Identification of alcohol-dependent clopidogrel metabolites using conventional liquid chromatography/triple quadrupole mass spectrometry.
BACKGROUND
Clopidogrel (CLO) is a prodrug used to prevent ischemic events in patients undergoing percutaneous coronary intervention or with myocardial infarction. A previous study found ethyl clopidogrel (ECLO) is formed by transesterification of CLO when incubated with alcohol in human liver microsomes. We hypothesize that ECLO will be subject to further metabolism and developed an assay to identify its metabolites.


METHODS
A liquid chromatography/triple quadrupole mass spectrometry (LC/MS/MS) method was developed to identify metabolites of ECLO. According to the predicted metabolic pathway of ECLO, precursor-product ion pairs were used to screen the possible metabolites of ECLO in human liver S9 fractions. Subsequently, the detected metabolites were characterized by the results of product ion scan.


RESULTS
In the presence of alcohol, CLO was tranesterified to ECLO, which was further oxidized to form ethylated 2-oxo-clopidogrel and several ethylated thiol metabolites including the ethylated form of the H4 active metabolite.


CONCLUSIONS
The ECLO formed by transesterification with alcohol is subject to metabolism by CYP450 enzymes producing ethylated forms of 2-oxo-clopidogrel and the active H4 thiol metabolite.
University of Tennessee Health Science Center, College of Pharmacy, Department of Clinical Pharmacy, Memphis, TN, 38163, USA.
Zhe-Yi
ZY
Hu
S Casey
SC
Laizure
Vanessa L
VL
Herring
Robert B
RB
Parker
D000438:Alcohols / Q000032:analysis / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D000077144:Clopidogrel; D004951:Esterification; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D008862:Microsomes, Liver / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism
D000438:Alcohols; D000077144:Clopidogrel; D013988:Ticlopidine