Section 13 · Monograph
Heparin
Reviewed Nov 2026FDA label
Heparin sodiumUnfractionated heparin
- Forms
- Inj: 1,000, 5,000, 10,000 units/mL; premixed bags
- Dose
- VTE prophylaxis: 5,000 units SC every 8-12 hours; neuro-ICU start once hemorrhage is stable per guidelines
- MOA
- Potentiates antithrombin III (inhibits factors Xa and IIa)
Indications
- Prophylaxis and treatment of venous thrombosis and pulmonary embolismFDA-labeled
- Atrial fibrillation with embolization; prevention of clotting in arterial and cardiac surgery; anticoagulation in extracorporeal circulationFDA-labeled
Mechanism of Action
- Binds antithrombin III, accelerating inactivation of thrombin and factor Xa (and others), preventing fibrin clot formation
Full Dosing
Adult / usual
- VTE prophylaxis: 5,000 units SC every 8-12 hours
- Neurocritical care: start prophylactic dosing once hemorrhage is stable on repeat imaging, typically 24-72 hours, per guidelines
- Therapeutic infusion regimens are protocol and aPTT/anti-Xa based
Contraindications
- Severe thrombocytopenia
- History of heparin-induced thrombocytopenia
- Uncontrolled active bleeding (except in DIC)
- Hypersensitivity (including pork-derived products)
Drug Interactions
- Antiplatelets, NSAIDs, thrombolytics and other anticoagulants increase bleeding risk
- Nitroglycerin infusion may reduce heparin effect
Adverse Effects
- Bleeding including intracranial
- Heparin-induced thrombocytopenia (typically days 5-14)
- Osteoporosis with long-term use
- Hyperkalemia (aldosterone suppression)
- Injection-site hematoma
Monitoring Parameters
- Platelet counts (baseline and every 2-3 days from day 4 to 14)
- Hemoglobin; aPTT or anti-Xa for therapeutic dosing
- Signs of bleeding; protamine reverses heparin
Pregnancy & Lactation
- Does not cross the placenta; used in pregnancy when anticoagulation is needed
- Not excreted in milk; compatible with breastfeeding