How to switch from warfarin to Eliquis (apixaban)?

How to Switch from Warfarin to Eliquis (Apixaban)

Discontinue warfarin and start apixaban when the INR falls below 2.0. 1, 2

Switching Protocol

Step 1: Stop Warfarin and Monitor INR

• Discontinue warfarin and check INR daily or every other day until it drops below 2.0 1
• The principle is to balance the waning effect of warfarin against the rapid onset of apixaban's anticoagulant effect 1
• Do not start apixaban while INR remains ≥2.0, as this creates overlapping anticoagulation and increases bleeding risk 1

Step 2: Initiate Apixaban at Appropriate INR

• Start apixaban when INR is below 2.0 1, 2
• The FDA-approved prescribing information confirms: "Warfarin should be discontinued and apixaban started when the international normalized ratio (INR) is below 2.0" 2
• Begin apixaban at the standard dose of 5 mg twice daily for atrial fibrillation 2

Step 3: Dose Adjustment Criteria

Reduce to 2.5 mg twice daily if the patient has at least 2 of the following characteristics: 2

• Age ≥80 years
• Body weight ≤60 kg
• Serum creatinine ≥1.5 mg/dL

Step 4: No Bridging Required

• Do not use bridging anticoagulation (such as heparin or low molecular weight heparin) during the transition 2
• Apixaban has rapid onset of action with peak levels at 3 hours and does not require overlap therapy 1

Critical Timing Considerations

Why INR <2.0 Matters

• Apixaban itself affects INR measurements, making INR unreliable once apixaban is started 2
• Starting apixaban at higher INR levels (≥2.0) creates excessive anticoagulation from both drugs simultaneously 1
• The target INR of 2.0-3.0 for warfarin represents optimal balance between stroke prevention and bleeding risk 3

Patient Counseling Points

• Emphasize adherence: Apixaban has a 9-14 hour half-life, meaning missed doses leave patients without anticoagulation protection 1
• If a dose is missed, take it as soon as possible on the same day, but do not double the dose 2
• Apixaban should be taken twice daily at approximately 12-hour intervals 2

Special Populations

Advanced Chronic Kidney Disease

• Apixaban can be used in patients with creatinine clearance 25-30 mL/min with standard dosing (5 mg twice daily or 2.5 mg twice daily based on dose reduction criteria) 4
• In this population, apixaban demonstrated superior safety compared to warfarin with less major bleeding (HR 0.34) 4

Drug Interactions

• Reduce apixaban dose by 50% when coadministered with combined P-glycoprotein and strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir) 2
• In patients already taking 2.5 mg twice daily, avoid these drug combinations entirely 2

Common Pitfalls to Avoid

• Do not wait for INR <1.5: The guideline-recommended threshold is INR <2.0, not <1.5 1, 2
• Do not use bridging therapy: Unlike switching from apixaban to warfarin (which requires overlap), switching from warfarin to apixaban does not require bridging 2
• Do not start both medications simultaneously: This creates dangerous overlap given apixaban's rapid onset 1
• Do not ignore dose reduction criteria: Failure to reduce to 2.5 mg twice daily in appropriate patients increases bleeding risk 2

Clinical Advantages of This Switch

Apixaban demonstrated superiority over warfarin in the ARISTOTLE trial with: 5

• Lower stroke/systemic embolism rate (1.27% vs 1.60% per year, HR 0.79)
• Lower major bleeding rate (2.13% vs 3.09% per year, HR 0.69)
• Lower mortality (3.52% vs 3.94% per year, HR 0.89)
• Significantly lower hemorrhagic stroke rate (0.24% vs 0.47% per year, HR 0.51)