Measurement of Anti-HIV Activity of Marketed Vaginal Products and Excipients Using a PBMC-Based In Vitro Assay

In Brief Background and Objective Because microbicides will be applied topically in the vagina, the active agent must be formulated as a gel or cream by combining the active agent with suitable excipients. Although a number of in vitro methods have been developed for testing anti-HIV activity of microbicides, most of these methods have not been used for testing microbicides as a gel or cream. Goal The goal of this study was to measure anti-HIV activity of marketed vaginal gel or cream products and excipients. Study Design A PBMC-based in vitro method has been developed for the evaluation of anti-HIV activity of gel or cream marketed products and formulated drug delivery systems. This method includes viral exposure to test compounds followed by differential centrifugation and filtration. Results Using this methodology, a number of marketed vaginal products showed 83% to 100% inactivation of a variety of X4 and R5 HIV of different clades. Cell viability as determined by the MTT assay for all marketed products was greater than 90%. Some of the excipients also showed anti-HIV activity (20–90%) of their own. Conclusion This knowledge of baseline anti-HIV activity of vaginal products (cream/gel) and excipients is useful for the final formulation and development of anti-HIV microbicides. Using a newly developed PBMC-based in vitro assay, a number of marketed vaginal products and excipients showed significant inactivation of a variety of X4 and R5 HIV of different clades. This knowledge of baseline anti-HIV activity of excipients and other vaginal products (cream/gel) is useful for the formu-lation and development of anti-HIV products.