As a clinical pharmacist, you will need to know when and why warfarin is sometimes preferred over a direct oral anticoagulant (DOAC). We’ve seen DOACs (Eliquis, etc) take the lead for most uses, such as for atrial fibrillation or venous thromboembolism (VTE). But sometimes warfarin is still the go-to.
Continue to rely on warfarin for patients with a mechanical heart valve. Pradaxa (dabigatran) seems to increase thrombosis risk compared to warfarin. Recent data also suggest that this is true for Eliquis (apixaban). And stick with warfarin in moderate to severe mitral stenosis. Xarelto (rivaroxaban) seems to increase risk of stroke and death in patients with atrial fibrillation and rheumatic heart disease, most with moderate to severe mitral stenosis compared to warfarin. Also expect to see warfarin preferred for less common uses, such as antiphospholipid syndrome with a history of thrombosis, or a left ventricular assist device. DOAC data for these uses are still limited, and warfarin has a longer track record. Usually avoid all DOACs with certain medications, such as rifampin or carbamazepine (Tegretol). These lower DOAC levels and may increase clot risk. In these cases, recommend warfarin with very close monitoring.
Weigh pros and cons of switching to warfarin if DOACs fail, such as a patient with atrial fibrillation who has a stroke despite a DOAC. For example, consider warfarin if the DOAC failure is due to nonadherence because of cost. But think twice about warfarin if patients can’t stick with frequent monitoring.
Use shared decision-making when the choice isn’t clear-cut. For instance, limited data support Eliquis as an option for patients on dialysis with atrial fib or VTE. But the ability to routinely confirm INR is in range may tip the decision toward warfarin.
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