A new study in mice has shown that a previously developed male hormonal (testosterone) oral contraceptive method is unable to stop the production and / or the release of sperm.  

Scientists demonstrated in their mice experiments that the male contraception approach by testosterone has an inherent problem — spermatogenesis still does not stop. They did find that that administering increasing doses of testosterone to infertile mutant mice did allow sexual function to return at a certain dosing threshold, which was expected.  

What was not expected, however, is that spermatogenesis also returned at that dose. This suggests that it is impossible to give a single dose of testosterone that allows for sexual function and the suppression of pituitary gonadotropin secretion, but also does not initiate sperm production.

"Our research in mice explains why the efficacy of male hormonal contraception is not as effective as expected and it provides clues on how to improve the method," said Ilpo Huhtaniemi, M.D., Ph.D., M.D.hc, FMed.Sci., a researcher involved in the work from the Institute of Reproductive and Developmental Biology at the Imperial College of London in London, UK.

"Ever since The Pill was developed, we've been aiming for an equivalent for men," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "This report suggests that we may be finally reaching the end of administering testosterone for this purpose."