What should the international normalized ratio (INR) level be for a patient before switching from warfarin to apixaban (Elequis)?

Switching from Warfarin to Apixaban: INR Requirements

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

Direct FDA-Approved Transition Protocol

The FDA-approved prescribing information for apixaban provides explicit guidance for this transition:

• Stop warfarin completely 1
• Wait until INR drops below 2.0 before initiating apixaban 1
• Start apixaban at the appropriate dose once this INR threshold is met 1

This straightforward approach eliminates the need for bridging anticoagulation during the transition period, as the residual warfarin effect provides anticoagulation coverage while the INR declines. 1

Rationale for the INR < 2.0 Threshold

The INR < 2.0 cutoff ensures that:

• Warfarin's anticoagulant effect is sufficiently diminished to avoid excessive anticoagulation when apixaban is added 1
• The patient remains protected during the transition, as INR values between 1.5-2.0 still provide some antithrombotic benefit, particularly in atrial fibrillation 2
• Overlap toxicity is minimized, since both agents affect different parts of the coagulation cascade 1

Practical Implementation

Monitoring Schedule

• Check INR every 1-2 days after stopping warfarin until it falls below 2.0 3, 4
• Most patients will reach INR < 2.0 within 4-5 days of stopping warfarin 5
• Patients requiring lower warfarin doses (elderly, lower body weight) may reach target INR more quickly 5

Dosing Apixaban After Transition

Once INR < 2.0 is confirmed:

• Standard dose: 5 mg twice daily for most patients with atrial fibrillation 1
• Reduced dose: 2.5 mg twice daily if patient has ≥2 of the following: age ≥80 years, weight ≤60 kg, or serum creatinine ≥1.5 mg/dL 1
• For VTE treatment: 10 mg twice daily for 7 days, then 5 mg twice daily 1

Common Pitfalls to Avoid

• Do not start apixaban while INR ≥ 2.0, as this increases bleeding risk without additional efficacy 1
• Do not use bridging anticoagulation (heparin or LMWH) during this transition—it is unnecessary and increases bleeding risk 1
• Do not check INR after starting apixaban to monitor anticoagulation, as apixaban artificially elevates INR (median 1.4-1.7, occasionally much higher) without reflecting true anticoagulant effect 6, 7
• Avoid apixaban in patients with mechanical heart valves—warfarin remains the only appropriate anticoagulant for this population 5

Special Considerations

Patients Requiring Urgent Transition

If more rapid transition is needed (e.g., warfarin-related bleeding, need for urgent procedure):

• Administer oral vitamin K 2.5 mg to accelerate INR reduction 5
• This approach shortens the time to INR < 2.0 from approximately 4-5 days to 2 days 5
• Recheck INR in 24-48 hours to confirm adequate reduction before starting apixaban 3

Patients with Renal Impairment

• Avoid apixaban if CrCl < 15 mL/min or on dialysis, as there is insufficient safety data 5, 1
• For CrCl 15-25 mL/min, use the reduced dose (2.5 mg twice daily) if other dose-reduction criteria are also met 1

Patients with Hepatic Impairment

• Avoid apixaban if transaminases > 2× upper limit of normal or total bilirubin > 1.5× upper limit of normal 5

Alternative Transition Approach (Not Recommended as First-Line)

The FDA label describes an alternative method involving parenteral anticoagulation, but this is unnecessarily complex for routine transitions:

• Discontinue apixaban and begin both parenteral anticoagulant and warfarin simultaneously
• Continue parenteral agent until INR reaches therapeutic range 1

This approach is only relevant when switching FROM apixaban TO warfarin, not for the question at hand. 1