HEPARIN SODIUM PRESERVATIVE FREE
Clinical safety rating: safe
Other drugs that affect hemostasis increase bleeding risk Can cause heparin-induced thrombocytopenia (HIT) and bleeding.
Heparin binds to antithrombin III (ATIII), causing a conformational change that accelerates the inactivation of thrombin (factor IIa) and factor Xa, as well as factors IXa, XIa, and XIIa. This inhibits clot formation and propagation.
| Metabolism | Heparin is primarily metabolized in the liver and by the reticuloendothelial system via desulfation and depolymerization; also undergoes renal clearance. |
| Excretion | Primarily renal; small amounts in urine as unchanged drug and metabolites. Biliary/fecal elimination is negligible (<5%). |
| Half-life | Terminal half-life is 0.5–2.5 hours (mean ~1.5 h) after IV administration; dose-dependent due to saturable clearance. At therapeutic doses, half-life averages 1–2 hours. |
| Protein binding | Highly bound (85–95%) to antithrombin III, albumin, and other plasma proteins. |
| Volume of Distribution | 0.03–0.06 L/kg (low, largely confined to intravascular space; does not distribute significantly into extravascular tissues). |
| Bioavailability | SC: 20–40% (due to first-pass degradation by mast cells and binding to local proteins). IV: 100%. |
| Onset of Action | IV: Immediate (within minutes). SC: 20–60 minutes (therapeutic anticoagulation in 2–4 hours with delay to steady state). |
| Duration of Action | IV: 2–6 hours (dose-dependent; higher doses prolong effect). SC: 8–12 hours (requires monitoring with aPTT at 6 h post-dose for dose adjustment). |
Initial bolus of 80 units/kg IV, followed by continuous infusion at 18 units/kg/hour IV; adjusted to maintain aPTT of 1.5-2.5 times control.
| Dosage form | INJECTABLE |
| Renal impairment | No specific GFR-based dose adjustment; increased bleeding risk in severe renal impairment (CrCl <30 mL/min) with accumulation; consider dose reduction or alternative. |
| Liver impairment | No formal Child-Pugh based guidelines; use with caution due to risk of coagulopathy; monitor aPTT and adjust accordingly. |
| Pediatric use | Loading dose of 75-100 units/kg IV over 10 minutes; maintenance infusion: infants 28 units/kg/hour, children 20 units/kg/hour, adolescents 18 units/kg/hour; titrate to aPTT goal. |
| Geriatric use | Lower doses may be needed due to altered pharmacokinetics and increased bleeding risk; consider starting at lower infusion rates (e.g., 15 units/kg/hour) and titrate carefully. |
| 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 high molecular weight. Compatible with breastfeeding. M/P ratio not applicable. |
| Teratogenic Risk | Heparin does not cross the placenta. No increased risk of fetal malformations or adverse outcomes in any trimester. Considered low risk. |
■ FDA Black Box Warning
Heparin is not intended for intramuscular use due to risk of hematoma. Also, there is a risk of heparin-induced thrombocytopenia (HIT) and heparin-induced thrombocytopenia with thrombosis (HITT); monitor platelet counts. Preservative-free heparin should not be used in neonates or infants due to potential toxicity from benzyl alcohol (if present; however, preservative-free formulation avoids this).
| Common Effects | bleeding |
| Serious Effects |
Hypersensitivity to heparin or pork products, history of heparin-induced thrombocytopenia (HIT), active major bleeding, severe thrombocytopenia, uncontrolled bleeding disorders, suspected intracranial hemorrhage, and when monitoring of coagulation parameters cannot be performed adequately.
| Precautions | Hemorrhage is the major complication; monitor coagulation parameters (aPTT), platelet counts, and signs of bleeding. Heparin-induced thrombocytopenia (HIT) requires immediate discontinuation. Use with caution in patients with renal impairment, hepatic disease, hypertension, or those with a history of allergies. Spinal/epidural hematoma risk with neuraxial anesthesia or spinal puncture. Not recommended for patients with severe thrombocytopenia or uncontrolled bleeding. |
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| Fetal Monitoring | Monitor activated partial thromboplastin time (aPTT) regularly. Assess for signs of bleeding, hemorrhage, and heparin-induced thrombocytopenia (HIT). Fetal monitoring includes ultrasound for growth and well-being if indicated. |
| Fertility Effects | No known adverse effects on fertility in males or females. |