However, because drug transporters also contribute to bilirubin elimination, the purpose of this work was to investigate the in vitro inhibition of OATP1B1, OATP1B3, MRP2, and BSEP of select test drugs known to elicit hyperbilirubinemia. Test drugs investigated in this study were atazanavir and indinavir, which are associated with hyperbilirubinemia and elevations in serum transaminase; ritonavir and nelfinavir, which are not associated with hyperbilirubinemia; and bromfenac, troglitazone, and trovafloxacin, which are associated with severe idiosyncratic hepatotoxicity exhibiting elevations in serum bilirubin and transaminase.