Development and in vitro evaluation of buccoadhesive tablets using a new model substrate for bioadhesion measures: The eggshell membrane

For oral delivery of antimicrobial and anti-inflammatory drugs, mucoadhesiv e tablets based on gelatin/hydroxypropylcellulose (HPC), gelatin/hydroxypro pylmethylcellulose (HPMC), and gelatin/sodium carboxymethylcellulose (NaCMC ) at different ratios were prepared by direct compression of the mixed powd ers. Metronidazole and benzydamine were used as model drugs. The in vitro b ioadhesive properties, evaluated by a commercial tensile tester, were signi ficantly affected by the model substrate employed, that is, a polypropylene (PP) membrane or a biological membrane (eggshell membrane). The use of the biological substrate seemed to supply more reliable data. All studied form ulations showed an erosion-diffusion mechanism of release, anomalous or non -Fickian release, in agreement with the behavior of the swellable systems.