heparin – Flashcards

• Potentiates the inhibitory effect of antithrombin on factor Xa and thrombin. • In low doses, prevents the conversion of prothrombin to thrombin by its effects on factor Xa. • Higher doses neutralize thrombin, preventing the conversion of fibrinogen to fibrin. Therapeutic Effect(s): • Prevention of thrombus formation. • Prevention of extension of existing thrombi (full dose).

Contraindicated in: • Hypersensitivity;• Uncontrolled bleeding;• Severe thrombocytopenia;• Open wounds (full dose);• Avoid use of products containing benzyl alcohol in premature infants. Use Cautiously in: • Severe liver or kidney disease; • Retinopathy (hypertensive or diabetic); • Untreated hypertension; • Ulcer disease; • Spinal cord or brain injury; • History of congenital or acquired bleeding disorder; • Malignancy; • OB: May be used during pregnancy, but use with caution during the last trimester and in the immediate postpartum period; • Geri: Women >60 yr have ↑ risk of bleeding. Exercise Extreme Caution in: • Severe uncontrolled hypertension; • Bacterial endocarditis, bleeding disorders; • GI bleeding/ulceration/pathology;• Hemorrhagic stroke; • Recent CNS or ophthalmologic surgery; • Active GI bleeding/ulceration; • History of thrombocytopenia related to heparin.

GI: drug-induced hepatitis. Derm: alopecia (long-term use), rashes, urticaria. Hemat: BLEEDING, HEPARIN-INDUCED THROMBOCYTOPENIA (HIT) (WITH OR WITHOUT THROMBOSIS), Local: pain at injection site. MS: osteoporosis (long-term use). Misc: fever, hypersensitivity.

Heparin is frequently used concurrently or sequentially with other agents affecting coagulation. The risk of potentially serious interactions is greatest with full anticoagulation Drug-Drug • Risk of bleeding may be ↑ by concurrent use of drugs that affect platelet function , including aspirin , NSAIDs , clopidogrel , dipyridamole , some penicillins , ticlopidine , abciximab , eptifibitide , tirofiban , and dextran . • Risk of bleeding may be ↑ by concurrent use of drugs that cause hypoprothrombinemia , including quinidine , cefoperazone , cefotetan , and valproic acid . • Concurrent use of thrombolytics ↑ risk of bleeding. • Heparins affect the prothrombin time used in assessing the response to warfarin . • Digoxin , tetracyclines , nicotine , and antihistamines may ↓ anticoagulant effect of heparin. • Streptokinase may be followed by relative resistance to heparin. Drug-Natural Products: ↑ risk of bleeding with arnica , anise , chamomile , clove , dong quai , fever few , garlic , ginger , and Panax ginseng .

Therapeutic Anticoagulation • IV (Adults): Intermittent bolus—10,000 units, followed by 5000-10,000 units q 4-6 hr. Continuous infusion—5000 units (35-70 units/kg), followed by 20,000-40,000 units infused over 24 hr (approx. 1000 units/hr or 15-18 units/kg/hr).. • IV (Children > 1 yr): Intermittent bolus—50-100 units/kg, followed by 50-100 units/kg q 4 hr. Continuous infusion—Loading dose 75 units/kg, followed by 20 units/kg/hr, adjust to maintain aPTT of 60-85 sec.. • IV (Neonates and Infants <1 yr): Continuous infusion—Loading dose 75 units/kg, followed by 28 units/kg/hr, adjust to maintain aPTT of 60-85 sec.. • SC (Adults): 5000 units IV, followed by initial subcut dose of 10,000-20,000 units, then 8000-10,000 units q 8 hr or 15,000-20,000 units q 12 hr.. Prophylaxis of Thromboembolism • SC (Adults): 5000 units q 8-12 hr (may be started 2 hr prior to surgery).. Cardiovascular Surgery • IV (Adults): At least 150 units/kg (300 units/kg if procedure <60 min; 400 units/kg if >60 min).. • IA (Neonates , Infants, and Children): 100-150 units/kg via an artery prior to cardiac catheterization.. Line Flushing • IV (Adults and Children): 10-100 units/mL (10 units/mL for infants <10 kg, 100 units/mL for all others) solution to fill heparin lock set to needle hub; replace after each use.. Total Parenteral Nutrition • IV (Adults and Children): 05-1 units/mL (final solution concentration) to maintain line patency.. Arterial Line Patency • IA (Neonates): 0.5-2 units/mL.

