Block That Sperm: A New Male Birth Control Method Shows Promise

In a study on monkeys, no pregnancies occurred. But there are still some complications to address

Photo Illustration: Vocativ
Feb 06, 2017 at 8:00 PM ET

Aside from condoms, vasectomies, and the dubious method of pulling out, men don’t have many contraceptive options today, often leaving the burden of birth control on female partners. For years, researchers have been chasing new methods of male birth control, including hormonal birth control, but so far nothing has hit the market. Now researchers have completed a successful test of a new procedure that would be a little more similar to an IUD in women, in that it’s both a reversible and long-lasting option.

Vasalgel is a gel that can be injected into a man’s body to block the vas defrens, the tube along which sperm move from the testicles into the urethra. If later, a man wants a child, the idea is that the substance could then be flushed out of the tubes, restoring fertility.

In the current study, published on Monday in the journal Basic and Clinical Andrology, the researchers tested Vasalgel on 16 sexually-mature male rhesus monkeys, one of humans’ closest relatives. Scientists had already tested Vasalgel in rabbits with positive results, but they needed a research subject with closer biology to humans. Now, the next step would be to test it in humans.

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In the monkey study, more than half the males, who were “of varying social ranks,” had already procreated, so the researchers knew they were fertile. They kept the males in enclosures with females from five months to more than two years.

Vasalgel did indeed work as intended — none of the monkeys fathered babies during the course of the study. But while most of the monkeys seemed to tolerate it well, there were some complications, including a buildup of sperm in five monkeys and, in one monkey, a leakage in the vas defrens. (All of these complications resulted in vasectomies for those monkeys.) The researchers note that the complications were likely due to improper placement of Vasalgel in the procedure, which could be improved with practice.

Vasalgel is still a long way from being offered to you at your doctor’s office. But the successful test in monkeys means that the researchers soon hope to test its safety and efficacy in humans. The researchers are also finishing another study, to evaluate the safety of flushing the Vasalgel out of the body, in rabbits, according to a press release.

The Parsemus Foundation, the organization developing the contraceptive, told Cosmopolitan last year that funding has been difficult, because of the high costs of bringing a new contraceptive to market. But with the holy grail of easy and effective male birth control closer within reach, the group expects to attract more investors.