The Lancet Publishes Carraguard Phase 3 Trial Results
Trial showed anti-HIV microbicide candidate is safe, but did not prove it effective
NEW YORK, NY (5 December 2008) — The Lancet today published the results of the Phase 3 clinical trial of the microbicide candidate Carraguard®. The trial evaluated the gel’s safety when used vaginally during a two-year period and assessed its efficacy for preventing male-to-female transmission of HIV.
The Population Council previously announced these results and informed trial participants, government officials, advocates, and other interested parties in February 2008 when the results were finalized.
Trial researchers found the product to be safe for vaginal use when used approximately once per week, on average, for up to two years. The trial did not demonstrate that Carraguard is effective in preventing male-to-female HIV transmission during vaginal intercourse.
There were 134 new HIV infections in the Carraguard group (an incidence of 3.3 infections per 100 woman-years) and 151 new infections in a placebo group (an incidence of 3.8 per 100 woman-years). The difference between the two groups is not statistically significant.
The Carraguard trial, which began in March 2004 and ended in March 2007, enrolled 6,202 women and was conducted at three sites in South Africa: the Setshaba Research Centre, through the University of Limpopo/Medunsa campus; the Empilisweni Centre for Wellness Studies, through the University of Cape Town; and the Isipingo Clinic (near Durban), through the Medical Research Council of South Africa. These sites are located in areas where the HIV epidemic is acute.
Carraguard is made of carrageenan, a seaweed derivative that is on the US Food and Drug Administration’s list of products “Generally Recognized As Safe” for consumption and topical application. Laboratory research has shown Carraguard to be effective in blocking cells from becoming infected by HIV and human papillomavirus and in protecting mice from herpes simplex infections. Carraguard and similar carrageenan formulations had undergone extensive safety testing involving more than 850 women and men in earlier clinical trials in Australia, Chile, the Dominican Republic, Finland, South Africa, Thailand, and the United States.
Half of the women enrolled in the Phase 3 study were given Carraguard gel and condoms, and the other half received a placebo gel and condoms. Participants received HIV education, gynecological exams, risk-reduction and safer-sex counseling, and testing and treatment for curable sexually transmitted infections. The Population Council helped fund medical and psychological services for women who were HIV-positive at screening or who became HIV-positive during the course of the trial.
The randomized, double-blind study found that there were no differences between women using Carraguard and women using the placebo in terms of safety, and that gel-related side effects were minor and infrequent. The finding regarding safety and lack of side effects is important because Carraguard’s favorable safety profile and physical properties make it a potentially useful vehicle for future-generation microbicides to be developed at the Population Council.
The trial was funded by the US Agency for International Development (USAID) and the Bill & Melinda Gates Foundation. Read more about the Population Council’s work on microbicides.
"Efficacy of Carraguard for prevention of HIV infection in women in South Africa: A randomised, double-blind, placebo-controlled trial" (subscribers to The Lancet will be able to access the full article online; nonsubscribers will be given access after paying a fee)
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Vaginal microbicides are being developed primarily as female-initiated methods for reducing male-to-female transmission of HIV and possibly other sexually transmitted infections when used during sex. Women need more options to protect themselves from infection because current prevention strategies are not always feasible. While no effective microbicides yet exist, they would most likely be formulated as gels, creams, films, or vaginal rings. Research to develop microbicides is being expanded to include rectal, oral, and a wider range of vaginal products, some for daily or continuous use. More information about microbicides research is available at http://www.global-campaign.org, http://www.rectalmicrobicides.org, and http://www.microbicide.org.
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