HEPARIN Drug Interactions: What You Need to Know

INTERACTIONS

• Drugs that interfere with coagulation, platelet aggregation or drugs that counteract coagulation may induce bleeding ( 7 )
• Andexanet alfa may reduce the efficacy of heparin when used concomitantly ( 7.3 )

7.1 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.

7.2 Platelet Inhibitors Drugs such as acetylsalicylic acid, dextran, phenylbutazone, ibuprofen, indomethacin, dipyridamole, hydroxychloroquine 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.

7.3 Unresponsiveness to Heparin With Concomitant Use With Andexanet Alfa Andexanet binds to heparin-bound antithrombin III (ATIII) and may reduce the anticoagulant effect of heparin. Unresponsiveness to unfractionated heparin may lead to serious and life-threatening thrombotic events. Use of andexanet alfa as an antidote for heparin has not been established. Avoid use of heparin after use of andexanet alfa for the reversal of direct Factor Xa inhibitors (apixaban and rivaroxaban). If anticoagulation is needed, use an alternative anticoagulant to heparin <span class="opacity-50 text-xs">[see Warnings and Precautions (5.4) ]</span> .

7.4 Other Interactions Digitalis, tetracyclines, nicotine, or antihistamines, or intravenous nitroglycerin 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.

7.5 Drug/Laboratory Tests Interactions Prothrombin time – Heparin sodium may prolong the one-stage prothrombin time. Therefore, when heparin sodium is given with warfarin, allow a period of at least 5 hours after the last intravenous dose or 24 hours after the last subcutaneous dose of heparin to elapse before blood is drawn to obtain a valid prothrombin time.

Hyperaminotransferasemia

Significant elevations of aminotransferase AST (SGOT) and ALT (SGPT) levels have occurred in a high percentage of patients (and healthy subjects) who have received heparin. Since aminotransferase determinations are important in the differential diagnosis of myocardial infarction, liver disease and pulmonary emboli, rises that might be caused by drugs (like heparin) should be interpreted with caution.

The use of 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 (5.3) ]
• Known hypersensitivity to heparin or pork products (e.g., anaphylactoid reactions) [see Warnings and Precautions (5.7) , Adverse Reactions (6.1) ]
• 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 (5.5) ]
• Uncontrollable active bleeding state except when this is due to disseminated intravascular coagulation [see Warnings and Precautions (5.2) ].
• History of heparin-induced thrombocytopenia (HIT) or heparin-induced thrombocytopenia and thrombosis (HITT). ( 4 )
• Known hypersensitivity to heparin or pork products. ( 4 )
• In whom suitable blood coagulation tests cannot be performed at appropriate intervals. ( 4 )
• Uncontrollable active bleeding state, except when this is due to disseminated intravascular coagulation. ( 4 )

AND PRECAUTIONS

• Fatal Medication Errors: Confirm choice of correct strength prior to administration. ( 5.1 )
• Hemorrhage: Fatal cases have occurred. Monitor for signs of bleeding and manage promptly. ( 5.2 )
• HIT or HITT: Monitor for signs and symptoms and discontinue if indicative of HIT or HITT. ( 5.3)
• Thrombocytopenia: Monitor platelet count during therapy; discontinue heparin if HIT or HITT is suspected. ( 5.4 )
• Monitoring: Blood coagulation tests guide therapy for full-dose heparin. Monitor platelet count and hematocrit in all patients receiving heparin. ( 5.5 )
• Heparin Resistance: Increased resistance to heparin is frequently encountered in fever, thrombosis, thrombophlebitis, infections with thrombosing tendencies, myocardial infarction, cancer and in postsurgical patients. ( 5.6 )
• Hypersensitivity Reactions: Use in patients with prior reactions only in life-threatening situations. ( 5.7 )
• Hyperkalemia: Measure plasma potassium in patients at risk of hyperkalemia before starting heparin therapy and periodically in all patients. ( 5.8 )
• Elevations of Serum Aminotransferases: Interpret elevation of these enzymes with caution. ( 5.9 )

5.1 Fatal Medication Errors Do not use this product as a &quot;catheter lock flush&quot; 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.

5.2 Hemorrhage Hemorrhage, including fatal events, has occurred in patients receiving heparin sodium. 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. Adrenal hemorrhage (with resultant acute adrenal insufficiency), ovarian hemorrhage, and retroperitoneal hemorrhage have occurred during anticoagulant therapy with heparin <span class="opacity-50 text-xs">[see Adverse Reactions (6.1) ]</span> . A higher incidence of bleeding has been reported in patients, particularly women, over 60 years of age <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.3) ]</span> . 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.

5.3 Heparin-Induced Thrombocytopenia (HIT) and Heparin-Induced Thrombocytopenia and Thrombosis (HITT) HIT is a serious immune-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 HITT. Thrombotic events may also be the initial presentation for HIT. 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. Once HIT or HITT is diagnosed or strongly suspected, discontinue all heparin sources (including heparin flushes) and use an alternative anticoagulant. Immune-mediated HIT is diagnosed based on clinical findings supplemented by laboratory tests confirming the presence of antibodies to heparin, or platelet activation induced by heparin. Obtain platelet counts at baseline and periodically during heparin administration. A drop in platelet count greater than 50% from baseline is considered indicative of HIT. Platelet counts begin to fall 5 to 10 days after exposure to heparin in heparin-naïve individuals and reach a threshold by days 7 to 14. In contrast, “rapid onset” HIT can occur very quickly (within 24 hours following heparin initiation), especially in patients with a recent exposure to heparin (i.e., previous 3 months). Thrombosis development shortly after documenting thrombocytopenia is a characteristic finding in almost half of all patients with HIT. Monitor thrombocytopenia of any degree closely. If the platelet count falls below 100,000/mm 3 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.

5.4 Thrombocytopenia 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/mm 3 or if recurrent thrombosis develops, promptly discontinue heparin, evaluate for HIT, and, if necessary, administer an alternative anticoagulant <span class="opacity-50 text-xs">[see Warnings and Precautions (5.3) ]</span>.

5.5 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 <span class="opacity-50 text-xs">[see Overdosage (10) ]</span> . Periodic platelet counts, hematocrits and tests for occult blood in stool are recommended during the entire course of heparin therapy <span class="opacity-50 text-xs">[see Dosage and Administration (2.2) ]</span> .

5.6 Heparin Resistance Increased resistance to heparin is frequently encountered in fever, thrombosis, thrombophlebitis, infections with thrombosing tendencies, myocardial infarction, cancer and in postsurgical patients, and patients with antithrombin III 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.

5.7 Hypersensitivity Reactions 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 <span class="opacity-50 text-xs">[see Adverse Reactions (6.1) ]</span> .

Because Heparin

Sodium in 5% Dextrose Injection is derived from animal tissue, monitor for signs and symptoms of hypersensitivity when it is used in patients with a history of allergy to pork products. 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.

5.8 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. Measure plasma potassium in patients at risk of hyperkalemia before starting heparin therapy and periodically in all patients treated for more than 5 days or earlier as deemed fit by the clinician.

5.9 Elevations of Serum Aminotransferases Significant elevations of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels have occurred in 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.