The use of progestins and androgens as a male contraceptive.
35 clinical studies testing whether progestins used alone or with androgens could be used as a male contraceptive were organized between 1971 and 1977 into a public-sector contraceptive development program. Results from these 35 studies are reviewed. It was demonstrated that when high doses of progestins were administered to men, sperm production was suppressed to very low levels in most cases; however, full suppression of sperm atogenies in all subjects was never achieved even when the high doses of progestins were combined with high doses of an androgen. All regimens tested and all drugs used (megestrol acetate, norethindrone, norethandrolone, d-norgestrel, norgestrienone, R 2323, and depo-medroxyprogesterone) were associated with weight gain and transient decreases in libido. Some regimens also caused side effects, including gynecomastia and liver function impairment. It was concluded that none of the 25 regimens tested so far is suited for further development; however, the finding that oligospermia (sometimes azoospermia) could be achieved without substantial side effects in some men was encouraging, and it is suggested that other combined regimens of more potent progestins and androgens which would yield sustained blood levels of these drugs merit testing to determine their potential as male contraceptive agents.