Paracellular transport of orally-administered drugs, the passage of molecul
es between adjacent intestinal epithelial cells, is impeded by a range of s
tructural and functional features found in the intestine. An increased know
ledge of the mechanisms that govern the paracellular barrier will enable th
e pharmaceutical scientist to design novel and rational formulations and de
livery platforms that will improve the oral bioavailability of therapeutic
molecules, particularly proteins and peptides, which would be taken-up by t
he paracellular pathway.