Population Council Research that makes a difference

Abstract

Combined transdermal testosterone gel and the progestin Nestorone suppresses serum gonadotropins in men (PDF) 
Mahabadi,Vahid; Amory,John K.; Swerdloff,Ronald S.; Bremner,William J.; Page,Stephanie T.; Sitruk-Ware,Regine; Christensen,Peter D.; Kumar,Narender; Tsong,Yun-yen; Blithe,Diana; Wang,Christina
Journal of Clinical Endocrinology and Metabolism 94(7): 2313-2320
Publication date: 2009


Context
Testosterone (T) plus progestin combinations are themost promising hormonal male contraceptives. Nestorone (NES),a progestin without estrogenic or androgenic activity, whencombined with T may be an excellent candidate for male contraception.

Objective
Our objective was to determine the effect of transdermalNES gel alone or with T gel on gonadotropin suppression.

Design and Setting
The randomized, unblinded clinical trialwas conducted at two academic medical centers.

Participants
A total of 140 healthy male volunteers participated.

Interventions
One hundred subjects were randomized initially(20 per group) to apply NES gel 2 or 4 mg, T gel 10 g, or Tgel 10 g plus NES gel 2 or 4 mg daily for 20 d. Because onlyabout half of the subjects in T plus NES 4 mg group suppressedserum gonadotropins to 0.5 IU/liter or less (suboptimal suppression),two additional groups of 20 men were randomized to apply dailyT gel 10 g plus NES gel 6 or 8 mg.

Main Outcome Variable
Suppression of serum LH and FSH concentrationsto 0.5 IU/liter or less after treatment was the main outcomevariable.

Results
A total of 119 subjects were compliant with gel applicationswith few study-related adverse events. NES alone reduced gonadotropinssignificantly but less than T gel alone. Combined T gel 10gplus NES gel 6 or 8 mg suppressed both serum gonadotropins to0.5 IU/liter or less in significantly more men than either gelalone.

Conclusion
Transdermal NES gel alone had gonadotropin suppressionactivity. Combined transdermal NES (6 or 8 mg) plus T gel demonstratedsafe and effective suppression of gonadotropins, justifyinga longer-term study of this combination for suppression of spermatogenesis.