Ion Cluster Techniques in Drug Metabolism: Use of a Mixture of Labeled and Unlabeled Cocaine to Facilitate Metabolite Identification

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Abstract
Cocaine disposition studies in the rat are described. A mixture of cocaine, cocaine-d3, cocaine-14C, and cocaine-3H was used as a dose. The urine was collected, extracted with organic solvents, and fractions collected using NPLC and TLC. The radioactive cocaine was useful in the separation of metabolites while the deuterium-labeled cocaine, creating an artificial isotopic cluster, provided specific identification of the metabolites by gas chromatography/mass spectrometry. Benzoylecgonine, ecgoninemethylester, ecgonidine, norcocaine, N-hydroxynorcocaine, hydroxycocaine, and hydroxymethoxycocaine were found to be the major metabolites, while ecgonine, benzoylnorecgonine, and cocaine-N-oxide seemed to be present in trace amounts. Dimethoxyhydroxy cocaine was tentatively identified. Several of these newly identified metabolites of cocaine were present in significant concentrations and could contribute to the toxic effects of cocaine.