Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 7/19/2022

Drug Summary

What Is Heparin?

Heparin (heparin sodium injectable) is a heterogeneous group of straight-chain anionic mucopolysaccharides, called glycosaminoglycans that have anticoagulant properties used to help prevent clot formation (for example, venous thrombosis, pulmonary embolisms, coagulopathies and coronary artery clots). Heparin is available as generic heparin and under other generic brand names.

What Are Side Effects of Heparin?

Common side effects of Heparin are:

  • easy bleeding and bruising;
  • pain, redness, warmth, irritation, or skin changes where the medicine was injected;
  • itching of your feet; or
  • bluish-colored skin.

Heparin may cause serious side effects including:

  • skin warmth or discoloration,
  • chest pain,
  • irregular heartbeats,
  • shortness of breath,
  • dizziness,
  • anxiety,
  • sweating,
  • unusual bleeding or bruising,
  • severe pain or swelling in your stomach, lower back or growing,
  • dark or blue-colored skin on your hands or feet,
  • nausea,
  • vomiting,
  • loss of appetite,
  • unusual tiredness,
  • bleeding that will not stop,
  • nosebleed,
  • blood in the urine or stool,
  • black or tarry stools,
  • coughing up blood or vomit that looks like coffee grounds,
  • skin changes where the medication was injected,
  • fever,
  • chills,
  • runny nose,
  • watery eyes,
  • easy bruising,
  • purple or red spots under your skin,
  • sudden numbness or weakness,
  • problems with vision or speech,
  • swelling or redness in an arm or leg
  • Thrombocytopenia
  • heparin-induced thrombocytopenia (HIT), and
  • heparin-induced thrombocytopenia and thrombosis (HITT)

Get medical help right away, if you have any of the symptoms listed above.

Seek medical care or call 911 at once if you have the following serious side effects:

  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheartedness, or passing out;
  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

Dosage for Heparin

  • Heparin is available in vials at strengths of 1000, 5000, 10,000 and 20,000 units per ml.
  • Dosage depends on the coagulation problem; many initial doses start with 5000 units IV, but this can change depending on the problem; guidelines for dosages are available.
  • If benzyl alcohol is listed as a preservative for the Heparin preparation, do not use in neonates and infants or nursing mothers.
  • If preparations without benzyl alcohol are used in pediatric patients, the initial dose is usually 50 units per Kg but a pediatric specialist should be consulted.

What Drugs, Substances, or Supplements Interact with Heparin?

Heparin may interact with aspirin or other NSAIDs (nonsteroidal anti-inflammatory drugs), other blood thinners, digoxin, dipyridamole, hydroxychloroquine, indomethacin, nicotine (cigarettes, gum, lozenges, or skin patches), nitroglycerin, antibiotics, and cold, allergy, or sleep medications. Tell your doctor all medications and supplements you use.

Heparin During Pregnancy and Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant while using Heparin. It is unknown if heparin will harm a fetus. Consult your doctor before breastfeeding.

Additional Information

Our Heparin Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

Drug Description


Heparin Sodium Injection, USP is a sterile, nonpyrogenic solution of heparin sodium (derived from porcine intestinal mucosa) in water for injection. Each container contains 10000, 12500, 20000 or 25,000 USP Heparin Units; 40 or 80 mg sodium chloride added to render isotonic (see HOW SUPPLIED section for various sizes and strength). May contain sodium hydroxide and/or hydrochloric acid for pH adjustment. pH 6.0 (5.0 to 7.5).

The solution contains no bacteriostat, antimicrobial agent or added buffer and is intended for use only as a single-dose injection. When smaller doses are required, the unused portion should be discarded.

Heparin sodium in the ADD-Vantage™ system is intended for intravenous administration only after dilution.

Heparin Sodium, USP is a heterogenous group of straight-chain anionic mucopolysaccharides, called glycosamino-glycans 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-2-sulfamino-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. The potency is determined by a biological assay using a USP reference standard based on units of heparin activity per milligram.

