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Development of a method for analysis of ketamine and norketamine enantiomers in equine brain and cerebrospinal fluid by capillary electrophoresis
Author(s) -
Theurillat Regula,
Larenza M. Paula,
Feige Karsten,
Bettschart Wolfensberger Regula,
Thormann Wolfgang
Publication year - 2014
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.201400093
Subject(s) - ketamine , cerebrospinal fluid , enantiomer , chemistry , capillary electrophoresis , chromatography , pentobarbital , blood–brain barrier , pharmacology , central nervous system , anesthesia , medicine , endocrinology , biology , stereochemistry
Ketamine and norketamine are being transported across the blood brain barrier and are also entering from blood into cerebrospinal fluid ( CSF ). Enantioselective distributions of these compounds in brain and CSF have never been determined. The enantioselective CE based assay previously developed for equine plasma was adapted to the analysis of these compounds in equine brain via use of an acidic pre‐extraction of interferences prior to liquid/liquid extraction at alkaline pH. CSF can be treated as plasma. With 100 mg of brain tissue and 0.5 mL of CSF or plasma, assay conditions for up to 30 nmol/g and 6 μM, respectively, of each enantiomer with LOQ s of 0.5 nmol/g and 0.1 μM, respectively, were established and the assays were applied to equine samples. CSF and plasma samples analyzed stemmed from anesthetized patient horses and brain, CSF and plasma were obtained from anesthetized horses that were euthanized with an overdose of pentobarbital. Data obtained indicate that ketamine and norketamine enantiomers are penetrating into brain and CSF with those of ketamine being more favorably transported than norketamine, whereas metabolites of norketamine are hindered. More work is required to properly investigate possible stereoselectivities of the ketamine metabolism and transport of metabolites from blood into brain tissue and CSF .