Male birth control pill shows promise but needs further study

A monthlong study of dimethandrolone undecanoate (DMAU), an oral contraceptive for men, presented at the Endocrine Society's annual meeting showed that the drug was safe and effective when taken daily. But the brevity of the study, along with a couple of side effects, mean that more work is needed before men can have their own birth control pill.

There has long been interest in an oral contraceptive for men: "Many men say they would prefer a daily pill as a reversible contraceptive, rather than long-acting injections or topical gels, which are also in development," said Stephanie Page, M.D., a professor of medicine at the University of Washington, one of the study sites. 

But the development of hormonal contraceptives for men has run into some obstacles. For example, a study investigating the injected contraceptive norethisterone enanthate combined with 1000 mg testosterone undecanoate, was halted due to reports of mood changes, depression, pain at the injection site and increased libido. This prompted an independent review panel to conclude "the risks to the study participants outweighed the potential benefits to the study participants." 

And taking testosterone orally can lead to liver inflammation. What's more, the body eliminates testosterone very quickly, necessitating a twice-daily dosing schedule. To address this, DMAU contains undecanoate, a long-chain fatty acid, which slows this process. 

The 28-day study involved 100 healthy men aged 18 to 50, who were divided into three groups. The investigators, at the University of Washington and Harbor-UCLA Medical Center, tested three doses of DMAU—100, 200 and 400 mg—and two different dosing forms. Each group had five patients who were randomly assigned to receive placebo. 

The patients receiving the 400 mg dose showed "marked suppression" of levels of their testosterone and two other hormones necessary for sperm production. All of the patients passed safety tests for liver and kidney function. 

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"Despite having low levels of circulating testosterone, very few subjects reported symptoms consistent with testosterone deficiency or excess," Page said. Eight men reported a lower sex drive while on the pill, Science News reported

While the results are promising, they come with some caveats. Men must take the medication with food, or else it will not work. All groups that took DMAU also posted weight gain—a common side effect of hormonal birth control in women—and a decrease in HDL, or good, cholesterol. 

Next up, the researchers will launch longer-term studies to see if blocking these hormones actually stops the production of sperm. If the three-month studies go well, couples will test the pill as contraception, Science News reported.