title: Gas chromatographic-mass spectrometric analysis of plasma oxybutynin using a deuterated internal standard.
abstract: A gas chromatographic-mass spectrometric method is described for the quantitative analysis of plasma oxybutynin. Deuterated oxybutynin served as the internal standard and its synthesis is described. Chromatographic separation on a methylsilicone capillary column avoided the thermal decomposition observed using a packed column. Electron-impact ionization and selected-ion monitoring of the alpha-cleavage fragments of drug and internal standard permitted quantitation of oxybutynin down to 0.25 ng/ml of plasma. At the 2 ng/ml level the accuracy and precision are 4 and 10%, respectively, and improved at higher drug concentrations. Application of the method to the pharmacokinetics of oral oxybutynin in man demonstrated rapid absorption and elimination of the drug.
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy, University of Tennessee, Memphis 38163.
authors.forename: K S
authors.initials: KS
authors.lastname: Patrick
authors.forename: J S
authors.initials: JS
authors.lastname: Markowitz
authors.forename: E J
authors.initials: EJ
authors.lastname: Jarvi
authors.forename: A B
authors.initials: AB
authors.lastname: Straughn
authors.forename: M C
authors.initials: MC
authors.lastname: Meyer
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D008333:Mandelic Acids / Q000097:blood*; D012015:Reference Standards
chemical_list: D008333:Mandelic Acids; C005419:oxybutynin