Part one of this two-part review addresses the transport of therapeutics ac
ross the intestinal barrier, and focuses on transcellular transport through
the intestinal epithelia. The anatomical, biochemical and physiological pa
rameters impacting transcellular uptake of orally administered drugs are de
scribed, and methods for overcoming obstacles limiting successful transcell
ular oral drug delivery are discussed. Part two will cover paracellular tra
nsport.