Transitioning from Warfarin to Lovenox (Enoxaparin)
Stop warfarin and start therapeutic-dose enoxaparin (1 mg/kg subcutaneously every 12 hours) immediately without waiting for INR normalization, as both agents can be safely overlapped for anticoagulation continuity. 1
Immediate Transition Protocol
Begin enoxaparin at full therapeutic dose (1 mg/kg subcutaneously every 12 hours) on the same day warfarin is discontinued. 1
No bridging period or INR monitoring is required when transitioning from warfarin to enoxaparin, as enoxaparin provides immediate anticoagulation while warfarin's effect wanes over 4-5 days. 1
The INR will naturally decline over the subsequent days as warfarin's effect dissipates, but therapeutic anticoagulation is maintained by the enoxaparin throughout this period. 1
Dosing Adjustments for Renal Impairment
For patients with creatinine clearance <30 mL/min, reduce enoxaparin to 1 mg/kg subcutaneously once daily instead of twice daily. 1
Enoxaparin is retained in patients with renal impairment, requiring dose adjustment to prevent accumulation and bleeding risk. 1
For patients with end-stage renal disease or on hemodialysis, consider using unfractionated heparin instead of enoxaparin, as UFH does not require renal dose adjustment and is not retained in renal failure. 1, 2
Monitor renal function before initiating enoxaparin and reassess periodically, especially in patients with compromised kidney function. 2, 3
Special Considerations for High Thrombotic Risk
For patients with mechanical prosthetic heart valves, enoxaparin is NOT recommended for thromboprophylaxis per FDA strengthened warnings, and warfarin should be continued or unfractionated heparin used if parenteral anticoagulation is required. 1
For patients with atrial fibrillation and high CHA₂DS₂-VASc scores (≥2), if transitioning off warfarin permanently, direct oral anticoagulants (DOACs) are preferred over long-term enoxaparin due to superior safety profiles and equivalent efficacy, unless contraindicated by severe renal impairment. 2, 3
In cancer patients requiring long-term anticoagulation for VTE, continuing LMWH (enoxaparin) is preferred over warfarin as it prevents more recurrences without increasing serious bleeding risk. 4
Monitoring and Safety
No routine coagulation monitoring is required for enoxaparin at standard therapeutic doses, unlike warfarin which requires INR monitoring. 4
Watch for bleeding complications, which occur at similar rates with enoxaparin and warfarin (approximately 1-2% major bleeding risk). 1, 4
Never switch patients back and forth between enoxaparin and unfractionated heparin, as this increases bleeding risk significantly. 1
Duration of Enoxaparin Therapy
For acute DVT or PE treatment, continue enoxaparin for a minimum of 5 days if transitioning back to oral anticoagulation. 1
For perioperative bridging in high thrombotic risk patients (mechanical valves, recent VTE), therapeutic-dose enoxaparin (1 mg/kg every 12 hours or 100 U/kg every 12 hours) should be used until 24 hours before surgery, then resumed 12-24 hours postoperatively once hemostasis is achieved. 1