Structure of Heparin Sodium (representative subunits):

Heparin Sodium Structural Formula Illustration

Indications & Dosage


Heparin sodium is indicated for:

  • Prophylaxis and treatment of venous thromboembolism and pulmonary embolism;
  • Atrial fibrillation with embolization;
  • Treatment of acute and chronic consumptive coagulopathies (disseminated intravascular coagulation);
  • Prevention of clotting in arterial and cardiac surgery;
  • Prophylaxis and treatment of peripheral arterial embolism;
  • Anticoagulant use in blood transfusions, extracorporeal circulation, and dialysis procedures.


Preparation For Administration

Confirm the selection of the correct formulation and strength prior to administration of the drug.

Instructions for Use for the freeflex® Bag

Leave bag in the overwrap until time of use.

The intact port cap provides visual tamper evidence. Do not use if port cap is prematurely removed.

Maintain strict aseptic technique during handling.

To Open
  1. Always inspect the bag before and after removal from the overwrap.
  2. Place the bag on a clean, flat surface. Starting in the bottom corner, peel the overwrap open and remove the bag.
  3. Check the bag for leaks by squeezing firmly. If leaks are found, discard the bag.
  4. Do not use if the solution is cloudy or a precipitate is present.
To Prepare For Administration
  1. Immediately before connecting the infusion set, firmly grasp the BLUE infusion port cap with the arrow pointing away from the bag between index finger and thumb. Gently break off the port cap. The membrane of the infusion port is sterile, and disinfection before initial use is not necessary if proper aseptic handling technique is followed.
  2. Use a non-vented infusion set or close the air-inlet on a vented set. The BLUE infusion port is compatible with spike systems produced according to ISO 8536-4, with an external spike diameter of 5.5 to 5.7 mm.
  3. Close the roller clamp of the infusion set.
  4. Hold the base of the BLUE infusion port and insert the spike by rotating your wrist slightly until the spike is fully inserted.
  5. The port membrane contains a self-sealing septum that helps prevent leakage after removing the spike. The infusion port is not intended to be spiked more than once.
  6. Hang from the hole at the top of the bag.
  7. For Single Use Only. Discard unused portion.

Do not admix with other drugs.

Do not use flexible container in series connections.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

Laboratory Monitoring For Efficacy and Safety

Adjust the dosage of heparin sodium according to the patient’s coagulation test results. When heparin is given by continuous intravenous infusion, determine the coagulation time approximately every 4 hours in the early stages of treatment. When the drug is administered intermittently by intravenous injection, perform coagulation tests before each injection during the early stages of treatment and at appropriate intervals thereafter. Dosage is considered adequate when the activated partial thromboplastin time (APTT) is 1.5 to 2 times the normal or when the whole blood clotting time is elevated approximately 2.5 to 3 times the control value.

Periodic platelet counts, hematocrits, and tests for occult blood in stool are recommended during the entire course of heparin therapy.

Therapeutic Anticoagulant Effect With Full-Dose Heparin

The dosing recommendations in Table 1 are based on clinical experience. Although dosage must be adjusted for the individual patient according to the results of suitable laboratory tests, the following dosage schedules may be used as guidelines:

Table 1: Recommended Adult Full-Dose Heparin Regimens for Therapeutic Anticoagulant Effect

Method of AdministrationFrequencyRecommended Dose*
IntermittentInitial Dose10,000 units
Intravenous Injection
Every 4 to 6 hours5,000 to 10,000 units
Continuous Intravenous InfusionInitial Dose5,000 units by intravenous injection
Continuous20,000 to 40,000 units per 24 hours
* Based on 150 lb. (68 kg) patient.

Pediatric Use

There are no adequate and well-controlled studies on heparin use in pediatric patients. Pediatric dosing recommendations are based on clinical experience.

