An exciting new animal study has pointed to a new possibility for male contraceptives. Researchers at the University of Minnesota created a birth control pill for male mice that was 99% effective in preventing pregnancy.
The contraceptive acts on a protein in the body that receives a form of vitamin A involved with sperm production and fertility.
The researchers gave male mice the compound, described as YCT529, for four weeks, and the mice’s sperm count dropped dramatically. Between four and six weeks after they stopped receiving the contraceptive, the animals were able to fertilize a female again.
Since the 1970s, scientists have been studying ways to create a birth control pill for men. The team responsible for this new study is excited about its promising results, but other scientists are skeptical and consider it to be just another interesting advance, one that very possibly will not make it to the market.
Experts said the male birth control pill is not expected to be available to the public for the foreseeable future.
“As long as I don’t see human data, I’m very skeptical,” said Amin Herati, director of the infertility and men’s health program at the Brady Urological Institute at Johns Hopkins Hospital.
According to him, there are crucial differences between the human and mouse reproductive systems and between how the genes of one and the other react.
“We’re talking about new compounds,” said Christina Wang, a contraceptive specialist at the Lundquist Institute at Harbor-UCLA Medical Center. “We have no way of knowing its effects until we do toxological studies.”
The scientists did toxicology studies on the mice, but Wang pointed out that human trials are needed to assess the safety of using the pill.
But even if this pill fails in future clinical trials, now that the compound has been discovered, scientists may be able to come up with other pill options, said Md Abdullah Al Noman, a graduate student at the University of Minnesota, who presented the study’s findings at a meeting of the Society. American Chemistry, last Wednesday. “What we have here is a pioneer of non-hormonal contraception.”
Gunda Georg, a professor of medical chemistry at the University of Minnesota and director of the research, pointed out the differences between this study and previous attempts to create a pill for men: the mice had no apparent side effects, even when tested at high doses. “They eat, drink and are sexually active even though they don’t have sperm.”
Georg said the pill could move into clinical trials later this year. But even in this fast-paced timeline, clinical trials would be an initial step on a path that will take years.
Are other forms of male contraception in trials?
The University of Minnesota research is the latest in a series of studies looking for a male equivalent of the female birth control pill.
The National Institutes of Health are funding a clinical trial of a contraceptive gel called NES/T, which men would have to apply to their shoulders and arms once a day. The hormone gel is undergoing phase 2 clinical trials, said Wang, one of the research leaders.
Her optimistic estimate is that the gel could be commercially available in five years, but even that would be a very quick process.
Contraline, a Virginia-based biotechnology company, is awaiting clinical trials of the injectable Adam hydrogel, which lasts for a year. The company describes the product as an “IUD for men”
Researchers in India are testing a non-surgical vasectomy procedure known as Reversible Inhibition of Sperm Under Guidance, or Risug, which involves injecting a gel into the tubes in the penis that store sperm.
But until these processes undergo substantial studies — and, crucially, human trials — a form of male contraception comparable to the pills, patches, injections and rings that are on the market for women is still a fantasy.
“I’ve been highly interested in animal studies for some time that promise results in terms of contraceptives for men,” said Bobby Najari, assistant professor of urology and population health and director of the Male Infertility Program at NYU Langone Health. “But I always end up disappointed.”
What contraceptive options are available for men today?
There are currently only two approved forms of male contraception: a vasectomy and a condom.
While vasectomies are reversible, Najari said he doesn’t recommend anyone having a vasectomy with the intention of reversing it later. The American Association of Urologists’ vasectomy guidelines point out that reversal is not always successful.
The reversal procedure is often longer than the original vasectomy, with longer recovery times, he said, and insurance companies don’t always cover it. Vasectomies have also been linked to complications such as infection and pain, both short-term and chronic.
Condoms have the added benefit of protecting people against sexually transmitted diseases, but they are “relatively unpopular,” Najari said.
Even when people use condoms, they can tear. The Centers for Disease Control and Prevention estimates the condom failure rate at 13%.
Why is there still no birth control pill for men?
In the 1990s the World Health Organization researched testosterone as a potential form of contraception and found it to be highly effective in reducing sperm count.
But it takes high levels of the hormone to suppress sperm sufficiently, and that had unpleasant side effects: weight gain, acne, irritability and mood swings.
These effects match the widely documented side effects reported by women taking hormonal birth control pills. “There’s a bit of double standard at work here,” commented Najari. The female birth control pill is also associated with blood clots.
But some research on male contraception has found especially devastating side effects. In 2012, researchers stopped a clinical trial of the hormones progestin and testosterone because men reported experiencing severe acne, depression and pain after receiving the injections.
“When you start messing with the testosterone receptors, the body is seriously unbalanced,” Herati said. And while women go through predictable ovulation cycles, men produce high concentrations of sperm daily, a fact that further complicates male hormonal changes.
When can we expect a contraceptive for men?
“There are numerous factors involved in this question — the research, but also the social changes that accompany male contraception,” said Heather Vahdat, executive director of the nonprofit Male Contraceptive Institute, which funded the Minnesota study.
But she estimates the male pill will take at least ten years to reach the market.
The pill proved highly effective in mice, but these results may not translate to success in men.
“If all the drugs that work well in mice worked in humans, we would already have a cure for cancer,” concluded Michael Eisenberg, professor of urology at Stanford University Medical Line.
Translation by Clara Allain.
