PROVIDENCE, R.I.--Don't say goodbye to condoms yet, but in the worldwide race to help women protect themselves against AIDS, early studies of vaginal microbicides offer some hope for a new kind of protection against HIV transmission in the genital track.
One of the early products in the drug development pipeline, called BufferGel, just cleared its first hurdle, according to Phase I study results reported by Kenneth Mayer, M.D., Jeffrey Peipert, M.D., and Susan Cu Uvin, M.D., at the Brown University AIDS program. Made by Reprotect LLC, the gel was non-toxic and well-tolerated by 27 women who used it daily or twice daily for two weeks. Side effects were reported by 18 women (primarily mild vaginal redness or itching) but not serious enough to discontinue use.
The mainstay of safe sex has been the male condom--an effective barrier to semen that may contain infectious HIV--whose success depends upon a cooperative male partner. There is strong interest in such woman-controlled anti-HIV products, according to a related study involving women at high risk of HIV infection through their own or their partners' drug use. BufferGel and other microbicides work by reducing the vaginal pH level, increasing the natural acidity that provides a harsh environment fatal to many microorganisms, including HIV. Semen, for example, raises the pH level, allowing sperm and other microorganisms to thrive.
Another paper by Mayer provides more clues for why some women may transmit HIV more readily, knowledge that may eventually help in the development of vaccines. Women with undetectable HIV levels in their blood may have detectable levels of virus in their genital tracks. Sensitive assays called DNA and RNA PCR (polymerase chain reaction) help to explain how the genital tract can have high levels of HIV replication even when the virus is not readily detected in the blood.