Effects of CYP2C19 variants on methadone metabolism in vitro

Abstract

CYP2C19 is an important member of the cytochrome P450 (CYP450) enzyme super family and is responsible for clearing approximately 10% of commonly used clinical drugs that undergo phase I metabolism. Genetic polymorphisms of CYP2C19 significantly influence the efficacy and safety of some drugs, which might cause undesirable adverse effects or cure failure at standard dosages. The aim of this study was to clarify the catalytic activities of 31 CYP2C19 alleles on the oxidative in vitro metabolism of methadone. Insect microsomes expressing the CYP2C19 alleles were incubated with 50-2000 μM methadone for 30 min at 37 °C and terminated by cooling to -80 °C immediately. Methadone and its metabolite EDDP were analyzed by an ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) system. Of the 31 tested CYP2C19 allelies variants, CYP2C19*1 is the wild-type. Compared with CYP2C19*1, two CYP2C19 variants (CYP2C19*3 and *35FS) had no detectable enzyme activity, one variant L16F exhibited slightly increased intrinsic clearance values, and one variant N277K showed no significant difference. In addition, 26 variants exhibited significantly decreased values (from 1.48% to 80.40%). These findings suggest that more attention should be paid in clinical administration of methadone to individuals carrying these CYP2C19 alleles. Copyright © 2016 John Wiley & Sons, Ltd.

Functional characterization of CYP2C19 variants in nebivolol 4‐hydroxlation in vitro

“…RCODS was used to detect the concentration of each of the recombinant CYP2C19 active holoproteins in microsomal proteins. CYP2C19 proteins were not detected in Sf 21 cells transfected with the allelic variants CYP2C19*3(W212X) and 35FS (Figure ), a finding that was similar to those of previous studies . Moreover, the protein levels of 2 variants expressed in Sf 21 cells, CYP2C19*29(K28I), CYP2C19*23(G91R), were much lower than that of wild‐type protein (Figure ).…”

Utilizing Pediatric Physiologically Based Pharmacokinetic Models to Examine Factors That Contribute to Methadone Pharmacokinetic Variability in Neonatal Abstinence Syndrome Patients

“…Allelic variants of CYP2B6, CYP2C19, and CYP3A4 have been shown to change in metabolic activities of their substrates, which include methadone, to a different extent in adults; however, limited information is available regarding their activity in neonates. The upper and lower range of the percentage of wild‐type activity for CYP2B6 (8%‐121%) and CYP2C19 (1.5%‐122%) were determined based on the contribution of the allelic variants toward the intrinsic clearance of methadone . Similarly, the percentage of wild‐type activity for CYP3A4 ranged from 16% to 100% and was based on the contribution of allelic variants toward the clearance of several CYP3A4 substrates .…”

Effects of CYP2C19 Variants on Fluoxetine Metabolism in vitro

“…Besides CYP2C19*1, we detected 30 allelic variants - 6 alleles were previously reported and 24 novel alleles with nonsynonymous coding changes were newly found; of the 24 novel alleles, 11 variations (CYP2C19 *2E, *2F, *2G, *2H, *2J, *3C, *29, *30, *31, *32, and *33) have been named by the Human Cytochrome P450 Allele Nomenclature Committee [16,17]. Previous reports revealed that most of those alleles, especially for CYP2C19 * 3 , * 35FS, and R124Q , exhibit decreased enzymatic activity in vitro and in vivo and can greatly reduce the transformation of fluoxetine to norfluoxetine [17,18]. However, few articles paid attention to the effect of CYP2C19 polymorphism on fluoxetine metabolism.…”