An in vitro model for the evaluation of the adhesion of solid oral dosage forms to the oesophagus.

Adhesion of solid oral dosage forms to the oesophagus can be a disadvantage when delivering drugs that may cause oesophageal damage, or can be an advantage when developing localised therapies for this region. In this study, apparatus to investigate coatings that may influence oesophageal retention was developed and evaluated. The apparatus incorporated a section of porcine oesophageal mucosa held flat by the application of a gentle vacuum and kept moist by the application of a simulated saliva solution. The resistance to the application of more physiologically relevant shear stresses was evaluated. Using a range of materials it was found that differences in oesophageal adhesion could be identified. Materials like sodium alginate were highly adhesive and had a tendency to re-adhere while paraffin waxes showed no adhesion. The rapid loss of the polymer coat from the surface for water swellable materials was identified as an issue.