Heparin is a heterogenous group of straight-chain anionic mucopolysaccharides, called glycosaminoglycans having anticoagulant properties. Although others may be present, the main sugars occurring in heparin are: (1) α-L-iduronic acid 2-sulfate, (2) 2-deoxy-2­sulfamino-α-D-glucose 6-sulfate, (3) β-D-glucuronic acid, (4) 2-acetamido-2-deoxy-α-D- glucose, and (5) α-L-iduronic acid. These sugars are present in decreasing amounts, usually in the order (2) > (1) > (4) > (3) > (5), and are joined by glycosidic linkages, forming polymers of varying sizes. Heparin is strongly acidic because of its content of covalently linked sulfate and carboxylic acid groups. In heparin sodium, the acidic protons of the sulfate units are partially replaced by sodium ions.

Heparin Sodium in Sodium Chloride Injection is a buffered, sterile, nonpyrogenic solution of Heparin Sodium, USP derived from porcine intestinal mucosa, standardized for anticoagulant activity supplied in single dose containers for vascular administration. It contains no antimicrobial agents. The potency is determined by a biological assay using a USP reference standard based on units of heparin activity per milligram.


Heparin Sodium in Sodium Chloride Injection at a concentration of 2 units/mL is indicated as an anticoagulant to maintain catheter patency.

Mechanism of Action

Heparin interacts with the naturally occurring plasma protein, Antithrombin III, to induce a conformational change, which markedly enhances the serine protease activity of Antithrombin III, thereby inhibiting the activated coagulation factors involved in the closing sequence, particularly Xa and IIa. Small amounts of heparin inhibit Factor Xa, and larger amounts inhibit thrombin (Factor IIa). Heparin also prevents the formation of a stable fibrin clot by inhibiting the activation of the fibrin stabilizing factor. Heparin does not have fibrinolytic activity; therefore, it will not lyse existing clots.


The recommended starting dose is 6 units per hour by intravenous infusion through an intravenous catheter to maintain catheter patency.


The use of Heparin Sodium in Sodium Chloride Injection is contraindicated in patients with the following conditions:

  • Uncontrollable active bleeding state, except when this is due to disseminated intravascular coagulation
  • History of heparin-induced thrombocytopenia (HIT) and heparin-induced thrombocytopenia with thrombosis (HITT)
  • Severe thrombocytopenia
  • Known hypersensitivity to heparin or pork products (e.g., anaphylactoid reactions)
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Hemorrhage: Avoid using heparin in the presence of major bleeding, except when the benefits of heparin therapy outweigh the potential risks. Hemorrhage can occur at virtually any site in patients receiving heparin. Fatal hemorrhages have occurred. A higher incidence of bleeding has been reported in patients, particularly women, over 60 years of age.

Use heparin sodium with caution in disease states in which there is increased risk of hemorrhage, including:

  • Cardiovascular – Subacute bacterial endocarditis, severe hypertension.
  • Surgical – During and immediately following (a) spinal tap or spinal anesthesia or (b) major surgery, especially involving the brain, spinal cord, or eye.
  • Hematologic – Conditions associated with increased bleeding tendencies, such as hemophilia, thrombocytopenia, and some vascular purpuras.
  • Gastrointestinal – Ulcerative lesions and continuous tube drainage of the stomach or small intestine.
  • Patients with hereditary antithrombin III deficiency receiving concurrent antithrombin III therapy – The anticoagulant effect of heparin is enhanced by concurrent treatment with antithrombin III (human) in patients with hereditary antithrombin III deficiency. To reduce the risk of bleeding, reduce the heparin dose during concomitant treatment with antithrombin III (human).
  • Other – Menstruation, liver disease with impaired hemostasis.

Heparin-Induced Thrombocytopenia and Heparin-Induced Thrombocytopenia with Thrombosis: Heparin-induced thrombocytopenia (HIT) is a serious immune-mediated reaction. HIT occurs in patients treated with heparin and is due to the development of antibodies to a platelet Factor 4-heparin complex that induce in vivo platelet aggregation. HIT may progress to the development of venous and arterial thromboses, a condition referred to as heparin-induced thrombocytopenia with thrombosis (HITT). Thrombotic events may also be the initial presentation for HITT. These serious thromboembolic events include deep vein thrombosis, pulmonary embolism, cerebral vein thrombosis, limb ischemia, stroke, myocardial infarction, mesenteric thrombosis, renal arterial thrombosis, skin necrosis, gangrene of the extremities that may lead to amputation, and possibly death.

Thrombocytopenia: Thrombocytopenia in patients receiving heparin has been reported at frequencies up to 30%. It can occur 2 to 20 days (average 5 to 9) following the onset of heparin therapy. Obtain platelet counts before and periodically during heparin therapy. Mild thrombocytopenia (count greater than 100,000/mm3) may remain stable or reverse even if heparin is continued. However, monitor thrombocytopenia of any degree closely.

Heparin Resistance: Increased resistance to heparin is frequently encountered in fever, thrombosis, thrombophlebitis, infections with thrombosing tendencies, myocardial infarction, cancer, in postsurgical patients, and patients with anti-thrombin deficiency. Consider measurement of anti-thrombin levels if heparin resistance is suspected. Monitor coagulation tests frequently in such patients. It may be necessary to adjust the dose of heparin based on coagulation test monitoring, such as anti-Factor Xa levels and/or partial thromboplastin time.

