New spermicide may be as good as nonoxynol-9: MedlinePlus

New spermicide may be as good as nonoxynol-9

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Friday, November 26, 2010
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By Lynne Peeples

NEW YORK (Reuters Health) - A new spermicide compound, not yet available in drugstores, may be as good a contraceptive as the drug now in existing gels, films, and foams, hints a new study.

All currently available gel, film and foam spermicides, such as Encare contraceptive inserts and VCF dissolving vaginal films, contain the compound nonoxynol-9. But researchers testing a new mixture of spermicidal compounds called C31G found it to be just as effective at preventing pregnancy, and perhaps even a bit safer to use.

"Spermicides are one of the least utilized contraceptive methods," lead researcher Dr. Anne E. Burke of The Johns Hopkins University School of Medicine, in Baltimore, told Reuters Health.

However, for women who would rather not depend on a male partner's cooperation in birth control, do not want to take hormones, or who simply do not have sex all that often, it would be helpful to have newer and ultimately better spermicide options available, she added.

Burke and her colleagues randomly assigned more than 1,500 young, sexually active women to use either a gel containing C31G or nonoxynol-9 for at least 6 months. Participants were not told which spermicide they were given and were asked to engage in sexual intercourse at least four times per month and use the study product as the primary means of contraception each time.

At six months, pregnancy rates were 12 percent in both groups, report the researchers in the journal Obstetrics & Gynecology.

Of course, not all women were perfect in their use of the spermicide, occasionally applying it incorrectly or not at all. When the researchers considered only correct and consistent use of the products, the pregnancy rates dropped to five percent in both groups.

The aim of the study was not to determine if C31G was better than nonoxonyl-9, noted Burke, but rather to see if it was "at least as good." Indeed, it was.

Moreover, participants reported fewer side effects with the new spermicide compared to the old standard. Among C31G users, 35 percent experienced at least one side effect -- such as irritation, vaginal or urinary tract infections, or menstrual changes -- over the course of the study compared to 41 percent of those using the nonoxynol-9 gel.

"There are concerns with nonoxynol-9, such as vaginal side effects and genital irritation for some users," she said. "It seems that C31G might offer improvements in those regards."

Exactly when new spermicidal products containing C31G might become available is unknown at this point, senior researcher Diana Blithe of the National Institute of Child Health and Human Development, in Rockville, Md., told Reuters Health in an e-mail.

One of the hopes among researchers developing new spermicides is that they might address not only the problems of unintended pregnancy but also sexually-transmitted infections such as HIV. As a result, C31G has already been extensively tested as a microbicide, however the current study was not designed to prove such an effect.

Despite showing C31G to be as effective at preventing pregnancy as existing spermicides, Burke cautioned that spermicides are still generally less effective than other contraceptive methods, such as birth control pills or condoms.

"For women who might prioritize effectiveness above all else," she said, "spermicides may not be the best choice."

SOURCE: http://link.reuters.com/kak96q Obstetrics & Gynecology, December 2010.
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New spermicide may be as good as nonoxynol-9: MedlinePlus