The Role of Transporters in Drug Delivery and Excretion

To appreciate the importance of the transporters in drug delivery and excretion, an understanding of the molecular and functional characteristics of drug transporters, such as their tissue distribution and the impact of transporters on drug disposition, is the focus of this chapter. The high expression levels and transport capacities of the influx transporters peptide transporter and MCT1 have resulted in their use as drug delivery targets in order to increase oral drug absorption. It has been clearly demonstrated that the transporters play an essential role in intestinal absorption, biliary excretion, and renal secretion and contribute to the barrier functions between the blood and various tissues such as brain, testis, and placenta. The potential importance of transporters for oral drug delivery in the small intestine and for transport into specific tissue sites, such as the brain, remains an area for further exploration, as people's molecular and functional understanding of transporters increases.