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Title: Induction of azoospermia in normal men with combined Nal-Glu gonadotropin-releasing hormone antagonist and testosterone enanthate.
Author: Tom L, Bhasin S, Salameh W, Steiner B, Peterson M, Sokol RZ, Rivier J, Vale W, Swerdloff RS.
Journal: J Clin Endocrinol Metab; 1992 Aug; 75(2):476-83. PubMed ID: 1639948.
Abstract:
The effects of a combined GnRH antagonist and testosterone (T) replacement regimen on gonadotropins and spermatogenesis were examined to assess its potential as a male contraceptive regimen. The potent Nal-Glu GnRH antagonist ([Ac-D2-Nal1,D4-Cl-Phe2,D3-Pal3,Arg5, D4-p-methoxybenzoyl-2-amino butyric acid6,D-Ala10]GnRH) was administered daily (7.5 mg, sc) to eight normal men for 16 weeks. T enanthate was given im starting at week 2 and every 2 weeks thereafter through week 14 of the treatment phase. Serum LH, FSH, T, and estradiol concentrations were measured frequently during the 5-week control period, the 16-week treatment phase, and the 14-week recovery phase. Semen analyses were performed every week during the control phase and every 2 weeks during the treatment and recovery phases. Seven of eight subjects became azoospermic by 6-10 weeks of treatment; the eighth subject, who failed to achieve azoospermia, suppressed his sperm count to 7 million/mL by week 14 (from a mean baseline of 42 million/mL) before treatment was prematurely terminated because of localized swelling at each of his injection sites. Sperm counts returned to baseline 10-14 weeks after the end of Nal-Glu administration. Seven of the eight subjects showed suppression of LH to the limit of assay detection (less than 0.2 U/L), whereas the eighth subject showed incomplete suppression. Serum bioactive and immunoreactive LH concentrations showed concordant responses. Mean serum FSH concentrations were also markedly suppressed. Serum T and estradiol concentrations declined dramatically during the first 2 weeks of Nal-Glu GnRH treatment, but returned to the normal physiological range after T enanthate replacement was initiated. Libido and sexual potency were maintained. No systemic side-effects, other than erythema and induration at injection sites, were observed. These data demonstrate that combined GnRH antagonist plus T treatment can predictably and reversibly induce azoospermia in most men and has potential as a male contraceptive regimen. This study examined the hypothesis that a gonadotropin-releasing hormone (GnRH) antagonist, given at a dose that will suppress gonadotropin secretion and combined with a replacement dose of androgen, will induce reversible azoospermia in normal men while maintaining sexual function. About 8 normal men aged 24-48 years participated in the study. Sperm concentration in all 8 subjects decreased during the treatment; 7 became azoospermic by 6-10 weeks of treatment. In the 8th subject, who failed to achieve azoospermia, the sperm count declined to 7 million/ml by week 14, when treatment was prematurely terminated because of localized inflammation and induration at each of the injection sites. Sperm count returned to baseline following the end of Nal-Glu administration. No statistically significant change was observed in the sperm function during the oligospermic phase of treatment from baseline. 7 subjects showed suppression of luteinizing hormone, while the 8th experienced edema and discomfort at the injection sites. Mean serum follicle stimulating hormone concentrations were suppressed. Serum testosterone and estradiol concentrations declined during the treatment but returned to normal following T enanthate replacement initiation. Main side effects of Nal-Glu GnRh treatment were local erythema and induration at the injection sites due to local histamine release. In conclusion, the combined GnHR antagonist and T treatment can induce azoospermia in most men and has potential as a male contraceptive regimen.

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