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02671 EROSION OF SURFACE COATING OF MICROBICIDE FORMULATIONS DUE TO SHEARING & CONTACT WITH VAGINAL FLUIDS Geonnotti, Anthony R.* A new in vitro assay analyzed erosion of microbicide formulation surface coating due to interactions with ambient vaginal fluids and shearing. Contacting layers of test formulations and fluid were subjected to defined external shear histories. Persistence of the formulation layer, and physical properties of both layers, were assessed vs. time. 4 vaginal formulations were tested: Carraguard (carrageenan); Replens (polycarbophil); KY Jelly (cellulose); Conceptrol (cellulose). 2mm layers of our vaginal fluid simulant or a new semen simulant were applied. Low shear viscosities modeled pre/post coital and high shear viscosities reflected coital conditions. Very significant differences occurred across gels. For example, rank orders for vaginal fluid contact were: gel layer viscosity retention KY > Carraguard > Conceptrol > Replens; fluid layer viscosity increase Conceptrol > Replens > Carraguard > KY. These were relatively independent of contact time (&Mac178; 70 min) and shear rate in the initial vaginal fluid testing series. Retention of microbicide coating is essential for function. Formulation composition and structure produce properties that govern the complex biophysics of coating retention. This new assay is being applied to a spectrum of biologically relevant conditions that model the natural history of formulation residence in the vagina. Initial results suggest differences in vaginal retention by these four test formulations. These putative differences can be tested by direct in vivo imaging of formulation retention. Supported by NIH AI48103. Anthony R. Geonnotti, III |
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