Male Birth Control Stopped Sperm In Mice, Study Found

A drug aimed at treating eyes immobilized sperm and prevented pregnancy in mice, encouraging researchers that it might work as a contraceptive for men. Injected into male mice, the drug was 100% effective in preventing pregnancy for 2 1/2 hours and about 91% effective for up to 3 1/2 hours, according to a study published Tuesday in the journal Nature Communications. The male mice were fertile after a day, the study found. The new approach is appealing for how quickly the contraceptive acts. The researchers said they would test the drug in other animals and aim for human trials in the coming years.

The drug presented in Tuesday’s study acts by deactivating an enzyme in mice and men that make sperm swim. “It’s like your on-switch on your TV,” said Jochen Buck, a pharmacologist at Weill Cornell Medicine, an author of the study. When the researchers added the drug to human and mice sperm in a dish, the cells stopped moving temporarily. Lower doses of the drug resulted in progressively more mobile sperm cells, Dr. Buck said. The drug took about 15 minutes to take effect. Male mice injected with the drug didn’t alter their mating behavior. Allowed to mate in the 2.5 hours after injection, none of 52 pairs of mice produced offspring. A third of mice partners in a control group of 50 had pregnancies. Mice given the drug were later able to father healthy pups, the study said.