“…Most importantly, bilirubin glucuronides are high affinity substrates for both OATP1B1 and OATB1B3 and thus, these transporters are partly responsible for controlling plasma levels of conjugated bilirubin ( König et al, 2000 ; Cui et al, 2001 ; van de Steeg et al, 2010 , 2012 ). Other endogenous conjugate substrates for these transporters include bile acid and steroid conjugates, such as ursodeoxycholate-AG, GCDCA-G and GCDCA-S, glycodeoxycholate-G (GDCA-G) and estradiol-17-G ( Takehara et al, 2017 ; Bi et al, 2019 ; Zhou et al, 2019 ; Neuvonen et al, 2021 ). Glucuronides of several drugs, such as ezetimibe, gemfibrozil and sorafenib, are transported by OATP1B1 and OATP1B3, which may contribute to the enterohepatic recycling of these drugs by directing the excretion of metabolites to the bile and feces, instead of excretion into the urine ( Oswald et al, 2008 ; Hirouchi et al, 2009 ; Zimmerman et al, 2013 ; Kimoto et al, 2015 ; Bins et al, 2017 ) .…”