A contraceptive pill for men is a step closer to approval after early trials of a once-daily pill showed it to be safe and effective, according to researchers.
The new pill, known as DMAU for its chemical name, dimethandrolone undecanoate, is similar to the female birth control pill. It contains a combination of hormones – an androgen, like testosterone, and progestin – said the study's senior investigator, Dr. Stephanie Page, a professor of medicine at the University of Washington.
Taken daily, it could bring sperm count low enough so a man cannot get his partner pregnant.
"DMAU is a major step forward in the development of a once-daily 'male pill,'" Page said at the Endocrine Society's annual conference. "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."
Development of the male birth control pill has been hindered because current available forms of oral testosterone could lead to liver inflammation and they clear the body too quickly, requiring two daily pills. However, DMAU contains undecanoate, which slows down this clearance.
Researchers studied 100 men taking different doses of DMAU, as well as a placebo pill. Men who were on the highest dose of the pill – 400 mg – showed "marked suppression" of levels of their testosterone and two hormones required for sperm production. Page said these results are consistent with effective male contraception shown in longer-term studies.
Participants did have a slight decrease in their HDL ("good") cholesterol and slight weight gain. However, both were minor. All men passed safety tests, including indicators of kidney and liver function, according to the study.
"Despite having low levels of circulating testosterone, very few subjects reported symptoms consistent with testosterone deficiency or excess," Page said. "These promising results are unprecedented in the development of a prototype male pill. Longer term studies are currently underway to confirm that DMAU taken every day blocks sperm production."
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