Monthly Archives: November 2016

Hormonal birth control for men is a thing

Male birth control just got one step closer to becoming a reality (finally!). A new study shows that giving contraceptive injections to men can effectively prevent pregnancy in their partners. The caveat: the shots won’t be available any time soon. Their formulation must be tweaked to reduce side effects, and larger studies are needed before they can be brought to market.

Hormonal birth control has never been an option for men, who currently have few choices when it comes to managing their fertility, including condoms, vasectomies, and the not-always-effective withdrawal method.

The new study, a phase II clinical trial, tested the safety and efficacy of injectable contraceptives in 320 men ages 18 to 45. The men received two hormones—a synthetic testosterone and progesterone—via injection, every eight weeks for up to a year and a half.

Synthetic testosterone suppresses sperm count, explains Jamin Brahmbhatt, MD, a urologic surgeon with the Orlando Health hospital system, because it tricks the body into thinking it has enough of the hormone. The body then shuts down production of real testosterone, which is needed to make sperm.

“We already prescribe this drug to men who have low testosterone levels, and we warn our patients that they may experience infertility as a side effect,” Dr. Brahmbhatt, who was not involved in the new study, told Health. Pairing testosterone with the other drug tested in the study—a type of synthetic progesterone—has been shown to alleviate other side effects, he adds.

 

The participants provided semen samples regularly. Once their samples were shown to contain less than 1 million sperm per milliliter—which for most men, occurred within 24 weeks—they were instructed to stop using other forms of birth control with their partners (women ages 18 to 38) and rely only on the injections.

In the second phase of the study—during which 266 men continued receiving injections for up to 56 more weeks—four pregnancies occurred. (That makes sense, says Dr. Brahmbhatt, since a tiny amount of sperm is still likely to be present.) The researchers determined the drug combo was nearly 96% effective at suppressing sperm counts. Condoms, in comparison, are 98% effective when used correctly.

The results were published online and will appear in the Journal of Clinical Endocrinology & Metabolism. The research was funded by several global health organizations, including the United Nations and the World Health Organization (WHO).