title: Tracing the human metabolism of stable isotope-labelled drugs by ex vivo NMR spectroscopy. A revision of S-carboxymethyl-L-cysteine biotransformation.
abstract: A direct structural identification, and quantitative assessment below the 50 nmol/ml level, of the full pattern of renally excreted metabolites is made possible by 13C NMR measurements of untreated urine samples when stable isotope-labelled (13C) drug analogues are administered to humans. The full potential of the new ex vivo NMR approach is exemplified by a study, for a group of volunteers, of S-carboxymethyl-L-cysteine metabolism. The metabolic sulphoxidation pathway of S-carboxymethyl-L-cysteine in man, accepted so far, needs to be profoundly revised on the basis of the 13C NMR results.
authors.affiliation: Dr. Margarete Fischer-Bosch-Institut für Klinische Pharmakologie, Stuttgart, Bundesrepublik Deutschland.
authors.forename: C O
authors.initials: CO
authors.lastname: Meese
authors.forename: P
authors.initials: P
authors.lastname: Fischer
mesh_terms: D000284:Administration, Oral; D001711:Biotransformation; D002233:Carbocysteine / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine; D002247:Carbon Isotopes; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods
chemical_list: D002247:Carbon Isotopes; D002233:Carbocysteine