Oral birth control for men might not be such a futuristic idea. Researchers have just finished the first human study on the experimental male oral contraceptive—called dimethandrolone undecanoate, or DMAU. They concluded that taking DMAU daily for a month is safe and does not lower libido or alter fertility permanently.

Via Vimeo/Lee Health

This pill is very similar to the one women use — it combines two hormones at the same time, an androgen (male hormone) like testosterone, and progestin.

To test DMAU’s safety, researchers developed a double-blind randomized, dose escalation, placebo-controlled study. Stephanie Page, MD, of the University of Washington in Seattle, and her colleagues observed that testosterone levels among patients who had received the highest dose of DMAU dropped to levels seen in medical castration for prostate cancer.

Even though testosterone levels dropped dramatically in the 28-day experiment, no symptoms of low testosterone emerged, increasing DMAU’s chances of becoming an oral male contraceptive according to Dr. Paige at ENDO 2018.

“These results are a big step forward in the development of a male pill,” she told MedPage Today. “We are very encouraged by the results of this safety trial.”

Participants ingested doses of 100 mg, 200 mg, and 400 mg of dimethandrolone in two delivery formulations — with castor oil or in a capsule. For each dose, there were 12-15 men and five placebo patients so that researchers could compare adverse effects. Participants took the pill with high-fat meals. Overall, 100 men between the ages 18 and 50 were enrolled in the trial and 82 completed all parts of the study.

“The men experienced no hot flashes and no mood changes, and no problems with sexual function compared with the placebo group,” Paige said. “There was no evidence of liver toxicity. We did see mild weight gain and an increase in cholesterol levels and that may require us to fine tune the dosing, but overall we are very encouraged about the safety profile of dimethandrolone.”

Dr. Page said her group will begin a 3-month study in April to see if any long-term toxicity appears, and then will do a study in couples to determine if DMAU does efficiently work as birth control. She added the current trial was to determine if the pill could be taken safely for more than one dose, but did not test its effectiveness as a contraceptive. Participants were told to use auxiliary contraception if the had sex while on the pill.

“Condoms are the only practical reversible form of male contraception — and it is more than 300-years-old,” she noted. She said that studies indicate that men would prefer oral contraception versus injection or gel implant.

Page explained that previous attempts to drive down testosterone levels to reduce sperm production led to side effects and liver toxicity. She added that an effective oral contraceptive for men was hard to produce until now, due to the rapid metabolization rates of androgenous hormones by the male body.

“Dimethandrolone is a modified form of testosterone, which has been chemically modified to get rid of the problem of liver toxicity,” she explained. “A long fatty acid chain has been added to another portion of the molecule to increase its absorption in the blood stream, so we can get around the twice-a-day dosing. Dimethandrolone is different than testosterone in that it binds to both the progesterone receptor and the androgen receptor so we don’t need two different steroids in order to have an effective male contraceptive,” Paige added.

A month after the treatment had stopped, testosterone levels returned to normal, Dr. Paige reported.

“This shows reversibility, the key feature of a hormonal contraceptive. This was much more potent than we had expected with just once-day dosing. Despite these incredibly low levels of testosterone, the men did not have symptoms of low testosterone. Because dimethandrolone is a modified form of testosterone, when we give the right dose of dimethandrolone, all those important secondary sexual characteristic in the man will be maintained in the body,” she added.

Until now, DMAU shows promising results. But for the trial to be complete, we need to see long-term effects and sperm count. Maybe the study that begins in April will present us encouraging findings as well as the one presented at ENDO 2018, the Endocrine Society’s 100th annual meeting in Chicago, on Sunday.