1. Anticoagulants, Antiplatelets, and Thrombolytics
Chapter 45
Anticoagulants, Antiplatelets, and Thrombolytics
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2. Drugs Used to Maintain or Restore Circulation
Anticoagulants: Prevent the formation of clots that inhibit circulation
Antiplatelets (antithrombotics): Prevent platelet aggregation
Thrombolytics: Attack and dissolve blood clots that have already formed
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3. Thrombus Formation Pathophysiology Formation of clot in artery or vein
Caused by decreased circulation, platelet aggregation on vessel wall, blood coagulation
Arterial clot formation
Platelets initiate process.
Fibrin formation occurs.
RBCs are trapped in fibrin mesh.
Venous clot formation
Platelet aggregation with fibrin that attaches to RBCs
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4. Action of the Parenteral Anticoagulant Heparin
Anticoagulants
Heparins
Action of the Parenteral Anticoagulant Heparin
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5. Anticoagulants (Cont.)
Heparins
Low-molecular-weight heparin (LMWH): enoxaparin sodium (Lovenox), dalteparin sodium (Fragmin), and tinzaparin sodium (Innohep)
Contraindications
Stroke, peptic ulcer, blood anomalies
Patients having eye, brain, or spinal surgery
Administration of heparins
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6. Anticoagulants (Cont.)
Heparins
Most commonly prescribed to prevent DVT and acute pulmonary embolism after orthopedic or abdominal surgery
Heparin laboratory values
PTT 1.5 to 2 times control value (control 60 to 70 seconds)
aPTT 30 to 85 seconds (control 20 to 35 seconds)
Side effects
Bleeding
Protamine
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7. Direct Thrombin Inhibitors
Directly inhibit thrombin from converting fibrinogen to fibrin
Administered intravenously:
Argatroban (Acova)
Bivalirubin (Angiomax)
Lepirudin (Refludan)
Administered subcutaneously:
Desirudin (Iprivask)
Oral anticoagulant that does not require routine coagulation monitoring:
Dabigatran (Pradaxa)
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8. Warfarin (Coumadin) Oral anticoagulants
Inhibit hepatic synthesis of vitamin K, thus affecting the clotting factors II, VII, IX, and X
Used mainly to prevent thromboembolic conditions such as thrombophlebitis, pulmonary embolism, and embolism formation caused by atrial fibrillation, which can lead to a stroke (CVA)
Monitor therapeutic range
PT 1.25 to 2.5 times control value (11 to 15 seconds)
INR 2 to 3 (normal 1.3 to 2)
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9. Warfarin (Coumadin) (Cont.)
Vitamin K
Antidote for warfarin overdose
24 to 48 hours to be effective
For acute bleeding, fresh frozen plasma is indicated.
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10. Xa Inhibitor: Oral Anticoagulants
Rivaroxaban (Xarelto)
Apixaban (Eliquis)
Do not require routine coagulation monitoring
Administered q.d. or b.i.d
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11. Anticoagulant Antagonists
Vitamin K1 (phytonadione)
Antagonist of warfarin
Used for warfarin overdose or uncontrollable bleeding
Usually 1 to 10 mg of vitamin K1 is given at once
Failure to control bleeding: Fresh whole blood, fresh-frozen plasma or platelets
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12. Nursing Process: Warfarin and Heparin
Assessment
Nursing diagnosis
Planning
Nursing interventions
Patient teaching
Cultural considerations
Evaluation
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13. Antiplatelets
Used to prevent thrombosis in the arteries by suppressing platelet aggregation
Heparin and warfarin prevent thrombosis in the veins.
