title: Simultaneous determination of unlabeled and carbon-13-labeled etoricoxib, a new cyclooxygenase-2 inhibitor, in human plasma using HPLC-MS/MS.
abstract: A method for the simultaneous determination of etoricoxib and its carbon-13 analog ((13)C(6)-etoricoxib) from human plasma has been developed and used to support bioavailability studies. Plasma samples (0.5 mL) were extracted by using a 3M Empore 96-well plate (C(8)) and the resulting extracts were analyzed by using a PE-Sciex API-3000 HPLC-MS/MS with a heated nebulizer interface (500 degrees C). The method was validated with two different calibration curve ranges, one for etoricoxib (5 to 2500 ng/mL) determined in the presence of lower concentrations of (13)C(6)-etoricoxib (0.5 to 250 ng/mL), and a second curve for the quantitation of similar concentrations of both etoricoxib and (13)C(6)-etoricoxib (0.5 to 250 ng/mL). Extraction recoveries of etoricoxib, (13)C(6)-etoricoxib, and a methylated internal standard were >70% over the range of concentrations included in both calibration curves. Intraday precision and accuracy for the quantitation of etoricoxib were 7.8% relative standard deviation (RSD) or less and within 3.4% respectively over the range of 5 to 2500 ng/mL, and 10.8% RSD or less and within 4 % respectively over the range of 0.5 to 250 ng/mL. Within-batch precision and accuracy for the quantitation of (13)C(6)-etoricoxib over the range of 0.5 to 250 ng/mL were 8.3% RSD or less and within 2.3%, respectively. The validated assay was used in support of human clinical trials.
authors.affiliation: Merck Research Laboratories, Department of Drug Metabolism, West Point, Pennsylvania 19486, USA. mark_rose@merck.com
authors.forename: M J
authors.initials: MJ
authors.lastname: Rose
authors.forename: N
authors.initials: N
authors.lastname: Agrawal
authors.forename: E J
authors.initials: EJ
authors.lastname: Woolf
authors.forename: B K
authors.initials: BK
authors.lastname: Matuszewski
mesh_terms: D002247:Carbon Isotopes / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000097:blood*; D004355:Drug Stability; D000077613:Etoricoxib; D005615:Freezing; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D013058:Mass Spectrometry / Q000379:methods; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases; D011725:Pyridines / Q000097:blood*; D013450:Sulfones / Q000097:blood*
chemical_list: D002247:Carbon Isotopes; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D011725:Pyridines; D013450:Sulfones; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D000077613:Etoricoxib