(HealthDay News) – A gel containing a combination of testosterone (T) and Nestorone (NES) is effective for suppressing spermatogenesis.

Niloufar Ilani, MD, from the Harbor-University of California Los Angeles Medical Center, and colleagues investigated the effectiveness of T gel alone or in combination with NES for suppressing spermatogenesis. Participants included 99 healthy male volunteers who were randomly allocated to apply daily transdermal gel (T 10mg + NES 0mg; T 10mg + NES 8mg; and T 10mg + NES 12mg). Analyses were performed on 56 men who adhered to the protocol and completed 20 weeks of treatment.

The researchers found that there was a significantly higher percentage of men whose sperm concentration was ≤1 million/mL with T+NES 8mg and T+NES 12mg compared with T+NES 0mg (88% and 89%, respectively, vs. 23%). In the T+NES 8mg and T+NES 12mg groups, significantly more men became azoospermic compared with the T+NES 0mg group (78% and 69%, respectively, vs. 23%). Irrespective of treatment group, the total and free T concentrations remained within the adult male range. During the recovery period all subjects recovered to a sperm concentration of ≥15 million/mL. There were minimal adverse effects observed in all groups.

“While this gel has great potential and minimal side effects, it does warrant further study as a male contraceptive,” a coauthor said in a statement.

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