A rapid and sensitive LC/MS/MS assay for quantitative determination of digoxin in rat plasma

Abstract Digoxin is a cardiac glycoside that is widely used for the treatment of congestive heart failure. To evaluate pharmacokinetics of digoxin in rats, a sensitive LC/MS/MS assay was developed and validated for the determination of digoxin concentration in rat plasma. For detection, a Sciex API3000 LC/MS/MS with atmospheric pressure ionization (API) mass spectrometry turbo ion spray inlet in the positive ion-multiple reaction monitoring mode was used to monitor precursor→product ions of m/z 798.6→651.6 for digoxin and m/z 577.6→433.3 for oleandrin, the internal standard (IS). The standard curve was linear ( r 2 ≥0.999) over the digoxin concentration range of 0.1–100 ng/ml in plasma for digoxin. The mean predicted concentrations of the quality control samples deviated by