Department of Drug Metabolism, Pfizer Global Research, La Jolla, California, USA.
Drug Metab Dispos. 2012 May;40(5):943-51. doi: 10.1124/dmd.111.043505. Epub 2012 Feb 10.
CYP2J2, an arachidonic acid epoxygenase, is recognized for its role in the first-pass metabolism of astemizole and ebastine. To fully assess the role of CYP2J2 in drug metabolism, a selective substrate and potent specific chemical inhibitor are essential. In this study, we report amiodarone 4-hydoxylation as a specific CYP2J2-catalyzed reaction with no CYP3A4, or other drug-metabolizing enzyme, involvement. Amiodarone 4-hydroxylation enabled the determination of liver relative activity factor and intersystem extrapolation factor for CYP2J2. Amiodarone 4-hydroxylation correlated with astemizole O-demethylation but not with CYP2J2 protein content in a sample of human liver microsomes. To identify a specific CYP2J2 inhibitor, 138 drugs were screened using terfenadine and astemizole as probe substrates with recombinant CYP2J2. Forty-two drugs inhibited CYP2J2 activity by ≥50% at 30 μM, but inhibition was substrate-dependent. Of these, danazol was a potent inhibitor of both hydroxylation of terfenadine (IC(50) = 77 nM) and O-demethylation of astemizole (K(i) = 20 nM), and inhibition was mostly competitive. Danazol inhibited CYP2C9, CYP2C8, and CYP2D6 with IC(50) values of 1.44, 1.95, and 2.74 μM, respectively. Amiodarone or astemizole were included in a seven-probe cocktail for cytochrome P450 (P450) drug-interaction screening potential, and astemizole demonstrated a better profile because it did not appreciably interact with other P450 probes. Thus, danazol, amiodarone, and astemizole will facilitate the ability to determine the metabolic role of CYP2J2 in hepatic and extrahepatic tissues.
细胞色素 P4502J2（CYP2J2）是花生四烯酸环氧化酶，其在阿司咪唑和依巴斯汀的首过代谢中起作用。为了全面评估 CYP2J2 在药物代谢中的作用，需要有选择性的底物和有效的特异性化学抑制剂。在这项研究中，我们报道了胺碘酮 4-羟化作用是 CYP2J2 催化的特异性反应，CYP3A4 或其他药物代谢酶不参与该反应。胺碘酮 4-羟化作用使 CYP2J2 的肝相对活性因子和体系间外推因子得以确定。胺碘酮 4-羟化作用与阿司咪唑 O-去甲基化作用相关，但与人类肝微粒体样本中的 CYP2J2 蛋白含量无关。为了鉴定特异性 CYP2J2 抑制剂，我们使用特非那定和阿司咪唑作为探针底物，用重组 CYP2J2 对 138 种药物进行了筛选。在 30 μM 时，有 42 种药物对 CYP2J2 活性的抑制率≥50%，但抑制作用与底物有关。其中，丹那唑是特非那定羟化（IC50=77 nM）和阿司咪唑 O-去甲基化（K(i)=20 nM）的强效抑制剂，抑制作用主要为竞争性。丹那唑对 CYP2C9、CYP2C8 和 CYP2D6 的抑制常数（IC50）分别为 1.44、1.95 和 2.74 μM。胺碘酮或阿司咪唑被纳入用于细胞色素 P450（CYP）药物相互作用筛选潜力的七种探针混合物中，阿司咪唑的作用更好，因为它与其他 CYP 探针没有明显相互作用。因此，丹那唑、胺碘酮和阿司咪唑将有助于确定 CYP2J2 在肝组织和肝外组织中的代谢作用。
