title: Analysis of cysteine and N-acetylcysteine in human plasma by high-performance liquid chromatography at the basal state and after oral administration of N-acetylcysteine.
abstract: A high-performance liquid chromatographic method for the determination of free reduced cysteine and N-acetylcysteine in human plasma at the basal state and after oral administration of N-acetylcysteine is described. The method is based on acid-catalysed conversion of plasma thiols to the corresponding S-nitroso derivatives by excess of nitrite and their subsequent cation-pairing RP-HPLC with detection at 333 nm. Recovery rates of cysteine and N-acetylcysteine added to human plasma were 94.6 and 99.6%, respectively. Inter- and intra-day precision were below 6%. In healthy humans (n = 5), free reduced cysteine was determined to be (mean+/-S.E.) 10.0+/-0.96 microM. No N-acetylcysteine was detected in plasma of these subjects above the limit of detection (e.g. 170 nM). The method was successfully applied to a pharmacokinetic study on orally administered N-acetylcysteine to healthy volunteers.
authors.affiliation: Institute of Clinical Pharmacology, Hannover Medical School, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Tsikas
authors.forename: J
authors.initials: J
authors.lastname: Sandmann
authors.forename: M
authors.initials: M
authors.lastname: Ikic
authors.forename: J
authors.initials: J
authors.lastname: Fauler
authors.forename: D O
authors.initials: DO
authors.lastname: Stichtenoth
authors.forename: J C
authors.initials: JC
authors.lastname: Frölich
mesh_terms: D000111:Acetylcysteine / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics; D000328:Adult; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003545:Cysteine / Q000097:blood*; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008297:Male; D009608:Nitrous Acid / Q000378:metabolism
chemical_list: D003545:Cysteine; D009608:Nitrous Acid; D000111:Acetylcysteine