• Assess for signs of bleeding and hemorrhage (bleeding gums; nosebleed; unusual bruising; black, tarry stools; hematuria; fall in hematocrit or BP; guaiac-positive stools). Notify health care professional if these occur. » Assess patient for evidence of additional or increased thrombosis. Symptoms will depend on area of involvement. » Monitor patient for hypersensitivity reactions (chills, fever, urticaria). SC • Observe injection sites for hematomas, ecchymosis, or inflammation. Lab Test Considerations • Monitor activated partial thromboplastin time (aPTT) and hematocrit prior to and periodically during therapy. When intermittent IV therapy is used, draw aPTT levels 30 min before each dose during initial therapy and then periodically. During continuous administration, monitor aPTT levels every 4 hr during early therapy. For Subcut therapy, draw blood 4-6 hr after injection. » Monitor platelet count every 2-3 days throughout therapy. May cause mild thrombocytopenia, which appears on 4th day and resolves despite continued heparin therapy. Heparin-induced thrombocytopenia (HIT), a more severe form which necessitates discontinuing medication, may develop on 8th day of therapy; may reduce platelet count to as low as 5000/mm3 and lead to increased resistance to heparin therapy. HIT may progress to development of venous and arterial thrombosis (HITT) and may occur up to several wk after discontinuation. Patients who have received a previous course of heparin may be at higher risk for severe thrombocytopenia for several months after the initial course. » May cause hyperkalemia and ↑ AST and ALT levels. Toxicity and Overdose • Protamine sulfate is the antidote. Due to short half-life, overdose can often be treated by withdrawing the drug.

• High Alert: Fatal hemorrhages have occurred in pediatric patients due to errors in which heparin sodium injection vials were confused with heparin flush vials. Carefully examine all heparin sodium injection vials to confirm the correct vial choice prior to administration. Have second practitioner independently check original order, dose calculation, and infusion pump settings. Unintended concomitant use of two heparin products (unfractionated heparin and LMW heparins) has resulted in serious harm or death. Review patients' recent (emergency department, operating room) and current medication administration records before administering any heparin or LMW heparin product. Do not confuse heparin with Hespan (hetastarch in sodium chloride). Do not confuse vials of heparin with vials of insulin. • Inform all personnel caring for patient of anticoagulant therapy. Venipunctures and injection sites require application of pressure to prevent bleeding or hematoma formation. Avoid IM injections of other medications; hematomas may develop. » In patients requiring long-term anticoagulation, oral anticoagulant therapy should be instituted 4-5 days prior to discontinuing heparin therapy. » Solution is colorless to slightly yellow.

• {Additive Compatibility: It is recommended that heparin not be mixed in solution with other medications when given for anticoagulation, even those that are compatible, because changes in rate of heparin infusion may be required that would also affect admixtures.} pH: 5.0-8.0. • SC: Administer deep into subcut tissue. Alternate injection sites between arm and the left and right abdominal wall above the iliac crest. Inject entire length of needle at a 45°- or 90°-angle into a skin fold held between thumb and forefinger; hold skin fold throughout injection. Do not aspirate or massage. Rotate sites frequently. Do not administer IM because of danger of hematoma formation. Solution should be clear; do not inject solution containing particulate matter. • Direct IV: Diluent: Administer loading dose undilutedConcentration: Varies depending upon vial used. • Rate: Administer over at least 1 min. Loading dose given before continuous infusion. • Continuous Infusion: Diluent: Dilute 25,000 units of heparin in 250-500 mL of 0.9% NaCl or D5W. Premixed infusions are already diluted and ready to use. Admixed solutions stable for 24 hr at room temperature or if refrigerated. Premixed infusion stable for 30 days once overwrap removed. Concentration: 50-100 units/mL. • Rate: See Route/Dosage section. Adjust to maintain therapeutic aPTT. Use an infusion pump to ensure accuracy. • Flush: To prevent clot formation in intermittent infusion (heparin lock) sets, inject dilute heparin solution of 10-100 units/0.5-1 mL after each medication injection or every 8-12 hr. To prevent incompatibility of heparin with medication, flush lock set with sterile water or 0.9% NaCl for injection before and after medication is administered.

• Advise patient to report any symptoms of unusual bleeding or bruising to health care professional immediately. » Instruct patient not to take medications containing aspirin or NSAIDs while on heparin therapy. • Caution patient to avoid IM injections and activities leading to injury and to use a soft toothbrush and electric razor during heparin therapy. » Advise patient to inform health care professional of medication regimen prior to treatment or surgery. » Patients on anticoagulant therapy should carry an identification card with this information at all times.

• Prolonged partial thromboplastin time (PTT) of 1.5-2.5 times the control, without signs of hemorrhage. • Prevention of deep vein thrombosis and pulmonary emboli. • Patency of IV catheters.

Therapeutic: anticoagulants Pharmacologic: antithrombotics

This medication bears a heightened risk of causing significant patient harm when it is used in error.