In general, the following dosage schedule may be used as a guideline in pediatric patients:

Initial Dose: 75 to 100 units/kg (intravenous bolus over 10 minutes)

Maintenance Dose Infants: 25 to 30 units/kg/hour; Infants < 2 months have the highest requirements (average 28 units/kg/hour) Children > 1 year of age: 18 to 20 units/kg/hour; Older children may require less heparin, similar to weight-adjusted adult dosage

Monitoring: Adjust heparin to maintain aPTT of 60 to 85 seconds, assuming this reflects an anti-Factor Xa level of 0.35 to 0.70.

Cardiovascular Surgery

Patients undergoing total body perfusion for open-heart surgery should receive an initial dose of not less than 150 units of heparin sodium per kilogram of body weight. Frequently, a dose of 300 units per kilogram is used for procedures estimated to last less than 60 minutes or 400 units per kilogram for those estimated to last longer than 60 minutes.

Converting To Warfarin

To ensure continuous anticoagulation when converting from Heparin Sodium to warfarin, continue full heparin therapy for several days until the INR (prothrombin time) has reached a stable therapeutic range. Heparin therapy may then be discontinued without tapering [see DRUG INTERACTIONS].

Converting To Oral Anticoagulants Other Than Warfarin

For patients currently receiving intravenous heparin, stop intravenous infusion of heparin sodium immediately after administering the first dose of oral anticoagulant; or for intermittent intravenous administration of heparin sodium, start oral anticoagulant 0 to 2 hours before the time that the next dose of heparin was to have been administered.

Extracorporeal Dialysis

Follow equipment manufacturer’s operating directions carefully. A dose of 25 to 30 units/kg followed by an infusion rate of 1,500 to 2,000 units/hour is suggested based on pharmacodynamic data if specific manufacturers' recommendations are not available.


Dosage Forms And Strengths

Heparin Sodium In 0.45% Sodium Chloride Injection Is Available As
  • Injection: 50 USP units per mL in 0.45% Sodium Chloride clear solution (25,000 USP units per 500 mL) in single-dose freeflex® bag
  • Injection: 100 USP units per mL in 0.45% Sodium Chloride clear solution (25,000 USP units per 250 mL) in single-dose freeflex® bag
Heparin Sodium In 5% Dextrose Injection Is Available As
  • Injection: 50 USP units per mL in 5% Dextrose clear solution (25,000 USP units per 500 mL) in single-dose freeflex® bag
  • Injection: 100 USP units per mL in 5% Dextrose clear solution (25,000 USP units per 250 mL) in single-dose freeflex® bag

Storage And Handling

Heparin Sodium in 0.45% Sodium Chloride Injection is supplied as follows:

Product CodeUnit of SaleStrengthEach
518077NDC 63323-518-77 Unit of 2425,000 USP units per 500 mL (50 USP units per mL)NDC 63323-518-01 500 mL Single Dose freeflex® Bag
517074NDC 63323-517-74 Unit of 2425,000 USP units per 250 mL (100 USP units per mL)NDC 63323-517-01 250 mL Single Dose freeflex® Bag

Heparin Sodium in 5% Dextrose Injection is supplied as follows:

Product CodeUnit of SaleStrengthEach
507277NDC 63323-522-77 Unit of 2425,000 USP units per 500 mL (50 USP units per mL)NDC 63323-522-01 500 mL Single Dose freeflex® Bag
507374NDC 63323-523-74 Unit of 2425,000 USP units per 250 mL (100 USP units per mL)NDC 63323-523-01 250 mL Single Dose freeflex® Bag

Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature]. Avoid excessive heat.

Do not freeze.

The container closure is not made with natural rubber latex.

Non-PVC, Non-DEHP, Sterile.

Manufactured for: Made in Norway, www.fresenius-kabi.com/us, 451475C. Revised: Dec 2019

Side Effects


The following serious adverse reactions are described elsewhere in the labeling:

  • Heparin-Induced Thrombocytopenia (HIT) and Heparin-Induced Thrombocytopenia and Thrombosis (HITT) [see WARNINGS AND PRECAUTIONS]
  • Thrombocytopenia [see WARNINGS AND PRECAUTIONS]
  • Heparin Resistance [see WARNINGS AND PRECAUTIONS]
  • Hypersensitivity [see WARNINGS AND PRECAUTIONS]

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of heparin sodium. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency.

