What is the recommended dose and usage of Enoxaparin (low molecular weight heparin) for preventing and treating deep vein thrombosis and acute coronary syndrome?

Enoxaparin Dosing and Usage

For acute coronary syndromes, use enoxaparin 1 mg/kg subcutaneously every 12 hours as initial therapy, and for DVT prophylaxis in hospitalized patients, use 40 mg subcutaneously once daily. 1

Acute Coronary Syndromes

NSTE-ACS Initial Therapy

• Administer 1 mg/kg subcutaneously every 12 hours 1
• Reduce to 1 mg/kg subcutaneously every 24 hours if creatinine clearance <30 mL/min 1
• Do not switch between enoxaparin and unfractionated heparin due to increased bleeding risk 1

STEMI with Fibrinolytic Therapy

Age-based dosing is critical to minimize intracranial hemorrhage risk:

• Age <75 years: 30 mg IV bolus, followed 15 minutes later by 1 mg/kg subcutaneously every 12 hours (maximum 100 mg for first 2 doses) 1
• Age ≥75 years: No IV bolus, give 0.75 mg/kg subcutaneously every 12 hours (maximum 75 mg for first 2 doses) 1
• All ages with CrCl <30 mL/min: 1 mg/kg subcutaneously every 24 hours regardless of age 1

The age-based dosing reflects evidence from large trials showing increased intracranial hemorrhage in elderly patients receiving standard dosing. 1

PCI Support

• If last subcutaneous dose was 8-12 hours prior: Give 0.3 mg IV 1
• If last dose was within 8 hours: No additional enoxaparin needed 1
• If only one subcutaneous dose given: Give 0.3 mg IV 1
• No prior anticoagulation: Give 0.5-0.75 mg/kg IV bolus 1

Deep Vein Thrombosis Prevention

Standard Prophylaxis

• Administer 40 mg subcutaneously once daily for moderate-risk hospitalized medical patients 2, 3
• Continue for the length of hospital stay or until fully ambulatory 2
• For surgical patients, continue at least 7-10 days 2

High-Risk Surgical Patients (Hip/Knee Replacement)

Two equally effective regimens: 3

• 40 mg subcutaneously once daily starting preoperatively, OR
• 30 mg subcutaneously every 12 hours starting postoperatively

Extended prophylaxis up to 35 days is recommended for hip arthroplasty patients 4

DVT/PE Treatment

Therapeutic Anticoagulation

Two FDA-approved regimens with equivalent efficacy: 1, 2

• 1 mg/kg subcutaneously every 12 hours (preferred for large PE or unstable patients), OR
• 1.5 mg/kg subcutaneously once daily (preferred for outpatient DVT treatment)

The once-daily regimen offers improved compliance and reduced healthcare costs while maintaining equivalent efficacy and safety. 5, 6

Cancer Patients

• Use 1 mg/kg twice daily or 1.5 mg/kg once daily 1
• Continue for at least 3-6 months 1, 2
• Consider dose reduction after the first month for long-term therapy 2

Critical Dose Adjustments

Renal Impairment (CrCl <30 mL/min)

Enoxaparin clearance is reduced by 44% in severe renal impairment: 2, 3

• Prophylactic dose: Reduce to 30 mg subcutaneously once daily 1, 2, 3
• Therapeutic dose: Reduce to 1 mg/kg subcutaneously once daily 1
• Consider anti-Xa monitoring for prolonged therapy (target 0.5-1.5 IU/mL) 2

Obesity (BMI >30 kg/m² or weight >150 kg)

Standard fixed dosing may be inadequate: 2, 3

• Prophylaxis: Consider 40 mg subcutaneously every 12 hours or 0.5 mg/kg every 12 hours 2, 3
• Therapeutic: Use weight-based dosing; for BMI ≥40 kg/m², use 0.8 mg/kg every 12 hours 2
• Consider anti-Xa monitoring to ensure adequate anticoagulation 3

Pregnancy

• For class III obesity: Use 0.5 mg/kg subcutaneously every 12 hours 2
• Anti-Xa monitoring recommended for therapeutic doses 3

Monitoring Requirements

Routine Monitoring Not Required

Most patients do not need coagulation monitoring due to predictable pharmacokinetics 5, 6

Anti-Xa Monitoring Indicated For:

• Pregnant patients on therapeutic doses 3
• Severe renal impairment on prolonged therapy 2
• Morbidly obese patients 3
• Target levels: 0.6-1.0 IU/mL for twice-daily dosing; 1.0-1.5 IU/mL for once-daily dosing 2, 3
• Timing: Measure 4-6 hours after dosing, after 3-4 doses administered 2, 3

Platelet Monitoring

• Check platelet count every 2-3 days from day 4 to day 14 2, 3
• Risk of heparin-induced thrombocytopenia is significantly lower than unfractionated heparin 1, 5

Critical Timing Considerations

Neuraxial Anesthesia

Spinal hematoma risk requires strict timing protocols: 2, 4

• Prophylactic doses: May start 4 hours after catheter removal, but not earlier than 12 hours after block performed 2
• Therapeutic doses: Hold for 24 hours before catheter manipulation; resume no earlier than 2 hours after catheter removal 4

Surgical Timing

• Start 2-4 hours preoperatively or 10-12 hours preoperatively for surgical patients 2
• For hip arthroplasty: Initiate 12 hours before or after surgery 4

Common Pitfalls to Avoid

1. Switching anticoagulants: Never switch between enoxaparin and unfractionated heparin—this significantly increases bleeding risk 1, 2

2. Ignoring renal function: Failure to adjust dose in renal impairment leads to drug accumulation and major bleeding 2, 3

3. Inadequate dosing in obesity: Standard fixed doses may provide subtherapeutic anticoagulation in patients >150 kg 2, 4

4. Neuraxial anesthesia timing errors: Improper timing with spinal/epidural procedures can cause devastating spinal hematomas 2

5. Age-related dosing in STEMI: Using standard dosing in patients ≥75 years increases intracranial hemorrhage risk 1

Advantages Over Unfractionated Heparin

Enoxaparin offers multiple clinical advantages: 5, 6

• Better bioavailability and longer half-life
• Predictable anticoagulation without monitoring
• Once or twice-daily subcutaneous dosing
• Outpatient self-administration capability
• Lower risk of heparin-induced thrombocytopenia
• Superior outcomes in acute coronary syndromes compared to unfractionated heparin 6