Taking a pill a day significantly reduces sperm counts in mice with no side effects, but many male birth control pills have previously failed human trials
March 23, 2022
A non-hormonal male contraceptive was 99 percent effective at preventing pregnancy in mice, and no side effects were observed. Human trials are planned, but some researchers have warned that safety concerns could prevent the drug from reaching the market.
despite many attempts exist make effective and the safe male birth control pill, no treatment through human clinical trials. Most are hormone-based, but non-hormonal contraceptives tend to have fewer side effects, say Medical PhD Abdullah Norman at the University of Minnesota in Minneapolis.
“Safety is very important for birth control pills, because people don’t take it because of a disease, so they have less tolerance for side effects,” Norman said.
He and his colleagues gave male mice a daily dose of a molecule called YCT529 for 4 weeks and found that their sperm counts dropped dramatically. Within four to six weeks after the mice stopped receiving treatment, they were able to reproduce normally again with no apparent side effects.
“When we reached doses 100 times higher than the effective dose, the compound did not show any toxicity,” said Noman, who presented the results today at the 2022 Spring Meeting of the American Chemical Society in San Diego, California.
The team tested more than 100 molecules to identify a drug candidate that targets a protein called retinoic acid receptor alpha (RAR-alpha). Inhibiting this protein blocks the action of retinoic acid, a derivative of vitamin A that plays an important role in cell development and sperm formation.
Previous research has shown that Gene-edited mice that lack RAR-α Gene There are no side effects other than the inability to produce sperm.
Noman and his colleagues have now licensed their drug to a private company called YourChoice Therapeutics, which is aiming for human trials in the United States later this year.
While Noman and his team didn’t observe any side effects in the mice, that doesn’t guarantee the drug is safe in humans, says Richard Anderson at the University of Edinburgh, UK. “If you’re developing a drug that targets an entirely new pathway, I think it’s appropriate to be cautious about safety in the absence of a record in the field.”
The vitamin A signaling system plays many important roles in the body’s systems. “In my opinion, it’s unlikely that a compound with this activity itself would be free of side effects,” says Richard Sharpalso at the University of Edinburgh.
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