The potential for an androgen male contraceptive

The potential for using an exogenous androgen as a reversible male contraceptive has been evaluated in 20 healthy men, 17 of whom completed the study. The experimental design consisted of a 10-week control period, an initial 12-week period with weekly 200-mg injections of testosterone enanthate (TE), a 36-week period with 200-mg injections of TE every 3 weeks, and a 28-week recovery period. Serum concentrations of testosterone were increased approximately 50% during the initial treatment period, and gonadotropins became very low or undetectable and essentially unresponsive to LRH. Sperm density fell, and 11 of the 19 men evaluated at the end of the weekly injection period had ≤1 million sperm/ml semen. Serum FSH and LH and sperm density rose when TE was given every 3 weeks, and on this regimen only 1 man consistently had suppressed gonadotropins and sperm counts of ≤1 million/ml. Each man's mean sperm count during the recovery period exceeded 25 million/ml, and 15 of the 17 men had average values which were similar to or exceeded their average control values. No serious side effects were observed during the study. Eleven men experienced an increase in acne, and body weight increased approximately 5 lb during the initial treatment period. These changes normalized when TE was given less frequently. The mean concentration of hemoglobin increased from 15.1 ± 0.2 g/dl to approximately 16.0 g/dl (P < 0.01) and the serum glutamic oxalopyruvic transaminase increased from 44 ± 4.5 to more than 60 centaunits (P < 0.01) during treatment. Serum concentrations of estradiol increased from 34.1 ± 2.6 to 59.4 ± 6.2 pg/ml (P < 0.002) when testosterone levels were increased. There were no significant changes in carbohydrate tolerance, cholesterol, triglyceride,. or clotting studies. In conclusion, the administration of 200 mg TE each week for 12 weeks reversibly suppressed serum concentrations of FSH and LH and sperm density and was relatively free of significant side effects; however, this regimen did not uniformly achieve azoospermia or oligospermia of sufficient degree to assure its effectiveness as a contraceptive agent.