Cj. Bagatell et al., COMPARISON OF A GONADOTROPIN-RELEASING-HORMONE ANTAGONIST PLUS TESTOSTERONE (T) VERSUS-T ALONE AS POTENTIAL MALE CONTRACEPTIVE REGIMENS, The Journal of clinical endocrinology and metabolism, 77(2), 1993, pp. 427-432
Efforts to develop a hormonal contraceptive regimen for men have focus
ed on administration of testosterone (T), alone or together with other
agents. Previous regimens have successfully induced azoospermia in on
ly 50-70% of subjects, however. GnRH antagonists, alone or in combinat
ion with T, have been shown to induce azoospermia in a very high perce
ntage of nonhuman primates. We tested the hypothesis that the addition
of a GnRH antagonist to a high-dose T regimen would lead to a higher
percentage of men developing azoospermia than would T alone. We admini
stered the GnRH antagonist, Nal-Glu (100 mug/kg. day sc), plus T enant
hate, 200 mg im weekly or placebo sc injections daily plus T enanthate
, 200 mg im weekly, to separate groups of healthy men for 16-20 weeks.
Seven of 10 men who received Nal-Glu plus T and 6 of 9 men who receiv
ed T alone became azoospermic; gonadotropin levels were suppressed and
T levels were increased similarly in both groups. There was a trend t
oward higher pretreatment gonadotropin levels and lower sperm counts i
n men who became azoospermic. Weight gain, development of acne, and in
creases in hematocrit and hemoglobin were similar in the two groups. I
n the majority of the men, sperm counts returned to the baseline level
s within 4-5 months after treatment ended. We conclude that with the d
osages of Nal-Glu and T we used in this study, the addition of GnRH an
tagonist to a high-dose T regimen does not increase the ability of T t
o suppress spermatogenesis in healthy men. Use of a higher dose of Nal
-Glu, a lower dose of T, delaying the start of T replacement until sev
eral weeks after Nal-Glu injections are initiated, or prolonged hormon
al administration might lead to a combination regimen that will suppre
ss spermatogenesis more fully than does T alone.