  • Hemorrhage - Hemorrhage is the chief complication that may result from heparin therapy [see WARNINGS AND PRECAUTIONS]. Gastrointestinal or urinary tract bleeding during anticoagulant therapy may indicate the presence of an underlying occult lesion. Bleeding can occur at any site but certain specific hemorrhagic complications may be difficult to detect:
    • Adrenal hemorrhage, with resultant acute adrenal insufficiency, has occurred with heparin therapy, including fatal cases.
    • Ovarian (corpus luteum) hemorrhage developed in a number of women of reproductive age receiving short- or long-term anticoagulant therapy.
    • Retroperitoneal hemorrhage.
  • HIT and HITT, including delayed onset cases [see WARNINGS AND PRECAUTIONS].
  • Hypersensitivity - Generalized hypersensitivity reactions have been reported with chills, fever, and urticaria as the most usual manifestations, and asthma, rhinitis, lacrimation, headache, nausea and vomiting, and anaphylactoid reactions, including shock, occurring more rarely. Itching and burning, especially on the plantar side of the feet, may occur [see WARNINGS AND PRECAUTIONS].
  • Elevations of serum aminotransferases - Significant elevations of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels have occurred in patients who have received heparin.
  • Others - Osteoporosis following long-term administration of high-doses of heparin, cutaneous necrosis after systemic administration, suppression of aldosterone synthesis, delayed transient alopecia, priapism, and rebound hyperlipemia on discontinuation of heparin sodium have also been reported.
Drug Interactions


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 salicylic acid, ibuprofen, indomethacin, and celecoxib), dextran, phenylbutazone, thienopyridines, dipyridamole, hydroxychloroquine, glycoprotein IIb/IIIa 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 Interactions

Digitalis, tetracyclines, nicotine, antihistamines, or intravenous nitroglycerin may partially counteract the anticoagulant action of heparin sodium.

Heparin Sodium In 5% Dextrose Injection

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).

Warnings & Precautions


Included as part of the PRECAUTIONS section.


Fatal Medication Errors

Do not use this product as a “catheter lock flush” product. Heparin is supplied in various strengths. Fatal hemorrhages have occurred due to medication errors. Carefully examine all heparin products to confirm the correct container choice prior to administration of the drug.


Avoid using heparin in the presence of major bleeding, except when the benefits of heparin therapy outweigh the potential risks.

Hemorrhage, including fatal events, has occurred in patients receiving Heparin Sodium. Hemorrhage can occur at virtually any site in patients receiving heparin. Adrenal hemorrhage (with resultant acute adrenal insufficiency), ovarian hemorrhage, and retroperitoneal hemorrhage have occurred during anticoagulant therapy with heparin [see ADVERSE REACTIONS]. A higher incidence of bleeding has been reported in patients, particularly women, over 60 years of age [see CLINICAL PHARMACOLOGY]. An unexplained fall in hematocrit or fall in blood pressure should lead to serious consideration of a hemorrhagic event.

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.
  • 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).
  • Gastrointestinal — Ulcerative lesions and continuous tube drainage of the stomach or small intestine.
  • Other — Menstruation, liver disease with impaired hemostasis.

Heparin-Induced Thrombocytopenia (HIT) And Heparin-Induced Thrombocytopenia and Thrombosis (HITT)

HIT is a serious antibody-mediated reaction resulting from irreversible aggregation of platelets. 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 known as heparin-induced thrombocytopenia and 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, thrombus formation on a prosthetic cardiac valve, mesenteric thrombosis, renal arterial thrombosis, skin necrosis, gangrene of the extremities that may lead to amputation, and possibly death. Monitor thrombocytopenia of any degree closely. If the platelet count falls below 100,000/mm3 or if recurrent thrombosis develops, promptly discontinue heparin, evaluate for HIT and HITT, and, if necessary, administer an alternative anticoagulant.

