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Researchers at the University of Minnesota have developed a contraceptive pill for males that is 99 percent effective and works without side effects—in mice. Human trials are planned.
Other attempts to create a male contraceptive drug have failed in clinical tests; a 2016 trial of an injectable version was halted after an array of side effects appeared, including acne, irregular heartbeats, and one attempted suicide, among other mood disorders.
The new version has sparked hope because, unlike other attempts at male contraception, this one is not based on altering a man’s hormonal balance.
Instead, it uses a molecule known as YCT529 that blocks the body’s ability to make a protein called retinoic acid receptor alpha. This protein is key in producing sperm.
The researchers gave the test mice a daily dose of YCT529 for four weeks and the mice’s sperm count plummeted. When the doses were discontinued, the mice’s normal fertility returned after a few weeks.
The mice showed no side effects, even when the scientists gave them 100 times the effective dose.
As a check on the technique’s safety, the scientists genetically engineered a flock of mice unable to produce retinoic acid receptor alpha. The altered mice showed no abnormalities other than infertility.
The university has licensed the discovery to YourChoice Therapeutics, a private drug company that plans to conduct human trials later this year.
The new drug has its doubters: retinoic acid receptor alpha, the targeted protein, is a derivative of vitamin A and plays a role in cell formation.
“It seems to me inherently unlikely that a compound with such activity would be free of side effects,” Richard Sharpe, a professor at the University of Edinburgh’s Centre for Reproductive Health, told Science magazine.
TRENDPOST: As with many of the steps toward gender equity, the technical aspect is likely to be the easiest part. Persuading some men to surrender their fertility, even temporarily, is likely to take longer than raising a generation of lab mice.