HEPARIN LOCK FLUSH
Clinical safety rating: safe
Other drugs that affect hemostasis increase bleeding risk Can cause heparin-induced thrombocytopenia (HIT) and bleeding.
Heparin potentiates the activity of antithrombin III, inactivating thrombin and activated factor X (FXa), thereby preventing fibrin formation and thrombus propagation.
| Metabolism | Primarily metabolized in the liver and by the reticuloendothelial system via desulfation and depolymerization; partial renal clearance. |
| Excretion | Primarily renal via glomerular filtration and tubular secretion; about 50% excreted unchanged in urine; remainder metabolized in the liver and reticuloendothelial system (heparinase); fecal elimination negligible (<5%). |
| Half-life | Terminal elimination half-life approximately 1-2 hours (mean 1.5 hours) at therapeutic doses; increases with dose; in renal failure, half-life prolonged up to 3-5 hours; clinical note: duration of effect short due to rapid clearance, requiring continuous infusion or frequent dosing. |
| Protein binding | Very high: 85-95% bound primarily to antithrombin III, also to albumin, fibrinogen, and lipoproteins; binding saturable. |
| Volume of Distribution | Approximately 0.05-0.1 L/kg (restricted to plasma volume); low Vd indicates heparin remains mainly in intravascular space; clinical meaning: distribution limited, initial dose proportional to body weight for systemic effect. |
| Bioavailability | Subcutaneous: ~30% (erratic, variable); intravenous: 100%. Heparin lock flush is administered via catheter, not for systemic absorption; bioavailability not applicable for intended local effect. |
| Onset of Action | Intravenous: immediate (within 1-2 minutes); subcutaneous: delayed for 20-30 minutes; clinical note: lock flush uses very low heparin concentrations, intended to maintain catheter patency, not systemic anticoagulation; systemic effects minimal with small volumes. |
| Duration of Action | Intravenous: 2-4 hours (dose-dependent); subcutaneous: 8-12 hours; clinical note: for heparin lock flush, effect on catheter patency lasts up to 24 hours due to local concentration; systemic anticoagulation not intended. |
| Molecular Weight | 15000 |
10-100 units/mL solution, 1-2 mL flush intravascularly after each catheter use or daily when catheter is not in use; typical adult dose: 10-100 units per flush.
| Dosage form | INJECTABLE |
| Renal impairment | No adjustment required; heparin is not renally eliminated. |
| Liver impairment | No specific adjustment for Child-Pugh class; caution in severe hepatic impairment due to increased bleeding risk. |
| Pediatric use | Neonates and children: 10-100 units/mL solution, 1-2 mL flush (or volume equal to catheter internal volume) after each use or daily; weight-based dosing not typically used for flush. |
| Geriatric use | No specific dose adjustment; elderly may have increased sensitivity to anticoagulation, monitor for bleeding. |
| 1st trimester | Limited data; no evidence of fetal harm. Use only if clearly needed. |
| 2nd trimester | No known risk; not known to cause fetal defects. |
| 3rd trimester | Increased risk of maternal hemorrhage during labor; use with caution. |
Clinical note
Other drugs that affect hemostasis increase bleeding risk Can cause heparin-induced thrombocytopenia (HIT) and bleeding.
| FDA category | Human |
| Placental transfer | Does not cross placenta due to high molecular weight, except possibly when administered in high doses or via continuous infusion. |
| Breastfeeding | Not absorbed orally; considered compatible with breastfeeding. Use with caution if high doses are used systemically. |
■ FDA Black Box Warning
Heparin Lock Flush should not be used interchangeably with heparin for therapeutic anticoagulation. Fatal hemorrhage has occurred due to dosing errors. Heparin is not intended for intramuscular use. Do not administer via parenteral routes other than for catheter lock. Spinal/epidural hematomas may occur in patients receiving anticoagulants or thrombolytics undergoing neuraxial anesthesia or spinal puncture, resulting in long-term or permanent paralysis.
| Common Effects | bleeding |
| Serious Effects |
Hypersensitivity to heparin or pork productsHistory of heparin-induced thrombocytopenia (HIT)Active major bleedingSevere thrombocytopenia
| Precautions | Risk of bleeding, especially in patients with conditions associated with increased bleeding risk. Heparin-induced thrombocytopenia (HIT) may occur; monitor platelet counts. Hypersensitivity reactions can occur. Do not use if solution is discolored or contains precipitate. Use with caution in patients with hepatic or renal impairment. |
Loading safety data…
| Lactation Rating | L1 (Safest) |
| Teratogenic Risk | HEPARIN LOCK FLUSH (unfractionated heparin) does not cross the placenta. No evidence of teratogenicity in first trimester. Risk of maternal hemorrhage and fetal bleeding in second/third trimester, but no structural defects. |
| Fetal Monitoring | Monitor maternal complete blood count (CBC), platelet counts, signs of bleeding or heparin-induced thrombocytopenia. For fetal monitoring, assess fetal growth if prolonged use; no specific fetal monitoring required except for standard obstetric care. |
| Fertility Effects | No known effects on fertility. Heparin does not impair spermatogenesis or oogenesis. No data suggesting adverse reproductive outcomes. |
| Food/Dietary | No direct food interactions; however, avoid excessive alcohol consumption as it may increase anticoagulant effects and bleeding risk. No dietary restrictions required. |
| Clinical Pearls | Use 10 units/mL concentration for neonates and <10 kg pediatric patients to minimize risk of hemorrhagic complications. Flush with 0.9% NaCl before and after heparin lock flush to avoid drug incompatibilities. Monitor for heparin-induced thrombocytopenia (HIT) with platelet counts every 2-3 days initially. Do not use if solution is discolored or contains precipitate. Avoid intramuscular administration due to hematoma risk. |
| Patient Advice | Report any signs of bleeding, such as easy bruising, nosebleeds, or blood in urine or stool. · Inform all healthcare providers that you are receiving heparin, including dentists and surgeons. · Do not take aspirin, ibuprofen, or other NSAIDs without consulting your doctor, as these increase bleeding risk. · Watch for symptoms of HIT, such as new rash, chest pain, shortness of breath, or leg swelling, and seek immediate medical attention. · Keep all appointments for blood tests to monitor your platelet count and clotting times. |