Evaluation of the endothelin receptor antagonists ambrisentan, darusentan, bosentan, and sitaxsentan as substrates and inhibitors of hepatobiliary transporters in sandwich-cultured human hepatocytes

• Published in: Canadian journal of physiology and pharmacology 2010-06, Vol.88 (6), p.682-691
• Main Authors: HARTMAN, J. Craig, BROUWER, Kenneth, MANDAGERE, Arun, MELVIN, Lawrence, GORCZYNSKI, Richard
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Antihypertensive Agents - metabolism; Antihypertensive Agents - pharmacology; ATP Binding Cassette Subfamily B Member 11; ATP-Binding Cassette Transporters - antagonists & inhibitors; ATP-Binding Cassette Transporters - metabolism; ATP-Binding Cassette, Sub-Family B, Member 1 - antagonists & inhibitors; ATP-Binding Cassette, Sub-Family B, Member 1 - metabolism; Biological and medical sciences; Biological Transport - drug effects; Cell Culture Techniques; Cell receptors; Cells, Cultured; Diagnosis; Drugs; Endothelin; Endothelin Receptor Antagonists; Enkephalin, D-Penicillamine (2,5)- - metabolism; Estradiol - analogs & derivatives; Estradiol - metabolism; Female; Fundamental and applied biological sciences. Psychology; Genetic aspects; Health aspects; Hepatocytes - drug effects; Hepatocytes - metabolism; Humans; Isoxazoles - metabolism; Isoxazoles - pharmacology; Liver; Liver cells; Male; Medical treatment; Middle Aged; Multidrug Resistance-Associated Proteins - antagonists & inhibitors; Multidrug Resistance-Associated Proteins - metabolism; Organic Anion Transporters - antagonists & inhibitors; Organic Anion Transporters - metabolism; Organic Anion Transporters, Sodium-Dependent - antagonists & inhibitors; Organic Anion Transporters, Sodium-Dependent - metabolism; Pathology; Phenylpropionates - metabolism; Phenylpropionates - pharmacology; Properties; Pulmonary hypertension; Pyridazines - metabolism; Pyridazines - pharmacology; Pyrimidines - metabolism; Pyrimidines - pharmacology; Studies; Sulfonamides - metabolism; Sulfonamides - pharmacology; Symporters - antagonists & inhibitors; Symporters - metabolism; Taurocholic Acid - metabolism; Thiophenes - metabolism; Thiophenes - pharmacology; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Young Adult
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/Y10-060

To evaluate potential mechanisms of clinical hepatotoxicity, 4 endothelin receptor antagonists (ERAs) were examined for substrate activity and inhibition of hepatic uptake and efflux transporters in sandwich-cultured human hepatocytes. The 4 transporters studied were sodium-dependent taurocholate cotransporter (NTCP), organic anion transporter (OATP), bile salt export pump (BSEP), and multidrug resistance-associated protein 2 (MRP2). ERA transporter inhibition was examined using the substrates taurocholate (for NTCP and BSEP), [(3)H]estradiol-17beta-D-glucuronide (for OATP), and [2-D-penicillamine, 5-D-penicillamine]enkephalin (for MRP2). ERA substrate activity was evaluated using probe inhibitors ritonavir (OATP and BSEP), bromosulfalein (OATP), erythromycin (P-glycoprotein), probenecid (MRP2 and OATP), and cyclosporin (NTCP). ERAs were tested at 2, 20, and 100 micromol*L-1 for inhibition and at 2 micromol*L-1 as substrates. OATP, NTCP, or BSEP transport activity was not reduced by ambrisentan or darusentan. Bosentan and sitaxsentan attenuated NTCP transport at higher concentrations. Only sitaxsentan decreased OATP transport (52%), and only bosentan reduced BSEP transport (78%). MRP2 transport activity was unaltered. OATP inhibitors decreased influx of all ERAs. Darusentan influx was least affected (84%-100% of control), whereas bosentan was most affected (32%-58% of control). NTCP did not contribute to influx of ERAs. Only bosentan and darusentan were shown as substrates for both BSEP and P-glycoprotein efflux. All ERAs tested were substrates for at least one hepatic transporter. Bosentan and sitaxsentan, but not ambrisentan and darusentan, inhibited human hepatic transporters, which provides a potential mechanism for the increased hepatotoxicity observed for these agents in the clinical setting.