title: Simple chromatography method for simultaneous determination of dextromethorphan and its main metabolites in human plasma with fluorimetric detection.
abstract: Dextromethorphan, the innocuous non-narcotic antitussive agent, is the most widely used probe drug to assess CYP2D6 function both in vivo and in vitro. For this reason a simple and selective high performance liquid chromatography method with fluorimetric detection for simultaneous quantitation of dextromethorphan, and its main metabolites in human plasma was developed and validated. The method involved a simple and rapid protein precipitation protocol, using a mixture of ZnSO(4) and methanol. The analysis was performed on a 3 microm, C(18) Tracer Excel 15 cm x 0.4 cm i.d. column by gradient elution in which Mobile phase A consisted of potassium dihydrogen phosphate buffer (pH = 3, 0.01 M):methanol:tetrahydrofuran (68.5:31:0.5), and mobile phase B consisted of methanol:tetrahydrofuran (93.25:6.75). Linear calibration curves were obtained in the range of 10-500 ng/ml for dextromethorphan, dextrorphan and hydroxymorphinan. The limit of quantitation (LOQ) was 10 ng/ml for each compound. The maximum within and between days precisions were 7.4 and 7.8%, respectively. The accuracies at four different concentration levels ranged from 88.2 to 111.5%. The recoveries were between 88.0 and 108.6%. The assay method was successfully applied to determine dextromethorphan metabolic ratio after an oral dose of 30 mg of dextromethorphan hydrobromide.
authors.affiliation: Biopharmaceutics and Pharmacokinetics Division, Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, 14155-6451 Tehran, Iran.
authors.forename: Minoo
authors.initials: M
authors.lastname: Afshar
authors.forename: Mohammad-Reza
authors.initials: MR
authors.lastname: Rouini
authors.forename: Mohsen
authors.initials: M
authors.lastname: Amini
mesh_terms: D000996:Antitussive Agents / Q000097:blood*; D002851:Chromatography, High Pressure Liquid; D003915:Dextromethorphan / Q000097:blood*; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D000996:Antitussive Agents; D003915:Dextromethorphan