Drug delivery to the lower female reproductive tract: mechanics and surface phenomena

Summary form only given. Drug delivery gels are currently applied to the human vagina for contraception and therapy (e.g. treatment of vaginitis; hormone replacement). An important future application will be prophylaxis against sexually transmitted diseases. Current intravaginal contraceptive products lack the efficacy that is both needed and technically possible. This may derive from inadequate distribution of formulations within the vagina, rather than the potency of their active ingredients per se. While there is much current research on improved active ingredients, little critical scientific attention has been devoted to design of the polymeric vehicles for delivering these ingredients. The vaginal surface consists of contiguous moist epithelium which contains small corrugations (rugae, of length scale 1 mm) and/or layers of mucus or other fluids. Mechanical and chemical interactions influence spreading over these surfaces, retention/adhesion to them, mixing with ambient fluids, and exchange of biologically active molecules from delivery gels to such surfaces and fluids - all functions critical to the performance of intravaginal formulations. Surface phenomena influence all these functions. There is great opportunity to utilize the rational analysis of such phenomena in the design of improved formulations. An understanding of deployment mechanisms can be developed by combination of experimental simulations of sub-processes with fundamental theory of the fluid and solid mechanics of those sub-processes. Measurement of material properties of vaginal formulations provides input data to the theoretical models