In conclusion, the present study demonstrated that induced severe oligozoospermia or azoospermia by weekly testosterone enanthate injection was sufficient for male contraception. The low rates of discontinuation due to side-effects of the hormone and incidental medical conditions in this study confirms the safety and acceptability of such androgen administration found in studies with up to 18 months exposure. The long-term hazards remain uncertain and require investigation for risk. The possible long-term benefits from androgen use for bone, muscle and blood metabolism will also need to be assessed before the net risk-benefit effects of an androgen-containing regimen can be fully evaluated. In summary, the contraceptive efficacy for male contraception in this study demonstrated that weekly injections of testosterone enanthate can provide safe and effective contraceptive protection. The practicability of this approach may be improved by the use of longer-acting testosterone preparations which are under development.
PIP: To assess the safety and efficacy of testosterone enanthate as a fertility control method, 17 healthy Thai men 21-45 years of age were administered weekly intramuscular injections of 200 mg of the androgen. All men were in stable relationships in which fertility had been established by a prior pregnancy. The study consisted of suppression, efficacy, and recovery phases. The median time required for the first semen sample to show azoospermia was 85 days. The three men who entered the efficacy phase still oligozoospermic (sperm concentrations under 3 million/ml) all achieved azoospermia early in the 12-month evaluation. There were no pregnancies during 6 months of exposure involving men with severe oligozoospermia and 152 months of exposure in azoospermic men. The regimen was associated with significant increases in body weight, hemoglobin, hematocrit, and testosterone and decreases in testicular volume, plasma urea, luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Plasma LH and FSH levels recovered to pretreatment levels after cessation of treatment. Two men discontinued during the efficacy phase: one because of weight gain and hypertension, and another due to abnormal liver function tests. Testosterone has the advantages of providing simultaneous gonadotropin suppression and androgen replacement, making it an ideal single-agent hormonal male contraceptive. Compliance would be improved by the use of long-acting depot preparations. Although this study confirms testosterone's well-sustained suppression of spermatogenesis and lack of short-term adverse effects, long-term effects on cardiovascular and prostatic disease require investigation.