In vitro evaluation of mucoadhesive properties of chitosan and some other natural polymers

A number of natural or partially modified polymers was screened for mucoadhesive properties by routinely measuring the force of detachment for swollen polymer films from pig intestinal mucosa in a saline medium. Suprisingly, hydroxypropyl- and carboxymethylcellulose showed almost no mucoadhesion, whereas the cationic polymer chitosan was fairly mucoadhesive in comparison to Polycarbophil as a reference substance. It is suggested that a strict difference be made between mucoadhesion of dry polymers on a wet tissue in air, and mucoadhesion of a swollen hydrogel in the presence of a third liquid phase. Cationic polymers should be further investigated with respect to possibly improved mucoadhesive properties in a neutral or slightly alkaline environment.