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

Can J Physiol Pharmacol. 2010 Jun;88(6):682-91. doi: 10.1139/Y10-060.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / antagonists & inhibitors
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • ATP Binding Cassette Transporter, Subfamily B, Member 11
  • ATP-Binding Cassette Transporters / antagonists & inhibitors
  • ATP-Binding Cassette Transporters / metabolism
  • Adolescent
  • Adult
  • Aged
  • Antihypertensive Agents / metabolism
  • Antihypertensive Agents / pharmacology
  • Biological Transport / drug effects
  • Bosentan
  • Cell Culture Techniques
  • Cells, Cultured
  • Endothelin Receptor Antagonists*
  • Enkephalin, D-Penicillamine (2,5)- / metabolism
  • Estradiol / analogs & derivatives
  • Estradiol / metabolism
  • Female
  • Hepatocytes / drug effects
  • Hepatocytes / metabolism*
  • Humans
  • Isoxazoles / metabolism*
  • Isoxazoles / pharmacology
  • Male
  • Middle Aged
  • Multidrug Resistance-Associated Protein 2
  • 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
  • Phenylpropionates / metabolism*
  • Phenylpropionates / pharmacology
  • Pyridazines / metabolism*
  • Pyridazines / pharmacology
  • Pyrimidines / metabolism*
  • Pyrimidines / pharmacology
  • Sulfonamides / metabolism*
  • Sulfonamides / pharmacology
  • Symporters / antagonists & inhibitors
  • Symporters / metabolism
  • Taurocholic Acid / metabolism
  • Thiophenes / metabolism*
  • Thiophenes / pharmacology
  • Young Adult

Substances

  • ABCB11 protein, human
  • ABCC2 protein, human
  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • ATP Binding Cassette Transporter, Subfamily B, Member 11
  • ATP-Binding Cassette Transporters
  • Antihypertensive Agents
  • Endothelin Receptor Antagonists
  • Isoxazoles
  • Multidrug Resistance-Associated Protein 2
  • Multidrug Resistance-Associated Proteins
  • Organic Anion Transporters
  • Organic Anion Transporters, Sodium-Dependent
  • Phenylpropionates
  • Pyridazines
  • Pyrimidines
  • SLCO1A2 protein, human
  • Sulfonamides
  • Symporters
  • Thiophenes
  • sodium-bile acid cotransporter
  • estradiol-3-glucoside
  • darusentan
  • Estradiol
  • Taurocholic Acid
  • Enkephalin, D-Penicillamine (2,5)-
  • ambrisentan
  • sitaxsentan
  • Bosentan