Abstract
Warfarin was so far the only oral anticoagulant drug used in patients with thromboembolic disease, atrial fibrillation, artificial valves, valvular disease or in the prevention of embolic events following surgery. Anticoagulation with warfarin in patients with atrial fibrillation reduces the risk of embolism by 64% and overall mortality by 26%, with acetylsalicylic acid reduces the risk of embolization only insignificantly (by 19%) and mortality affect all.
The advantage of warfarin is its cost, long clinical experience and the easy availability of antidotes in the development of bleeding. Disadvantages include the need for regular checks INR fluctuations anticoagulant effect, interactions with drugs and food, and individual response to the administered dose.
Clinical studies show that 48% of bleeding episodes with warfarin occurs at supratherapeutic INR values and 44% of thrombotic events occurring at subtherapeutic levels. As shown in normal clinical practice, only 50-60% of the measurements achieve therapeutic INR values 2-3 and in approximately 80% of patients varies warfarin maintenance dose of about 5 mg / day.