Identification of human cytochrome P450 isoforms and esterases involved in the metabolism of mirabegron, a potent and selective β₃-adrenoceptor agonist

Abstract

1. Human cytochrome P450 (CYP) enzymes and esterases involved in the metabolism of mirabegron, a potent and selective human β₃-adrenoceptor agonist intended for the treatment of overactive bladder, were identified in in vitro studies.

2. Incubations of mirabegron with recombinant human CYP enzymes showed significant metabolism of mirabegron by CYP2D6 and CYP3A4 only. Correlation analyses showed a significant correlation between mirabegron metabolism and testosterone 6β-hydroxylation (CYP3A4/5 marker activity). In inhibition studies using antiserum against CYP3A4, a strong inhibition (at maximum 80% inhibition) of the metabolism of mirabegron was observed, whereas the inhibitory effects of monoclonal antibodies against CYP2D6 were small (at maximum 10% inhibition). These findings suggest that CYP3A4 is the primary CYP enzyme responsible for in vitro oxidative metabolism of mirabegron, with a minor role of CYP2D6.

3. Mirabegron hydrolysis was catalyzed in human blood, plasma and butyrylcholinesterase (BChE) solution, but not in human liver microsomes, intestinal microsomes, liver S9, intestinal S9 and recombinant acetylcholinesterase solution. K_m values of mirabegron hydrolysis in human blood, plasma and BChE solution were all similar (13.4–15.2 μM). The inhibition profiles in human blood and plasma were also similar to those in BChE solution, suggesting that mirabegron hydrolysis is catalyzed by BChE.

Keywords::

• CYP3A4
• CYP2D6
• butyrylcholinesterase

Acknowledgements

We gratefully thank Ellen van der Aar, PhD and Marnix Hoitink, PhD at the former Yamanouchi Europe B.V. for their considerable contribution to the CYP enzyme identification part of this study.

Declaration of interest

Shin Takusagawa, Aiji Miyashita, Takafumi Iwatsubo, and Takashi Usui are full time employees of Astellas Pharma Inc. Kanako Yajima and Shotaro Uehara are full time employees of Shin Nippon Biomedical Laboratories, Ltd. and were contracted by Astellas Pharma Inc.