Gas chromatographic-mass spectrometric analysis of plasma oxybutynin using a deuterated internal standard.
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.
Patrick
K S
KS
Department of Medicinal Chemistry, College of Pharmacy, University of Tennessee, Memphis 38163.
Markowitz
J S
JS
Jarvi
E J
EJ
Straughn
A B
AB
Meyer
M C
MC
D055598:Chemical Phenomena; D002621:Chemistry; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D008333:Mandelic Acids / Q000097:blood*; D012015:Reference Standards
D008333:Mandelic Acids; C005419:oxybutynin