April 17, 2014
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Title: Transporter-‐driven Vectorial Transport of Cationic, Anionic, and Zwitterionic Drugs in the Intestine
Presenter: Dhiren R. Thakker, Ph.D. Ferguson Distinguished Professor and Associate Dean, Entrepreneurial Development and Global Engagement UNC Eshelman School of Pharmacy The University of North Carolina at Chapel Hill
Date: Wednesday, May 7th, 2014
Time: 5:00 PM (GMT +1) 4:00 PM (GMT) 8:00 AM (PDT) 11:00 AM (EDT)
Intestinal epithelium is the first line of defense for all ingested food products, drugs, and xenobiotics. Accordingly, its physical and biochemical architecture is highly specialized to perform the dual function of assisting absorption of nutrients while keeping foreign compounds from accessing the systemic circulation.
Transporters play a major role in both assisting as well as attenuating absorption of many drugs, particularly those that are charged at physiologic pH values. For hydrophilic and charged compounds that cannot cross cell membrane by passive diffusion, transporters are obligatory for acceptable oral absorption/bioavailability.
Uptake transporters on the membrane of the enterocytes that faces intestinal lumen (apical) and efflux transporters on the membrane that is in contact with blood capillaries (basolateral) mediate a vectorial transport for anionic and zwitterionic compounds, whereas only the apical uptake transporters are involved in the absorption of cationic compounds because of the absence of any efflux transporters for cationic compounds on the basolateral membrane of enterocytes.
Efflux transporters on the apical membrane of enterocytes attenuate intestinal absorption of cationic, anionic, and zwitterionic drugs. The uptake and efflux transporters in the intestinal epithelium have significant implications in drug absorption as well as drug-drug and drug-diet interactions, which will be discussed.
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