title: Vectorial transport of fexofenadine across Caco-2 cells: involvement of apical uptake and basolateral efflux transporters.
abstract: Fexofenadine is a nonsedative antihistamine that exhibits good oral bioavailability despite its zwitterionic chemical structure and efflux by P-gp. Evidence exists that multiple uptake and efflux transporters play a role in hepatic disposition of fexofenadine. However, the roles of specific transporters and their interrelationship in intestinal absorption of this drug are unclear. This study was designed to elucidate vectorial absorptive transport of fexofenadine across Caco-2 cells involving specific apical uptake and efflux transporters as well as basolateral efflux transporters. Studies with cellular models expressing single transporters showed that OATP2B1 expression stimulated uptake of fexofenadine at pH 6.0. Apical uptake of fexofenadine into Caco-2 cells was decreased by 45% by pretreatment with estrone 3-sulfate, an OATP inhibitor, at pH 6.0 but not at pH 7.4, indicating that OATP2B1 mediates apical uptake of fexofenadine into these cells. Examination of fexofenadine efflux from preloaded Caco-2 cells in the presence or absence of (i) the MRP inhibitor MK-571 and (ii) the P-gp inhibitor GW918 showed that apical efflux is predominantly mediated by P-gp, with a small contribution by MRP2, whereas basolateral efflux is predominantly mediated by MRP3. These results also showed that while OSTαβ is functionally active in the basolateral membrane of Caco-2 cells, it does not play a role in the export of fexofenadine. MK-571 decreased the absorptive transport of fexofenadine by 17%. However, the decrease in absorptive transport by MK-571 was 42% when P-gp was inhibited by GW918. The results provide a novel insight into a vectorial transport system mainly consisting of apical OATP2B1 and basolateral MRP3 that may play an important role in delivering hydrophilic anionic and zwitterionic drugs such as pravastatin and fexofenadine into systemic circulation upon oral administration.
authors.affiliation: Division of Molecular Pharmaceutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7360, United States.
authors.forename: Xin
authors.initials: X
authors.lastname: Ming
authors.forename: Beverly M
authors.initials: BM
authors.lastname: Knight
authors.forename: Dhiren R
authors.initials: DR
authors.lastname: Thakker
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D018938:Caco-2 Cells; D002460:Cell Line; D016764:Cell Polarity; D004285:Dogs; D020895:Enterocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D039563:Histamine H1 Antagonists, Non-Sedating / Q000378:metabolism*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D007686:Kidney Tubules, Distal / Q000187:drug effects / Q000378:metabolism; D049990:Membrane Transport Modulators / Q000494:pharmacology; D008954:Models, Biological; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D027361:Organic Anion Transporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011355:Prodrugs / Q000378:metabolism; D021381:Protein Transport; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016593:Terfenadine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D039563:Histamine H1 Antagonists, Non-Sedating; D049990:Membrane Transport Modulators; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D027361:Organic Anion Transporters; D011355:Prodrugs; D011994:Recombinant Proteins; D016593:Terfenadine; C513055:ABCB1 protein, human; C000715087:ABCC2 protein, human; C450859:SLCO2B1 protein, human; C114462:multidrug resistance-associated protein 3; C093230:fexofenadine