.4 +/- 1.0, and 14.0 +/- 1.2 weeks in groups CPA-100, CPA-50, and TE alone, respectively (P = NS). Throughout treatment, both gonadotropins tended to be higher in the TE alone group than in the other groups. This difference was mostly due to the higher gonadotropin levels present in the 2 men treated with TE alone that remained oligospermic. No difference in testosterone or estradiol levels was found among the groups. No significant change in lipoprotein levels or liver function tests could be detected. In the CPA-100 and CPA-50 groups, hemoglobin, hematocrit, and red blood cells were lower at the end of the treatment phase, whereas no change was detected in TE alone group. A tendency for a decrease in body weight was detected in subjects treated with CPA, whereas there was no change in subjects receiving TE alone. At the end of the treatment phase, a decrease in testis size was present in all groups. There was no significant change in sexual function, aggressive behavior, mood states, or satisfaction with relationship in any group. These results suggest that the combined administration of CPA and TE is very effective in suppressing spermatogenesis and may represent a promising regimen for reversible contraception in males.