LC–MS/MS assay of fluoropezil and its two major metabolites in human plasma: an application to pharmacokinetic studies

Background: LC-MS/MS methods were developed for pharmacokinetic analysis and verified to measure fluoropezil, a new AchE inhibitor for Alzheimer's disease treatment, and its two primary metabolites (N-debenzyl fluoride fluoropezil [M1] and N-oxidized fluoropezil [M11]) in human plasma. Methods & results: Analytes were extracted from 50 μl plasma using protein precipitation and separated by HPLC using a bridged ethyl hybrid column and gradient elution procedure. Analytical detection was performed with a triple quadrupole mass spectrometer and electrospray ionization source in multiple reaction monitoring mode. The LC-MS/MS method was fully validated. The quantification linear ranges were 0.100-50.0 ng/ml (fluoropezil), 0.0500-25.0 ng/ml (M1) and 0.0500-25.0 ng/ml (M11). Conclusion: A sensitive, reliable LC-MS/MS method was established and used successfully to explore the pharmacokinetics of fluoropezil.