Inactivation of Human Cytochrome P450 3A4 and 3A5 by Dronedarone andN-Desbutyl Dronedarone

Abstract

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 NADPHdependent 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 mM and 0.039 minute 21 , respectively, for dronedarone, and 6.24 mM and 0.099 minute 21, respectively, for NDBD. For CYP3A5 inactivation, the inactivator concentration at the halfmaximum rate of inactivation and inactivation rate constant at an infinite inactivator concentration are 2.19 mM and 0.0056 minute 21 for dronedarone and 5.45 mM and 0.056 minute 21 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.

Application of Static Modeling ­­in the Prediction of In Vivo Drug–Drug Interactions between Rivaroxaban and Antiarrhythmic Agents Based on In Vitro Inhibition Studies

“…The common structural features in these antiarrhythmic agents and their metabolites are the alkylamine and furan that are in turn associated with mechanismbased inactivation (MBI) of P450 (Orr et al, 2012). Indeed, corroborating previous findings, our laboratory established the reversible and irreversible inhibition of CYP3A4-and CYP2J2-mediated metabolism of FDA-recommended probe substrates by amiodarone and NDEA (Ohyama et al, 2000;McDonald et al, 2015;Karkhanis et al, 2016) as well as dronedarone and NDBD (Hong et al, 2016;Karkhanis et al, 2016). Independently, amiodarone and dronedarone have been reported as P-gp inhibitors (FDA, 2009b(FDA, , 2012.…”

“…Rivaroxaban was not tested as a substrate in previous in-house studies investigating the CYP3A4 and CYP2J2 inhibitory potencies of amiodarone, dronedarone, and their metabolites (Hong et al, 2016;Karkhanis et al, 2016). In this study, we observed a significantly slower rate of rivaroxaban clearance by CYP3A4 as compared with CYP2J2 during initial assay optimization (data not published).…”

Cytochrome P450 3A4 and CYP3A5-Catalyzed Bioactivation of Lapatinib

“…Thus, the estimated k inact /K I ratio is nearly 20-fold higher for CYP3A4 compared with CYP3A5, indicating that lapatinib inactivates CYP3A4 to a greater extent than CYP3A5. Other CYP3A substrates, such as dronedarone (Hong et al, 2016), have also been shown to display differences in inactivation characteristics for CYP3A4 and CYP3A5. Time-dependent inhibition of CYP3A4 by lapatinib may be clinically relevant based on previous studies regarding the pharmacokinetics of lapatinib in vivo.…”

Bioactivation and Regioselectivity of Pig Cytochrome P450 3A29 towards Aflatoxin B1

“…However, some researchers still think CYP3A4 plays a more important role in AFB 1 activation based on the following experimental facts: (i) CYP3A4 is far more abundant than CYP1A2 in the human liver [ 14 ]; (ii) CYP3A4 transforms AFB 1 into exo-8,9-epoxide and a detoxification product AFQ 1 [ 15 ]; and (iii) CYP1A2 metabolizes AFB 1 into detoxification product AFM 1 , exo- and endo-8,9-epoxides [ 15 ], in which endo-8,9-epoxide is not biologically active [ 16 , 17 ]. As the most abundant CYP in the human liver and also the major enzyme responsible for the metabolism of many exogenous and endogenous compounds, CYP3A4 has been studied extensively [ 18 , 19 , 20 , 21 ]. Some CYP3A4 orthologs in other species or tissues have been identified and proved to play the same important roles as human CYP3A4 in AFB 1 activation.…”