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American Journal of Medicine
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American Journal of Medicine
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From personal clinical experience in directing a large thrombosis clinic in Boston, we know that physicians are all aware of the challenges of treatment with VKA:
• The delayed onset of action, which requires concomitant administration of a parenteral drug (warfarin’s half-life on average is about 36 to 40 hours, so it takes days for its effect to manifest).
• The narrow therapeutic window -- the INR must be in the range of 2 to 3
• The multiple drug and food interactions that necessitate frequent monitoring of the INR.
Warfarin was recently cited as the number one medication necessitating emergency department evaluations that usually resulted in hospital admission, often for bleeding complications.[5] The need for frequent monitoring, the drug and food interactions, and the risk of major hemorrhage all have constituted significant barriers to treatment adherence in our patients, not only in the short-term but also in the longer term. Hylek E. Am J Med 2013; published on-line at http://education.amjmed.com/00000.
[5] Budnitz DS, Lovegrove MC, Shehab N, Richards CL. Emergency hospitalizations for adverse drug events in older Americans. N Engl J Med. 2011;365:2002-2012.