Absorption: Erratically absorbed following subcut or IM administration.
Distribution: Does not cross the placenta or enter breast milk.
Protein Binding: Very high (to low-density lipoproteins, globulins, and fibrinogen).
Metabolism/Excretion: Probably removed by the reticuloendothelial system (lymph nodes, spleen).
Half-life: 1–2 hr (↑ with increasing dose); affected by obesity, renal and hepatic function, malignancy, presence of pulmonary embolism, and infections.
Contraindicated in:
- Hypersensitivity
- Uncontrolled bleeding
- History of heparin-induced thrombocytopenia
- Severe thrombocytopenia
- Open wounds (full dose)
- Pedi: Avoid use of products containing benzyl alcohol in premature infants.
Use Cautiously in:
- Severe liver or kidney impairment
- Retinopathy (hypertensive or diabetic)
- Ulcer disease
- Spinal cord or brain injury
- History of congenital or acquired bleeding disorder
- Malignancy
- OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk; avoid use of products containing benzyl alcohol
- Lactation: Use while breast feeding only if potential maternal benefit justifies potential risk to infant; avoid use of products containing benzyl alcohol
- Geri: Women >60 yr have ↑ risk of bleeding.
Exercise Extreme Caution in:
- Severe uncontrolled hypertension
- Bacterial endocarditis, bleeding disorders
- GI bleeding/ulceration/pathology
- Hemorrhagic stroke
- History of thrombocytopenia related to heparin
- Recent CNS or ophthalmologic surgery
- Active GI bleeding/ulceration
Derm: alopecia (long-term use), rash, urticaria.
GI: drug-induced hepatitis.
Hemat: BLEEDING, HEPARIN-INDUCED THROMBOCYTOPENIA (HIT) (WITH OR WITHOUT THROMBOSIS), anemia.
Local: pain at injection site.
MS: osteoporosis (long-term use).
Misc: fever, hypersensitivity reactions.
Heparin is frequently used concurrently or sequentially with other agents affecting coagulation. The risk of potentially serious interactions is greatest with full anticoagulation.
Drug-Drug:
- Risk of bleeding may be ↑ by concurrent use of drugs that affect platelet function, including aspirin, NSAIDs, clopidogrel, dipyridamole, some penicillins, eptifibatide, tirofiban, and dextran.
- Risk of bleeding may be ↑ by concurrent use of drugs that cause hypoprothrombinemia, including quinidine, cefotetan, and valproic acid.
- Concurrent use of thrombolytics↑ risk of bleeding.
- Heparins affect the prothrombin time used in assessing the response to warfarin.
- Digoxin, tetracyclines, nicotine, and antihistamines may ↓ anticoagulant effect of heparin.
- Streptokinase may be followed by relative resistance to heparin.
Drug-Natural Products:
Therapeutic Anticoagulation
- IV (Adults): Intermittent bolus — 10,000 units, followed by 5000–10,000 units every 4–6 hr. Continuous infusion — 5000 units (35–70 units/kg), followed by 20,000–40,000 units infused over 24 hr (approx. 1000 units/hr or 15–18 units/kg/hr).
- IV (Children >1 yr): Intermittent bolus — 50–100 units/kg, followed by 50–100 units/kg every 4 hr. Continuous infusion — Loading dose 75 units/kg, followed by 20 units/kg/hr, adjust to maintain aPTT of 60–85 sec.
- IV (Neonates and Infants <1 yr): Continuous infusion — Loading dose 75 units/kg, followed by 28 units/kg/hr, adjust to maintain aPTT of 60–85 sec.
- SC (Adults): 5000 units IV, followed by initial subcut dose of 10,000–20,000 units, then 8000–10,000 units every 8 hr or 15,000–20,000 units every 12 hr.
Prophylaxis of Thromboembolism
- SC (Adults): 5000 units every 8–12 hr (may be started 2 hr prior to surgery).
Cardiovascular Surgery
- IV (Adults): At least 150 units/kg (300 units/kg if procedure <60 min; 400 units/kg if >60 min).
- IA (Neonates , Infants, and Children): 100–150 units/kg via an artery prior to cardiac catheterization.
Line Flushing
- IV (Adults and Children): 10–100 units/mL (10 units/mL for infants <10 kg, 100 units/mL for all others) solution to fill heparin lock set to needle hub; replace after each use.
Total Parenteral Nutrition
- IV (Adults and Children): 0.5–1 units/mL (final solution concentration) to maintain line patency.
Arterial Line Patency
- IA (Neonates): 0.5–2 units/mL.
Therapeutic Classification: anticoagulants
Pharmacologic Classification: antithrombotics
