Contraceptive effectiveness of azoospermia and oligozoospermia caused by testosterone enanthate
The first-ever multicenter study of contraceptive efficacy among healthy men receiving a prototype hormone therapy, conducted during 1986-1990, provided strong evidence that after laboratory diagnosis of azoospermia, normal men became infertile and could maintain safe, effective, and reversible contraception for at least 12 months. There was variation in the rate of achievement of azoospermia among men of the same genetic background. However, men in Chinese centers achieved azoospermia more often than men in Caucasian centers. A second phase to evaluate whether hormonally induced severe oligozoospermia is associated with an acceptable level of contraceptive effectiveness began in 1990. If this study demonstrates that contraceptive efficacy is high even if spermatogenesis is not completely suppressed, the goal of male development with hormonal antifertility agents will be greatly simplified.
Long-acting androgen preparations
Studies of androgenic suppression of spermatogenesis to date have been conducted with relatively short-acting drugs. Now more physiological ways of replacing androgens with a long duration are becoming available, not only for the treatment of male hypogonadism, but also in the development of all types of hormonal methods for men. These include biodegradable testosterone microcapsules, testosterone and testosterone bucciclate granules, and testosterone ester. The first clinical trial with hypogonadal men showed that circulating serum testosterone levels were restored to the low normal range within 12 weeks with a single intramuscular injection of 600 mg of the latter. The first clinical trial to study the suppression of testosterone spermatogenesis by buciclatide in healthy men has been launched. Given ethnic differences in response to contraceptive steroids, all such studies will be conducted in centers in China and Indonesia.
Studies in the 1970s found that progestogen-androgen combinations were safe and relatively effective in suppressing sperm production in Caucasian men, but rarely achieved more than 50% of azoospermia cases. Recently, three injections at monthly intervals of depot medroxyprogesterone acetate (DMPA, 200 mg or 100 mg) and testosterone enanthate (250 mg or 100 mg) were shown to induce spermatogenesis suppression to azoospermia in 19 of 20 Indonesian men. A five-center study in Indonesia evaluated the comparative efficacy of two androgens, testosterone enanthate and the longer-acting 19-norethisterone-hexyl-oxy-phenylpropionate, when each was combined with DMPA.