A male contraceptive that works by deforming sperm could available within just a few years, if tests on men go well. This fast track development is possible because the drug is already licensed for use in treating a rare genetic disorder in people, called Gaucher鈥檚 disease.
The drug is taken as a pill, not injected, and it could have fewer side effects than experimental hormonal male contraceptives, which include a cocktail of hormones designed to suppress sperm production while maintaining normal testosterone levels.
Furthermore, its contraceptive effects may be more completely reversible than other non-hormonal drugs in development, say the researchers conducting the experiments at the University of Oxford, UK.
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In tests on mice, low doses of the drug interfered with the metabolism of sugar-fat compounds essential for sperm production. Sperm from the treated mice showed a range of defects, including tails that were coiled around the sperm head and abnormally shaped nuclei. Every mouse in the study was rendered infertile, and there were no obvious side effects.
鈥淚鈥檓 excited by the potential of the new compound,鈥� says Richard Sharpe of the MRC Human Reproductive Sciences Unit at the University of Edinburgh, Scotland. But he warns that many promising male contraceptives that have shown similar results in animal models in the past have fallen by the wayside.
Usually, this has been because of problems relating to side-effects or irreversibility in people, or because a drug that has worked well in mice has not been successful when tried in men.
40 days, 40 nights
The drug, N-butyldeoxynojirimycin (NB-DNJ), inhibits an enzyme that produces glucosylceramide. This sugar-fat compound is vital for sperm creation.
In mice, sperm live no longer than three weeks before being replaced. After three weeks on the drug, the mouse in the study became fully infertile. After three weeks off, they regained their fertility. In men, the on-off period would be about 40 days, says Oxford University鈥檚 Frances Platt, who led the new work.
Men would probably have to take a pill every day, she says. But she believes there would be a demand for such a drug. 鈥淧eople innately believe that men are not reliable individuals when it comes to contraception,鈥� she told 麻豆传媒. 鈥淏ut different people have different requirements, and this may offer an alternative.鈥�
Sharpe agrees that there is a 鈥渉uge unmet need鈥� for alternatives to condoms or a vasectomy. 鈥淲hat is most appealing about these new findings is that the same or related compounds are already in clinical use, so we can be assured that no major adverse side effects have been seen,鈥� he says.
Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.262586099)