What is the recommended dose of Lovenox (enoxaparin) for bridging Coumadin (warfarin) levels?

Recommended Lovenox Dosing for Bridging Coumadin Therapy

For patients requiring bridging therapy when transitioning to or from Coumadin (warfarin), therapeutic-dose enoxaparin (Lovenox) should be administered at 1 mg/kg subcutaneously twice daily or 1.5 mg/kg once daily until the INR reaches therapeutic range. 1

Dosing Protocol for Bridging Therapy

Pre-procedural Bridging (when stopping warfarin):

1. Stop warfarin: 5-6 days before procedure
2. Start LMWH: Begin enoxaparin 3 days after stopping warfarin
   • Standard dosing: 1 mg/kg twice daily or 1.5 mg/kg once daily
3. Last pre-procedure dose: Administer the last pre-procedure dose 24 hours before surgery at half the total daily dose
4. Check INR: Proceed with surgery if INR ≤ 1.5

Post-procedural Bridging (when restarting warfarin):

• Low bleeding risk procedures:

  • Resume therapeutic-dose enoxaparin within 24 hours
  • Restart warfarin on the evening of or morning after procedure
  • Continue enoxaparin until INR > 1.9

• High bleeding risk procedures:

  • Wait 48-72 hours before resuming full-dose enoxaparin
  • Consider intermediate dose (enoxaparin 40 mg twice daily) initially
  • Resume warfarin therapy on day 1 post-procedure
  • Continue enoxaparin until INR > 1.9

Special Population Considerations

Renal Impairment:

• Severe renal insufficiency (CrCl < 30 mL/min):
  • Reduce enoxaparin to 1 mg/kg once daily 1
  • Consider using unfractionated heparin instead 1
  • Monitor anti-Xa levels if using enoxaparin

Obesity:

• Weight 90-150 kg:
  • Use total body weight for dosing calculations 2
• Weight > 150 kg or BMI ≥ 40 kg/m²:
  • Consider reduced dosing (0.75-0.85 mg/kg) as this may increase percentage of patients achieving therapeutic anti-Xa levels 3
  • Monitor anti-Xa levels
  • Alternative: unfractionated heparin 2

Common Pitfalls and Caveats

1. Timing errors: Administering LMWH too close to procedure increases bleeding risk. Ensure last pre-procedure dose is given at least 24 hours before surgery 1

2. Dose calculation errors: Calculate dose based on actual body weight, not ideal body weight, for most patients (except in extreme obesity where adjustments may be needed)

3. Failure to adjust for renal function: Always check creatinine clearance before initiating bridging therapy

4. Inadequate monitoring: Check INR before procedure and regularly during post-procedure bridging

5. Premature discontinuation: Continue bridging until INR is consistently therapeutic (> 1.9) for at least 24 hours 1

6. Overlapping full-dose anticoagulants: Never administer full-dose LMWH and warfarin simultaneously once INR is therapeutic, as this significantly increases bleeding risk

7. Switching between agents: Patients initially treated with enoxaparin should not be switched to unfractionated heparin and vice versa due to increased bleeding risk 1

The evidence strongly supports using therapeutic-dose enoxaparin for bridging therapy, with appropriate dose adjustments for special populations and careful timing around procedures to minimize both thrombotic and bleeding complications.