Is the combination of aspirin, clopidogrel, and warfarin appropriate and effective or inappropriate and too dangerous?

A common scenario is a patient who needs clopidogrel and aspirin after a coronary stent plus warfarin for atrial fibrillation, deep venous thrombosis.

As a pharmacist, you will see warfarin (Marevan) used in combination with aspirin AND clopidogrel (Plavix) in more cardiac patients especially the elderly. Older patients are at higher risk for conditions that require two antiplatelet drugs plus anticoagulation.

A common scenario is a patient who needs clopidogrel and aspirin after a coronary stent, plus warfarin for atrial fibrillation, deep venous thrombosis, or mechanical heart valves. These drugs prevent different types of clots.

  • Anticoagulants (warfarin, etc.) are for "red clots," red blood cells and fibrin that form in the veins or atrium of the heart.
  • Antiplatelet drugs (aspirin, clopidogrel, etc.) are more specific for "white clots", mostly platelets that form in the arteries.

The problem is that triple antithrombotic therapy can increase bleeding risk, especially in the elderly. Try to lower bleeding risk when triple therapy is needed.

  • For warfarin, suggest a lower-end INR target of 2 to 2.5 unless patients have a higher risk of thrombosis.
  • For aspirin, suggest a low dose of just 75 to 81 mg/day.
  • For clopidogrel (Plavix), suggest stopping as soon as it's safe, often after 4 weeks for a bare-metal stent or one year for a drug-eluting stent, but this can vary. Be cautious about using prasugrel instead of clopidogrel because prasugrel causes more bleeding.


References

  1. Hermosillo AJ, Spinler SA. Aspirin, clopidogrel, and warfarin: is the combination appropriate and effective or inappropriate and too dangerous?. Ann Pharmacother. 2008;42(6):790-805.