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Combined Transdermal Testosterone Gel and the Progestin Nestorone Suppresses Serum Gonadotropins in Men

Department of Medicine (V.M., P.D.C., R.S.S., C.W.), Division of Endocrinology, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, California 90509; Department of Medicine (J.K.A., W.J.B., S.T.P.), University of Washington, Seattle, Washington 98195; Center for Biomedical Research (R.S.-W., N.K., Y.-Y.T.), Population Council, New York, New York 10021; and Contraception and Reproductive Health Branch (D.B.), National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20852

Address all correspondence and requests for reprints to: Christina Wang, M.D., General Clinical Research Center, 1000 West Carson Street, Torrance, California 90509. E-mail: wang{at}labiomed.org.

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

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

Design and Setting: The randomized, unblinded clinical trial was 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 T gel 10 g plus NES gel 2 or 4 mg daily for 20 d. Because only about half of the subjects in T plus NES 4 mg group suppressed serum gonadotropins to 0.5 IU/liter or less (suboptimal suppression), two additional groups of 20 men were randomized to apply daily T gel 10 g plus NES gel 6 or 8 mg.

Main Outcome Variable: Suppression of serum LH and FSH concentrations to 0.5 IU/liter or less after treatment was the main outcome variable.

Results: A total of 119 subjects were compliant with gel applications with few study-related adverse events. NES alone reduced gonadotropins significantly but less than T gel alone. Combined T gel 10g plus NES gel 6 or 8 mg suppressed both serum gonadotropins to 0.5 IU/liter or less in significantly more men than either gel alone.

Conclusion: Transdermal NES gel alone had gonadotropin suppression activity. Combined transdermal NES (6 or 8 mg) plus T gel demonstrated safe and effective suppression of gonadotropins, justifying a longer-term study of this combination for suppression of spermatogenesis.