ENOXAPARIN SODIUM (PRESERVATIVE FREE)
Clinical safety rating: safe
Other drugs that affect hemostasis increase bleeding risk Can cause spinal or epidural hematoma leading to paralysis with neuraxial anesthesia.
Enoxaparin binds to antithrombin III (ATIII), accelerating its inhibition of coagulation factors Xa and IIa (thrombin). Its anti-factor Xa to anti-factor IIa activity ratio is approximately 3.6:1.
| Metabolism | Enoxaparin is primarily metabolized in the liver via desulfation and depolymerization, with some renal clearance. It does not rely on cytochrome P450 enzymes. |
| Excretion | Renal excretion of anti-Factor Xa activity accounts for approximately 40% of total clearance; a small fraction undergoes biliary/fecal elimination (<10%). |
| Half-life | Terminal elimination half-life is 4.5 hours after subcutaneous administration based on anti-Factor Xa activity; prolonged to 6-7 hours in renal impairment (CrCl <30 mL/min). |
| Protein binding | Approximately 92-95% bound to antithrombin III (ATIII) and other plasma proteins. |
| Volume of Distribution | 0.10-0.13 L/kg; confined primarily to intravascular space, indicating limited extravascular distribution. |
| Bioavailability | Subcutaneous: Approximately 92-100% absorbed; intravenous administration yields 100% bioavailability. |
| Onset of Action | Subcutaneous: Onset of anti-Factor Xa activity occurs within 1-2 hours; peak effect at 3-5 hours. |
| Duration of Action | Subcutaneous: Anti-Factor Xa activity persists for approximately 12-24 hours; once-daily dosing maintains therapeutic levels. |
1 mg/kg subcutaneously every 12 hours or 1.5 mg/kg subcutaneously once daily. For prophylaxis: 40 mg subcutaneously once daily or 30 mg subcutaneously every 12 hours.
| Dosage form | INJECTABLE |
| Renal impairment | For CrCl <30 mL/min: reduce dose to 1 mg/kg subcutaneously once daily for treatment; for prophylaxis: 30 mg subcutaneously once daily. Not recommended if CrCl <15 mL/min. |
| Liver impairment | No specific dose adjustment guidelines for hepatic impairment; use with caution in severe hepatic impairment due to increased bleeding risk. |
| Pediatric use | Dose based on age: neonates and infants <2 months: 1.5 mg/kg subcutaneously every 12 hours; children ≥2 months: 1 mg/kg subcutaneously every 12 hours. For prophylaxis: 0.5 mg/kg subcutaneously every 12 hours. |
| Geriatric use | Increased risk of bleeding, especially in elderly ≥75 years; consider dose reduction and monitor renal function and anti-Xa levels. For treatment in elderly ≥75 years: 1 mg/kg subcutaneously every 12 hours; no routine dose reduction but caution advised. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other drugs that affect hemostasis increase bleeding risk Can cause spinal or epidural hematoma leading to paralysis with neuraxial anesthesia.
| FDA category | Human |
| Breastfeeding | Enoxaparin is excreted into breast milk in negligible amounts. The milk-to-plasma ratio is approximately 0.04. It is considered compatible with breastfeeding due to poor oral bioavailability in the infant. No adverse effects reported. |
| Teratogenic Risk | Enoxaparin does not cross the placenta and is considered low risk for teratogenicity. No increased risk of congenital anomalies has been reported in humans. First trimester: no known teratogenic effects. Second trimester: no known fetal harm. Third trimester: risk of maternal hemorrhage, which may indirectly affect fetus; use with caution. |
■ FDA Black Box Warning
Spinal/epidural hematomas may occur in patients receiving enoxaparin who are undergoing neuraxial anesthesia or spinal puncture, resulting in long-term or permanent paralysis. Risk is increased by use of indwelling epidural catheters, concomitant use of other anticoagulants, or history of spinal surgery/deformity. Monitor for signs of neurological impairment and manage emergently.
| Common Effects | bleeding |
| Serious Effects |
["Active major bleeding","History of immune-mediated heparin-induced thrombocytopenia (HIT) within 100 days","Known hypersensitivity to enoxaparin, heparin, or pork products","Concomitant use with other anticoagulants (except under close monitoring)"]
| Precautions | ["Risk of spinal/epidural hematoma with neuraxial procedures","Increased bleeding risk, especially in patients with renal impairment, thrombocytopenia, or concurrent use of anticoagulants/antiplatelets","Heparin-induced thrombocytopenia (HIT) possible; monitor platelet counts","Use with caution in patients with bleeding disorders, uncontrolled hypertension, or recent surgery","Not interchangeable with other heparins (unit-for-unit)"] |
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| Fetal Monitoring | Monitor complete blood counts, platelet counts (risk of heparin-induced thrombocytopenia), anti-Xa levels if needed (target 0.5-1.0 U/mL for therapeutic dosing). Fetal monitoring: ultrasound for growth and well-being if indicated by maternal condition. Monitor for signs of bleeding: hematuria, ecchymosis, epistaxis, bleeding from puncture sites. |
| Fertility Effects | No known adverse effects on fertility in humans. Animal studies have not demonstrated impaired fertility. Enoxaparin does not affect sperm parameters or ovulation. No expected impact on conception rates. |