Premium
CE provides evidence of the stereoselective hydroxylation of norketamine in equines
Author(s) -
Schmitz Andrea,
Theurillat Regula,
Lassahn PaulGerhard,
Mevissen Meike,
Thormann Wolfgang
Publication year - 2009
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200900221
Subject(s) - chemistry , hydroxylation , cyclohexanone , metabolite , chromatography , microsome , demethylation , stereochemistry , organic chemistry , biochemistry , in vitro , enzyme , catalysis , gene expression , dna methylation , gene
CE with multiple isomer sulfated‐CD as selector was used for the simultaneous analysis of the stereoisomers of ketamine, norketamine, 5,6‐dehydronorketamine and hydroxylated metabolites of norketamine in liquid/liquid extracts of (i) in vitro incubations with ketamine or norketamine and equine liver microsomes and (ii) plasma and urine of ponies receiving a target‐controlled infusion of ketamine under isoflurane anesthesia. Hydroxynorketamine metabolites with the hydroxy group at the cyclohexanone ring could be shown to be formed stereoselectively both in vitro and in vivo . Due to the lack of standard compounds, urinary extracts were fractionated by HPLC followed by characterization of the collected fractions with CE and LC‐MS n with 0.7 mmu mass discrimination. Comparison of LC‐MS n data obtained with the fractions, an in vitro microsomal sample, and both pony urine and hydrolyzed pony urine led to the identification of four hydroxylated norketamine metabolites with hydroxylation at the cyclohexanone ring, two with hydroxylation at the aromatic ring and four hydroxylated metabolites of ketamine. Due to the lower detection sensitivity, only the four hydroxynorketamine metabolites with hydroxylation at the cyclohexanone ring were observed by CE. The data suggest that demethylation of ketamine followed by hydroxylation of norketamine at the cyclohexanone ring is the major metabolic pathway in equine species and that the ketamine metabolism is highly stereoselective.