Is a permanent but reversible birth control method for men finally on the horizon? Recent research out of the University of California is hopeful. Tests conducted on male rhesus monkeys have shown that Vasalgel, a gel-based form of vasectomy developed by non-profit Parsemus Foundation, can prove an effective contraceptive for over two years.

Male Contraceptive Gel Moves Forward

Medical forms of contraception have always required big commitments from women, but little work from men. Despite widespread availability, vasectomy is still under-utilized. In a 2010 analysis of government statistics, urologists at UC San Francisco found that only 6% of American men had opted for surgical sterilization procedures. Nearly 16% of women, on the other hand, had chosen to rely on the female-version of surgical sterilization, tubal ligation, as their primary birth control method.

Rhesus Macaque

Now, a group of scientists at the California National Primate Research Center believe they may have discovered a simpler option for men. While vasectomy has been shown a safe and effective procedure, it still involves a degree of tissue damage. Each patient’s vas deferens must be either crushed, severed or tied off, so that sperm are unable to enter the ejaculate. The procedure is reversible, but tissue damage can make turning the clock back difficult in practice, says Catherine VandeVoort, Professor of Obstetrics and Gynecology at the University of California, Davis School of Medicine. Vasalgel, on the other hand, could be reversed simply with an injection of baking soda and water.

How Does Vasalgel Work?

How does it work? Vasalgel is a polymer gel that can be injected into a man’s vas deferens, tubes that carry sperm from the testicles to the urethra. After injection, Vasalgel fills the vas deferens, creating a soft barrier that pads out tiny folds in the organ walls. Sperm are too large to penetrate the barrier and never reach the urethra, where they would be mixed into seminal fluid prior to ejaculation.

The new Vasalgel method was tested in sixteen male rhesus macaque monkeys over the course of two years. Every monkey injected with the gel polymer has remained infertile, WebMD reports, even during a 6-month breeding season in which the males were housed with female macaques.

Today, the California team is hoping to move on to the next step in research – testing the gel’s reversibility in primates. In theory, the contraceptive effects of Vasalgel will be reversible using a second injection that flushes the birth control gel out of the vas deferens. While reversibility has been successfully demonstrated in rabbits, the technique still requires a little work in primates, study co-author Elaine Lissner, founder of the Parsemus Foundation, told WebMD.

For human males, researchers are hoping that Vasalgel will reach the point where an injection of everyday materials – baking soda and water – is enough to flush out the contraceptive plug.

Big Pharma Dismisses Male Contraception As “Fantasy”

Permanent contraceptives are difficult to sell – especially when men are being targeted as the primary patients. As the Parsemus Foundation notes, large pharmaceutical corporations aren’t interested in long-term forms of birth control, since there’s far more money to be made selling monthly pills.

Instead of relying on corporate capital, the Parsemus Foundation has turned to public support, accepting donations as low as $5 to support its research into male contraception. A previous version of Vasalgel, called Risug, has reached advanced clinical trials in India, but remains unavailable in the United States.

Making a birth control method work for males is also harder from a biological standpoint, NPR reports. Men produce millions of sperm continuously; an effective contraceptive needs to deal with all of them at once. Women, on the other hand, produce one egg per month.

VasalGel isn’t the only form of male birth control that Parsemus has in the works. The foundation has also launched early research on a contraceptive pill for males that would result in semen-free orgasms. The idea, known as the “Clean Sheets Pill,” would also be designed to lower the risk of HIV transmission.