SAN DIEGO, Calif. — A contraceptive pill for men may be on the horizon after a new treatment prevented male mice from getting females pregnant. The non-hormonal drug offers hope of expanding birth control options for men and their partners.
Researchers say clinical trials for humans could begin within six months.
“Scientists have been trying for decades to develop an effective male oral contraceptive, but there are still no approved pills on the market,” says lead author Abdullah Al Noman, a graduate student at Minnesota University, in a media release.
Most contraceptives in clinical trials target the male sex hormone testosterone, which can lead to obesity, depression, and high levels of bad cholesterol.
“We wanted to develop a non-hormonal male contraceptive to avoid these side effects,” Noman says.
The pill, presented at the 2022 spring meeting of the American Chemical Society, works by blocking vitamin A — a crucial nutrient in conception.
Women have many choices for birth control, ranging from pills to patches to intrauterine devices. As a result, they bear most of the burden of preventing pregnancy. Men have just two: condoms or a vasectomy. The former is a single-use only option and prone to failure. The latter is surgical sterilization which is expensive to reverse and not always successful.
Targeting vitamin A to prevent pregnancy
Study authors say men need an effective, long-lasting contraceptive, similar to the women’s pill. They targeted a gene called RAR-α that produces retinoic acid, a form of vitamin A that fuels sperm and embryonic development. The compound called YCT529 made male lab rodents sterile, without any side-effects or harm to related proteins.
After four weeks of oral administration, the pill dramatically reduced sperm counts and was 99 percent effective in preventing pregnancy. The mice could also father pups again four to six weeks after they stopped receiving the pill.
Co-author Professor Gunda Georg, who heads the lab, says testing in humans will begin in the third or fourth quarter of 2022.
“Because it can be difficult to predict if a compound that looks good in animal studies will also pan out in human trials, we’re currently exploring other compounds, as well,” Prof. Georg adds.
To identify these next-generation pills, the researchers are modifying YCT529 and trying out new structural versions. They hope their efforts will finally bring the elusive oral male contraceptive to fruition. It would help reduce unintended pregnancies and abortions, while also improving maternal health and decreasing infant mortality.
More choice for men
The female pill has helped millions of women take control of their fertility and reproductive health since it became available in 1961. Its convenience and non-invasiveness has provided little incentive for pharmaceutical giants to develop a male equivalent.
A recent study that injected men with testosterone and progestogen – similar to hormones found in the female pill – was halted before its conclusion. Pregnancy rates for female partners of men receiving the injections fell below that typically seen for women on the pill. However, adverse side-effects included acne, mood disorders, and increased libido. These side-effects proved too severe, despite the desired drop in sperm production.
South West News Service writer Mark Waghorn contributed to this report.