Measurement of anti-HIV activity of marketed vaginal products and excipients using a PBMC-based in vitro assay.

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.