San Jose Mercury News Examines Microbicides Currently in Development
The San Jose Mercury News yesterday examined ongoing efforts to develop an effective microbicide to protect women against HIV, pregnancy and other sexually transmitted diseases. Microbicides, "spermicide-like gels" applied to the vagina before sex, are viewed as a "critical AIDS-prevention strategy" in the developing world, where women sometimes have difficulty negotiating condom use with their partners. According to a study by researchers with the London School of Hygiene and Tropical Medicine, a microbicide that is at least 60% effective could prevent 2.5 million HIV infections over three years if it were introduced in 73 developing nations. Although 52 experimental microbicides are in the research pipeline, a successful compound is not expected to be on the market for at least five years. "The idea was if you took a broad-spectrum product and tested it in thousands of women, it would work, but the complications of toxicity and acceptability -- and the way HIV is actually transmitted -- are much, much more complicated than we thought," Anne-Marie Corner, CEO of Biosyn, a biotechnology firm that is testing a number of microbicides, explained. Among the microbicide candidates currently under development:
- Carraguard: Developed by the Population Council, Carraguard is a gel derived from a seaweed derivative known as carrageen that works by binding to the HIV envelope, thus deactivating the virus. Carraguard is expected to be tested in clinical trials in Africa by 2003.
- BufferGel: Developed by ReProtect, BufferGel changes the acidity of the vagina to make it "less hospitable" to HIV.
- Pro2000: Developed by Indevus Pharmaceuticals, Pro2000 blocks HIV's ability to bind to and fuse with uninfected cells. Pro2000 and BufferGel will be tested together in a trial starting next year in India and Africa.
- Tenofovir: Tenofovir was approved by the FDA last year as an antiretroviral drug, but manufacturer Gilead Sciences is researching the drug's potential to serve as a microbicide. Gilead announced in May that it would soon begin a NIH-sponsored study on tenofovir's microbicidal potential among women in the United States (Ostrov, San Jose Mercury News, 6/4).
