HEPARIN SODIUM 12,500 UNITS IN SODIUM CHLORIDE 0.45% IN PLASTIC CONTAINER
Clinical safety rating
safeNo significant drug interactions Can cause hypernatremia and fluid overload.
Heparin binds to antithrombin III (ATIII), accelerating its inhibition of thrombin (factor IIa) and factor Xa, thereby preventing fibrin clot formation.
| Metabolism | Heparin undergoes hepatic metabolism (desulfation) and is partially depolymerized; clearance is via reticuloendothelial system and renal excretion. |
| Excretion | Primarily renal (via reticuloendothelial system); 40-50% excreted unchanged in urine; 20-30% metabolized to uroheparin and excreted renally; minor biliary (<5%). |
| Half-life | Terminal elimination half-life: 1-2 hours (dose-dependent, saturable clearance); prolonged to 2-6 hours in renal impairment, obese patients, or with high doses; clinical anticoagulant effect may persist 2-4 hours after a single IV bolus. |
| Protein binding | Heparin binds extensively to antithrombin III (AT-III) and multiple plasma proteins including histidine-rich glycoprotein, platelet factor 4, vitronectin, fibronectin, and lipoproteins; very high overall protein binding (nearly 100% to AT-III when bound, but free fraction varies due to competition). |
| Volume of Distribution | Vd approximately 0.03-0.10 L/kg (largely confined to plasma volume; limited extravascular distribution); increased Vd in pregnancy, obesity, and nephrotic syndrome. |
| Bioavailability | SC: 80-93% relative to IV (due to first-pass hepatic metabolism and local degradation); IV: 100%. |
| Onset of Action | IV: immediate (within seconds); SC: 20-30 minutes. |
| Duration of Action | IV: 2-4 hours (aPTT returns to baseline); SC: 8-12 hours (duration depends on dose and monitoring); continuous infusion: effect persists as long as infusion continues. |
| Molecular Weight | 15000 Da (mean, range 3000-30000) |
Intravenous: Initial bolus of 5,000 units followed by continuous infusion of 13-21 units/kg/hour (typically 1,000-2,000 units/hour) titrated to aPTT 1.5-2.5 times control. Subcutaneous: 5,000 units every 8-12 hours for prophylaxis; 10,000-20,000 units every 12 hours for treatment.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment for GFR; monitor aPTT closely in renal impairment (CrCl <30 mL/min) due to increased bleeding risk. For continuous infusion, consider lower initial rates (e.g., 13 units/kg/hour) and titrate carefully. |
| Liver impairment | No established guidelines; use with caution in Child-Pugh B or C due to coagulopathy and decreased antithrombin III levels. Monitor aPTT more frequently. |
| Pediatric use | Intravenous: Bolus 50-100 units/kg, then continuous infusion 15-25 units/kg/hour. Subcutaneous: 50-100 units/kg every 6-8 hours for prophylaxis; 100-150 units/kg every 6 hours for treatment. Titrate to age-appropriate aPTT (e.g., 60-85 seconds in neonates). |
| Geriatric use | Lower initial doses (e.g., 50-70% of usual) with careful titration; increased risk of bleeding due to altered clearance. Monitor aPTT and renal function closely. |
| 1st trimester | Unfractionated heparin (UFH) does not cross the placenta and is not associated with teratogenicity. It is the anticoagulant of choice in pregnancy when anticoagulation is necessary. |
| 2nd trimester | Safe for use. Heparin does not cross the placenta and no increased risk of fetal harm. |
| 3rd trimester | Safe for use. However, maternal heparin use may increase the risk of bleeding during delivery. Use with caution near term. |
Clinical note
No significant drug interactions Can cause hypernatremia and fluid overload.
| FDA category | Animal |
| Placental transfer | Heparin does not cross the placenta due to its high molecular weight and negative charge. |
| Breastfeeding | Heparin is not excreted into breast milk due to its high molecular weight and polarity; therefore, it is considered compatible with breastfeeding. |
| Lactation Rating | L1 - Safe |
| Teratogenic Risk | Pregnancy category C. Heparin does not cross the placenta; no risk of fetal teratogenesis. However, increased risk of maternal bleeding, which may indirectly affect fetal well-being. Use only if clearly needed. |
| Fetal Monitoring | Monitor maternal coagulation parameters (aPTT, anti-Xa), platelet count (risk of HIT), and signs of bleeding. Assess fetal heart rate and uterine activity if used during labor. Monitor for maternal hemorrhage. |
| Fertility Effects | No known direct effects on fertility. Heparin may be used in treatment of recurrent pregnancy loss associated with thrombophilia, potentially improving fertility outcomes. |
■ FDA Black Box Warning
Spinal/epidural hematomas: Risk hemiparesis or paralysis with neuraxial anesthesia or spinal puncture, especially in patients on anticoagulants or with indwelling catheters.
| Common Effects | fluid replacement |
| Serious Effects |
Active major bleedingHistory of heparin-induced thrombocytopenia (HIT) (confirmed or strongly suspected)Known hypersensitivity to heparin or pork productsSevere thrombocytopeniaInability to perform appropriate monitoring (aPTT, platelet counts)Epidural or spinal needle placement or indwelling catheter (risk of spinal hematoma when used for thromboprophylaxis)
| Precautions | Hemorrhage risk (monitor for bleeding; adjust dose based on aPTT), Heparin-induced thrombocytopenia (HIT) Type II (immune-mediated, monitor platelets), HIT Type I (non-immune thrombocytopenia), Hyperkalemia due to aldosterone suppression (risk in renal impairment, diabetes, or K+-sparing drugs), Heparin resistance (low ATIII levels), Osteoporosis with long-term use (>6 months) |
| Food/Dietary | No specific food interactions. However, vitamin K-rich foods (e.g., leafy greens) may antagonize effects if given with warfarin; heparin effect is not vitamin K-dependent. |
| Clinical Pearls | Heparin is an anticoagulant used for prophylaxis and treatment of thromboembolic disorders. Monitor aPTT closely; therapeutic range typically 1.5-2.5 times control. Avoid intramuscular administration due to risk of hematoma. Use with caution in renal impairment. Protamine sulfate is the antidote for heparin overdose. |
| Patient Advice | Do not take aspirin or NSAIDs unless prescribed by your doctor, as they increase bleeding risk. · Report any unusual bleeding, bruising, or dark stools immediately. · Use a soft toothbrush and electric razor to avoid cuts. · Keep all appointments for blood tests to monitor your therapy. · Wear a medical alert bracelet indicating you are on heparin. |
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