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 β(3)-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.

Pharmacokinetics of Mirabegron, a β3-Adrenoceptor Agonist for Treatment of Overactive Bladder, in Healthy East Asian Subjects

“…7,16 In addition, cytochrome 450 (CYP) 3A4 is the primary isoenzyme responsible for the hepatic oxidative metabolism of mirabegron in vitro, with a minor role of CYP2D6. 16 Mirabegron is cleared by multiple metabolic enzymes with no single enzyme dominant.…”

“…In study 2, urine samples for measurement of unchanged mirabegron were collected no more than 12 hours before dosing and from 0 to 12 hours, 12 to 24 hours, 24 to 48 hours, 48 to 72 hours, and 72 to 96 hours after dosing. In studies 4 and 5, blood samples were collected before dosing and at 0.5, 1, 2, 3, 4, 5, 6,7,8,12,16,24,36,48,72, and 96 hours after dosing in the single-dose period and on the final day in the multiple-dose period, before the first administration of study drug in the multiple-dose period, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, and 24 hours after dosing on the first day in the multiple-dose period, and before dosing on days 5, 6, and 7 in the multiple-dose period. Plasma was collected by centrifugation, and plasma and urine samples were stored at -651C or below until analysis.…”

Screening of Specific Inhibitors for Human Carboxylesterases or Arylacetamide Deacetylase

“…The reaction was initiated by the addition of PNPA after a 2-minute preincubation at 37°C. The preincubation time referred to previous reports (Karanth and Pope, 2000;Takusagawa et al, 2012;Yanjiao et al, 2013;Ohura et al, 2014). After a 1-minute incubation at 37°C, the reaction was terminated by the addition of 100 ml of ice-cold methanol.…”

“…Butyrylcholinesterase exists in human plasma. Jbilo et al (1994) reported that butyrylcholinesterase mRNA was detected in human liver, but the enzyme activity appeared to be undetectable in the liver as well as in intestinal fractions (Takusagawa et al, 2012). Taken together, if a drug is found to be hydrolyzed by human liver microsomes, the enzymes responsible for the hydrolysis are likely CES or AADAC.…”

Mirabegron in the treatment of overactive bladder

“…At steady state, mirabegron shows a large volume of distribution of 1670 l [52]. The metabolism of mirabegron is mainly due to the liver; in particular, it is metabolized by different metabolic pathways such as N-dealkylation, oxidative metabolism catalysed by CYP 3A4/5 [54], with a minor role for CYP2D6, amide hydrolysis by esterases and uridine diphosphateglucuronosyltransferases-mediated glucuronidation [55]. At least 10 metabolites are derived from liver metabolism of mirabegron, but none of them has pharmacological activity [55].…”