title: A validated SIM GC/MS method for the simultaneous determination of dextromethorphan and its metabolites dextrorphan, 3-methoxymorphinan and 3-hydroxymorphinan in biological matrices and its application to in vitro CYP2D6 and CYP3A4 inhibition study.
abstract: Dextromethorphan is used as a probe drug for assessing CYP2D6 and CYP3A4 activity in vivo and in vitro. A SIM GC/MS method without derivatization for the simultaneous determination of dextromethorphan and its metabolites, dextrorphan, 3-methoxymorphinan and 3-hydroxymorphinan, in human plasma, urine and in vitro incubation matrix was developed and validated. Calibration curves indicated good linearity with a coefficient of variation (r) better than 0.995. The lower limit of quantitation was found to be 10 ng/mL for all analytes in all matrices. Intra-day and inter-day precision for dextromethorphan and its metabolites was better than 9.02 and 9.91%, respectively and accuracy ranged between 91.76 and 106.27%. Recovery for dextromethorphan, its metabolites and internal standard levallorphan was greater than 72.68%. The method has been successfully applied for the in vitro inhibition of metabolism of dextromethorphan by CYP2D6 and CYP3A4 using known inhibitors of CYPs such as quinidine and verapamil.
authors.affiliation: Department of Pharmacognosy, School of Pharmacy, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
authors.forename: Marios
authors.initials: M
authors.lastname: Spanakis
authors.forename: Ioannis S
authors.initials: IS
authors.lastname: Vizirianakis
authors.forename: Maria
authors.initials: M
authors.lastname: Mironidou-Tzouveleki
authors.forename: Ioannis
authors.initials: I
authors.lastname: Niopas
mesh_terms: D000996:Antitussive Agents / Q000097:blood / Q000378:metabolism / Q000652:urine; D002138:Calibration; D019389:Cytochrome P-450 CYP2D6 / Q000378:metabolism; D065690:Cytochrome P-450 CYP2D6 Inhibitors; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism; D065692:Cytochrome P-450 CYP3A Inhibitors; D003915:Dextromethorphan / Q000031:analogs & derivatives* / Q000032:analysis* / Q000097:blood / Q000378:metabolism* / Q000652:urine; D003917:Dextrorphan / Q000032:analysis* / Q000097:blood / Q000652:urine; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000996:Antitussive Agents; D065690:Cytochrome P-450 CYP2D6 Inhibitors; D065692:Cytochrome P-450 CYP3A Inhibitors; D003917:Dextrorphan; C028657:3-methoxymorphinan; D003915:Dextromethorphan; D019389:Cytochrome P-450 CYP2D6; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; C054116:norlevorphanol