Bioadhesive dosage forms for esophageal drug delivery

The esophagus as a site for drug delivery has been much overlooked in comparison to the remainder of the gastrointestinal tract. The low permeability and transient nature of the esophagus means that it is unsuitable for delivery of drugs for systemic action. However, esophageal disorders including fungal infection, cancers, motility dysfunction, and damage due to gastric reflux may be treated using locally acting agents that offer benefits of reduced dosage and decreased side effects. Bioadhesive dosage forms that adhere to the esophageal mucosa and prolong contact have been investigated to improve the efficacy of locally acting agents. The rationale for local esophageal drug delivery and its limitations, the factors that determine adhesion to this organ, and the experimental models used in esophageal drug delivery research are reviewed.