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14. Antiplatelets (Cont.) Prophylactic use in
Prevention of myocardial infarction or stroke for patients with familial history
Prevention of a repeat myocardial infarction or stroke
Prevention of a stroke for patients having transient ischemic attacks
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15. Aspirin
Effective and inexpensive treatment for suppressing platelet aggregation
Long-term, low-dose therapy
Inhibits cyclooxygenase, an enzyme needed by platelets to synthesize thromboxane A2 (TxA2)
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16. Other Antiplatelet Drugs
Dipyridamole (Persantine)
Ticlopidine (Ticlid)
Clopidogrel (Plavix)
Anagrelide HCl (Agrylin)
Abciximab (ReoPro)
Eptifibatide (Integrilin)
Tirofiban (Aggrastat)
Ticagrelor (Brilinta)
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17. Thrombolytics Purpose Function Thrombolytic drugs Dissolve clot
Promotes conversion of plasminogen to plasmin
Thrombolytic drugs
Streptokinase (Streptase)
Urokinase (Abbokinase)
Alteplase tPA (Activase)
Reteplase rPA (Retavase)
Tenecteplase TNK-tPA (TNKase)
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18. Thrombolytics (Cont.) Myocardial infarction Thrombolic stroke
Thrombus, or blood clot, disintegrates when a thrombolytic drug is administered within 4 hours.
Thrombolic stroke
Thrombolytic drug should be administered within 3 hours.
Pulmonary embolism
DVT
Noncoronary arterial occlusion from an acute thromboembolism
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19. Nursing Process: Thrombolytics
Assessment
Nursing diagnoses
Planning
Nursing interventions
Patient teaching
Cultural considerations
Evaluation
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20. Case Study
A patient is recovering from surgery to replace her right hip. In the early postoperative phase, the nurse anticipates administration of which drug to prevent deep vein thrombosis?
Dipyridamole (Persantine)
Low-molecular-weight heparin
Abciximab (ReoPro)
Anagrelide HCl (Agrylin)
Answer: B
Rationale: Low-molecular-weight heparins are derivatives of standard heparin and were introduced to prevent venous thromboembolism. The other drugs are platelet inhibitors. Antiplatelets are used to prevent thrombosis in the arteries by suppressing platelet aggregation.
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21. Case Study
The patient develops a deep vein thrombosis. The nurse anticipates administration of which medication?
Intravenous heparin
Clopidogrel (Plavix)
Vitamin K
Protamine sulfate (Protamine)
Answer: A
Rationale: Intravenous heparin is indicated for rapid anticoagulant effect when a thrombosis occurs because of a deep vein thrombosis (DVT), pulmonary embolism (PE), or an evolving stroke. The effects of subcutaneous heparin take longer to occur.
Clopidogrel (Plavix) is an antiplatelet drug that is mainly for prophylactic use in
prevention of myocardial infarction or stroke. Vitamin K is the antidote for warfarin, and protamine is the antidote for heparin.
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22. Case Study
The patient is being discharged home on warfarin (Coumadin) therapy. Which information will the nurse include when teaching the patient?
Results of activated partial thromboplastin time (aPTT) will determine if the medication is effective.
International normalized ratio (INR) results should be between 2 to 3.
A normal response to warfarin (Coumadin) is for your stools to look tarry.
Increase the amount of green leafy vegetables in your diet.
Answer: B
Rationale: Today, international normalized ratio (INR) is the laboratory test most frequently used to report PT results; a value of 2 to 3 is considered acceptable. Partial thromboplastin time (PTT) and activated partial thromboplastin time (aPTT) are laboratory tests to detect deficiencies of certain clotting factors, and these tests are used to monitor heparin therapy. Tarry stools indicate GI bleeding. Green leafy vegetables contain vitamin K, which is the antidote for warfarin (Coumadin).
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23. Practice Question #1
A patient is prescribed aspirin, 81 mg, and clopidogrel (Plavix). The nurse identifies the drug classification of clopidogrel as
anticoagulant.
thrombotic inhibitor.
antiplatelet.
thrombolytic.
Answer: C
Rationale: Clopidogrel is an antiplatelet drug.
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24. Practice Question #2
A patient arrived in the emergency department 2 hours after an acute ischemic stroke. The patient is given an intravenous (IV) injection of alteplase tPA (Activase). It is most important for the nurse to monitor what? (Select all that apply.)
