Rectal Gel Shows Promise in Warding Off HIV
A gel that has been shown to reduce the risk of HIV infection in women during vaginal sex has also shown promise toward preventing transmission during anal sex, U.S. researchers said on Monday.
"HIV was significantly inhibited in tissue samples from participants who used tenofovir gel daily for one week compared to tissue from participants who used the placebo gel," the study said.
The results came from the first clinical trial of tenofovir gel for rectal use, and were released at a medical conference in Boston.
The study size was small, comprising just 18 men and women who were sexually abstinent and HIV negative and who applied the gel rectally for a week.
Researchers at the University of California, Los Angeles and the University of Pittsburgh then took biopsies of rectal tissue from the subjects and exposed the tissue to HIV in a lab to see how the product protected against infection.
"We are very encouraged about these findings that indicate applying tenofovir gel topically to the rectum could be a promising approach to HIV prevention," said lead author Peter Anton, director of the Center for Prevention Research at UCLA.
However, only one in four reported that they liked using the gel, and two of the study participants said they had endured "severe gastrointestinal side effects, including diarrhea and lower abdominal cramps," the study said.
"These results tell us that tenofovir gel was relatively safe to use in the rectum for most participants, but we need to address side effects to make it more acceptable to use," said Anton.
Researchers also tested a single dose oral tablet and a single dose of rectal gel, and found those methods provided no protection against HIV.
"While a slight anti-viral effect was noted in tissue from participants who received a single dose of tenofovir gel, the finding was not statistically significant," the study said.
"The single dose of oral tenofovir did not provide any protection against HIV in rectal tissue samples."
Tenofovir is an antiretroviral drug marketed as Viread by the California-based pharmaceutical company Gilead Sciences, and was approved by the U.S. Food and Drug Administration in 2006.
A separate study that compared the oral tablet to the gel in 144 women in the United States, Uganda and South Africa, found that the gel resulted in a 100 times higher concentration of the drug in vaginal tissue.
The tablet was associated with a 20-times higher active drug concentration in blood.
African women said they found that the gel helped enhance sexual pleasure, while the American women said they preferred to take the oral tablet.
Researchers say that further analysis will help determine the best dose and delivery method for different populations.
Six out of 10 new HIV infections in sub-Saharan Africa -- where an estimated 22.5 million people are living with HIV, or two-thirds of all HIV patients in the world -- occur in women who get the virus through unprotected sex with men.
The gel and pill are seen as a hopeful options because unlike male condoms, women have more control over their use.
Source: Agence France Presse
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