Publication
Title
Identification of in vitro metabolites of ethylphenidate by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry
Author
Abstract
Ethylphenidate is a new potent synthetic psychoactive drug, structurally related to methylphenidate. Using human liver microsomes and cytosol, we have investigated for the first time the Phase-I and Phase-II in vitro metabolism of ethylphenidate. The structure of the metabolites was elucidated by hybrid quadrupole time-of-flight mass spectrometry. Overall, seven Phase-I, but no Phase-II metabolites were detected. Ethylphenidate underwent hydroxylation forming two primary mono-hydroxylated metabolites and, subsequently, dehydration and ring opening with an additional hydroxylation, forming secondary metabolites. The involvement of different human cytochrome P450 (CYP) enzymes in the formation of ethylphenidate metabolites was investigated using a panel of human recombinant CYPs (rCYPs). rCYP2C19 was the most active recombinant enzyme involved in the formation of all seven ethylphenidate metabolites detected, although other rCYPs (rCYP1A2, rCYP2B6, rCYPC9, rCYP2D6, and rCYP3A4, but not rCYP2E1) played a role in the metabolism of ethylphenidate. All metabolites identified in the present study can be considered as potential specific biomarkers of ethylphenidate in toxicological studies. Additionally, ritalinic acid and methylphenidate were formed by non-enzymatic hydrolysis and trans-esterification, and, therefore, they cannot be considered as (oxidative) metabolites of ethylphenidate. The presence of methylphenidate and ritalinic acid cannot be exclusively associated to the use of ethylphenidate, since methylphenidate is a drug itself and ritanilic acid can be formed from both ethylphenidate and methylphenidate. (C) 2015 Elsevier B.V. All rights reserved.
Language
English
Source (journal)
Journal of pharmaceutical and biomedical analysis. - Oxford
Publication
Oxford : 2016
ISSN
0731-7085
Volume/pages
117(2016), p. 474-484
ISI
000365145500058
Full text (Publisher's DOI)
Full text (open access)
Full text (publisher's version - intranet only)
UAntwerpen
Faculty/Department
Research group
[E?say:metaLocaldata.cgzprojectinf]
Advanced tools for exposure assessment and biomonitoring (A-TEAM).
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identification
Creation 15.01.2016
Last edited 16.09.2017
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