Strategies for local drug delivery targeting the oesophagus

Localised, targeted drug delivery to the oesophagus offers the potential for more effective delivery and reduced drug dosages, coupled with increased patient compliance. This thesis considers bioadhesive liquids, orally retained tablets and films as well as chewable dosage forms as drug delivery systems to target the oesophagus. Miconazole nitrate was used as a model antifungal agent. Chitosan and xanthan gum hydrogels were evaluated as viscous polymer viables with the in vitro retention, drug release and minimum inhibitory concentration values of the formulations measured. Xanthan showed prolonged retention on the oesophageal surface in vitro yet chitosan reduced the MIC value; both polymers offer potential for local targeting to the oesophagus. Cellulose derivatives were investigated within orally retained dosage forms. Both drug and polymer dissolution rates were measured to investigate the drug release mechanism and to develop a formulation with concomitant drug and polymer release to target the oesophagus with solubilised drug within a viscous media. Several in vitro dissolution methods were evaluated to measure drug release from chewable dosage forms with both drug and polymer dissolution quantified to investigate the effects of dissolution apparatus on drug release. The results from this thesis show that a range of drug delivery strategies that can be used to target drug to the oesophagus. The composition of these formulations as well as the methodology used within the development are crucial to best understand the formulation and predict its performance in vivo.