HEPARIN SODIUM 5,000 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, accelerating its inactivation of thrombin (factor IIa) and factor Xa, thereby inhibiting coagulation.
| Metabolism | Heparin undergoes desulfation and partial depolymerization in the liver and reticuloendothelial system; primarily cleared by the kidneys. |
| Excretion | Renal: 40% as unchanged drug; reticuloendothelial system (liver, spleen): 60% metabolized to low molecular weight forms, then renally eliminated. |
| Half-life | Terminal half-life: 1-2 hours (dose-dependent; mean 1.5 hours). Clinical context: Prolonged in hepatic/renal insufficiency; obesity (increased Vd). IV bolus: 30-60 min; continuous infusion: 1-2 hours. |
| Protein binding | High, >95% bound to antithrombin III, albumin, and other plasma proteins. |
| Volume of Distribution | 0.04-0.06 L/kg (confined to plasma; does not cross placenta). Clinical meaning: Low Vd reflects limited extravascular distribution; predominantly intravascular. |
| Bioavailability | SC: 20-30% (due to first-pass hepatic metabolism and local inactivation). |
| Onset of Action | IV: immediate (within minutes); SC: 20-30 minutes (therapeutic APTT at 1-2 hours). |
| Duration of Action | IV: 2-6 hours (dose-dependent); SC: 8-12 hours (with 5,000 units). Clinical notes: Effect monitored via APTT; neutralized by protamine sulfate. |
5,000 units IV bolus, followed by continuous IV infusion of 18 units/kg/hr (initial based on actual body weight) for treatment of venous thromboembolism; or 5,000 units subcutaneously every 8-12 hours for prophylaxis of deep vein thrombosis. Titrate to aPTT 1.5-2.5 times control.
| Dosage form | INJECTABLE |
| Renal impairment | No standard dose adjustment for GFR; however, close monitoring of aPTT and for bleeding is recommended in severe renal impairment (CrCl <30 mL/min) due to increased risk of accumulation. |
| Liver impairment | No specific dose adjustment based on Child-Pugh class; use with caution in hepatic disease due to decreased clearance and increased risk of bleeding. Monitor aPTT and clinical response. |
| Pediatric use | Loading dose: 75-100 units/kg IV over 10 minutes. Maintenance infusion: For age ≤1 year: 28 units/kg/hr; age >1 year: 20 units/kg/hr; adjust to achieve aPTT of 60-85 seconds or anti-Xa level of 0.3-0.7 units/mL. |
| Geriatric use | Increased risk of bleeding; consider lower initial infusion rates (e.g., 12-15 units/kg/hr) and more frequent aPTT monitoring. Use caution due to age-related renal function decline and concurrent medications. |
| 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 high molecular weight and poor oral bioavailability. Considered safe during breastfeeding; M/P ratio is not applicable (undetectable in milk). |
| Teratogenic Risk | Heparin does not cross the placenta; no known teratogenic risk. First trimester: No increased risk of major malformations. Second/third trimesters: Risk of maternal hemorrhage, placental abruption, or preterm labor if anticoagulation is excessive. No direct fetal toxicity. |
■ FDA Black Box Warning
Spinal or epidural hematomas, including subsequent paralysis, may occur in patients anticoagulated with heparin who receive neuraxial anesthesia or undergo spinal puncture. Risk is increased by indwelling epidural catheters, concomitant use of drugs affecting hemostasis (e.g., NSAIDs, platelet inhibitors, anticoagulants), traumatic or repeated puncture. Monitor for signs/symptoms of neurological impairment.
| Common Effects | fluid replacement |
| Serious Effects |
Hypersensitivity to heparin or pork products, history of heparin-induced thrombocytopenia (HIT), active major bleeding (except when due to disseminated intravascular coagulation), severe thrombocytopenia, inability to perform adequate coagulation monitoring.
| Precautions | Risk of hemorrhage, especially in patients with bleeding disorders, recent surgery, or concurrent use of antiplatelet agents or anticoagulants. Monitor platelet counts for heparin-induced thrombocytopenia (HIT). May cause hyperkalemia by suppressing aldosterone secretion. Use with caution in hepatic or renal impairment. Avoid intramuscular injection. |
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| Fetal Monitoring | Monitor activated partial thromboplastin time (aPTT) to maintain therapeutic range (1.5-2.5 times control). Platelet count for heparin-induced thrombocytopenia. Fetal surveillance via ultrasound for growth and well-being if long-term use. Monitor for signs of bleeding (maternal and fetal). |
| Fertility Effects | Heparin does not impair fertility in animal studies. No human data suggest adverse effects on fertility. Indirect effects possible only through underlying disease (e.g., antiphospholipid syndrome). |