Hypersensitivity: Hypersensitivity reactions with chills, fever and urticaria as the most usual manifestations and also asthma, rhinitis, lacrimation, and anaphylactoid reactions have been reported. Patients with documented hypersensitivity to heparin should be given the drug only in clearly life-threatening situations. Because Heparin Sodium in Sodium Chloride Injection is derived from animal tissue, it should be used with caution in patients with a history of allergy to pork products.

Hyperkalemia: Heparin can suppress adrenal secretion of aldosterone leading to hyperkalemia, particularly in patients with diabetes mellitus, chronic renal failure, pre-existing metabolic acidosis, a raised plasma potassium, or taking potassium sparing drugs. The risk of hyperkalemia appears to increase with duration of therapy but is usually reversible upon discontinuation of heparin.

Elevations of Serum Aminotransferases: Significant elevations of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels have occurred patients who have received heparin. Elevation of these enzymes in patients receiving heparin should be interpreted with caution. These elevations typically resolve upon heparin discontinuation.

Laboratory Tests: Periodic platelet counts, hematocrits, and tests for occult blood in stool are recommended during the entire course of heparin therapy, regardless of the route of administration.


Oral Anticoagulants: Heparin sodium may prolong the one-stage prothrombin time. Therefore, when heparin sodium is given with dicumarol or warfarin sodium, a period of at least 5 hours after the last intravenous dose or 24 hours after the last subcutaneous dose should elapse before blood is drawn if a valid prothrombin time is to be obtained.

Platelet Inhibitors: Drugs such as NSAIDS (including acetylsalicylic acid, ibuprofen, indomethacin, and celecoxib), dextran, phenylbutazone, thienopyridines, dipyridamole, hydroxychloroquine, glycoprotein IIv/IIa antagonists (including abciximab, eptifibatide, and tirofiban), and others that interfere with platelet-aggregation reactions (the main hemostatic defense of heparinized patients) may induce bleeding and should be used with caution in patients receiving heparin sodium. To reduce the risk of bleeding, a reduction in the dose of antiplatelet agent or heparin is recommended.

Other Medications that May Interfere with Heparin: Digitalis, tetracyclines, nicotine or antihistamines may partially counteract the anticoagulant action of heparin sodium. Intravenous nitroglycerin administered to heparinized patients may result in a decrease of the partial thromboplastin time with subsequent rebound effect upon discontinuation of nitroglycerin. Careful monitoring of partial thromboplastin time and adjustment of heparin dosage are recommended during coadministration of heparin and intravenous nitroglycerin.

Antithrombin III (human): The anticoagulant effect of heparin is enhanced by concurrent treatment with antithrombin III (human) in patients with hereditary antithrombin III deficiency. To reduce the risk of bleeding, a reduced dosage of heparin is recommended during treatment with antithrombin III (human).


Pregnancy: There are no available data on Heparin Sodium in Sodium Chloride Injection use in pregnant women to inform a drug-associated risk of major birth defects and miscarriage. In published reports heparin exposure during pregnancy did not show evidence of an increased risk of adverse maternal or fetal outcomes in humans. Consider the benefits and risks of Heparin Sodium in Sodium Chloride Injection for the mother and possible risks to the fetus when prescribing Heparin Sodium in Sodium Chloride Injection to a pregnant woman.

Lactation: There is no information regarding the presence of heparin in human milk, the effects on the breastfed child, or the effects on milk production. Due to its large molecular weight, heparin is not likely to be excreted in human milk.

The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for heparin and any potential adverse effects on the breastfed child from heparin or from the underlying maternal condition.

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

Geriatric Use: A higher incidence of bleeding has been reported in patients over 60 years of age, especially women. Clinical studies indicate that lower doses of heparin may be indicated in these patients.


An overdose requires immediate medical attention and treatment. Bleeding is the chief sign of heparin overdosage. Easy bruising, petechial formations, nosebleeds, blood in urine or tarry stools may be the first signs or symptoms of a heparin overdose. In the event of symptomatic heparin overdose, consider stopping heparin infusion.

Neutralization of heparin effect:

When clinical circumstances (bleeding) require reversal of heparinization, protamine sulfate (1% solution) by slow infusion will neutralize heparin sodium. No more than 50 mg should be administered, very slowly in any 10-minute period. Each mg of protamine sulfate neutralizes approximately 100 USP heparin units. The amount of protamine required decreases over time as heparin is metabolized. Although the metabolism of heparin is complex, it may, for the purpose of choosing a protamine dose, be assumed to have a half-life of about 30 minutes after intravenous injection.

Ideally, the dose required to neutralize the action of heparin should be guided by blood coagulation tests or calculated from a protamine neutralization test.

Because fatal reactions often resembling anaphylaxis have been reported with protamine, it should be given only when resuscitation techniques and treatment of anaphylactoid shock are readily available.

For additional information consult the labeling of Protamine Sulfate Injection.

Blood or plasma transfusions may be necessary; these dilute but do not neutralize heparin.


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