Warfarin monitoring guidance ( INR )

Warfarin, a vitamin K antagonist, is a cornerstone anticoagulant used in the prevention and treatment of thromboembolic disorders. Its therapeutic effect is finely balanced between the prevention of clot formation and the risk of bleeding. The individualized nature of warfarin dosing is underscored by its narrow therapeutic index and the variability in response among patients. This variability is influenced by genetic factors, diet, drug interactions, and the presence of other medical conditions.

Monitoring warfarin therapy is critical and is accomplished through the International Normalized Ratio (INR), a standardized measure of the blood's clotting tendency. Achieving and maintaining the target INR range is pivotal for ensuring therapeutic efficacy and minimizing adverse effects. The INR provides a reliable guide for clinicians to adjust warfarin dosages and is most accurately measured using venous blood samples, although capillary blood is often used in clinical practice for convenience.