Male birth control drug that blocks sperm in mice hailed as ‘game changer’ for male contraception

New contraceptive that stops sperm swimming for two hours brings us closer to ‘on-demand male pill’
New contraceptive that stops sperm swimming for two hours brings us closer to ‘on-demand male pill’ Copyright Euronews
Copyright Euronews
By Camille Bello
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Scientists hope their findings will pave the way to a contraceptive pill that men could take shortly before sex.


Picture this: A man walks into a pharmacy and buys "the male pill" as the burden of birth control is finally more equally shared among genders.

Scientists have been working on an oral male contraceptive for decades - and they’re now one step closer after an experimental drug was found to temporarily block sperm in mice and prevent pregnancies in preclinical trials.

In a paper published this week in Nature Communications, scientists from Cornell University said their findings could be a "game changer" for male contraception.

Other than condoms, which have existed for about 2,000 years - with their early versions being made from animal intestines or oiled silk paper - men haven’t had many reliable options to prevent their sperm from impregnating their partner unless they get a vasectomy.

Previous studies on experimental male contraceptives have achieved impressive success rates of up to 94 per cent, but most of them impact sperm development, meaning it takes months for the contraceptive to be reliable, and it also takes weeks to reverse its effect.

Dr Lonny Levin, co-author of the Weill Cornell Medicine study, says that potential contraceptives for men must clear a much higher bar for safety and side effects.

Because men don't bear the risks associated with carrying a pregnancy, he explained, the field assumes men will have a low tolerance for potential side effects.

Meanwhile, women have been taking contraceptive pills since the 1960s. And while the pill quickly became one of the world’s most popular forms of birth control and revolutionised women's reproductive health, criticism of the lack of male contraceptives has been a longstanding issue.

Many people argue that the burden of contraception is unfairly placed on women, who have limited options for birth control, and sometimes face side effects from the synthetic hormones in the pill, including severe migraines, vomiting, depression and anxiety.

How does this new male contraceptive work?

The researchers at Weill Cornell Medicine discovered that a single dose of an inhibitor called TDI-11861 immobilises sperm in mice for up to two and a half hours.

In their experiments, male mice showed normal mating behaviour yet did not impregnate females in 52 different mating attempts after they were treated with the drug, which inhibits an enzyme called soluble adenylyl cyclase (sAC).

Three hours later, sperm in mice started regaining motility, and within 24 hours, nearly all sperm recovered normal movement.

"Our inhibitor works within 30 minutes to an hour," Balbach said. "Every other experimental hormonal or nonhormonal male contraceptive takes weeks to bring sperm count down or render them unable to fertilise eggs," he added.

The investigators think their preclinical model could pave the way to a pill that men could take shortly before sex, only as needed, allowing them to make day-to-day decisions about their fertility.

Levin says the team is already working on making sAC inhibitors better suited for use in humans.

The next step of the experiments will see the scientists repeat their trials in different preclinical models and lay the groundwork for human clinical trials - which means we’ll still have to wait several more years before a male contraceptive pill can be found in pharmacies.

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