Prediction of Drug-Induced Hyperbilirubinemia by In Vitro Testing

Abstract

Bilirubin, the end product of heme catabolism, is produced continuously in the body and may reach toxic levels if accumulates in the serum and tissues; therefore, a highly efficient mechanism evolved for its disposition. Normally, unconjugated bilirubin enters hepatocytes through the uptake transporters organic anion transporting polypeptide (OATP) 1B1 and 1B3, undergoes glucuronidation by the Phase II enzyme UDP glucuronosyltransferase 1A1 (UGT1A1), and conjugated forms are excreted into the bile by the canalicular export pump multidrug resistance protein 2 (MRP2). Any remaining conjugated bilirubin is transported back to the blood by MRP3 and passed on for uptake and excretion by downstream hepatocytes or the kidney. The bile salt export pump BSEP as the main motor of bile flow is indirectly involved in bilirubin disposition. Genetic mutations and xenobiotics that interfere with this machinery may impede bilirubin disposition and cause hyperbilirubinemia. Several pharmaceutical compounds are known to cause hyperbilirubinemia via inhibition of OATP1Bs, UGT1A1, or BSEP. Herein we briefly review the in vitro prediction methods that serve to identify drugs with a potential to induce hyperbilirubinemia. In vitro assays can be deployed early in drug development and may help to minimize late-stage attrition. Based on current evidence, drugs that behave as mono- or multispecific inhibitors of OATP1B1, UGT1A1, and BSEP in vitro are at risk of causing clinically significant hyperbilirubinemia. By integrating inhibition data from in vitro assays, drug serum concentrations, and clinical reports of hyperbilirubinemia, predictor cut-off values have been established and are provisionally suggested in this review. Further validation of in vitro readouts to clinical outcomes is expected to enhance the predictive power of these assays.

Hepatic transporter‐mediated pharmacokinetic drug–drug interactions: Recent studies and regulatory recommendations

“…Therefore, MATEs were recommended to be considered for investigational drugs with a renal secretion ≥25% of their total clearance. Retrospective analysis of BSEP and MRP2 inhibition can be a beneficial approach to determine the mechanism of drug‐induced toxicity as the inhibition of BSEP is associated with cholestasis (Kenna et al., 2018), and impaired activity of MRP2 results in conjugated hyperbilirubinemia (Tatrai & Krajcsi, 2020). However, routine screening of their inhibition is not warranted, as the cutoff values (IC50 or Ki) of their inhibition potential are not known to indicate increased risk of hepatotoxicity (Hillgren et al., 2013).…”

Jaundice as a Diagnostic and Therapeutic Problem: A General Practitioner’s Approach

“…Additionally, hemolysis develops due to extravascular or intravascular degradation of erythrocytes. Drugs which may interfere with hepatocyte bilirubin uptake and further contribute to prehepatic jaundice are antivirals, antibiotics, and immunosuppressives [10].…”

Inhibition of Human UDP-Glucuronosyltransferases1A1–Mediated Bilirubin Glucuronidation by the Popular Flavonoids Baicalein, Baicalin, and Hyperoside Is Responsible for Herb (Shuang-Huang-Lian)-Induced Jaundice

“…1). Finally, BG are excreted into the bile by the canalicular efflux pump multidrug resistance protein 2 (MRP2) and passed on for excretion via feces and urine (Tátrai and Krajcsi, 2020). UGT1A1 is the sole enzyme responsible for bilirubin glucuronidation, playing an important role in bilirubin metabolism and detoxification (Bock, 2015).…”