Enoxaparin (Lovenox)

• Core Use: LMWH used for VTE prophylaxis, VTE/PE treatment, and ACS. More predictable pharmacokinetics than UFH with higher anti-Xa:anti-IIa activity; usually does not require routine lab monitoring
• Prophylaxis Dosing: Adults: 40 mg SC once daily (general medical/surgical); 30 mg SC q12h (many orthopedic/trauma patients)
• Treatment Dosing: Adults: 1 mg/kg SC q12h or 1.5 mg/kg SC q24h for VTE/PE; 1 mg/kg SC q12h for ACS
• Renal Adjustment: In CrCl <30 mL/min, common regimen is 1 mg/kg SC q24h with caution or consider UFH instead (renally cleared)
• Key Dangers: Major bleeding, HIT (less common than UFH but still possible), spinal/epidural hematoma with neuraxial anesthesia (boxed warning), accumulation in renal failure

• Generic Name: Enoxaparin sodium
• Brand Names: Lovenox, various generics

Low molecular weight heparin (LMWH); indirect factor Xa inhibitor (antithrombin-mediated)

Mechanism of Action:

• Low molecular weight heparin that binds to antithrombin (AT) and enhances AT-mediated inhibition of factor Xa and, to a lesser extent, factor IIa (thrombin)
• Compared with unfractionated heparin (UFH), enoxaparin has a higher anti-Xa:anti-IIa activity ratio, leading to more selective factor Xa inhibition and more predictable anticoagulant response
• Does not directly break down clots; instead, it prevents further clot propagation and new clot formation while endogenous fibrinolytic systems work

Pharmacokinetics:

• Route: Administered subcutaneously; occasionally as IV bolus in ACS/STEMI regimens
• Bioavailability: About 90% after SC injection
• Onset: Peak anti-Xa activity at 3–5 hours after SC dose
• Half-life: About 4–7 hours after SC dose in normal renal function; prolonged in renal impairment
• Elimination: Primarily renal; accumulation occurs in CrCl <30 mL/min and in the elderly
• Key Advantage: More predictable dose–response than UFH, allowing fixed weight-based dosing with limited need for routine monitoring; anti-Xa levels are used in select populations (pregnancy, obesity, renal failure, extremes of weight)

• Prophylaxis of deep vein thrombosis (DVT) in medical, surgical, and trauma patients at moderate to high VTE risk
• Treatment of acute DVT and PE, typically as bridge to oral anticoagulants (warfarin, DOACs) or as standalone in some outpatient regimens
• ACS: NSTEMI/unstable angina and STEMI, in combination with antiplatelet therapy and reperfusion strategies per cardiology guidelines
• Off-label: anticoagulation in certain pregnancy-associated VTE and high-risk thrombophilia patients (often hematology-directed)

Available Forms:

• Prefilled syringes for SC injection: 30 mg/0.3 mL, 40 mg/0.4 mL, 60 mg/0.6 mL, 80 mg/0.8 mL, 100 mg/mL, 120 mg/0.8 mL, 150 mg/1 mL (strengths vary by manufacturer)
• Multi-dose vials available in some settings (e.g., 100 mg/mL)
• Always double-check mg and mL to avoid dosing errors, especially in weight-based regimens

Dosing – Enoxaparin (Adult):

Therapeutic Drug Monitoring (Anti-Xa):

• Routine monitoring is not required for most patients on prophylactic or therapeutic enoxaparin
• Consider anti-Xa monitoring in: pregnancy, morbid obesity, very low body weight, renal impairment, and high bleed/thrombosis risk where drug exposure is uncertain
• Typical therapeutic peak anti-Xa range (q12h dosing): about 0.6–1.0 IU/mL, measured ~4 hours after SC dose (institution-specific)
• Prophylactic peak anti-Xa goals are lower (roughly 0.2–0.5 IU/mL), depending on protocol

Absolute Contraindications:

• Active major bleeding or conditions with high risk of uncontrolled hemorrhage (e.g., ongoing GI bleed, intracranial hemorrhage)
• History of immune-mediated heparin-induced thrombocytopenia (HIT) with heparin or LMWH, or presence of HIT antibodies; avoid all heparin products unless cleared by hematology
• Severe uncontrolled hypertension when full-dose anticoagulation is not absolutely necessary
• Hypersensitivity to enoxaparin, heparin, or pork products

