Enoxaparin (Lovenox) | Medication Reference

Bedside Snapshot

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

Brand & Generic Names

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

Medication Class

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

Pharmacology

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)

Indications

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)

Dosing & Administration

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):

Indication / Scenario	Typical Dose	Route / Frequency	Notes
VTE prophylaxis – general medical/surgical	40 mg	SC once daily	Standard adult dose with normal renal function
VTE prophylaxis – orthopedic/trauma (common)	30 mg	SC q12h	Many trauma/ortho protocols; adjust for renal function and bleeding risk
VTE prophylaxis – CrCl <30 mL/min	30 mg	SC once daily	Alternatively consider UFH, especially in significant renal failure
Treatment of DVT/PE (standard)	1 mg/kg	SC q12h	Weight-based dose using actual body weight; cap doses per local policy if extreme weight
Treatment of DVT/PE – once-daily regimen	1.5 mg/kg	SC once daily	Not used in all centers; avoid in obesity and high-risk PE
Treatment of DVT/PE – CrCl <30 mL/min	1 mg/kg	SC once daily	Use caution; anti-Xa monitoring or UFH often preferred in significant renal failure
ACS – NSTEMI/UA	1 mg/kg	SC q12h	With aspirin and other ACS therapy; CrCl <30 mL/min: 1 mg/kg SC q24h
ACS – STEMI (example adult regimen)	30 mg IV bolus then 1 mg/kg SC	SC q12h	Omit IV bolus and reduce dose in older patients or CrCl <30 mL/min; follow cardiology guidelines

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

Contraindications

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

Boxed Warning: Risk of spinal/epidural hematoma with neuraxial anesthesia, potentially causing permanent paralysis. Follow timing guidelines carefully. In CrCl <30 mL/min, UFH is often a better choice because it is not renally cleared and is fully reversible with protamine.

Adverse Effects

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)

Special Populations

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

Monitoring

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

Clinical Pearls

Easier Than UFH: For many stable patients, enoxaparin is easier and safer to manage than UFH drips: fixed weight-based dosing, fewer lab draws, and predictable effect.

Renal Impairment: In CrCl <30 mL/min or rapidly changing renal function, UFH is often a better choice because it is not renally cleared and is fully reversible with protamine.

Procedural Timing: When starting high-dose prophylaxis or therapeutic LMWH around procedures, coordinate timing carefully with surgeons/anesthesiology, especially for neuraxial blocks.

HIT Awareness: Do not forget that patients may have received heparin or LMWH recently elsewhere; a falling platelet count or new thrombosis should prompt evaluation for HIT.

Injection Technique: Teach patients and staff proper SC injection technique: rotate sites, avoid rubbing after injection, and use abdomen or thigh per policy to minimize local reactions.

References

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.