PLAVIX AND WARFARIN INTERACTION

Drug interactions between Plavix and Warfarin

Using warfarin together with clopidogrel can increase the risk of bleeding complications. Call your doctor promptly if you experience any unusual bleeding or bruising, vomiting or coughing up blood, blood in your urine or stools, headache, dizziness, weakness, or swelling. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Warfarin, Aspirin, and Clopidogrel in Atrial Fibrillation

Thomas L. Schwenk, MD, Kirsten E. Fleischmann, MD, MPH reviewing Hansen ML et al. Arch Intern Med 2010 Sep 13.

Any combination raises risk for bleeding without lowering risk for ischemic stroke.

Many patients with new-onset atrial fibrillation (AF) receive anticoagulation with warfarin, but many have coexisting vascular disease that requires platelet inhibition. Combinations of warfarin, aspirin, and clopidogrel often are used and even endorsed in some practice guidelines, but their safety and benefit are not fully characterized.

Danish investigators used national registries to identify 119,000 patients who survived first hospitalizations for AF. Nearly 83,000 were discharged on warfarin, aspirin, clopidogrel, or combinations thereof — most commonly with warfarin alone (42.9%), aspirin alone (40.0%), or warfarin plus aspirin (15.5%). In analyses adjusted for age, sex, comorbidity, and concomitant medical therapies, risk for fatal or serious nonfatal bleeding was 3.7-fold higher in patients who received triple therapy (warfarin plus aspirin plus clopidogrel) versus warfarin alone, 3.1-fold higher in patients who received warfarin plus clopidogrel, and 1.7- to 1.8-fold higher in patients who received aspirin plus clopidogrel or aspirin plus warfarin. No benefit was noted for triple therapy or warfarin plus clopidogrel in lowering risk for ischemic stroke.

COMMENT

These results show that adding platelet inhibition to warfarin — a common practice — significantly raised risk for fatal and serious bleeding. Warfarin plus clopidogrel and triple therapy are particularly risky combinations. These data argue for much greater care in the use of platelet inhibition with warfarin even when a strong indication exists to use both. For example, in a patient with a mechanical prosthetic valve or AF with high risk for stroke who requires antiplatelet therapy for stenting, bare-metal (rather than drug-eluting) stents should be considered preferentially to shorten the length of time that the patient receives triple therapy.