Contraceptive Gel Called the “IUD For Men” Makes It Through Monkey Trials

An IUD is a remarkably elegant device. Though not risk-free, it’s relatively safe and easy to insert, and equally simple to remove. It’s no wonder that so many American women rely on it to avoid unwanted pregnancy: Use of this contraceptive in the United states has increased nearly five-fold in the past decade. But until now, there hasn’t been an equivalent option for men.

The only long-term contraceptive for men in the U.S. is the vasectomy, a surgery that’s more invasive than an IUD and far more difficult to undo. (That’s why most of the men who choose it don’t plan on fathering any more children.) Now scientists have taken the next step in pioneering a new male contraceptive method that could be much easier for men to both do and undo.  

"Having an alternative to a vasectomy that could actually be reversible might actually be really appealing to a lot of men," says Catherine VandeVoort, a primate reproduction researcher at the University of California at Davis. "We're trying to get the word out that this could be effective." Unlike condoms and birth control pills, which are at risk of being undermined by human error, the solution her team is researching could give men a relatively surefire way to prevent conception.

A vasectomy requires cutting and either tiying off or cauterizing the vas deferens, the tube that carries sperm from the testicles to the penis. Though the surgical procedure is often marketed as reversible, VandeVoort says, it requires another full surgery that only about 5 percent of men elect to take. Furthermore, she says, that second surgery is not always successful; scar tissue from the vasectomy or its reversal can block the path of sperm, decreasing fertility.

"Vasectomy is really considered permanent contraception," VandeVoort says. "Something like this could change that for men." What VandeVoort is referring to is Vasalgel, a form of long-acting reversible contraceptive VandeVoort compares to “an IUD for men.” Vasalgel is being tested in the U.S. by the Parsemus Foundation, a California-based company that researches low-cost medical treatments like non-surgical neutering for pets and shrinking prostates with electromagnetic fields. 

Vasalgel isn’t new; the technology was first developed in 1979 in India, by a researcher looking to help control his country's skyrocketing population. It works by injecting a form of polymer into the vas deferens, which forms a gel that blocks sperm from passing through the tube. The injection requires only one incision to reach the vas deferens, and can be done easily as an outpatient procedure. The procedure could then be reversed by flushing out the gel with saline or another liquid, VandeVoort says.

While a form of Vasalgel is already being tested on humans in India, the procedure is still in early animal tests in the U.S. The FDA does not recognize any clinical trials conducted on animals or humans in foreign countries for its approval process, so the procedure must be studied extensively in the U.S. before it can be used widely. So far, it's been shown to be both effective and reversible in rabbits.

And now, in a study published this week in the journal Basic and Clinical Andrology, VandeVoort and her team report on VasalGel's effectiveness among a closer human relative: monkeys.

"The fact that these males don't have offspring is a real indicator that it's effective," VandeVoort says of the new study.

She and her team injected Vasalgel into 16 adult male rhesus monkeys at the California National Primate Research Center. Males are housed with juvenile male and female monkeys to help teach them social skills, says VandeVoort, and in the past, adult males in these roles underwent vasectomies to avoid unintentionally impregnating any juvenile female who happened to reach sexual maturity before researchers noticed.

VandeVoort, who has previously worked with the Parsemus Foundation on the possibility of using ultrasound as a contraceptive, decided two years ago that these males would make a perfect test group for Vasalgel and performed the procedure on them. Since then, none of the 16 males have conceived a child. This is especially striking given that roughly 80 percent of females conceive in a breeding season when fertile males and females are housed together, VandeVoort says. Paternity tests of all babies born at the research center further confirmed that none of the 16 males were fathers.

But just proving that the gel works as a contraceptive isn’t enough. "The next challenge will be to show that the injection is reversible," says John Amory, a University of Washington physician who focuses on male contraception. Amory points out that the easy reversibility marketed by Vasalgel's backers has yet to be proven.

VandeVoort is aiming to raise funds now to design, seek approval for and conduct reversibility studies among primates. Testing in humans is at least a few years down the road, she concedes. But even if it proves to be unsuccessful, she and Amory think that Vasalgel could make a useful alternative to vasectomy since it would require less cutting and trauma to the vas deferens, potentially reducing complications and recovery time.  

In any case, researching more forms of birth control is never a waste, VandeVoort says. "In general," she says, "people need more options for contraception."

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Ben Panko is a staff writer for Smithsonian.com