HEPARIN SODIUM 20,000 UNITS IN DEXTROSE 5%
Clinical safety rating: safe
Other drugs that affect hemostasis increase bleeding risk Can cause heparin-induced thrombocytopenia (HIT) and bleeding.
Heparin sodium binds to antithrombin III, causing a conformational change that accelerates the inactivation of thrombin and factor Xa, and to a lesser extent factors IXa, XIa, and XIIa, thereby inhibiting coagulation. It also inhibits platelet aggregation and prolongs clotting times.
| Metabolism | Heparin is partially metabolized in the liver by depolymerization and desulfation via hepatocytes and reticuloendothelial system. Unchanged heparin is also excreted in urine. Clearance is dose-dependent involving both saturable (binding to cells) and non-saturable (renal) mechanisms. |
| Excretion | Renal: 50-60% as unchanged drug via glomerular filtration; hepatic metabolism (desulfation) accounts for minor clearance; fecal elimination negligible (<1%). |
| Half-life | Terminal half-life 1.5 hours (range 1-3 hours) for therapeutic doses; dose-dependent, with higher doses prolonging half-life; half-life prolonged in hepatic or renal impairment. |
| Protein binding | Highly protein-bound: 95-99% to antithrombin III, albumin, and other plasma proteins. |
| Volume of Distribution | 0.07-0.08 L/kg; reflects low distribution primarily to intravascular space. |
| Bioavailability | Subcutaneous: 30-40% (bioavailability inversely related to dose due to saturable absorption); Intravenous: 100%. |
| Onset of Action | Intravenous: immediate (within seconds); Subcutaneous: 20-30 minutes. |
| Duration of Action | Intravenous: 2-4 hours for anticoagulant effect (aPTT elevation); Subcutaneous: 8-12 hours for prophylactic effect; duration dose-dependent. |
Adults: Initial IV bolus 80 units/kg, then continuous IV infusion at 18 units/kg/hour. For therapeutic anticoagulation, adjust to target aPTT 1.5-2.5 times control. Dosing per institutional nomogram.
| Dosage form | INJECTABLE |
| Renal impairment | No specific GFR-based dose adjustment required. Heparin is partially renally cleared; monitor aPTT closely in severe renal impairment (CrCl <30 mL/min) due to increased bleeding risk. |
| Liver impairment | No specific Child-Pugh based dose adjustment. Hepatic impairment may cause altered coagulation factors; monitor aPTT and adjust dose accordingly. |
| Pediatric use | Neonates and infants: Initial IV bolus 75-100 units/kg, then continuous infusion 28 units/kg/hour (neonates) or 20 units/kg/hour (infants). Older children: Initial IV bolus 75-100 units/kg, then continuous infusion 18-20 units/kg/hour. Adjust to target aPTT 1.5-2.5 times control. |
| Geriatric use | Elderly patients may have reduced heparin clearance and increased bleeding risk. Use lower initial doses (e.g., bolus 50 units/kg, infusion 15 units/kg/hour) with careful aPTT monitoring. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other drugs that affect hemostasis increase bleeding risk Can cause heparin-induced thrombocytopenia (HIT) and bleeding.
| FDA category | Human |
| Breastfeeding | Heparin is not excreted into breast milk due to its high molecular weight and ionization, making it compatible with breastfeeding. M/P ratio: Not applicable (non-secreted). |
| Teratogenic Risk | Heparin does not cross the placenta and is not associated with teratogenic effects. First trimester: No increased risk of major malformations. Second/third trimester: No fetal risk; however, maternal complications (e.g., hemorrhage, thrombocytopenia) may indirectly affect pregnancy. |
■ FDA Black Box Warning
Heparin is contraindicated in patients with a history of heparin-induced thrombocytopenia (HIT) or heparin-induced thrombocytopenia and thrombosis (HITTS). Close monitoring of platelet counts is mandatory due to the risk of HIT.
| Common Effects | bleeding |
| Serious Effects |
["History of heparin-induced thrombocytopenia (HIT) or heparin-induced thrombocytopenia and thrombosis (HITTS)","Active major bleeding or conditions with high risk of hemorrhage (e.g., hemophilia, severe thrombocytopenia, recent CNS surgery)","Severe hypotension or shock","Hypersensitivity to heparin or pork products","Inability to perform appropriate coagulation monitoring (e.g., aPTT)"]
| Precautions | ["Risk of major bleeding, including intracranial and retroperitoneal hemorrhage","Heparin-induced thrombocytopenia (HIT) and thrombosis (HITTS)","Monitor platelet counts frequently during therapy","Use with caution in patients with increased bleeding risk (e.g., hemophilia, liver disease, recent surgery)","Risk of hyperkalemia due to suppression of aldosterone, especially in patients with diabetes or renal impairment","Preservative-free formulations needed for neonates and patients with hypersensitivity to benzyl alcohol","Rebound hypercoagulability upon abrupt discontinuation","Enzyme immunoassays for HIT may yield false positives"] |
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| Fetal Monitoring | Monitor platelet counts (risk of heparin-induced thrombocytopenia), signs of bleeding (hematuria, bruising), activated partial thromboplastin time (aPTT) to maintain therapeutic range, and fetal surveillance with nonstress test or biophysical profile if maternal condition warrants. |
| Fertility Effects | No known direct effects on fertility. Heparin does not impair spermatogenesis or oogenesis. Indirect effects may arise from underlying conditions (e.g., antiphospholipid syndrome) for which heparin is used. |