Infection by HIV, the virus that causes AIDS, can actually be prevented. In the lab, the drug tenofovir blocks HIV before it can attack cells. But getting the drug to work in the real world has been an enormous challenge. Now, researchers have found a method of implementing tenofovir that's hugely effective in animal trials, using the familiar intravaginal contraceptive ring.
In order for tenofovir to block sexually transmitted HIV in women, the drug must be present in the vaginal mucosa. However, incorporating the drug in a topical gel has been ineffective, in part due to the difficulty of properly timing doses before and after sexual contact. So a team led by Northwestern University Professor Patrick Kiser developed an intravaginal ring (IVR) that delivers a continuous dose of the protective drug. In a small trial on monkeys published last week in Proceedings of the National Academy of Sciences, the drug-dispensing ring was 100% effective in blocking HIV infection.
The IVR could solve the major problems that have prevented tenofovir from being effective in the human population. Unlike gels, which must be precisely timed around sexual encounters to be effective, a tenofovir IVR would provide a sustained drug dose over a longer term. Contraceptive IVRs are already in wide use, meaning one less challenge for implementation.
As with any medical advance, these findings must be viewed with restraint. While this first round of animal testing is encouraging, we're still a long way from a world without HIV. The first human safety trials, which will measure only how much drug is released, begin later this year, and we're still far away from studying whether tenofovir IVRs can block HIV in humans. But it's a promising move toward a reliable and effective tool to fight HIV infection in women. [MedicalXpress]