A birth control pill for men 99% effective in mice

The researchers estimate that clinical trials in humans could be carried out in the second half of 2022.

A team of scientists announced on Wednesday, March 23, that they had developed a male contraceptive pill that is 99% effective in mice without causing any visible side effects, and could be tested in men by the end of the year. These results will be presented at the American Chemical Society Spring Conference. They mark an important step for male contraception, which is still very marginal within couples.

The search for a contraceptive pill for men dates back to the authorization in the 1960s of its equivalent for women, Md Abdullah Al Noman, a master’s student at the University of Minnesota, who will present this work at the conference, told AFP. “Many studies show that men are interested in sharing the responsibility of contraception within the couple”, he says, but to date there are only two recognized and effective solutions: condoms and vasectomy, a long-lasting solution that is sometimes difficult (and expensive) to go back on. Other practices, such as hot underpants and the ring around the testicles, remain confidential and not validated by health authorities.

The operation of the female pill is based on hormones that interrupt the menstrual cycle. Researchers have long tried to develop a male equivalent using the same method and by acting on a male hormone, testosterone. But these attempts caused unwanted side effects, including weight gain, bouts of depression, and increased cholesterol levels, which increases the risk of heart disease. The female pill also causes side effects, including an increased risk of blood clots.

There’s no guarantee of success… but I’d be very surprised if I didn’t see an effect in humans as well. »

Professor Gunda Georg

To develop a non-hormonal pill, Md Abdullah Al Noman, who works in Professor Gunda Georg’s lab, focused on a protein, retinoic acid receptor alpha (RAR-alpha). In the human body, vitamin A is converted into many elements, including retinoic acid, which plays an important role in cell growth, sperm formation, and embryonic development. Retinoic acid needs these RAR-alpha receptors to act: laboratory experiments have shown that mice deprived of the gene that codes for this receptor are sterile.

For their work, this laboratory has developed a compound that blocks the action of RAR-alpha. The researchers used a computer model to identify the best possible molecular structure. Its chemical compound, called YCT529, was designed to interact only with RAR-alpha and not with two other neighboring receptors, RAR-beta and RAR-gamma, to limit side effects. Administered orally to male mice for four weeks, YCT529 dramatically reduced sperm production and was 99% effective in preventing pregnancy, with no side effects observed. And six weeks after stopping the YCT529 ingestion, the mice were able to reproduce again.

The team, funded by the US Institutes of Health (NIH) and the nonprofit Male Contraceptive Initiative, is working with YourChoice Therapeutics to begin clinical trials in the second half of 2022, Professor Gunda Georg said. “I think you can fast forward”he said, estimating that commercialization could happen within five years. “There is no guarantee of success…but I would be very surprised if I didn’t see an effect in humans as well”the chemist added.

However, would women trust men enough to take charge of a matter that until now has depended almost exclusively on them? Studies have shown that most women would be willing to trust their partner, and a significant number of men have reported that they are willing to take birth control pills. “Male contraception will add to existing options and allow men and women to choose the contraceptive method that seems most appropriate to them”praised the Male Contraceptive Initiative.

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