McDonald Matthew G, Au Nicholas T, Rettie Allan E
Department of Medicinal Chemistry, University of Washington, Seattle, Washington (M.G.M., N.T.A., A.E.R.).
Department of Medicinal Chemistry, University of Washington, Seattle, Washington (M.G.M., N.T.A., A.E.R.)
Drug Metab Dispos. 2015 Nov;43(11):1661-9. doi: 10.1124/dmd.115.065623. Epub 2015 Aug 21.
In this study, IC50 shift and time-dependent inhibition (TDI) experiments were carried out to measure the ability of amiodarone (AMIO), and its circulating human metabolites, to reversibly and irreversibly inhibit CYP1A2, CYP2C9, CYP2D6, and CYP3A4 activities in human liver microsomes. The [I]u/Ki,u values were calculated and used to predict in vivo AMIO drug-drug interactions (DDIs) for pharmaceuticals metabolized by these four enzymes. Based on these values, the minor metabolite N,N-didesethylamiodarone (DDEA) is predicted to be the major cause of DDIs with xenobiotics primarily metabolized by CYP1A2, CYP2C9, or CYP3A4, while AMIO and its N-monodesethylamiodarone (MDEA) derivative are the most likely cause of interactions involving inhibition of CYP2D6 metabolism. AMIO drug interactions predicted from the reversible inhibition of the four P450 activities were found to be in good agreement with the magnitude of reported clinical DDIs with lidocaine, warfarin, metoprolol, and simvastatin. The TDI experiments showed DDEA to be a potent inactivator of CYP1A2 (KI = 0.46 μM, kinact = 0.030 minute(-1)), while MDEA was a moderate inactivator of both CYP2D6 (KI = 2.7 μM, kinact = 0.018 minute(-1)) and CYP3A4 (KI = 2.6 μM, kinact = 0.016 minute(-1)). For DDEA and MDEA, mechanism-based inactivation appears to occur through formation of a metabolic intermediate complex. Additional metabolic studies strongly suggest that CYP3A4 is the primary microsomal enzyme involved in the metabolism of AMIO to both MDEA and DDEA. In summary, these studies demonstrate both the diversity of inhibitory mechanisms with AMIO and the need to consider metabolites as the culprit in inhibitory P450-based DDIs.
在本研究中，进行了IC50位移和时间依赖性抑制（TDI）实验，以测定胺碘酮（AMIO）及其循环中的人体代谢产物对人肝微粒体中CYP1A2、CYP2C9、CYP2D6和CYP3A4活性进行可逆和不可逆抑制的能力。计算了[I]u/Ki,u值，并用于预测由这四种酶代谢的药物在体内的AMIO药物-药物相互作用（DDIs）。基于这些值，预测次要代谢产物N,N-双去乙基胺碘酮（DDEA）是与主要由CYP1A2、CYP2C9或CYP3A4代谢的异生物素发生DDIs的主要原因，而AMIO及其N-单去乙基胺碘酮（MDEA）衍生物是涉及抑制CYP2D6代谢的相互作用的最可能原因。从对四种P450活性的可逆抑制预测的AMIO药物相互作用与报道的利多卡因、华法林、美托洛尔和辛伐他汀临床DDIs的程度高度一致。TDI实验表明DDEA是CYP1A2的强效失活剂（KI = 0.46 μM，kinact = 0.030分钟-1），而MDEA是CYP2D6（KI = 2.7 μM，kinact = 0.018分钟-1）和CYP3A4（KI = 2.6 μM，kinact = 0.016分钟-1）的中度失活剂。对于DDEA和MDEA，基于机制的失活似乎是通过形成代谢中间复合物而发生的。额外的代谢研究强烈表明CYP3A4是参与AMIO代谢生成MDEA和DDEA的主要微粒体酶。总之，这些研究证明了AMIO抑制机制的多样性以及在基于P450抑制的DDIs中需要将代谢产物视为罪魁祸首。
