Heparin-induced thrombocytopenia (HIT) is a serious antibody-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. 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 sodium should be evaluated for HIT or HITT.
Serious and fatal adverse reactions including “gasping syndrome” can occur in neonates and infants treated with benzyl alcohol-preserved drugs, including Heparin Sodium Injection vials. The “gasping syndrome” is characterized by central nervous system depression, metabolic acidosis, and gasping respirations.
When prescribing Heparin Sodium Injection vials in infants consider the combined daily metabolic load of benzyl alcohol from all sources including Heparin Sodium Injection vials (contains 10.42 mg of benzyl alcohol per mL) and other drugs containing benzyl alcohol. The minimum amount of benzyl alcohol at which toxicity may occur is not known [see Use in Specific Populations (8.4)].
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. 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 HITT, and, if necessary, administer an alternative anticoagulant [see Warnings and Precautions (5.3)].
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, discontinue heparin promptly [see Overdosage (10)]. Periodic platelet counts and hematocrits are recommended during the entire course of heparin therapy, regardless of the route of administration [see Dosage and Administration (2.3) ].
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.
Because Heparin Sodium Injection is derived from animal tissue, it should be used with caution in patients with a history of allergy.
The following clinically significant adverse reactions are described elsewhere in the labeling:
- Hemorrhage [see Warnings and Precautions (5.2) ]
- Heparin-Induced Thrombocytopenia and Heparin-Induced Thrombocytopenia and Thrombosis [see Warnings and Precautions (5.3) ]
- Risk of Serious Adverse Reactions in Infants Due to Benzyl Alcohol Preservative [see Warnings and Precautions (5.4) ]
- Thrombocytopenia [see Warnings and Precautions (5.5) ]
- Heparin Resistance [see Warnings and Precautions (5.7) ]
- Hypersensitivity [see Warnings and Precautions (5.8) ]
The following adverse reactions have been identified during post approval use of Heparin Sodium Injection. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
- Hemorrhage is the chief complication that may result from heparin therapy [see Warnings and Precautions (5.2) ]. 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 heparin therapy.
- Retroperitoneal hemorrhage
- HIT and HITT, including delayed onset cases [see Warnings and Precautions (5.3) ].
- Local Irritation – Local irritation, erythema, mild pain, hematoma or ulceration may follow deep subcutaneous (intrafat) injection of heparin sodium. Because these complications are much more common after intramuscular use, the intramuscular route is not recommended.
- Histamine-like reactions – Such reactions have been observed at the site of injections. Necrosis of the skin has been reported at the site of subcutaneous injection of heparin, occasionally requiring skin grafting [see Warnings and Precautions (5.3) ].
- 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 less frequently. Itching and burning, especially on the plantar side of the feet, may occur [see Warnings and Precautions (5.8) ].
- Elevations of aminotransferases – Significant elevations of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels have occurred in patients who have received heparin.
- Miscellaneous — 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.
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.
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.
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).
There are no available data on Heparin Sodium 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. 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 45,000 units/day [see Data ]. Consider the benefits and risks of Heparin Sodium Injection for the mother and possible risks to the fetus when prescribing Heparin Sodium Injection to a pregnant woman.
If available, preservative-free Heparin Sodium Injection is recommended when heparin therapy is needed during pregnancy. There are no known adverse outcomes associated with fetal exposure to the preservative benzyl alcohol through maternal drug administration; however, the preservative benzyl alcohol can cause serious adverse events and death when administered intravenously to neonates and infants [see Warnings and Precautions (5.4) ]
The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.
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.
In a published study conducted in rats and rabbits, pregnant animals received heparin intravenously during organogenesis at a dose of 10,000 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.
If available, preservative-free Heparin Sodium Injection is recommended when heparin therapy is needed during lactation. Benzyl alcohol present in maternal serum is likely to cross into human milk and may be orally absorbed by a nursing infant. There is no information regarding the presence of Heparin Sodium 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 Injection and any potential adverse effects on the breastfed infant from Heparin Sodium Injection or from the underlying maternal condition [see Use in Specific Populations (8.4) ].
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 (2.5) ].
Carefully examine all Heparin Sodium Injection vials and syringes to confirm choice of the correct strength prior to administration of the drug. Pediatric patients, including neonates, have died as a result of medication errors in which Heparin Sodium Injection vials have been confused with “catheter lock flush” vials [see Warnings and Precautions (5.1) ].
Benzyl Alcohol Toxicity
Use preservative-free Heparin Sodium Injection in neonates and infants.
Serious adverse reactions including fatal reactions and the “gasping syndrome” occurred in premature neonates and infants in the neonatal intensive care unit who received drugs containing benzyl alcohol as a preservative. In these cases, benzyl alcohol dosages of 99 to 234 mg/kg/day produced high levels of benzyl alcohol and its metabolites in the blood and urine (blood levels of benzyl alcohol were 0.61 to 1.378 mmol/L). Additional adverse reactions included gradual neurological deterioration, seizures, intracranial hemorrhage, hematologic abnormalities, skin breakdown, hepatic and renal failure, hypotension, bradycardia, and cardiovascular collapse. Preterm, low-birth weight infants may be more likely to develop these reactions because they may be less able to metabolize benzyl alcohol.
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, particularly women, over 60 years of age [see Warnings and Precautions (5.2) ]. Patients over 60 years of age may require lower doses of heparin.
Lower doses of heparin may be indicated in these patients [see Clinical Pharmacology (12.3) ].
Bleeding is the chief sign of heparin overdosage.
Neutralization of Heparin Effect
When clinical circumstances (bleeding) require reversal of the heparin effect, 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 1/2 hour after intravenous injection.
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.
Heparin is a heterogeneous group of straight-chain anionic mucopolysaccharides, called glycosaminoglycans, possessing anticoagulant properties. It is composed of polymers of alternating derivations of α-D-glucosamido (N -sulfated O -sulfated or N -acetylated) and O -sulfated uronic acid (α-L-iduronic acid or β-D-glucoronic acid).
Structure of heparin sodium (representative subunits):
Heparin Sodium Injection, USP is a sterile solution of heparin sodium derived from porcine intestinal mucosa, standardized for anticoagulant activity. It is to be administered by intravenous or deep subcutaneous routes. The potency is determined by a biological assay using a USP reference standard based on units of heparin activity per milligram.
Heparin Sodium Injection, USP preserved with Benzyl Alcohol is available in the following concentrations/mL:
|Heparin Sodium||Sodium Chloride||Benzyl Alcohol|
|1,000 USP units||8.6 mg||10.42 mg|
|5,000 USP units||7 mg||10.42 mg|
|10,000 USP units||5 mg||10.42 mg|
pH 5.0-7.5; sodium hydroxide and/or hydrochloric acid added, if needed, for pH adjustment.
Heparin Sodium Injection, USP, preservative-free is available in the following concentrations:
5,000 USP units/1 mL
|5,000 USP units/0.5 mL||5 mg|
pH 5.0-7.5; sodium hydroxide and/or hydrochloric acid added, if needed, for pH adjustment.
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