A drug intended to treat the eyes immobilized sperm and prevented pregnancy in mice , which encouraged researchers to think that it might work as a contraceptive for men. Injected into male mice, the drug was 100% effective at preventing pregnancy for 2 1/2 hours and approximately 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 one day, the study found. The new approach is attractive because of the rapidity with which the contraceptive works. The researchers said they would test the drug in other animals and aim for human trials in the coming years.
The drug featured in Tuesday’s study works by turning off an enzyme in mice and men that makes sperm swim. “It’s like turning on the TV,” said Jochen Buck, a pharmacologist at Weill Cornell Medicine, an author of the study. When the researchers added the drug to human and mouse sperm in a dish, the cells temporarily stopped moving. Lower doses of the drug resulted in progressively more motile sperm, Dr. Buck said. The drug took about 15 minutes to take effect. Male mice injected with the drug did not alter their mating behavior. Allowed to mate within 2.5 hours of injection, none of the 52 pairs of mice produced offspring. A third of the pairs of mice in a control group of 50 had pregnancies. Mice given the drug were then able to father healthy pups, according to the study.
