![Bacteria Lowers PrEP Drugs' Effectiveness]()
For the first time, researchers have shown how vaginal bacteria changes the effectiveness of two topical HIV prevention (PrEP) drugs: tenofovir gel and dapivirine ring. In a study published online on July 12 in JCI Insight, Betsy C. Herold, M.D. and colleagues demonstrated that some bacteria alter the ways cells are able to utilize the drugs. Among the finding were that Gardnerella vaginalis blocked the uptake of tenofovir by human cells and Lactobacillus crispatus competed with human cells for drug by actively transporting and metabolizing it. Higher drug levels overcame the negative effects. Importantly, other PrEP drugs were not impacted by microbiota and may be better candidates for future formulations. These findings likely contribute to the disappointing clinical trial results, where only partial protection has been observed, and highlight the importance of preclinical and early clinical evaluation of the impact of the vagina microenvironment on drug pharmacokinetics. Dr. Herold is the Harold and Muriel Block Chair in Pediatrics, director of the Translational Prevention Research Center, professor and chief of the division of pediatric infectious diseases, and vice chair for research in the department of pediatrics.
Posted on: Thursday, July 19, 2018