HEPARIN SODIUM 1,000 UNITS IN SODIUM CHLORIDE 0.9% IN PLASTIC CONTAINER
Clinical safety rating: safe
No significant drug interactions Can cause hypernatremia and fluid overload.
Heparin binds to antithrombin III, causing a conformational change that accelerates the inactivation of thrombin (factor IIa) and activated factor X (factor Xa), thereby inhibiting coagulation.
| Metabolism | Heparin is primarily cleared via the reticuloendothelial system and undergoes desulfation and depolymerization. A portion is excreted unchanged in urine. |
| Excretion | Renal: Heparin is primarily cleared by the reticuloendothelial system and the liver via desulfation and depolymerization, with metabolites excreted in urine. Only about 50% of an administered dose is excreted unchanged in urine at therapeutic doses; the remainder is metabolized. Biliary/fecal excretion is minimal. |
| Half-life | Terminal elimination half-life is dose-dependent: 0.5–1.5 hours after intravenous administration of 100 U/kg, increasing to 1.5–2.5 hours after 200 U/kg, and up to 3–6 hours after 400 U/kg. Clinically, the anticoagulant effect (aPTT) has a half-life of approximately 1–2 hours, and this is used for dosing adjustments. |
| Protein binding | Heparin binds extensively to various plasma proteins, including antithrombin III (high affinity), albumin, and other proteins. Overall protein binding is approximately 95%. |
| Volume of Distribution | 0.06–0.07 L/kg (low, as heparin is largely confined to the intravascular space). |
| Bioavailability | Subcutaneous: approximately 30–40% (low due to poor absorption and metabolism at injection site). Intravenous: 100%. |
| Onset of Action | Intravenous: immediate (within minutes). Subcutaneous: 1–2 hours (with a lag of 1 hour). |
| Duration of Action | Intravenous: 2–6 hours (dose-dependent; effect monitored via aPTT). Subcutaneous: 8–12 hours (requires twice-daily dosing for therapeutic anticoagulation). |
Adult: IV bolus 5,000 units followed by continuous IV infusion at 1,000 units/hour (25,000-40,000 units/24h) titrated to aPTT 1.5-2.5 times control. Subcutaneous: 5,000 units every 8-12 hours.
| Dosage form | INJECTABLE |
| Renal impairment | No specific GFR-based dose adjustment required; monitor aPTT. In severe renal impairment (CrCl <30 mL/min), reduce infusion rate by 20-50% and monitor anti-Xa levels. |
| Liver impairment | Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce dose by 25-50% with close aPTT monitoring. Child-Pugh Class C: Avoid or use with extreme caution; reduce dose by 50-75%. |
| Pediatric use | IV bolus: 50-100 units/kg, then continuous IV infusion: 15-25 units/kg/hour. Titrate to aPTT 60-85 seconds or anti-Xa 0.3-0.7 units/mL. |
| Geriatric use | Elderly patients may have reduced clearance; use lower initial infusion rates (e.g., 750 units/hour) and monitor aPTT frequently. Start with 50% of the usual bolus dose in patients >70 years. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions Can cause hypernatremia and fluid overload.
| FDA category | Animal |
| Breastfeeding | Heparin is not excreted into breast milk due to its high molecular weight and negative charge, making it compatible with breastfeeding. M/P ratio is not applicable as it is undetectable in milk. |
| Teratogenic Risk | Heparin is not known to cross the placenta due to its high molecular weight and negative charge, and is not associated with fetal teratogenicity. First trimester: No increased risk of major malformations. Second and third trimesters: No known teratogenic effects; use for treatment or prevention of thrombosis is considered safe. Risk of maternal hemorrhage and placental abruption exists with overdose. |
■ FDA Black Box Warning
Heparin is not intended for intramuscular use due to risk of hematoma. Monitor for signs of bleeding, especially in patients with risk factors. Epidural or spinal hematomas may occur with concurrent neuraxial anesthesia or spinal puncture, resulting in long-term or permanent paralysis.
| Common Effects | fluid replacement |
| Serious Effects |
["Active major bleeding (e.g., intracranial, gastrointestinal, retroperitoneal)","History of heparin-induced thrombocytopenia (HIT)","Severe thrombocytopenia (platelet count <100,000/µL)","Hypersensitivity to heparin or porcine products","Known coagulation disorders (e.g., hemophilia, von Willebrand disease)","Inability to perform appropriate coagulation monitoring (e.g., aPTT)"]
| Precautions | ["Risk of hemorrhage: monitor coagulation parameters (aPTT) and adjust dose accordingly.","Heparin-induced thrombocytopenia (HIT): monitor platelet counts; discontinue if HIT suspected.","Hyperkalemia: heparin suppresses aldosterone synthesis; monitor potassium in high-risk patients.","Osteoporosis with long-term use ( >3 months).","Use with caution in patients with severe hepatic or renal impairment, uncontrolled hypertension, or history of gastrointestinal ulcers."] |
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| Fetal Monitoring | Monitor maternal platelet counts (risk of heparin-induced thrombocytopenia, HIT), activated partial thromboplastin time (aPTT) to maintain therapeutic range (1.5-2.5 times control), signs of bleeding (ecchymosis, hematuria, gastrointestinal bleeding), and fetal surveillance (ultrasound for growth and placental assessment if used for antiphospholipid syndrome or thrombosis). |
| Fertility Effects | Heparin is not known to impair fertility. It is used in assisted reproductive technology for thromboprophylaxis without adverse effects on fertility outcomes. |