When should Lovenox (enoxaparin) be initiated in a patient on a 4-day warfarin hold?

Timing of Lovenox During a 4-Day Warfarin Hold

Lovenox (enoxaparin) should be initiated 24 hours after the last warfarin dose when implementing a 4-day warfarin hold to ensure adequate anticoagulation coverage without excessive bleeding risk. 1

Rationale for Timing

When warfarin therapy needs to be interrupted for procedures, bridging anticoagulation with Lovenox requires careful timing to:

1. Prevent thrombotic events during the period of subtherapeutic INR
2. Avoid excessive anticoagulation that could increase bleeding risk
3. Ensure appropriate coverage throughout the perioperative period

Dosing Protocol for Warfarin Hold

Day 1:

• Stop warfarin
• Wait 24 hours after last warfarin dose
• Start Lovenox at therapeutic dose:
  • 1 mg/kg twice daily OR
  • 1.5 mg/kg once daily 1

Days 2-3:

• Continue Lovenox at therapeutic dose
• Monitor for signs of bleeding

Day 4:

• Last dose of Lovenox should be administered:
  • For twice-daily regimen: Give last dose 24 hours before procedure
  • For once-daily regimen: Give last dose 24 hours before procedure 1

Post-procedure:

• Restart Lovenox 6-8 hours after procedure if hemostasis is adequate 1
• Resume warfarin when safe (typically evening of procedure day)
• Continue Lovenox until INR reaches ≥2.0 for at least 24 hours 1

Dose Selection Considerations

The appropriate Lovenox dose depends on the patient's thrombotic risk:

• High thrombotic risk (recent VTE within 3 months, mechanical heart valve): Use full therapeutic dose

  • 1 mg/kg twice daily OR
  • 1.5 mg/kg once daily 1

• Moderate thrombotic risk: Use prophylactic or intermediate dose

  • Prophylactic: 40 mg once daily
  • Intermediate: 0.5 mg/kg twice daily 1

Important Precautions

• Renal function: Reduce dose in severe renal impairment (CrCl <30 mL/min) or avoid Lovenox altogether 2
• Weight extremes: Consider anti-Xa monitoring in patients >120 kg 1
• Drug interactions: Avoid concurrent use of other anticoagulants or antiplatelet agents if possible 1
• Neuraxial procedures: Special timing considerations apply for spinal/epidural procedures 1

Monitoring

• Routine monitoring of anti-Xa levels is not required for most patients
• Consider monitoring in patients with renal impairment, extreme weight, or prolonged therapy 1

Potential Pitfalls

1. Excessive anticoagulation: Never administer UFH bolus while patient still has therapeutic enoxaparin levels (can cause dangerous over-anticoagulation) 3

2. Inadequate anticoagulation: Critically ill patients may have lower anti-Xa levels with standard subcutaneous dosing 4

3. Delayed warfarin restart: Remember that warfarin requires 5-7 days of overlap with Lovenox to achieve therapeutic anticoagulation 5

4. Rebound hypercoagulability: Abrupt discontinuation of anticoagulation without bridging may increase thrombotic risk in high-risk patients 1

By following this protocol, you can ensure appropriate anticoagulation coverage during a warfarin hold while minimizing bleeding risk.