microbicides

Microbicides are substances applied topically to the vagina or rectum with the aim of reducing the transmission of sexually transmitted infections, particularly human immunodeficiency virus (HIV). They are intended as a female-controlled prevention option that can be used alongside condoms and other HIV prevention measures. Microbicide candidates range from antiviral drugs delivered in gels, creams, films, and intravaginal rings to non-specific agents and barrier-forming formulations. Rectal microbicides are also under development to address transmission via receptive anal intercourse.

Most products act either by delivering antiviral agents that block replication at the mucosal surface or by preventing a pathogen from establishing infection, and some provide a physical barrier. Safety and acceptability are central concerns because mucosal irritation or inflammation could increase risk if the product is not used correctly.

Clinical development has included several major products. Antiretroviral-based topical gels and dapivirine-containing vaginal rings have advanced to late-stage trials, with results indicating partial protection that depends on adherence. Earlier non-specific agents historically failed due to safety concerns. Regulatory reviews and country-specific implementations vary, and no microbicide has achieved universal, broad-based protection to date.

Delivery formats and implementation: A variety of formats—gels, creams, films, rings, and inserts—are being pursued to suit different lifestyles, preferences, and contexts. Effectiveness in real-world use is influenced by adherence, access, cost, and integration with existing prevention strategies, including condoms and pre-exposure prophylaxis (PrEP). Microbicides remain an active area of research with potential to expand HIV prevention options, especially for populations with limited agency over protective measures.