A study of a birth-control shot for men was nixed because subjects reported side effects including depression.
By Francie Diep
(Photo: Pedro Ribeiro Simões/Flickr)
A clinical trial of a long-term, reversible birth control shot for men has found that it was effective for 92.5 percent of study volunteers, according to a new paper. Eighty-two percent of the male study volunteers said they would be willing to use this birth-control method. Despite these positive results, an ethics board overseeing the study put a halt on the trial, after some study participants reported troubling side effects including mood disorders such as depression.
The study was one of the few to ever test whether a long-acting, reversible contraceptive for men would work as couples’ sole method of birth control. Previous studies of hormone shots for men mostly tested whether they adequately suppressed men’s sperm counts, but didn’t ask couples to rely on the method to prevent pregnancies.
“All the people in the field were disappointed,” says Doug Colvard, the study’s lead scientist and a male fertility specialist with CONRAD, the reproductive-health research group that co-sponsored the study alongside the World Health Organization. “At this time, neither WHO nor CONRAD has funds to continue to develop a male method and that’s one of the difficulties of the field,” Colvard says. “Whereas 10, 15 years ago, several large pharmaceutical companies were actively engaged in male contraceptive R&D to develop new products, they pretty much left that as a priority area for their firms, so there’s very limited funding currently available in this area.”
“All the people in the field were disappointed.”
The contraceptive injection Colvard studied contained a combination of two hormones, an androgen and a progesterone. Men had to receive the shots every eight weeks. If tests showed the injections lowered a volunteer’s sperm count to fewer than one million sperm per milliliter of semen — normal levels are 15 million to 150 million per milliliter — then researchers asked him to try relying on the shots alone. Among the couples who went on to use the shot for birth control, 1.57 out of 100 became pregnant.
The main side effects reported by the male study volunteers were acne, pain from the shot, increased libido, and mood problems including depression. The effects were mild for the vast majority of volunteers, but some experienced more severe troubles and dropped out of the study.
If these side effects sound similar to what some women using hormonal birth control such as “the pill” experience, that’s because they are. Women’s birth control also contains progesterone. “Just as women experience mood changes as progesterone levels rise and fall, some of those same kinds of effects occur in men,” Colvard says. But it’s impossible to scientifically say whether the mood shifts men experienced during the study are more or less severe than what women on the pill feel — or indeed what women not using hormonal birth control feel as a result of the naturally fluctuating progesterone levels from their menstrual cycles.
The big takeaways, according to Colvard, are that androgen-progesterone combination shots are effective, but may need to be reformulated to reduce side effects. But another research group will have to answer those questions for sure.