How to Switch from Coumadin to Eliquis
Discontinue warfarin and start apixaban when the INR falls below 2.0. 1
Switching Protocol
The FDA-approved protocol for transitioning from warfarin (Coumadin) to apixaban (Eliquis) is straightforward:
- Stop warfarin immediately and monitor the INR 1
- Begin apixaban when the INR drops below 2.0 1
- No bridging anticoagulation is required during this transition period 1
The typical time frame for INR to fall below 2.0 after stopping warfarin is 3-5 days, depending on the patient's warfarin dose and individual metabolism 2. During this waiting period, patients remain on warfarin's residual anticoagulant effect, which provides continued protection against thromboembolism.
Dosing Apixaban After the Switch
Once the INR is below 2.0, initiate apixaban at the appropriate dose 1:
- Standard dose: 5 mg twice daily for most patients with atrial fibrillation 1
- Reduced dose: 2.5 mg twice daily if the patient meets at least 2 of the following criteria 1:
- Age ≥80 years
- Body weight ≤60 kg
- Serum creatinine ≥1.5 mg/dL
For treatment of DVT/PE, start with 10 mg twice daily for 7 days, then reduce to 5 mg twice daily 1.
Critical Contraindications to Switching
Do not switch patients with mechanical heart valves to apixaban - they must remain on warfarin 3, 2. Direct oral anticoagulants including apixaban are contraindicated in this population and associated with increased thrombotic risk 3.
Exercise caution in patients with end-stage renal disease or on hemodialysis - warfarin is preferred over apixaban in this population 3. While some pharmacokinetic data suggest apixaban 2.5 mg twice daily may be used in patients with creatinine clearance 25-30 mL/min 4, there is limited safety data for patients on dialysis 5.
Post-Conversion Monitoring
- No routine INR monitoring is needed after switching to apixaban 3
- Assess renal function before initiating apixaban and periodically during treatment, especially in elderly patients 3
- Evaluate bleeding risk factors at regular intervals 3
- Check for drug interactions, particularly with combined P-glycoprotein and strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir), which require dose reduction of apixaban 1
Common Pitfalls to Avoid
Do not start apixaban while INR is still ≥2.0 - this creates excessive anticoagulation and increases bleeding risk. Wait for the INR to fall below 2.0 before initiating apixaban 1.
Do not use bridging anticoagulation (heparin or low-molecular-weight heparin) during the transition from warfarin to apixaban - this is unnecessary and increases bleeding risk 1.
Do not assume all patients on warfarin can switch to apixaban - verify the indication for anticoagulation first, as mechanical valves and moderate-to-severe mitral stenosis are absolute contraindications 3, 2.
Ensure patients understand they cannot use INR to monitor apixaban - while apixaban can affect INR values 5, INR is not a reliable measure of apixaban's anticoagulant effect and should not be used for monitoring 3.