A stable isotope assay for pseudoracemic warfarin from human plasma samples

Area of Science:

• Pharmacokinetics and Drug Metabolism
• Analytical Chemistry
• Biomedical Analysis

Background:

• Warfarin is a widely prescribed anticoagulant with stereospecific effects.
• Accurate quantification of warfarin enantiomers in biological matrices is crucial for therapeutic drug monitoring.
• Existing analytical methods may face challenges with sensitivity, specificity, or matrix interferences.

Purpose of the Study:

• To develop and validate a novel analytical method for the simultaneous determination of (R)-warfarin and (S)-warfarin in human plasma.
• To establish a reliable assay for quantifying warfarin enantiomers at submicrogram levels.

Main Methods:

• A pseudoracemic approach using a stable isotope-labeled enantiomer.
• High-performance liquid chromatography (HPLC) for sample clean-up and separation.
• Mass spectrometry (MS) for sensitive and selective detection.

Main Results:

• The developed assay allows for simultaneous quantification of both (R)- and (S)-warfarin enantiomers.
• The method demonstrated high reliability, accuracy, and precision within 5% at submicrogram concentrations.
• Effective elimination of ion interferences from co-administered drugs or sample contamination was achieved.

Conclusions:

• The pseudoracemic stable isotope method provides a robust and accurate means for determining warfarin enantiomers in human plasma.
• This assay is suitable for pharmacokinetic studies and clinical applications requiring precise warfarin level monitoring.