Major Precautions:

• Renal impairment (CrCl <30 mL/min): increased enoxaparin exposure and bleeding risk; dose reduction, anti-Xa monitoring, or switching to UFH may be appropriate
• Spinal/epidural anesthesia or puncture: risk of spinal/epidural hematoma and permanent paralysis; follow timing guidelines for neuraxial procedures and LMWH dosing
• Recent surgery or trauma, especially neurosurgical, ocular, or spinal procedures: heightened bleeding risk
• Low body weight (<50 kg) or high body weight (morbid obesity): unpredictable exposure; consider monitoring and careful dosing
• Concomitant use of other anticoagulants, antiplatelets, NSAIDs, or thrombolytics increases bleeding risk; reassess risk–benefit frequently
• Pregnancy and postpartum: often preferred over warfarin/DOACs for VTE, but dosing and monitoring should be under obstetric/hematology guidance

Common:

• Minor bleeding and bruising at injection sites
• Mild thrombocytopenia (non-immune, early-onset)
• Injection-site pain, erythema, or hematoma

Serious:

• Major bleeding (GI, intracranial, retroperitoneal, intra-abdominal, hemopericardium)
• Immune-mediated HIT with thrombosis (rare but serious); suspect with platelet fall >50% or new thrombosis 5–14 days after starting heparin/LMWH
• Spinal/epidural hematoma with neuraxial anesthesia, potentially causing permanent paralysis
• Hyperkalemia due to heparin-induced hypoaldosteronism (rare)
• Anaphylaxis or severe hypersensitivity reactions (rare)

Renal Impairment:

• CrCl ≥30 mL/min: Usually no dose adjustment required
• CrCl <30 mL/min: Reduce dose (e.g., 1 mg/kg SC q24h for treatment; 30 mg SC q24h for prophylaxis)
• Consider UFH as alternative in significant renal failure
• Anti-Xa monitoring may be helpful

Obesity:

• Use actual body weight for dosing
• Consider anti-Xa monitoring to ensure therapeutic levels
• Some protocols cap maximum dose per injection

Low Body Weight (<50 kg):

• Increased bleeding risk with standard weight-based dosing
• Consider anti-Xa monitoring
• Use caution and monitor closely for bleeding

Pregnancy & Lactation:

• Preferred over warfarin/DOACs for VTE in pregnancy (does not cross placenta)
• Dosing and monitoring should be under obstetric/hematology guidance
• Anti-Xa monitoring often recommended
• Adjust dose as pregnancy progresses (changing body weight)

Elderly Patients:

• Often have reduced renal function; assess CrCl
• Higher bleeding risk; monitor closely
• Consider dose adjustment based on renal function

Clinical Monitoring:

• Clinical monitoring for bleeding: melena, hematemesis, hematuria, flank/abdominal pain, neurologic changes
• Monitor for signs of HIT: platelet drop >50%, new thrombosis despite anticoagulation

Laboratory Monitoring:

• Baseline CBC (Hgb/Hct, platelets), PT/INR, creatinine before starting therapeutic LMWH when possible
• Periodic CBC to assess for occult blood loss (falling hemoglobin) and to screen for thrombocytopenia/HIT, especially between days 4–14 of therapy
• Renal function (SCr, CrCl) to guide dose adjustments and to evaluate for accumulation
• Anti-Xa levels in selected patients (pregnant, obese, renal failure, or high-risk) per protocol

• 1. Lexicomp. (2024). Enoxaparin: Drug information. Wolters Kluwer.
• 2. Kearon, C., Akl, E. A., Ornelas, J., et al. (2016). Antithrombotic therapy for VTE disease: CHEST guideline and expert panel report. Chest, 149(2), 315–352.
• 3. Linkins, L.-A., Dans, A. L., Moores, L. K., et al. (2012). Treatment and prevention of heparin-induced thrombocytopenia. Chest, 141(2 Suppl), e495S–e530S.
• 4. Lovenox (enoxaparin) [Package insert]. (2023). Sanofi-Aventis.
• 5. Garcia, D. A., Baglin, T. P., Weitz, J. I., & Samama, M. M. (2012). Parenteral anticoagulants: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed. Chest, 141(2 Suppl), e24S–e43S.