Oral insulin delivery.

An oral form of insulin has been the elusive goal for many investigators since the protein's initial discovery by Banting and Best in 1922. This paper will attempt to answer why this is the case by describing the substantial barriers to the development of oral insulin formulations. Following this description, specific strategies to overcome the barriers to oral insulin administration will be discussed. Most notably, the use of permeation enhancers, protease inhibitors, enteric coatings and polymer microsphere formulations will be covered, including commentary on which methods hold more promise towards the successful development of oral insulin.