Male birth control drug is 100 per cent effective in mice

A male contraceptive that fixes sperm for 2 hours prevented pregnancy in mice without adverse side effects

To Grace Wade

A drug that temporarily paralyzes sperm could be the first on-demand male contraceptive. In mice, the contraceptive drug was 100% effective in preventing pregnancy for approximately 2 hours, with full fertility restored after 24 hours.

“This is absolutely revolutionary in the field of male contraception,” says Jochen Buck of Cornell University in New York. Most of the other male contraceptive candidates in clinical development are only effective after eight to 12 weeks, he says.

Previous studies have shown that a protein called soluble adenylyl cyclase (sAC) is required for sperm migration and that men who fail to produce sAC due to a rare genetic mutation are infertile. . Buck et al. therefore evaluated whether drugs that inhibit sAC could be used as male contraceptives. If the sperm is immobile, it cannot move up the vaginal canal to fertilize the egg.

The team assessed sperm motility taken from 17 male mice, eight of which were drugged. On average, only about 6% of the sperm were able to migrate, compared to about 30% in the mouse samples. The effect disappeared after about 24 hours. “This means that not only do we have on-demand contraceptives, but we can also reverse them rapidly,” says her Melanie Balbach, also from Cornell University.

In another test, researchers paired 52 male mice with females 30 minutes after the males were given contraceptives. Two hours later, each pair mated, but did not conceive, and was 100% contraceptive. The drug caused no noticeable side effects, even when mice received three times the standard dose of the equivalent compound for 42 consecutive days.

“What I like about the contraceptives proposed in this study is the on-demand option,” said Ulrike Schimpf of KTH Royal Institute of Technology, Sweden. “It’s temporary, fast-acting, and effective on the first dose.”

Buck and Barbach plan to refine the drug to make it last longer before testing it in humans.

“We need more [birth control] Men need options so that women don’t have to bear the burden of contraception,” Barbach says. “We are very optimistic that men taking inhibitors will have the same effect.”

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