Antiretroviral Drug–Based Microbicides to Prevent HIV-1 Sexual Transmission

The development of a vaginal (and perhaps a rectal) microbicide would be of major benefit for slowing the global spread of human immunodeficiency virus type 1 (HIV-1). A microbicide is a gel or related device that, when inserted vaginally or rectally, acts to prevent infection of a woman or a man by HIV-1 during sexual intercourse. A practical microbicide must be not only effective, safe, and user-friendly but also economically affordable in the developing world. To date, the performance of microbicide candidates in efficacy trials has been disappointing, but next-generation concepts now in or approaching clinical trials offer improved prospects for efficacy. The most plausible approaches involve topical application of antiretroviral agents with specific activity against HIV-1, compounds similar to drugs used to treat HIV-1 infection. How these inhibitors are applied may also be critical, with sustained-release formulations and vaginal ring delivery systems now becoming a high priority.