A safe and effective birth control pill for men is one step closer to becoming a reality.
That’s according to new research presented this week at ENDO 2018, the Endocrine Society's 100th annual meeting in Chicago, which found that the new pill, called dimethandrolone undecanoate (or DMAU), successfully reduced testosterone and other hormone levels responsible for sperm production without causing major side effects.
"People have been working on male hormonal contraception for 40 to 50 years," Dr. Stephanie Page, an endocrinologist at the University of Washington School of Medicine and lead author of the study, told CNN. "There are ways of delivering male contraceptives with long-acting implants and injections, but men are interested in having an oral pill available, and the work we presented here is a step forward."
For the study, researchers carried out a trial with 83 men, aged 18 to 50. Each man was randomly assigned to either one of three treatment groups, or a control group. The treatment groups received varying doses (100, 200 and 400 milligrams) of the drug, and the control group took a placebo.
After 28 days, the men taking the drug saw a significant reduction in testosterone. In fact, their testosterone levels dropped to "castrate levels" with all three doses. The group receiving 400 mg, the highest dose of the drug, also saw a significant reduction in LH and FSH, hormones that work to regulate sperm and testosterone production by the testes.
"Normal testosterone in a man is anywhere from 350 to 1,100 nanograms per deciliter," Dr. Seth Cohen, an assistant professor of urology at NYU Langone Health, who was not involved in the study, told CNN. "And they got these guys down to 13 nanograms per deciliter."
But the study did have its limitations. Considering the relatively small sample size, more trials need to be undertaken to fully understand the effects of the drug. Nine of the participants in the study experienced a major decrease in libido, or sex drive, as well.
"When you put that on a large, multimillion-person basis, you have a huge portion of men running around with very low libido," Cohen said.
Nonetheless, Page remains confident that the drug appears safe for men, allowing them to maintain all important male characteristics.
"The brain, which is important in sex drive, maintain muscle, all of those important male characteristics are maintained by the hormone that we're giving the men," she told CBS News. "The very important point here is that despite having those low levels of testosterone, the steroid that is given in this prototyped male pill provides the androgen activity in the man in all the other parts of their body."
Page also stressed that there needs to be more birth control options available to men.
"The important next step is to show that this does, in fact, suppress the production of sperm, and that requires at least a three-month study, which we're going to be undertaking starting next month," Page said. "After that, we'll need longer-term studies to look in detail about fine-tuning any potential side effects and ultimately doing a study in couples that actually demonstrates that it works in a real-world use."
This isn't the first time that researchers have attempted to develop an effective male birth control method. A study published in 2016 revealed that men can take hormone injections to prevent pregnancy in their partners with nearly the same success rate that women have with the pill. However, the shot caused a variety of negative side-effects – including depression, acne and lowered sex drive.