IN-VITRO EX-VIVO METHODS FOR THE EVALUATION OF BIOADHESIVE POLYMERS -A PRELIMINARY-STUDY

Two apparatuses for the evaluation of the bioadhesive properties of ph armaceutical polymers were described and tested. The first apparatus w as designed in our laboratory, whilst the second is a commercially-ava ilable equipment: Texture Analyser. Both systems are fitted with speci fic probes for in vitro and ex vivo experiments. Different polymeric s amples were tested in the form of tablets, and, as reference substrate s, either a flat surface of Plexiglas or a bovine buccal mucosa were u sed. Bioadhesion was established in standardized conditions, and the f orce needed to separate the sample from the substrate was recorded as a function of distance. To describe the adhesion properties of the sam ples, maximum strength and work of adhesion were considered, and the r esults obtained with the two apparatuses were compared. The data obtai ned were reproducible, and, from both in vitro and ex vivo experiments , the polymers analyzed show good adhesion properties. Finally, to sim ulate buccal application, the bioadhesion properties of the same polym ers were evaluated ex vivo as a function of contact time and degree of hydration. These two parameters seem to play an important role in the establishment of bioadhesion bonding.