HEPARIN SODIUM 12,500 UNITS IN SODIUM CHLORIDE 0.9%
Clinical safety rating: safe
No significant drug interactions Can cause hypernatremia and fluid overload.
Heparin binds to antithrombin III, potentiating its inhibition of factor Xa and thrombin, thereby preventing fibrin formation and thrombus propagation.
| Metabolism | Primarily metabolized in the liver by depolymerization and desulfation; also cleared by the reticuloendothelial system. Not metabolized by cytochrome P450 enzymes. |
| Excretion | Renal (primarily via reticuloendothelial system depolymerization; elimination of metabolites in urine; minimal unchanged drug excreted renally). Approximately 50% of a dose is eliminated renally as metabolites. |
| Half-life | Terminal elimination half-life is dose-dependent: for bolus doses of 100, 400, and 800 U/kg, half-lives are approximately 1, 2.5, and 5 hours, respectively. In severe renal impairment, half-life may be prolonged. |
| Protein binding | Highly bound to antithrombin III (ATIII), and also binds to various plasma proteins (e.g., platelet factor 4, histidine-rich glycoprotein, fibronectin, vitronectin); overall binding >85%. |
| Volume of Distribution | 0.05–0.07 L/kg (confined primarily to plasma volume; limited extravascular distribution due to high molecular weight and protein binding). |
| Bioavailability | Subcutaneous: approximately 20–30% (dose-dependent and variable; higher doses yield greater bioavailability). Intravenous: 100%. |
| Onset of Action | Intravenous (IV): immediate. Subcutaneous (SC): 20–30 minutes (peak anticoagulant effect at 2–4 hours). |
| Duration of Action | IV: 2–6 hours (dose-dependent); effects last 2–4 hours after a single bolus. SC: 8–12 hours (prolonged with higher doses; monitoring of aPTT recommended). |
For treatment of venous thromboembolism: Initial IV bolus of 80 units/kg, then continuous IV infusion at 18 units/kg/hour. For prophylaxis: Subcutaneous injection of 5000 units every 8-12 hours. Heparin sodium 12,500 units/250 mL (50 units/mL) is typically used for continuous IV infusion.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required for heparin as it is minimally renally cleared. However, in severe renal impairment (CrCl <30 mL/min), increased risk of bleeding may necessitate closer monitoring of aPTT and dose titration. |
| Liver impairment | Heparin is not hepatically metabolized; no adjustment needed based on Child-Pugh score. However, severe hepatic impairment may increase bleeding risk due to coagulopathy; monitor aPTT closely. |
| Pediatric use | For venous thromboembolism: Initial IV bolus of 75-100 units/kg over 10 minutes, followed by continuous IV infusion: infants <1 year: 28 units/kg/hour; children ≥1 year: 20 units/kg/hour. Prophylaxis: Subcutaneous 100 units/kg/dose every 12 hours. Adjust to maintain aPTT 60-85 seconds. |
| Geriatric use | Elderly patients (>65 years) may have reduced renal function and increased bleeding risk. No specific dose adjustment, but lower initial doses (e.g., 50 units/kg IV bolus, 15 units/kg/hour infusion) and more frequent aPTT monitoring recommended. |
| 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 safe for use during breastfeeding. M/P ratio: Not applicable (undetectable in milk). |
| Teratogenic Risk | Heparin does not cross the placenta and is not associated with teratogenicity in any trimester. First trimester: No increased risk of major malformations. Second and third trimesters: No fetal adverse effects reported; however, risk of maternal hemorrhage and osteoporosis with prolonged use. |
■ FDA Black Box Warning
Heparin-induced thrombocytopenia (HIT) with or without thrombosis may occur; monitor platelet counts. Risk of hemorrhage, especially in patients with bleeding disorders or undergoing invasive procedures. Spinal/epidural hematomas with neuraxial anesthesia.
| Common Effects | fluid replacement |
| Serious Effects |
["History of heparin-induced thrombocytopenia (HIT)","Active major bleeding","Severe thrombocytopenia (platelet count <100,000/μL)","Uncontrolled bleeding disorders","Hypersensitivity to heparin","Pregnancy (preservative-free formulations preferred)"]
| Precautions | Monitor for signs of bleeding; avoid intramuscular injections; use cautiously in patients with renal impairment, liver disease, or history of HIT; requires monitoring of aPTT; risk of hyperkalemia due to aldosterone suppression. |
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| Fetal Monitoring | Monitor maternal complete blood count (platelet count for heparin-induced thrombocytopenia), anti-Xa levels or activated partial thromboplastin time (aPTT) for therapeutic dosing, and signs of bleeding. Fetal monitoring via ultrasound for growth and well-being if long-term therapy is required. |
| Fertility Effects | No direct effects on fertility reported. Heparin does not interfere with ovulation, spermatogenesis, or implantation. |