Development of buccal film formulations and their mucoadhesive performance in biomimetic models

When developing buccal films for oromucosal drug administration, adhesion is essential to ensure sufficient time for permeation of the active ingredient(s) through the oral mucosa and avoid the detachment and subsequent swallowing of the film. In this study, biomimetic materials were evaluated as a replacement for buccal mucosa in mucoadhesion testing and potential adhesives were compared regarding their suitability to increase the adhesion of hypromellose-based oromucosal films. Gelatin gels, as possible biomimetics, failed to mimic the buccal mucosa. Furthermore, esophageal tissue lead to a wider variance of adhesion data despite showing a good correlation with buccal tissue. A synthetic copolymer hydrogel based on hydroxyethylmethacrylate (HEMA) and N-acryloyl glucosamine (AGA) was able to mimic the buccal mucosa in these tests and reduced the variation in the data compared to animal tissue. Adding polyacrylic acid and polyvinylpyrrolidone to the film formulations at a concentration of 5% w/w approximately doubled the maximum detachment force and work of adhesion. Sodium alginate enhanced the adhesive properties moderately but adding chitosan did not significantly increase mucoadhesion. Polyvinylpyrrolidone and polyacrylic acid are rated as strong adhesion enhancers for buccal films and the HEMA/AGA hydrogel is considered as a suitable alternative for animal mucosa in mucoadhesion testing.