Tátrai Péter, Krajcsi Péter
Solvo Biotechnology, Science Park, Building B1, 4-20 Irinyi József utca, H-1117 Budapest, Hungary.
Faculty of Health Sciences, Semmelweis University, H-1085 Budapest, Hungary.
Pharmaceutics. 2020 Aug 11;12(8):755. doi: 10.3390/pharmaceutics12080755.
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.
胆红素是血红素分解代谢的终产物,在体内持续产生,如果在血清和组织中蓄积,可能会达到毒性水平;因此,进化出了一种高效的处理机制。正常情况下,未结合胆红素通过摄取转运体有机阴离子转运多肽(OATP)1B1和1B3进入肝细胞,经II相酶尿苷二磷酸葡萄糖醛酸基转移酶1A1(UGT1A1)进行葡萄糖醛酸化,结合形式的胆红素通过胆小管输出泵多药耐药蛋白2(MRP2)排泄到胆汁中。任何剩余的结合胆红素由MRP3转运回血液,并传递给下游肝细胞或肾脏进行摄取和排泄。胆盐输出泵BSEP作为胆汁流动的主要动力,间接参与胆红素的处理。干扰这一机制的基因突变和外源性物质可能会阻碍胆红素的处理并导致高胆红素血症。已知几种药物化合物可通过抑制OATP1B、UGT1A1或BSEP导致高胆红素血症。本文简要综述了用于识别具有诱发高胆红素血症潜力药物的体外预测方法。体外试验可在药物研发早期开展,有助于减少后期淘汰。根据目前的证据,在体外表现为OATP1B1、UGT1A1和BSEP单特异性或多特异性抑制剂的药物有导致临床显著高胆红素血症的风险。通过整合体外试验的抑制数据、药物血清浓度和高胆红素血症的临床报告,已建立了预测截断值,并在本综述中临时提出。体外读数与临床结果的进一步验证有望提高这些试验的预测能力。