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A New Male Birth Control Has Passed Human Safety Tests

The oral pill fuses forms of progesterone and testosterone together in a hybrid hormone to curb sperm production. But the drug won’t be hitting shelves any time soon.

ByKatherine J. WuNOVA NextNOVA Next
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Right now, only women have the option of hormonal birth control. But based on preliminary trials of a drug that might lower sperm counts in men, that might someday change. Image Credit: iStock, crankyT

Despite numerous attempts at commercializing male hormonal birth control, most research efforts eventually find themselves shooting blanks.

But on Sunday, a team of scientists led by Christina Wang of the Los Angeles BioMed Research Institute announced the development of one option, in the form of a daily contraceptive pill, that might someday hit its mark—in the next decade, that is.

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So far, the researchers have successfully ferried their new method, which is intended to curb sperm production, through a preliminary, 28-day trial that assessed the drug’s safety in healthy men. But the drug is still a long way from the pharmacy shelf.

The team’s pill is comparable to a male version of the estrogen- and progesterone-based oral contraceptives that many women use. While many female hormonal birth control options exist, “the standard is not equal for the genders,” Wang told Jamie Ducharme at TIME.

Stunting sperm production hasn’t been easy to achieve in the past (neither condoms nor vasectomies hamper the genesis of sperm, instead blocking their most common route out of the body). To nip these swimmers in the bud, researchers have turned to tinkering with testosterone, which triggers the production of sperm in the testes.

One way to do this could be to dose men with progestin, a form of progesterone, which naturally dampens testosterone levels. But testosterone drives much more than male fertility—and blocking its actions throughout the entire body can have a lot of side effects, including weight gain, a reduction in muscle mass, and an increased risk of blood clots and depression.

So Wang and her colleagues tried a different approach. Their pill still contains a kind of progestin, but it’s fused with a modified form of testosterone. Ideally, the resulting hybrid molecule will alter sperm counts—and nothing else.

During the 28-day trial, the researchers monitored the health of 40 participants taking either the drug or an innocuous placebo. No major medical problems came up, but 22 of the 30 men on the active pill reported minor side effects, including acne, headaches, lower sex drive, mild erectile dysfunction, fatigue, and slight weight changes. Several of these complaints were among those that ended a trial for another male contraceptive in 2016 (though other, more severe issues might also have occurred as a result of the treatment in question). Notably, comparable symptoms have not historically stymied the greenlighting of female contraceptive methods, several of which can increase the risk of stroke and certain cancers.

None of the men in this most recent trial, however, suffered side effects bad enough to make them stop taking the pill.

That’s a step forward. But many years of hurdles remain between this initial safety test and commercialization, including more trials to assess long term safety. Importantly, the researchers also have yet to measure actual sperm counts in men taking the new drug.

The drugs’ effects could at least two or three months to kick in, so checking sperm levels would have been pointless in this initial 28-day experiment, Wang said in a statement. Blood samples from the trial’s participants suggest that the pill suppressed two hormones required for sperm production, implying effective contraception—but that’s just a proxy for the true end goal.

Further research is needed to ensure that these men are making less sperm and that sexually active couples using the pill have a decreased likelihood of fertilization. And while the drug’s effects are reversible in theory, that, too, will need confirmation. Additionally, the months-long waiting period before the drug kicks in could be a big deterrent to users—especially considering that so many female hormonal contraceptives exert their effects within days. With all these caveats and open questions, Wang estimates there’s about a decade’s worth of work before the product goes to market.

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A new contraceptive pill for men has passed preliminary safety tests in humans. The drug appears to suppress two hormones required for sperm production after a month of use, but would probably take an additional month or two to actually curb sperm count. Image Credit: Julia Simina and Olga Zarytska, iStock

And then there are the cultural obstacles. As a whole, the idea of male birth control has had trouble taking root. Due in part to the success of female contraceptives, there’s been “zero industry interest” from pharmaceutical firms to fund new birth control technologies geared toward men, Wang told Arielle Pardes at Wired. And surveys of the general population have yielded mixed reactions from men, Pardes reports.

In the meantime, though, Wang and her team are keeping busy. She and her team have already produced a separate oral contraceptive with similar design principles that has also passed preliminary tests. They’re also planning to deploy their progestin-testosterone hybrid hormone in other forms, including an injectable and a topical gel.

For those open to leveling the contraceptive playing field, they might soon have a wealth of options to choose from. With any luck, the question of male hormonal birth control will no longer be a question of if, but when.

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