Microbicide gels that use anti-retroviral medicines to prevent HIV infection are the newest arsenals in the global battle against AIDS. One such candidate is a gel called tenofovir, which as been found safe for daily use by women in simultaneous trials conducted in India and the US, announced researchers at the International Microbicides Conference being held in New Delhi.
Human trials at Pune’s National AIDS Research Institute (NARI), the University of Alabama at Birmingham (UAB) and the University of Pittsburgh School of Medicine showed that the gel was safe for use. The active ingredient in tenofovir gel is a class of anti-retroviral drugs called nucleotide reverse transcriptase inhibitors, which act against HIV by blocking the virus’ ability to replicate and grow inside the body.
“Microbicides are one of the top 10 technologies identified to have a positive impact on the health needs of people living in developing countries. There is an urgent need for more methods to prevent HIV infection, especially those that put women in control,” says Dr N. K. Ganguly, distinguished biotechnology fellow and former director general, ICMR, which is hosting the New Delhi conference.
The findings are significant because of the failure of the first-generation microbicide gel Carraguard, which was safe but did not protect from HIV infection. One arm of another microbicide, PRO 2000, was dropped earlier this month.
Microbicides are synthetic or natural substances – manufactured in the form of a gel, cream, suppository or film – that can neutralise or kill the HIV virus. Unlike condoms, an HIV microbicide could be used without the cooperation or knowledge of one’s partner, offering protection to women at risk of unprotected sex with a person who may be HIV-positive.
“The Phase II trial in Pune and the US evaluated if tenofovir was safe to use every day for six months, or safe to use prior to each act of sex. The next step is to determine whether tenofovir gel and other gels with HIV-specific compounds prevent sexual transmission of HIV in women when other approaches have failed to do so,” said Sharon L. Hillier, director of reproductive infectious disease research at the University of Pittsburgh School of Medicine and principal investigator on the Phase II study.
The study included 200 sexually active HIV-negative women at NARI, UAB and the Bronx-Lebanon Hospital Centre in New York. The participants were all HIV-negative and aged between 19 and 50. Of them, 64 per cent were married.
There was no disruption of liver, blood or kidney function in each group of women using a different gel regimen, including those given a placebo gel that looked and felt identical to the tenofovir gel.
The women study participants said if tenofovir gel is approved for the prevention of HIV infection, they would be willing to apply the gel to themselves daily or before sex, whichever is determined the best use.