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Vasectomies are on the rise, but not all men are ready to commit to a permanent form of birth control. While the surgery can sometimes be reversed, it's expensive and doesn’t always work. What if there was another option?
Virginia-based biotech company Contraline is testing a new type of male contraceptive akin to a vasectomy but made to be fully reversible. Today, the company announced that surgeons in Australia have safely performed the procedure on 23 men in an early-stage trial.
The approach uses a soft, water-based substance called a hydrogel that’s injected into the vas deferens—the pair of tubes in the male reproductive tract that transport mature sperm. Within 30 days of being inserted, the gel led to a more than 99 percent reduction in the number of moving sperm, according to the company. No serious side effects have been reported.
Kevin Eisenfrats, cofounder and CEO of Contraline, says it’s like an IUD for men. “Right now, there is nothing out there that’s long-lasting and reversible for men,” he says. “This is made for people who are not ready to have kids, are spacing out having kids, or think they are done having kids but maybe not ready for that permanent option.”
In a vasectomy, the vas deferens are cut and sealed so that sperm can’t travel from the testicles to the urethra, the tube inside the penis.
Contraline’s method involves making a small piercing in the scrotum and using a handheld injector to push the hydrogel through a catheter that’s connected to the vas deferens. The catheter is then taken out, and the puncture heals on its own.
Once injected, the hydrogel is meant to block sperm from getting into semen. Eisenfrats likens the gel to a coffee filter, where sperm are the coffee grounds. Sperm can’t get through the filter, but semen, a liquid, can still pass through.
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Men in the trial ranged from age 25 to 65 and were placed into two groups that received different amounts of hydrogel: a lower volume and a higher one. Implanting the gel took about 20 minutes and was done under local anesthesia, unless someone chose to be sedated instead.
Eisenfrats says sperm concentration and movement in the men are comparable to levels seen with a vasectomy. “We’re seeing that this is working.”
The purpose of the current trial is to assess the gel’s safety and longevity, not how well it prevents pregnancy. Participants were asked to use a back-up form of birth control while being enrolled in the trial.
The gel is designed to dissolve at the end of its lifetime, so the men will be followed for two years to determine how long it takes for that to happen. Eisenfrats says the goal is to have a product that lasts one to two years.
But men might want to restore their fertility before that time frame, so Contraline wants to show that it can safely reverse the procedure. The company has tested the reversibility of the gel in dogs, showing that sperm counts and sperm quality rebounded after removing the gel. It plans to launch a second trial this year to test the on-demand reversibility in people. Only men who said they do not want to have children were included in the initial trial.
While the study is small, Heather Vahdat, executive director of the Male Contraceptive Initiative, a nonprofit based in North Carolina, is encouraged by the safety profile so far. Her organization funds research into nonhormonal male birth control and has contributed funding to Contraline. “Reversibility seems very feasible,” she says.
The nonprofit Parsemus Foundation has been researching a similar gel, called Vasalgel, for several years, but has faced delays getting it to human trials. The San Francisco-based health organization partnered with a biotech company, NEXT Life Sciences, in 2022 to further develop Vasalgel. In a 2017 paper, researchers with the foundation showed that Vasalgel could be flushed out in rabbits with an injection of baking soda. Sperm flow returned in the animals after reversal.
“These are not complex components in these polymers. They’re pretty well characterized, and we know how they behave,” Vahdat says.
But any medical procedure could cause side effects or complications. Raevti Bole, a urologist specializing in men’s health at the Cleveland Clinic who’s not involved in the trial, says an injection into the vas deferens could come with a risk of skin infection, mild discomfort, or minor bruising, she says.
And there are still unknowns about the gel itself. While hydrogels are biocompatible and generally safe, Bole says she would want to know if Contraline’s product could cause permanent scarring or changes to the vas deferens and whether repeat injections could be done safely.
One practical consideration is how doctors will monitor patients to make sure that the gel is still working. “Even if the risk of pregnancy is low, I would want to know the risk to counsel my patients and allow them to compare their options,” Bole says.
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Contraline’s gel is still years from becoming commercially available. The company will need to conduct trials of hundreds of men and their female partners to test its efficacy in preventing pregnancy. Eisenfrats says the company aims to launch a larger trial in the US in the next few years.
Meanwhile, there are other forms of male birth control in the pipeline. The US National Institutes of Health and the Population Council, an international nonprofit focused on health and social sciences, are testing a hormone-based gel that men apply daily to their shoulders to block sperm production. And in December, a small trial launched in the UK to test a hormone-free contraceptive pill developed by YourChoice Therapeutics. It prevents sperm production by blocking access to vitamin A.
YourChoice and Contraline are avoiding hormones because they tend to produce unpleasant side effects. A previous trial of an injectable hormonal contraceptive for men was stopped early when a safety monitoring board found a high number of adverse events, including acne, mood disorders, increased sexual drive, and muscle pain. The rate of side effects was high compared to what women typically experience while on hormonal birth control.
There’s evidence that men are interested in trying new types of contraception. In a US survey conducted in 2017, the Male Contraceptive Initiative found that 85 percent of the 1,500 male respondents aged 18 to 44 were interested in preventing their partner from getting pregnant.
“Men want to step up. They’re realizing that their partners have all these effects from birth control,” Eisenfrats says. “They need more options to take charge of their reproduction.”
