Can I give Pradaxa (dabigatran) to a patient with a history of atrial fibrillation, deep vein thrombosis, or pulmonary embolism who is currently on Warfarin (coumarin)?

Can You Give Pradaxa to a Patient Currently on Warfarin?

Yes, you can switch from warfarin to Pradaxa (dabigatran) in patients with atrial fibrillation, DVT, or PE, but only after confirming the patient does not have contraindications and following a specific transition protocol based on INR levels. 1, 2

Absolute Contraindications - Do NOT Switch If Present

Before considering the switch, you must exclude these patients:

• Mechanical heart valves - warfarin is definitively superior and required 1, 2, 3
• Moderate-to-severe mitral stenosis - warfarin remains mandatory 1, 2, 3
• Severe renal failure (CrCl <15 mL/min or dialysis) - dabigatran is contraindicated 1, 2
• Advanced liver disease with impaired baseline clotting function 1

Why Consider Switching: The Evidence

DOACs including dabigatran are now preferred over warfarin for eligible patients with nonvalvular atrial fibrillation because they provide superior outcomes: 1, 2

• 51% reduction in intracranial hemorrhage compared to warfarin 2, 3
• 19% reduction in stroke or systemic embolic events (RR 0.81) 2
• 10% reduction in all-cause mortality (HR 0.90) 2
• Dabigatran 150 mg twice daily showed 34% reduction in stroke/systemic embolism compared to warfarin (1.11% vs 1.71% per year, p<0.001) 1

Pre-Switch Assessment - Required Steps

Before switching, you must evaluate:

1. Renal function - Calculate creatinine clearance to determine eligibility and dosing 2, 4
2. Hepatic function - Advanced liver disease is a contraindication 2
3. Bleeding risk - Use HAS-BLED score to assess 2
4. Current INR control - Patients with excellent INR control (time in therapeutic range >70%) may have less to gain from switching 1

Dosing Based on Renal Function

Standard dose: 150 mg twice daily for CrCl >30 mL/min 1, 2

Reduced dose: 110 mg twice daily (not FDA-approved in US, but 75 mg twice daily is approved) for: 1, 2

• Age ≥80 years
• CrCl 30-49 mL/min
• High bleeding risk (HAS-BLED ≥3)
• Concomitant use of P-glycoprotein inhibitors

Note: The FDA-approved dose for CrCl 15-30 mL/min is 75 mg twice daily, though this was not studied in RE-LY 1

Transition Protocol from Warfarin to Dabigatran

Stop warfarin and wait for INR to drop: 2

• If INR <2.0: Start dabigatran immediately
• If INR 2.0-3.0: Wait until INR <2.0, then start dabigatran
• If INR >3.0: Recheck INR daily until <2.0, then start dabigatran

Do not overlap warfarin and dabigatran - this increases bleeding risk unnecessarily.

Critical Monitoring After Switch

Renal function monitoring is mandatory: 2, 4

• Assess at minimum annually
• More frequently if CrCl 30-50 mL/min or age >75 years
• Renal impairment significantly increases bleeding risk with dabigatran

No routine coagulation monitoring required - this is a key advantage over warfarin 2, 5, 6

Periodic hepatic function assessment recommended 2

Important Safety Considerations

No specific antidote was available at the time of initial approval (though idarucizumab is now available), with a half-life of 12-17 hours 1, 4

Higher dyspepsia rate: 11.8% with dabigatran vs 5.8% with warfarin - counsel patients about this common side effect 1

Twice-daily dosing required - patient compliance is critical as missed doses increase thromboembolism risk due to short half-life 1

Slightly higher myocardial infarction signal (0.82% vs 0.64% with warfarin), though not statistically significant 1

When NOT to Switch

Patients already on warfarin with excellent INR control (time in therapeutic range >70%) may have minimal benefit from switching, as the RE-LY trial showed warfarin patients had INR in range only 64.4% of the time 1

Consider keeping stable patients on warfarin if they have: 1

• Consistently therapeutic INRs
• Good medication adherence
• Access to quality anticoagulation monitoring
• No history of intracranial bleeding
• Patient preference for warfarin