What is the recommended dose of Enoxaparin (Low Molecular Weight Heparin) for patients with Non-ST-Elevation Myocardial Infarction (NSTEMI) and impaired renal function?

Enoxaparin Dosing for NSTEMI Patients with Impaired Renal Function

For NSTEMI patients with impaired renal function (creatinine clearance <30 mL/min), enoxaparin should be given at a reduced dose of 1 mg/kg subcutaneously once daily. 1

Dosing Algorithm Based on Renal Function

Severe Renal Impairment (CrCl <30 mL/min):

• Dose: 1 mg/kg SC once daily 1
• Alternative option: Consider unfractionated heparin (UFH) instead 1

Moderate Renal Impairment (CrCl 30-50 mL/min):

• Standard dosing may lead to increased bleeding risk 2
• Consider dose adjustment:
  • First dose: 1 mg/kg SC
  • Subsequent doses: 0.8 mg/kg SC every 12 hours 3

Normal Renal Function (CrCl >50 mL/min):

• Standard dose: 1 mg/kg SC every 12 hours 1
• An initial IV loading dose of 30 mg may be used in selected patients 1

Clinical Considerations and Monitoring

Bleeding Risk

• Patients with renal impairment have significantly higher bleeding risk with standard enoxaparin dosing
• One study showed 4.7 times higher odds of major bleeding in patients with moderate renal impairment compared to those with normal renal function 2
• Elderly patients (>75 years) have additional bleeding risk and may require further dose adjustment 1

Anti-Xa Monitoring

• Consider monitoring anti-Xa levels in patients with severe renal impairment 1
• Target range for twice-daily dosing: 0.6-1.0 anti-Xa units/mL 1
• Target range for once-daily dosing: 1.0 anti-Xa units/mL 1

Treatment Duration

• Continue for the duration of hospitalization or until PCI is performed 1

Special Populations

Elderly Patients (≥75 years):

• Higher bleeding risk
• For STEMI patients ≥75 years: 0.75 mg/kg SC every 12 hours without initial IV bolus 1, 4
• For elderly NSTEMI patients with renal impairment: consider further dose reduction or UFH

Patients Undergoing PCI:

• For patients with NSTEMI managed with a planned invasive approach, either enoxaparin or UFH are reasonable choices 1
• Do not switch between enoxaparin and UFH due to increased bleeding risk 1

Important Caveats

• Avoid switching between enoxaparin and UFH due to increased bleeding risk 1
• In patients with both renal impairment and high bleeding risk, consider bivalirudin or fondaparinux as alternatives 1
• Renal function is the main factor affecting enoxaparin pharmacokinetics 5
• Enoxaparin clearance decreases by approximately 31% in moderate renal impairment and 44% in severe renal impairment 3
• Women may have slower clearance of enoxaparin than men with similar creatinine levels 5

Remember that proper dose adjustment in renal impairment is critical to balance the risk of thrombotic events against the increased risk of bleeding complications.