HEPARIN SODIUM 5,000 UNITS AND 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 factor Xa and thrombin, thereby inhibiting coagulation.
| Metabolism | Primarily cleared via reticuloendothelial system and desulfation; partially metabolized by heparinase; renal excretion of metabolites. |
| Excretion | Heparin is primarily eliminated via the reticuloendothelial system and metabolized in the liver. Renal excretion of unchanged heparin is minimal (<5%) at therapeutic doses. Biliary/fecal excretion is negligible. |
| Half-life | The terminal elimination half-life of heparin is dose-dependent, ranging from 0.5 to 2 hours for intravenous doses of 100-400 U/kg. At higher doses, half-life may extend to 2.5 hours. Clinical context: linear pharmacokinetics; half-life increases with dose due to saturable clearance mechanisms (reticuloendothelial uptake and hepatic metabolism). |
| Protein binding | Heparin is extensively bound to antithrombin III (AT-III) with high affinity. It also binds to other plasma proteins including platelet factor 4, histidine-rich glycoprotein, and fibrinogen. Nonspecific binding to albumin occurs but is low affinity; overall binding is not expressed as a simple percentage due to complex binding interactions. |
| Volume of Distribution | Volume of distribution is approximately 0.05-0.1 L/kg (5-10% body weight), confined largely to the plasma volume. Clinical meaning: heparin does not distribute to extravascular tissues; its Vd approximates blood volume. |
| Bioavailability | Subcutaneous: bioavailability is 20-30% due to poor absorption; intravenous: 100%. |
| Onset of Action | Intravenous: immediate (within seconds) due to rapid binding to antithrombin III. Subcutaneous: onset in 20-60 minutes; delayed absorption from injection site. |
| Duration of Action | Intravenous: anticoagulant effect lasts 2-4 hours after bolus; continuous infusion maintains steady state. Subcutaneous: duration 8-12 hours; clinical note: effect monitored by aPTT, typically drawn 6 hours after subcutaneous dose due to peak at 2-4 hours. |
For venous thromboembolism prophylaxis: 5000 units subcutaneously every 8-12 hours. For therapeutic anticoagulation: weight-based IV bolus (60-80 units/kg) followed by continuous IV infusion (12-18 units/kg/hour) adjusted to target aPTT. 1.5-2.5 times control.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required based on GFR; however, heparin is primarily cleared by the liver and reticuloendothelial system, and renal impairment does not significantly alter pharmacokinetics. Use with caution in severe renal impairment due to increased bleeding risk. |
| Liver impairment | No formal Child-Pugh based dosing adjustments. Hepatic impairment may prolong heparin's half-life; consider reducing initial bolus and infusion rates, monitor aPTT closely. |
| Pediatric use | For prophylaxis: 50-100 units/kg subcutaneously every 12 hours. For therapeutic anticoagulation: initial bolus 75-100 units/kg IV over 10 minutes; maintenance infusion: age-based: infants <1 year: 28 units/kg/hour; children >1 year: 20 units/kg/hour; adolescents: 18 units/kg/hour. Titrate to target aPTT. |
| Geriatric use | Elderly patients may have altered pharmacokinetics and increased bleeding risk. Initial dosing should be based on actual body weight; consider lower initial infusion rates (e.g., 10-15 units/kg/hour) with close monitoring of aPTT and signs of bleeding. |
| 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 large molecular weight and ionic charge. The American Academy of Pediatrics considers heparin compatible with breastfeeding. M/P ratio is not applicable as drug is not detected in milk. |
| Teratogenic Risk | Heparin does not cross the placenta and is not associated with fetal teratogenicity in any trimester. No increased risk of congenital anomalies has been reported. However, maternal use may cause bleeding complications affecting pregnancy outcomes. |
■ FDA Black Box Warning
Spinal/epidural hematomas may occur in patients receiving anticoagulants, including heparin, who are undergoing neuraxial anesthesia or spinal puncture, resulting in long-term or permanent paralysis.
| Common Effects | fluid replacement |
| Serious Effects |
Hypersensitivity to heparin or pork products. Active major bleeding. History of heparin-induced thrombocytopenia. Severe thrombocytopenia. Uncontrolled bleeding disorders.
| Precautions | Risk of hemorrhage: monitor for bleeding, especially at invasive procedure sites. Heparin-induced thrombocytopenia (HIT): monitor platelet counts. Hypersensitivity reactions. Elevated hepatic enzymes. Osteoporosis with prolonged use. |
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| Fetal Monitoring | Monitor maternal activated partial thromboplastin time (aPTT) to maintain therapeutic range (1.5-2.5 times control). Assess platelet counts every 2-3 days to detect heparin-induced thrombocytopenia. Monitor for signs of bleeding, bruising, or hemorrhage. Fetal monitoring includes assessment of fetal heart rate and uterine activity for evidence of placental abruption or fetal distress. |
| Fertility Effects | No known adverse effects on fertility in males or females. Heparin is not associated with ovarian toxicity or impaired spermatogenesis. |