HEPARIN SODIUM 5,000 UNITS IN SODIUM CHLORIDE 0.45%
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 inhibition of thrombin and activated factor X (factor Xa). It also catalyzes the inhibition of other coagulation factors including XIIa, XIa, IXa, and VIIa.
| Metabolism | Heparin is partially metabolized by the reticuloendothelial system and desulfated. Clearance is dose-dependent and saturable, primarily via the liver (heparinase) and to a lesser extent renal excretion. |
| Excretion | Primarily renal, with some hepatic metabolism and reticuloendothelial system clearance. Unchanged heparin is excreted in urine via glomerular filtration; high molecular weight fractions are cleared more rapidly than low molecular weight fractions. |
| Half-life | Mean terminal elimination half-life is 1-2 hours at therapeutic doses, but it is dose-dependent and can increase with higher doses. Clinical context: Anticoagulant effect persists longer than plasma levels due to irreversible binding to antithrombin III. |
| Protein binding | Very high; ~95% bound primarily to antithrombin III, with some binding to albumin and other proteins. |
| Volume of Distribution | 0.05-0.07 L/kg (approximately 4-5 L in adults). Clinical meaning: Low Vd indicates predominantly intravascular distribution; heparin does not cross the placenta or blood-brain barrier. |
| Bioavailability | Subcutaneous: 20-30% (due to first-pass metabolism and binding); Intravenous: 100%. |
| Onset of Action | Intravenous: Immediate. Subcutaneous: 20-30 minutes. |
| Duration of Action | Intravenous: 2-6 hours (dose-dependent). Subcutaneous: 8-12 hours (prolonged with higher doses). Clinical note: Effect monitored via aPTT; prolonged use may require dose adjustment. |
IV: Initial bolus 80 units/kg, then continuous infusion at 18 units/kg/hr, adjusted to aPTT 1.5-2.5 times control. Subcutaneous: 5,000 units every 8-12 hours.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl <30 mL/min: Reduce infusion rate by 50% or consider alternative. Monitor aPTT closely. |
| Liver impairment | Child-Pugh Class B or C: Reduce dose by 50% due to decreased clearance; monitor aPTT. |
| Pediatric use | IV bolus 75-100 units/kg, then infusion: Infants <1 year: 28 units/kg/hr; Children >1 year: 20 units/kg/hr; adjust to aPTT 60-85 seconds. |
| Geriatric use | Reduce initial bolus to 50-60 units/kg and infusion rate to 15 units/kg/hr due to altered clearance; frequent aPTT monitoring. |
| 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; considered compatible with breastfeeding. M/P ratio not applicable. |
| Teratogenic Risk | Heparin does not cross the placenta; no known teratogenic effects in any trimester. Risk of maternal hemorrhage and fetal bleeding during delivery. |
■ FDA Black Box Warning
Heparin is contraindicated in patients with a history of heparin-induced thrombocytopenia (HIT). Fatal hemorrhages have occurred. Monitor platelets closely.
| Common Effects | fluid replacement |
| Serious Effects |
["History of heparin-induced thrombocytopenia (HIT) or heparin-induced thrombocytopenia with thrombosis (HITT)","Active major bleeding","Severe thrombocytopenia","Uncontrolled bleeding disorders (e.g., hemophilia, disseminated intravascular coagulation except for defibrination syndrome)","Hypersensitivity to heparin or any component of the formulation","When suitable blood coagulation tests cannot be performed at required intervals","Suspected intracranial hemorrhage"]
| Precautions | ["Risk of hemorrhage: Monitor for bleeding, especially in patients with predisposing factors (e.g., renal failure, recent surgery).","Heparin-induced thrombocytopenia (HIT): Monitor platelet counts regularly; discontinue if HIT is suspected.","Heparin-induced thrombocytopenia with thrombosis (HITT): May require alternative anticoagulation.","Osteoporosis: Long-term use may lead to bone density loss.","Hyperkalemia: Heparin may suppress adrenal aldosterone secretion, leading to hyperkalemia, especially in renal impairment or diabetes.","Heparin resistance: May occur in antithrombin III deficiency or elevated heparin clearance."] |
Loading safety data…
| Fetal Monitoring | Monitor maternal aPTT, platelet count, and signs of bleeding. Fetal surveillance not required; monitor for signs of placental abruption or hemorrhage. |
| Fertility Effects | No known adverse effects on human fertility based on available data. |