Why would a patient be switched from Lovenox (enoxaparin) to Fondaparinux?

Reasons for Switching from Lovenox (Enoxaparin) to Fondaparinux

The primary reason to switch from Lovenox (enoxaparin) to fondaparinux is increased bleeding risk, particularly in patients with non-ST-elevation acute coronary syndromes (NSTE-ACS), as fondaparinux demonstrates a significantly better safety profile with reduced bleeding events while maintaining similar efficacy in preventing ischemic events. 1

Main Indications for Switching

Bleeding Risk Considerations

• Fondaparinux is preferred in patients with NSTE-ACS who have an increased bleeding risk, as it shows substantially lower rates of major bleeding compared to enoxaparin (2.2% vs 4.1%) 1
• For in-hospital patients with NSTEMI and increased bleeding risk, where anticoagulant therapy is not contraindicated, fondaparinux is considered a reasonable choice (Class IIa, LOE B) 2
• Recent multicenter registry data confirms fondaparinux provides a favorable net clinical benefit compared to enoxaparin in contemporary management of NSTE-ACS, primarily driven by bleeding reduction 3

Specific Clinical Scenarios

• Fondaparinux may be considered in the hospital for patients treated specifically with non-fibrin-specific thrombolytics (e.g., streptokinase), provided the creatinine is <3 mg/dL (Class IIb, LOE B) 2
• In patients with acute pulmonary embolism (PE), guidelines suggest LMWH or fondaparinux over IV unfractionated heparin (UFH) and over SC UFH 2
• Fondaparinux may be used as an alternative to UFH in patients with STEMI undergoing contemporary PCI, though there is an increased risk of catheter thrombi with fondaparinux alone 2

Heparin-Induced Thrombocytopenia (HIT)

• A major reason for switching to fondaparinux is suspected or confirmed heparin-induced thrombocytopenia (HIT), as fondaparinux has no cross-reactivity with anti-PF4 antibodies 2
• Registry data shows that 94% of patients receiving fondaparinux for prophylaxis had documentation of HIT 4
• Fondaparinux has been successfully used in HIT patients with complete platelet recovery 5

Important Considerations When Switching

Cautions and Contraindications

• Patients initially treated with enoxaparin should not be switched to UFH and vice versa because of increased risk of bleeding (Class III, LOE C) 2
• Fondaparinux is eliminated exclusively by the kidney and should not be used in cases of severe renal failure 2
• Dose adjustment is necessary for fondaparinux in patients with renal impairment 2

Dosing Considerations

• Fondaparinux is typically administered as 2.5 mg IV initially, followed by 2.5 mg SC once daily 2
• For HIT treatment, fondaparinux dosing should take into account patient weight (5 mg if <50 kg, 7.5 mg if 50-100 kg, and 10 mg if >100 kg), age, and kidney function 2

Procedural Considerations

• When using fondaparinux during PCI, co-administration of UFH (50 to 100 U/kg bolus) may be needed to avoid catheter thrombi 2
• The benefit of fondaparinux may be enhanced in patients undergoing transradial approach for coronary procedures 3

Potential Risks

• In thoracic surgery patients, switching from enoxaparin to fondaparinux for VTE prevention has been associated with increased risk of postoperative major bleeding 6
• Fondaparinux may be associated with increased risk of catheter thrombi when used alone during PCI 2

By carefully evaluating these factors, clinicians can make informed decisions about when switching from Lovenox to fondaparinux would provide the optimal balance of efficacy and safety for their patients.