FEB 10, 2017 1:56 PM PST

Male Contraceptive Gel Shows Success In Monkeys


A new form of male birth control has shown success in monkeys. But will it be safe for humans?

While women have a range of contraceptive methods and brands to try, options for male contraceptives have been limited to condoms or the withdrawal method during sex. These methods are prone to error, leading to ineffectiveness at preventing pregnancy. The third option is a vasectomy, which, although highly effective, is invasive, costly, and may be permanent.

The limited options have spurred many attempts at producing other successful but non-invasive forms of male birth control to rival the options available to women. But, the logistics of stopping millions of sperm, as opposed to one egg, has proven to be quite difficult.

One of the more successful attempts at a reversible, condom-free male birth control alternative is the Vasalgel. This alternative is a soft gel injected into the vas deferens to physically block sperm from passing through. "It's a sticky gel that goes into (the tubes) and basically filters out sperm," said Elaine Lissner, executive director of the Parsemus Foundation, the medical research organization behind Vasalgel that is also leading the trials.

In effect, the Vasalgel is like a reversible vasectomy, as another injection should dissolve the gel plug and remove the blockage for sperm.

The latest update on Vasalgel proves promising, as researchers say the treatment passed safety and efficacy in monkeys.

Specifically, University of California researchers injected the Vasalgel into a group of 16 adult male monkeys, including 10 that had already successfully fathered offsprings. After a week, the treated males were allowed to join with fertile females. The researchers noted normal matings, and the absence of any pregnancy for two full breeding periods. This indicated that the injection worked as expected to prevent sperm release. Furthermore, the safety of the treatment was comparable to that of monkeys who received vasectomies.

“The study shows that, in adult male monkeys at least, the gel is an effective form of contraception,” said Allan Pacey, professor of andrology at the University of Sheffield, who was not involved in the study.

However, Pacey and others pointed out that the researchers did not yet demonstrate reversibility in the monkeys. That is, can the gel plugs disintegrate with another injection, and can those monkeys go on to father offspring as usual?

"In order for it to have a chance of replacing the traditional surgical method of vasectomy, the authors need to show that the procedure is reversible, and it's reassuring that apparently such studies are ongoing," said Pacey.

Of note, the Vasalgel treatment may still be as nearly as invasive as a vasectomy, as the injection is not done laproscopically.

Still, Lissner is focused on the big prospects of their success in monkeys. "What was important here was that this worked and was safe in animals similar to humans," said Lissner. If the Vasalgel succeeds in humans, it will be the first condom-free, reversible contraceptive for males in over a century.

Additional sources: BBC

About the Author
Doctorate (PhD)
I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at TheGeneTwist.com.
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