ABCB11 and cholestasis: Indeed, in cases of elevated transaminases or cholestasis enzymes during a trial, testing for inhibition of BSEP in vitro by the drug helps design the study’s safety plan and the metabolism of the drug; the relationship of the peak concentration at the end of infusion of the drug to the inhibitory affinity to BSEP is a crucial parameter to evaluate a potential iDILI.