title: Determination of fexofenadine in human plasma using 96-well solid phase extraction and HPLC with tandem mass spectrometric detection.
abstract: A fast and sensitive HPLC-MS/MS method, utilizing atmospheric pressure chemical ionization, for the determination of fexofenadine in human plasma is described. A deuterated analog, d6-fexofenadine is used as the internal standard (IS). Plasma samples are prepared using 96-well solid phase extraction with plates containing Waters Oasis HLB sorbent. The analytes are chromatographed on a Restek Ultra IBD column (3.2 mm x 50 mm, 3 microm) using a mobile phase consisting of a mixture of 90% acetonitrile and 10% 10 mM ammonium acetate buffer and 0.1% formic acid. Quantitation of the analyte is based on the response from the multiple reaction monitoring of the precursor to product ion pairs for fexofenadine (m/z 502 --> 466) and d6-fexofenadine (m/z 508 --> 472). The assay has been validated over the concentration range of 1-200 ng/ml based on the analysis of 0.5 ml aliquots of plasma. Within-day assay accuracy was between 97 and 102% of nominal, while within-day precision was better than 3.5% CV at all points on the standard curve. Analyte extraction recovery was better than 70% over the range of the standard curve. The method was found to be suitable for the analysis of human plasma samples obtained 24 h following the administration of a single 60 mg dose of fexofenadine.
authors.affiliation: Department of Drug Metabolism, Merck Research Laboratories, West Point, PA 19486, USA. irong_fu@merck.com
authors.forename: I
authors.initials: I
authors.lastname: Fu
authors.forename: E J
authors.initials: EJ
authors.lastname: Woolf
authors.forename: B K
authors.initials: BK
authors.lastname: Matuszewski
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D016593:Terfenadine / Q000031:analogs & derivatives* / Q000097:blood* / Q000737:chemistry
chemical_list: D016593:Terfenadine; C093230:fexofenadine