Bleeding
Vital signs
PT levels
Allergic reactions
Electrocardiogram
Answer: A, B, D, E
Rationale: The nurse should monitor the patient receiving thrombolytics for adverse effects, such as bleeding, allergic reactions, and cardiac dysrhythmias. An increased heart rate with a decreased BP usually indicates blood loss from bleeding.
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25. Practice Question #3
Which information will the nurse include when teaching a patient about warfarin (Coumadin) therapy?
Increase the amount of green, leafy vegetables in your diet.
Rinse your mouth instead of brushing your teeth.
Follow up with laboratory tests such as PT or INR to regulate warfarin (Coumadin) dose.
Use a new razor blade each time you shave.
Answer: C
Rationale: Laboratory tests such as PT or INR are performed to regulate warfarin (Coumadin) dose. The patient should avoid consuming large amounts of green, leafy vegetables; broccoli; legumes; soybean oil; coffee; tea; cola; excessive alcohol, and certain nutritional supplements such as coenzyme Q10. Patients are encouraged to perform oral hygiene and use a soft tooth brush to prevent gums from bleeding. Patients should be instructed to use an electric razor when shaving.
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26. Practice Question #4
A patient manifests symptoms of a thrombolic stroke. The emergency department nurse is aware that thrombolytics need to be administered in this situation within how many hours of the onset of symptoms?
1 hour
2 hours
3 hours
4 hours
Answer: D
Rationale: A thrombolytic drug should be administered within 3 hours of a thrombolic stroke.
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27. Practice Question #5
A patient is on heparin therapy secondary to deep vein thromboses. The nurse has which medication on hand as an antidote in case it is needed?
Vitamin K
Protamine sulfate
Warfarin (Coumadin)
Aminocaproic acid (Amicar)
Answer: B
Rationale: Vitamin K is the antidote for warfarin (Coumadin), not heparin, therapy; warfarin (Coumadin) is an anticoagulant, and aminocaproic acid (Amicar) is a plasminogen inactivator used to control excessive bleeding from hyperfibrinolysis.
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28. Practice Question #6
Four patients are considered as potential candidates for thrombolytic therapy. Which patient is most likely to receive thrombolytic therapy?
The patient who recently used acetaminophen (Tylenol)
The patient with a history of severe hypertension
The patient who recently had spinal surgery
The patient with a history of warfarin (Coumadin) use
Answer: A
Rationale: Acetaminophen (Tylenol) does not interfere with the coagulation system. Contraindications for use of thrombolytics include a recent CVA, active bleeding, severe hypertension, recent history of traumatic injury, especially head injury, and anticoagulant therapy. The nurse should report if the patient takes aspirin or NSAIDs.
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29. Practice Question #7
The nurse is caring for a patient who received alteplase tPA (Activase) for treatment of acute coronary syndrome. The patient starts to bleed. The nurse anticipates administration of which medication?
Protamine sulfate (protamine)
Vitamin K (phytonadione)
Warfarin (Coumadin)
Aminocaproic acid (Amicar)
Answer: D
Rationale: Aminocaproic acid (Amicar) is used to stop bleeding by inhibiting plasminogen activation, which inhibits thrombolysis.
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30. Practice Question #8
A patient visits an outpatient clinic. The patient has been noncompliant with anticoagulation therapy and states, “I don’t like having to have blood work all of the time.” The nurse anticipates prescription of which medication?
Abciximab (ReoPro)
Tirofiban (Aggrastat)
Eptifibatide (Integrilin)
Rivaroxaban (Xarelto)
Answer: D
Rationale: Two oral anticoagulants form a new anticoagulant category called Xa inhibitors. Rivaroxaban (Xarelto) was FDA-approved in July 2011, and apixaban (Eliquis) was FDA-approved in December These drugs do not require routine coagulation monitoring and are given q.d. or b.i.d. The other medications are administered intravenously.
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