Tyler Dunlap, a 27-year-old newlywed in San Francisco, is just one of the many American men eagerly awaiting the results of a large clinical trial in India. 

The trial is studying a new male contraceptive, RISUG (Reversible Inhibition of Sperm Under Guidance): a reversible, nonhormonal contraceptive that provides 10 or more years of protection after a 10-15 minute procedure. Researchers received approval this week to begin enrolling additional study volunteers, after a delay of nearly four years.

"RISUG would be exciting because it would mean that, finally, I could take control of my own future, instead of leaving it to someone else," says Tyler Dunlap, a 27-year-old San Francisco newlywed. "Being in a committed long-term relationship means that I don't want to rely on condoms for birth control. I'm not ready for a vasectomy, though. This new procedure could be the answer that gives men the decisive control we lack with current contraceptives."

In the RISUG study, doctors inject a gel into the tube that sperm travel through after they are produced (known as the vas deferens). The gel then disables the sperm as they swim by. In study animals, male fertility returns if the RISUG is flushed out with another injection that dissolves the gel.

Elaine Lissner, director of the nonprofit Male Contraception Information Project in San Francisco, says she is not surprised that American men are watching the RISUG trial with keen interest. She emphasizes that the method has the potential to be the first truly affordable, reversible, long-term male contraceptive.

In 2002, when enrollment in the Indian study was halted, more than 140 men were already using RISUG. Concern about side effects and insufficiency of safety data caused a temporary suspension of the project. However, expert panels subsequently concluded that the major side effect -- several weeks of non-painful scrotal swelling in about a third of the subjects --was not enough to stop the study.

Additional Safety Tests

Since 2002, researchers have conducted several additional laboratory safety tests on RISUG.

"When we first began using RISUG in volunteers more than 15 years ago, we didn't have access to the more sophisticated toxicity tests available today," says Dr. H. C. Das, one of the lead investigators. "Last year we sent RISUG to an FDA-registered laboratory in the United States for more tests, and the results came back clean. We've also done more studies at the Industrial Toxicology Research Centre in Lucknow, India with the latest equipment. We're glad to be able to provide men this additional reassurance."

Dr. R. S. Sharma, deputy director general of the Indian Council of Medical Research (ICMR), concurs that the safety results were "very satisfactory." The ICMR is working to arrange study sites throughout India, beginning with Jaipur, Ludhiana, Udhampur, and India's capital New Delhi. Three data monitoring committees will watch for any safety concerns.

Next Steps

But Lissner cautions that progress will be slow without sufficient political will. "A reversibility study in men is key," she stresses. "And we're hoping that the Indian government is committed enough to this research to get the next batch of RISUG made to the FDA's latest Good Manufacturing Practice standards. If it is, the results will carry more weight internationally. Then men in other countries -- such as the US -- can hope for faster government approval."

Currently, RISUG's developers are arranging a collaboration with US researchers. Lissner says that to gain FDA approval, US researchers will have to begin with animal tests, so studies in North American men would not start for several years. Still, she notes that "We shouldn't be discouraged. We already know that RISUG works, which is half the battle in drug development. Men in studies in India have been using it for more than a decade. Now we just have to finish our homework."

RISUG's chief developer, Prof. Sujoy Guha of the Indian Institute of Technology, says myths about men not being interested in contraception are just that: myths. "I get letters from men all over the world who beg to come to India and participate in this study at their own expense."