This in vitro assay simulates the erosion of surface coating experienced by formulations in vivo. Viscosity as a measure of coating integrity relates to coating flow and retention. This methodology analyzes gel interaction with relevant fluids in the vagina, such as vaginal fluid and semen. It also includes an initial analysis of the simultaneous effects of fluid shear on coating layer integrity.
Initial studies have shown that current vaginal gels (for example, spermicides, lubricants, moisturizers) have significantly different interactions with vaginal fluid and semen. These gels are based upon different macromolecules, which respond differently to the low pH of vaginal fluid and the high pH of semen. In some instances, coating layers erode very quickly, especially after contact with vaginal fluid. In other instances, coating layers may retain much of their mechanical integrity for hours after initial fluid contact.