What is the protocol for switching a patient from Coumadin (warfarin) to Xarelto (rivaroxaban)?

Switching from Coumadin (Warfarin) to Xarelto (Rivaroxaban)

Discontinue warfarin and start rivaroxaban as soon as the INR falls below 3.0 to avoid periods of inadequate anticoagulation. 1

Transition Protocol

The FDA-approved protocol for switching from warfarin to rivaroxaban is straightforward and does not require bridging with parenteral anticoagulation:

• Stop warfarin immediately and monitor the INR daily until it drops below 3.0 1
• Start rivaroxaban at the appropriate dose for the indication as soon as the INR is below 3.0 1
• No bridging therapy with heparin or low molecular weight heparin is needed during this transition 2

This approach ensures continuous anticoagulation coverage while avoiding excessive bleeding risk from overlapping anticoagulants.

Rivaroxaban Dosing by Indication

The appropriate rivaroxaban dose depends on the clinical indication and renal function:

For Atrial Fibrillation:

• Standard dose: 20 mg once daily with the evening meal 2, 1
• Reduced dose: 15 mg once daily with the evening meal if creatinine clearance is 15-50 mL/min 2, 1

For Venous Thromboembolism (DVT/PE):

• Initial treatment: 15 mg twice daily with food for the first 21 days 2, 1
• Maintenance: 20 mg once daily with food thereafter 2, 1
• Extended prevention: 10 mg once daily after completing at least 6 months of treatment 2

Critical Timing Considerations

Rivaroxaban has rapid onset of action (2-4 hours to peak effect), so there should be minimal gap between stopping warfarin and starting rivaroxaban once the INR is appropriate 1, 3. This is a key advantage over warfarin-to-dabigatran or warfarin-to-edoxaban transitions, which require 5-10 days of parenteral anticoagulation bridging 2.

Monitoring Requirements

• Check INR daily during the transition period until it falls below 3.0 2
• No routine coagulation monitoring is required once rivaroxaban therapy is established, unlike warfarin 3
• Assess renal function before initiating rivaroxaban, as 33% of the drug is renally cleared 2, 4

Important Contraindications and Precautions

Avoid Rivaroxaban in These Situations:

• Severe renal impairment (CrCl <15 mL/min) or patients on hemodialysis 2, 1
• Antiphospholipid antibody syndrome, particularly triple-positive patients, where rivaroxaban showed increased thrombotic events compared to warfarin 5
• Severe hepatic impairment with coagulopathy 2
• Active gastrointestinal malignancy, where DOACs may increase bleeding risk compared to LMWH 2

Drug Interactions to Review:

• Strong CYP3A4 inhibitors or inducers (e.g., ketoconazole, rifampin) significantly alter rivaroxaban levels 2, 3
• P-glycoprotein inhibitors (e.g., dronedarone, systemic azole antifungals) increase rivaroxaban exposure 2, 3
• Medications affecting renal function can impair rivaroxaban clearance and increase bleeding risk 4

Administration Details

Rivaroxaban 15 mg and 20 mg doses must be taken with food to ensure adequate absorption, while the 10 mg dose can be taken without regard to meals 1. The evening meal is specifically recommended for once-daily dosing in atrial fibrillation to optimize absorption 2, 1.

For patients unable to swallow tablets, rivaroxaban may be crushed and mixed with applesauce, but the 15 mg and 20 mg doses must still be followed immediately by food 1.

Common Pitfalls to Avoid

• Do not overlap warfarin and rivaroxaban at therapeutic doses, as this significantly increases bleeding risk without improving efficacy 2
• Do not start rivaroxaban while INR is still ≥3.0, as warfarin's effect combined with rivaroxaban creates excessive anticoagulation 1
• Do not use bridging heparin during the warfarin-to-rivaroxaban transition, as it is unnecessary and increases bleeding risk 2
• Do not forget to account for renal function, as even mild-to-moderate renal impairment requires dose adjustment and closer monitoring 4
• Do not assume all DOACs transition the same way—dabigatran and edoxaban require parenteral bridging when switching from warfarin, but rivaroxaban and apixaban do not 2