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.
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.
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.
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.