Male contraceptive pill test stopped sperm swimming, scientists say

An on-demand male contraceptive pill is one step closer after an experimental drug was found to temporarily stop sperm movement in mice.

The results of a study published in Nature Communications showed that the drug prevented pregnancy, demonstrating a potential avenue for male contraception.

The discovery could be a "game-changer" for the field, lead authors Dr Jochen Buck and Dr Lonny Levin of Weill Cornell Medicine said.

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Essentially, should this version of the pill one day be marketed to men, users will be able to take one as needed and block their fertility for a few hours.

The new study demonstrated that a single dose of an sAC inhibitor immobilised mouse sperm for up to two and half hours, and that the effects persist in the female reproductive tract after mating.

After three hours, some sperm began regaining motility. By 24 hours, nearly all sperm had recovered normal movement.

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"Our inhibitor works within 30 minutes to an hour," lead authors' associate Dr Melanie Balbach said.

"Every other experimental hormonal or non-hormonal male contraceptive takes weeks to bring sperm count down or render them unable to fertilise eggs."

Balbach said it also took weeks to reverse the effects of other hormonal and non-hormonal male contraceptives in development.

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She said that since the new inhibitors wear off within hours, men could take it only when, and as often, as needed — effectively making day-to-day decisions about their fertility.

"The team is already working on making sAC inhibitors better suited for use in humans," Dr Levin said.

Testing will continue.

But other experts have told the BBC that this version of a male contraceptive pill would not obviate the use of condoms, which are still the most effective method of preventing the spread of sexually transmitted diseases.

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