HIT or HITT can occur up to several weeks after the discontinuation of heparin therapy. Patients presenting with thrombocytopenia or thrombosis after discontinuation of heparin should be evaluated for HIT or HITT.


Thrombocytopenia has been reported to occur in patients receiving heparin with a reported incidence of 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. Monitor thrombocytopenia of any degree closely. If the count falls below 100,000/mm3 or if recurrent thrombosis develops, promptly discontinue heparin, evaluate for HIT and, if necessary, administer an alternative anticoagulant [see WARNINGS AND PRECAUTIONS].

Coagulation Testing and Monitoring

When using a full dose heparin regimen, adjust the heparin dose based on frequent blood coagulation tests. If the coagulation test is unduly prolonged or if hemorrhage occurs, heparin sodium should be discontinued promptly [see OVERDOSAGE]. Periodic platelet counts, hematocrits are recommended during the entire course of heparin therapy [see DOSAGE AND ADMINISTRATION].

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 antithrombin III deficiency. Close monitoring of coagulation tests is recommended in these cases. Adjustment of heparin doses based on anti-Factor Xa levels may be warranted.


Patients with documented hypersensitivity to heparin should be given the drug only in clearly life-threatening situations [see ADVERSE REACTIONS]. Because heparin sodium is derived from animal tissue, monitor for signs and symptoms of hypersensitivity when it is used in patients with a history of allergy.

Heparin Sodium In 5% Dextrose Injection

This product contains sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. Sulfite sensitivity is seen more frequently in asthmatic than in nonasthmatic people.

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment Of Fertility

No long-term studies in animals have been performed to evaluate the carcinogenic potential of heparin. Also, no studies in animals have been performed concerning mutagenesis or impairment of fertility.

Use In Specific Populations


Risk Summary

There are no available data on heparin sodium 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. No teratogenicity, but early embryo-fetal death was observed in animal reproduction studies with administration of heparin sodium to pregnant rats and rabbits during organogenesis at doses approximately 10 times the maximum recommended human dose (MRHD) of 40,000 units/24 hours infusion (see Data). Consider the benefits and risks of Heparin Sodium in 0.45% Sodium Chloride Injection or Heparin Sodium in 5% Dextrose Injection to a pregnant woman and possible risks to the fetus when prescribing Heparin Sodium in 0.45% Sodium Chloride Injection or Heparin Sodium in 5% Dextrose Injection to a pregnant woman.

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.


Human Data

The maternal and fetal outcomes associated with uses of heparin via various dosing methods and administration routes during pregnancy have been investigated in numerous studies. These studies generally reported normal deliveries with no maternal or fetal bleeding and no other complications.

Animal Data

In a published study conducted in rats and rabbits, pregnant animals received heparin intravenously during organogenesis at a dose of 10,000 USP units/kg/day, approximately 10 times the maximum human daily dose based on body weight. The number of early resorptions increased in both species.

There was no evidence of teratogenic effects.


Risk Summary

There is no information regarding the presence of Heparin Sodium in 0.45% Sodium Chloride Injection or Heparin Sodium in 5% Dextrose Injection in human milk, the effects on the breastfed infant, or the effects on milk production. Due to its large molecular weight, heparin is not likely to be excreted in human milk, and any heparin in milk would not be orally absorbed by a nursing infant. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for Heparin Sodium in 0.45% Sodium Chloride Injection or Heparin Sodium in 5% Dextrose Injection and any potential adverse effects on the breastfed infant from Heparin Sodium in 0.45% Sodium Chloride Injection or Heparin Sodium in 5% Dextrose Injection or from the underlying maternal condition [see Use In Specific Populations].

Pediatric Use

There are no adequate and well-controlled studies on heparin use in pediatric patients. Pediatric dosing recommendations are based on clinical experience [see DOSAGE AND ADMINISTRATION].

