Inactivation of Human Cytochrome P450 3A4 and 3A5 by Dronedarone and N-Desbutyl Dronedarone.
Dronedarone is an antiarrhythmic agent approved in 2009 for the treatment of atrial fibrillation. An in-house preliminary study demonstrated that dronedarone inhibits cytochrome P450 (CYP) 3A4 and 3A5 in a time-dependent manner. This study aimed to investigate the inactivation of CYP450 by dronedarone. We demonstrated for the first time that both dronedarone and its main metabolite N-desbutyl dronedarone (NDBD) inactivate CYP3A4 and CYP3A5 in a time-, concentration-, and NADPH-dependent manner. For the inactivation of CYP3A4, the inactivator concentration at the half-maximum rate of inactivation and inactivation rate constant at an infinite inactivator concentration are 0.87 µM and 0.039 minute(-1), respectively, for dronedarone, and 6.24 µM and 0.099 minute(-1), respectively, for NDBD. For CYP3A5 inactivation, the inactivator concentration at the half-maximum rate of inactivation and inactivation rate constant at an infinite inactivator concentration are 2.19 µM and 0.0056 minute(-1) for dronedarone and 5.45 µM and 0.056 minute(-1) for NDBD. The partition ratios for the inactivation of CYP3A4 and CYP3A5 by dronedarone are 51.1 and 32.2, and the partition ratios for the inactivation of CYP3A4 and CYP3A5 by NDBD are 35.3 and 36.6. Testosterone protected both CYP3A4 and CYP3A5 from inactivation by dronedarone and NDBD. Although the presence of Soret peak confirmed the formation of a quasi-irreversible metabolite-intermediate complex between dronedarone/NDBD and CYP3A4/CYP3A5, partial recovery of enzyme activity by potassium ferricyanide illuminated an alternative irreversible mechanism-based inactivation (MBI). MBI of CYP3A4 and CYP3A5 was further supported by the discovery of glutathione adducts derived from the quinone oxime intermediates of dronedarone and NDBD. In conclusion, dronedarone and NDBD inactivate CYP3A4 and CYP3A5 via unique dual mechanisms of MBI and formation of the metabolite-intermediate complex. Our novel findings contribute new knowledge for future investigation of the underlying mechanisms associated with dronedarone-induced hepatotoxicity and clinical drug-drug interactions.
Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore (Y.H., Y.M.F.C., R.H.Y., G.V., C.L.L.C., E.C.Y.C.); Singapore Eye Research Institute, Singapore (S.K.K., L.Z.); and Department of Cardiology and Cardiac Electrophysiology, National University Heart Centre, Singapore (P.K.).
Yanjun
Y
Hong
Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore (Y.H., Y.M.F.C., R.H.Y., G.V., C.L.L.C., E.C.Y.C.); Singapore Eye Research Institute, Singapore (S.K.K., L.Z.); and Department of Cardiology and Cardiac Electrophysiology, National University Heart Centre, Singapore (P.K.).
Yvonne Mei Fen
YM
Chia
Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore (Y.H., Y.M.F.C., R.H.Y., G.V., C.L.L.C., E.C.Y.C.); Singapore Eye Research Institute, Singapore (S.K.K., L.Z.); and Department of Cardiology and Cardiac Electrophysiology, National University Heart Centre, Singapore (P.K.).
Ray Hng
RH
Yeo
Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore (Y.H., Y.M.F.C., R.H.Y., G.V., C.L.L.C., E.C.Y.C.); Singapore Eye Research Institute, Singapore (S.K.K., L.Z.); and Department of Cardiology and Cardiac Electrophysiology, National University Heart Centre, Singapore (P.K.).
Gopalakrishnan
G
Venkatesan
Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore (Y.H., Y.M.F.C., R.H.Y., G.V., C.L.L.C., E.C.Y.C.); Singapore Eye Research Institute, Singapore (S.K.K., L.Z.); and Department of Cardiology and Cardiac Electrophysiology, National University Heart Centre, Singapore (P.K.).
Siew Kwan
SK
Koh
Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore (Y.H., Y.M.F.C., R.H.Y., G.V., C.L.L.C., E.C.Y.C.); Singapore Eye Research Institute, Singapore (S.K.K., L.Z.); and Department of Cardiology and Cardiac Electrophysiology, National University Heart Centre, Singapore (P.K.).
Christina Li Lin
CL
Chai
Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore (Y.H., Y.M.F.C., R.H.Y., G.V., C.L.L.C., E.C.Y.C.); Singapore Eye Research Institute, Singapore (S.K.K., L.Z.); and Department of Cardiology and Cardiac Electrophysiology, National University Heart Centre, Singapore (P.K.).
Lei
L
Zhou
Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore (Y.H., Y.M.F.C., R.H.Y., G.V., C.L.L.C., E.C.Y.C.); Singapore Eye Research Institute, Singapore (S.K.K., L.Z.); and Department of Cardiology and Cardiac Electrophysiology, National University Heart Centre, Singapore (P.K.).
Pipin
P
Kojodjojo
Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore (Y.H., Y.M.F.C., R.H.Y., G.V., C.L.L.C., E.C.Y.C.); Singapore Eye Research Institute, Singapore (S.K.K., L.Z.); and Department of Cardiology and Cardiac Electrophysiology, National University Heart Centre, Singapore (P.K.) phaccye@nus.edu.sg.
Eric Chun Yong
EC
Chan
D000638:Amiodarone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism*; D065607:Cytochrome P-450 Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D000077764:Dronedarone; D006801:Humans; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology
D065607:Cytochrome P-450 Enzyme Inhibitors; C510164:CYP3A5 protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D000077764:Dronedarone; D000638:Amiodarone