NES Gel-1, To Evaluate Nestorone Gel in Combination With Testosterone Gel

The success of hormonal male contraception depends on the near complete suppression of spermatogenesis without producing any untoward effects on libido or other androgen-dependent functions or any other adverse events. The treatment with androgen alone has geen shown to be highly effective in Asian men but less effective in non-Asian men in clinical trials. To increase the efficacy of androgen alone treatment on spermatogenesis, combined regimens of a progestin and an androgen have shown promising results. The steady-state delivery of a progestin and an androgen by transdermal gel application would be a user-friendly delivery method as compared to injectable or implant approaches. Nestorone (NES) is a synthetic progestin that does not have any androgenic and estrogenic activity and is not expected to have some of the undesirable side effects of other drugs. We propose to evaluate whether NES gel alone or in combination with T gel applied transdermally will result in more effective suppression of gonadotropins than NES or T gel applied alone in healthy men. Fifty healthy male subjects, age 18-50 will be enrolled at each center (2 sites).