Experimental Male Contraceptive Works for Monkeys; Humans May Be Next

Researchers have successfully tested a new form of reversible male contraceptive on rhesus monkeys. Kiyoshi Ota/REUTERS

One would think that with all of the miraculous advances in medicine humans would have a bevy of options when it comes to birth control, and that there would be plenty for men. Sadly, this is not the case. The onus is still mostly on women, and the industry hasn't changed all that much in the last few decades. That could be a large part of why about 40 percent of all pregnancies worldwide are unplanned, according to the Guttmacher Institute.

While there is an assortment of long-acting, effective and reversible forms of birth control for women—hormonal pills, IUDs, patches and implants—options for men are still limited (and limiting). There's the condom, which studies find are roughly 82 percent effective, mostly because people often don't use them correctly or consistently. For men, the closest to completely foolproof birth control is a vasectomy, but that's typically permanent.

But a Bay Area-based organization has for years been working to develop a new form of contraception for men. Vasalgel is essentially a non-surgical and reversible vasectomy, a polymer that forms into a hydrogel when it's injected into the vas deferens, the tube sperm swim through on their way from the testicle to the urethra. The substance blocks the swimmers until it's flushed out with a sodium bicarbonate solution.

Vasalgel has a potential to revolutionize the industry—and take some of the family planning pressure off women. It's already proven to work on rabbits. Now, a new paper published this week in Basic and Clinical Andrology finds Vasalgel prevents pregnancy in rhesus monkeys, which impresses animal experts.

"Rhesus monkeys are very fecund animals," says Dr. Angela Colagross-Schouten, a veterinarian specializing in laboratory animal medicine and first author on the paper.

Revolution Contraceptives LLC, a subsidiary of Parsemus Foundation that developed Vasagel decided to test the product in rhesus monkeys since they're prolific breeders that share anatomical similarities to homo sapiens . The only main difference, says Colagross-Schouten, is that the vas deferens is much deeper in monkeys than it is in humans. This means the procedure is likely to be even less invasive when it's performed on men.

"As a vet, I felt like once we were able to perfect our technique it was more straightforward than a traditional vasectomy," Colagross-Schouten says. Recovery time was also a lot a lot quicker than traditional vasectomy.

The researchers reported only a few minor complications. In one monkey, the Vasalgel was placed incorrectly, which caused a sperm granuloma, a small lesion in the scrotum that is treatable or heals naturally.

Like a vasectomy, there is some recovery time involved in Vasalgel injection, something a human would be much more attuned to than a monkey. "In people, it's great, you can advise no sex for several months, don't stretch up to reach anything, but you can't tell rhesus monkeys anything," says Colagross-Schouten. "We really can't tell them to take it easy."

It may be a while before Vasalgel makes its way to your local doctor's office. The Parsemus Foundation is pursuing funding for a series of studies on Vasalgel for human use. The first will examine the efficacy of the product for preventing pregnancy, and later studies will evaluate health outcomes after the polymer is flushed out to restore sperm flow. While Vasalgel reversal has been done on rabbits, it has yet to be tried on rhesus monkeys.