In vitro evaluation of some parameters involved in mucoadhesion of aqueous polymeric dispersions

Context: The mucoadhesive formulations are constantly developing due to their relevance in the drug delivery to various districts of the organism. Objective: The purpose of this study was to find a direct link between physicochemical properties of the polymers and their adhesive ability in order to offer guidelines for the development of mucoadhesive semisolid formulations. Materials and methods: Twelve polymers were dispersed in water and characterized with regard to their mucoadhesiveness, apparent viscosity, contact angle on solid surface, and hydrodynamic diameter of their molecules. The adhesive properties were related to the other measured parameters. Results and discussion: The data seem to indicate the existence of an optimal value of viscosity, around 5–6 Pa s, to obtain the highest mucoadhesiveness of the polymeric dispersions. Regarding the molecular sizes, the best mucoadhesive performances seem to be given from polymers with a hydrodynamic diameter lower than 350–400 nm. In any case, the ability to wet the surface by the polymeric dispersion seems to play an essential role in bioadhesion process, capable of strongly limiting the phenomenon. Conclusions: Performing simple in vitro measurements, it seems possible to identify the best polymeric concentration to obtain a semisolid formulation with good mucoadhesive properties.