Article date: May 2008
By: Uday P. Kulkarni, Balkrishna D. Swar, Dilip R. Karnad, Sanish Davis, Anil M. Patwardhan, Nilima A. Kshirsagar, Nithya J. Gogtay, in Volume 65, Issue 5, pages 787-790
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT
AIMS
To assess the correlation between plasma total warfarin concentration, plasma 7‐hydroxywarfarin concentration and INR and the weekly doses of warfarin in patients on long‐term anticoagulation.
METHODS
Twenty‐five patients on long‐term anticoagulation with warfarin were studied. Plasma total warfarin and 7‐hydroxywarfarin concentrations and INR were determined. Equations were derived with the weekly warfarin dose as the dependent variable and plasma total warfarin concentration : plasma 7‐hydroxywarfarin concentration, INR : plasma total warfarin concentration and INR : plasma 7‐hydroxywarfarin concentration as independent variables.
RESULTS
There was a good correlation between INR : plasma total warfarin concentration and the weekly dose of warfarin (y = 46.73e−0.30x, r2 = 0.65). There was a better correlation between INR : plasma 7‐hydroxywarfarin concentration and the weekly dose of warfarin (y = 156.52x−0.63, r2 = 0.74)
CONCLUSIONS
Pharmacokinetic parameters along with INR seem to correlate with the weekly doses of warfarin in patients on long‐term anticoagulation. These parameters may therefore be useful for predicting warfarin doses.
DOI: 10.1111/j.1365-2125.2008.03113.x
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