Table1_Contributions of UDP-Glucuronosyltransferases to Human Hepatic and Intestinal Metabolism of Ticagrelor and Inhibition of UGTs and Cytochrome P450 Enzymes by Ticagrelor and its Glucuronidated Metabolite.DOCX

Ticagrelor is the first reversibly binding, direct-acting, oral P2Y12 receptor inhibitor. The contribution of UDP-glucuronosyltransferases (UGTs) enzymes to the metabolism of ticagrelor to its glucuronide conjugation, ticagrelor-O-glucuronide, in human liver microsomes (HLM) and human intestinal microsomes (HIM), was well characterized in the current study. The inhibition potential of human major UGTs by ticagrelor and ticagrelor-O-glucuronide was explored. The inhibitory effects of ticagrelor-O-glucuronide on cytochrome P450s (CYPs) enzymes were investigated as well. Ticagrelor glucuronidation exhibits substrate inhibition kinetics in both HLM and HIM with apparent Km values of 5.65 and 2.52 μM, Vmax values of 8.03 and 0.90 pmol min−1·mg protein−1, Ksi values of 1,343.0 and 292.9 respectively. The in vitro intrinsic clearances (Vmax/Km) for ticagrelor glucuronidation by HLM and HIM were 1.42 and 0.36 μl min−1·mg protein−1, respectively. Study with recombinant human UGTs suggested that multiple UGT isoforms including UGT1A9, UGT1A7, UGT1A3, UGT1A4, UGT1A1, UGT2B7 and UGT1A8 are involved in the conversion of ticagrelor to ticagrelor-O-glucuronide with UGT1A9 showing highest catalytic activity. The results were further supported by the inhibition studies on ticagrelor glucuronidation with typical UGT inhibitors in pooled HLM and HIM. Little or no inhibition of UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9 and UGT2B7 by ticagrelor and ticagrelor-O-glucuronide was noted. Ticagrelor-O-glucuronide also exhibited limited inhibitory effects toward CYP2C8, CYP2D6 and CYP3A4. In contrast, ticagrelor-O-glucuronide weakly inhibited CYP2B6, CYP2C9 and CYP2C19 activity with apparent IC50 values of 45.0, 20.0 and 18.8 μM, respectively. The potential of ticagrelor-O-glucuronide to cause drug-drug interactions warrant further study.

替卡格雷洛作为一种可逆结合、直接作用的口服P2Y12受体抑制剂，其作用机制备受关注。本研究详细阐释了UDP-葡萄糖醛酸基转移酶（UGTs）酶在替卡格雷洛在人体肝微粒体（HLM）及人体肠微粒体（HIM）中代谢生成其葡萄糖醛酸结合物——替卡格雷洛-O-葡萄糖醛酸的过程。本研究进一步探讨了替卡格雷洛及其-O-葡萄糖醛酸对主要UGTs的抑制潜力，并对替卡格雷洛-O-葡萄糖醛酸对细胞色素P450（CYPs）酶的抑制作用进行了研究。替卡格雷洛的葡萄糖醛酸化在HLM和HIM中均表现出底物抑制动力学，其表观Km值为5.65和2.52 μM，Vmax值为8.03和0.90 pmol·min−1·mg蛋白−1，Ksi值分别为1,343.0和292.9。体外固有清除率（Vmax/Km）为HLM和HIM对替卡格雷洛葡萄糖醛酸化的转化分别为1.42和0.36 μl·min−1·mg蛋白−1。使用重组人UGTs进行的研究表明，包括UGT1A9、UGT1A7、UGT1A3、UGT1A4、UGT1A1、UGT2B7和UGT1A8在内的多个UGT同工酶参与了替卡格雷洛向替卡格雷洛-O-葡萄糖醛酸的转化，其中UGT1A9展现出最高的催化活性。这一发现得到了典型UGT抑制剂在混合HLM和HIM中对替卡格雷洛葡萄糖醛酸化抑制研究的进一步证实。在替卡格雷洛及其-O-葡萄糖醛酸对UGT1A1、UGT1A3、UGT1A4、UGT1A6、UGT1A9和UGT2B7的抑制研究中，未观察到明显的抑制作用。此外，替卡格雷洛-O-葡萄糖醛酸对CYP2C8、CYP2D6和CYP3A4也表现出有限的抑制作用。然而，它对CYP2B6、CYP2C9和CYP2C19活性的抑制作用较弱，其表观IC50值分别为45.0、20.0和18.8 μM。鉴于替卡格雷洛-O-葡萄糖醛酸可能引发的药物相互作用，其潜在风险需要进一步研究。