Geriatric Use

There are limited adequate and well-controlled studies in patients 65 years and older. However, a higher incidence of bleeding has been reported in patients over 60 years of age, especially women [see WARNINGS AND PRECAUTIONS]. Lower doses of heparin may be indicated in these patients [see CLINICAL PHARMACOLOGY].



Bleeding may result from heparin overdosage.

Neutralization Of Heparin Effect

When circumstances (e.g., 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 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 1/2 hour after intravenous injection.

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

For additional information, consult the prescribing information for Protamine Sulfate Injection, USP.



The use of Heparin Sodium in 0.45% Sodium Chloride Injection or Heparin Sodium in 5% Dextrose Injection is contraindicated in patients with the following conditions:

  • History of Heparin-Induced Thrombocytopenia (HIT) and Heparin-Induced Thrombocytopenia and Thrombosis (HITT) [see WARNINGS AND PRECAUTIONS]
  • Known hypersensitivity to heparin or pork products (e.g., anaphylactoid reactions) [see ADVERSE REACTIONS]
  • In whom suitable blood coagulation tests — e.g., the whole blood clotting time, partial thromboplastin time, etc., - cannot be performed at appropriate intervals (this contraindication refers to full-dose heparin; there is usually no need to monitor coagulation parameters in patients receiving low-dose heparin) [see WARNINGS AND PRECAUTIONS]
  • An uncontrolled bleeding state [see WARNINGS AND PRECAUTIONS], except when this is due to disseminated intravascular coagulation.
Clinical Pharmacology


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 clotting 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.


Bleeding time is usually unaffected by heparin. Various times (activated clotting time, activated partial thromboplastin time, prothrombin time, whole blood clotting time) are prolonged by full therapeutic doses of heparin; in most cases it is not measurably affected by low doses of heparin.



Heparin is not absorbed through the gastrointestinal tract and therefore administered via parenteral route. Peak plasma concentration and the onset of action are achieved immediately after intravenous administration.


Heparin is highly bound to antithrombin, fibrinogens, globulins, serum proteases and lipoproteins. The volume of distribution is 0.07 L/kg.



Heparin does not undergo enzymatic degradation.


Heparin is mainly cleared from the circulation by liver and reticuloendothelial cells mediated uptake into extravascular space. Heparin undergoes biphasic clearance, a) rapid saturable clearance (zero order process due to binding to proteins, endothelial cells and macrophage) and b) slower first order elimination. The plasma half-life is dose-dependent and it ranges from 0.5 to 2 h.

Specific Population

Geriatric Patients

Patients over 60 years of age, following similar doses of heparin, may have higher plasma levels of heparin and longer activated partial thromboplastin times (APTTs) compared with patients under 60 years of age [see Use In Specific Populations].

Medication Guide



Inform patients that it may take them longer than usual to stop bleeding, that they may bruise and/or bleed more easily when they are treated with heparin, and that they should report any unusual bleeding or bruising to their physician. Hemorrhage can occur at virtually any site in patients receiving heparin. Fatal hemorrhages have occurred [see WARNINGS AND PRECAUTIONS].

Prior To Surgery

Advise patients to inform physicians and dentists that they are receiving heparin before any surgery is scheduled [see WARNINGS AND PRECAUTIONS].

Heparin-Induced Thrombocytopenia

Inform patients of the risk of heparin-induced thrombocytopenia (HIT). HIT may progress to the development of venous and arterial thromboses, a condition known as heparin-induced thrombocytopenia and thrombosis. HIT and HITT can occur up to several weeks after the discontinuation of heparin therapy [see WARNINGS AND PRECAUTIONS].


Inform patients that generalized hypersensitivity reactions have been reported [see WARNINGS AND PRECAUTIONS, ADVERSE REACTIONS].

Other Medications

Because of the risk of hemorrhage, advise patients to inform their physicians and dentists of all medications they are taking, including non-prescription medications, and before starting any new medication [see DRUG INTERACTIONS].

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