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Determination of free and total warfarin concentrations in plasma using UPLC MS / MS and its application to a patient samples
Author(s) -
Radwan Mahasen A.,
Bawazeer Ghada A.,
Aloudah Nouf M.,
AlQuadeib Bushra T.,
AboulEnein Hassan Y.
Publication year - 2012
Publication title -
biomedical chromatography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 65
eISSN - 1099-0801
pISSN - 0269-3879
DOI - 10.1002/bmc.1616
Subject(s) - warfarin , chemistry , chromatography , protein precipitation , pharmacokinetics , ultrafiltration (renal) , coefficient of variation , high performance liquid chromatography , pharmacology , medicine , atrial fibrillation
Warfarin is routinely monitored by assessing its pharmacologic effects on the international normalized ratio. However, having a patient with INR not responding to increasing warfarin dose mandates a direct measurement of warfarin concentrations (total and free) for better patient clinical management of warfarin therapy. Therefore, a new fully validated specific, precise and accurate ultra‐performance liquid chromatography tandem mass spectrometry was developed for the determination of free and total warfarin in human plasma. Free warfarin was measured in plasma filtrate, prepared by ultrafiltration, and sample pretreatment involved protein precipitation with acetonitrile. Linear response ( r 2 ≥ 0.99) was observed over the studied range of free and total warfarin, with the lower limit of detection of 0.25 ng/mL. The intra‐ and inter‐day precision (relative standard deviation) values were <10% and the accuracy (relative error) was ≤6.6 for free and total warfarin. There was no significant difference ( p > 0.05) between inter‐ and intra‐day studies for the free and total warfarin, which confirmed the reproducibility of the assay method. The mean extraction efficiency was 88.6–107.2% of free and total warfarin. The assay was sensitive to follow warfarin pharmacokinetics (free and total) in a patient with resistance to warfarin up to 24 h after a daily dose of warfarin. Copyright © 2011 John Wiley & Sons, Ltd.