Regioselective hydroxylation of an antiarrhythmic drug, propafenone, mediated by rat liver cytochrome P450 2D2 differs from that catalyzed by human P450 2D6

Abstract

1. Propafenone, an antiarrhythmic drug, is a typical human cytochrome P450 (P450) 2D6 substrate used in preclinical studies. Here, propafenone oxidation by mammalian liver microsomes was investigated in vitro.

2. Liver microsomes from humans and marmosets preferentially mediated propafenone 5-hydroxylation, minipig, rat and mouse livers primarily mediated 4′-hydroxylation, but cynomolgus monkey and dog liver microsomes differently mediated N-despropylation.

3. Quinine, ketoconazole or anti-P450 2D antibodies suppressed propafenone 4′/5-hydroxylation in human and rat liver microsomes. Pretreatments with β-naphthoflavone or dexamethasone increased N-despropylation in rat livers.

4. Recombinant rat P450 2D2 efficiently catalysed propafenone 4′-hydroxylation in a substrate inhibition manner, comparable to rat liver microsomes, while human P450 2D6 displayed propafenone 5-hydroxylation. Human and rat P450 1A, 2C and 3A enzymes mediated propafenone N-despropylation with high capacities.

5. Carbon-4′ of propafenone docked favourably into the active site of P450 2D2 based on an in silico model; in contrast, carbon-5 of propafenone docked into human P450 2D6.

6. These results suggest that the major roles of individual P450 2D enzymes in regioselective hydroxylations of propafenone differ between human and rat livers, while the minor roles of P450 1A, 2C and 3A enzymes for propafenone N-despropylation are similar in livers of both species.

Keywords:

• Cytochrome P450
• CYP2D2
• CYP2D6
• propafenone

Acknowledgements

The authors acknowledge the technical expertise of Dr Yuichiro Higuchi, Ms Nao Yoneda, Mr Hiroaki Kato, Ms Mizuho Noda, Mr Hiroaki Kato and Mr Yasuhiko Ando, and the helpful advice of Dr Mamoru Ito, Dr Yasuyuki Ohnishi and Dr Hidetaka Kamimura. We thank Natasha Beeton-Kempen, PhD, from Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.

Disclosure statement

The authors report no conflict of interest.

Additional information

Funding

This work was supported by the Platform Project for Supporting Drug Discovery and Life Science Research (Basis for Supporting Innovative Drug Discovery and Life Science Research (BINDS)) from AMED under grant number JP18am0101121j0002; and partially by the Japan Society for the Promotion of Science Grant-in-Aid for Young Scientists B under grant number 17K15520 to Shotaro Uehara.