London, July 8 : Anti-HIV gels made to prevent women from acquiring the infection may eventually end up protecting male partners more than females because their repeated use by women may promote drug resistance, say researchers.
Biomathematician Sally Blower of the University of California, Los Angeles, and her colleagues modelled drug resistance and HIV transmission in women using microbicide gels, applied once a day by women whose partners refuse to wear condoms.
The researchers based the models on data from an ongoing, large-scale clinical trial of a gel containing the antiretroviral drug dapivirine.
They varied several parameters, including the likelihood that drugs in the gel would be absorbed into the bloodstream, which may raise the risk of the virus becoming resistant because it is in contact with the drug more often.
Studying the models, the researchers came to the conclusion that the gels may be a powerful too in the fight against the disease if they work well to prevent HIV infection.
However, just in case the gels promoted drug resistance, men could actually benefit more from the microbicides than women.
"Because women are using the microbicides, they're more likely to acquire drug resistance," Nature magazine quoted study co-author David Wilson of the University of New South Wales in Sydney, Australia, as saying.
Given that drug-resistance strains are generally less easily transmissible, "there will be a lower incidence of transmission from women to men than from men to women," Wilson added.
Michael Lederman, an HIV researcher at Case Western Reserve University in Cleveland, Ohio, said that the threat of drug resistance was a real one.
He, however, remains unconvinced that the microbicides will provide better protection for men than women.
"I'm not yet persuaded. While this might occur, the assumptions used in the model have to be validated," he said.
Meanwhile, Wilson and Blower both said that the gels should continue to be developed.
"Microbicides are one of the great hopes at the moment," said Wilson.
Blower agreed: "Although there's good reason to be very cautious, we've also shown that there's great potential to reduce HIV infection."
A research article on the study has been published in the Proceedings of the National Academy of Sciences USA.