The gel injection called Reversible Inhibition of Sperm Under Guidance, invented more than 30 years ago in India and still under clinical trial there, is now clearing regulatory hurdles ahead of planned testing in the United States later this year.
RISUG, brand-named Vasagel in the United States, is a spermicidal polymer gel injected into the vas deferens, the tube sperm travel through, as an alternative male contraceptive to the well-known vasectomy ("vas cutting") and to a series of hormone treatments, according to the Male Contraception Information Project (MCIP), a non-profit educational and advocacy group that states it promotes non-hormonal forms of male contraception. The sperm-killing gel coats the inner walls of the vas deferens and can be flushed away by another injection to restore fertility, after months or years, an article on the the group's website explains.
News about RISUG began spreading around the world, including in the United States, around 2003, after clinical trials of the method began in India in 2002. News media interest in RISUG increased again about five years ago, as clinical trials in India advanced. Now that preclinical studies may be about to begin in the United States this year, and clinical trials could follow as soon as 2012, news stories about RISUG are appearing again, some suggesting it will revolutionize male contraception, given its reversibility (though it can last at least a decade), immediacy (compared to vasectomies), convenience (compared to condoms) and lack of side-effects (compared to hormonal treatments).
Also, according to the MCIP article:
RISUG is made of powdered styrene maleic anhydride (SMA, a polymer), and dimethyl sulfoxide (DMSO, a solvent).
For the 15 minute procedure that is effective minutes after completion and lasts at least ten years, a small amount of the gel is injected by the same method used in "no scalpel" vasectomies.
RISUG has undergone decades of study, development and testing on animals and humans in India since it was invented by Sujoy K. Guha, professor of biomedical engineering at the Indian Institute of Technology.
In 2010, MCIP's interest in RISUG sprouted The Parsemus Foundation (with a mission of "finding low-cost solutions neglected by the pharmaceutical industry") and it bought the rights to test and develop RISUG in the United States.
Now Parsemus needs more funding to continue regulation-mandated preclinical studies of RISUG, and MCIP is campaigning for more widespread awareness and support of the project.
The procedure could be available on the U.S. market by 2015, if the approval process continues on schedule.
But RISUG has raised concerns along the way, over swelling and possible kidney toxicity, The Hindu reported in 2002.
A 2006 press-release by MCIP on Eurekalert.org stated, the RISUG clinical trials were halted in 2002, until panels of experts reviewed the safety data and side-effects and recommended the studies be allowed to continue. In 2005 an FDA-registered laboratory tested RISUG and found no evidence the gel would harm men who get the injection, according to the announcement.
RISUG kills sperm on contact through a chemical action called the polyelectrolytic effect, according to a research abstract on PubMed.gov: the gel coating inside the vas deferens disrupts sperm membranes by generating surface charge imbalances, causing essential enzymes to leak out, so the sperm become nonviable.