Chemical Contraception in Men

CHEMICAL CONTRACEPTION IN MEN

Although many studies have been conducted, an effective oral contraceptive for men has not yet been found. For example, various androgens, including testosterone and testosterone enanthate, in a dosage of 400 mg per month, produced azoospermia in less than half the men treated. Minor adverse reactions, including gyneco-mastia and acne, were encountered. Testosterone in combination with danazol was well tolerated but no more effective than testos-terone alone. Androgens in combination with a progestin such as medroxyprogesterone acetate were no more effective. However, preliminary studies indicate that the intramuscular administration of 100 mg of testosterone enanthate weekly together with 500 mg of levonorgestrel daily orally can produce azoospermia in 94% of men.

Cyproterone acetate, a very potent progestin and antiandrogen, also produces oligospermia; however, it does not cause reliable contraception.

At present, pituitary hormones—and potent antagonist analogs of GnRH—are receiving increased attention. A GnRH antagonist in combination with testosterone has been shown to produce reversible azoospermia in nonhuman primates.

GOSSYPOL

Extensive trials of this cottonseed derivative have been conducted in China. This compound destroys elements of the seminiferous epithelium but does not significantly alter the endocrine function of the testis.

In Chinese studies, large numbers of men were treated with 20 mg/d of gossypol or gossypol acetic acid for 2 months, fol-lowed by a maintenance dosage of 60 mg/wk. On this regimen, 99% of men developed sperm counts below 4 million/mL. Preliminary data indicate that recovery (return of normal sperm count) following discontinuance of gossypol administration is more apt to occur in men whose counts do not fall to extremely low levels and when administration is not continued for more than 2 years. Hypokalemia is the major adverse effect and may lead to transient paralysis. Because of low efficacy and signifi-cant toxicity, gossypol has been abandoned as a candidate male contraceptive.