40 Questions
What is the primary action of antifibrinolytic drugs?
Prevent the lysis of fibrin, resulting in promoting clot formation.
What is the indication for alteplase (Activase) therapy?
MI and strokes.
What is the primary adverse effect of thrombolytic therapy?
Internal, intracranial, and superficial bleeding.
What is the primary action of desmopressin (DDAVP)?
It is a synthetic polypeptide that mimics the action of vasopressin, an antidiuretic hormone.
What is the primary nursing implication for heparin administration?
IV doses should be double-checked with another nurse.
What is the primary action of aminocaproic acid (Amicar)?
It prevents and controls excessive bleeding resulting from surgery or overactivity of the fibrinolytic system.
What is the primary reason for assessing patient history and medication history before administering thrombolytic therapy?
To identify contraindications and potential drug interactions.
What is the primary reason for applying pressure to the site of venous lab work?
To prevent bleeding complications.
What is the main difference between dabigatran and argatroban in terms of administration?
Dabigatran is an oral direct thrombin inhibitor, while argatroban is only given IV.
What is the primary indication for dabigatran in patients with non-valvular atrial fibrillation?
Prevention of strokes and thrombosis.
Why is laboratory monitoring not necessary for enoxaparin and dabigatran?
Both have a predictable pharmacological effect and do not require lab monitoring.
What is the primary concern when administering heparin therapeutically?
Measurement of aPTT is necessary to ensure therapeutic effects.
What is the main difference between heparin and enoxaparin in terms of their elimination half-life?
Enoxaparin has a longer elimination half-life compared to heparin.
What is the primary adverse effect of dabigatran?
Bleeding and GI bleeding.
What is the main indication for argatroban in patients at risk for HIT?
Percutaneous coronary intervention procedures.
What is the primary characteristic of enoxaparin that makes it a prototypical LMWH?
Greater affinity for factor Xa than for factor IIa.
What is the mechanism of action of antiplatelet drugs in preventing platelet adhesion at the site of blood vessel injury?
Antiplatelet drugs work to prevent platelet adhesion by preventing platelet activation and aggregation.
List three examples of antiplatelet drugs that prevent platelet adhesion.
Aspirin, Cilostazol (Pletal), and Clopidogrel (Plavix)
What is the contraindication for aspirin use in children and teenagers?
Aspirin is contraindicated for flu-like symptoms in children and teenagers due to the risk of Reye's syndrome.
What is the mechanism of action of thrombolytic drugs?
Thrombolytic drugs activate the fibrinolytic system to break down the clot in the blood vessel quickly, reestablishing blood flow to the heart muscle.
What are the indications for thrombolytic drug therapy?
Acute myocardial infarction (MI), arterial thrombolysis, deep vein thrombosis (DVT), occlusion of shunts or catheters, pulmonary embolus, and acute ischemic stroke.
What are the common adverse effects of thrombolytic drug therapy?
Bleeding (internal, intracranial, superficial), nausea, vomiting, hypotension, anaphylactoid reactions, cardiac dysrhythmias.
What is the primary action of eptifibatide (Integrilin) in antiplatelet therapy?
Eptifibatide is a GP Iib/IIIa inhibitor, which prevents platelet aggregation and thrombus formation.
What is the primary indication for clopidogrel (Plavix) therapy?
Acute coronary syndrome, including unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI).
What is the risk of administering IV vitamin K to patients who are experiencing severe bleeding due to warfarin overdose?
anaphylaxis
What is the specific antidote for dabigatran, and what is its purpose?
Idarucizumab (Praxbind); reverses anticoagulant effects for emergency surgery or in life-threatening or uncontrolled bleeding
What is the mechanism of action of warfarin, and how does it relate to vitamin K?
Warfarin is a vitamin K antagonist, which means it inhibits the synthesis of vitamin K-dependent clotting factors
What is the name of the antidote for factor Xa inhibitors, and what are the potential risks associated with its use?
Andexxa (Coagulation Factor Xa [recombinant] Inactivated-zhzo); risk of thromboembolic events, including MI, ischemic stroke, cardiac arrest, and sudden death
What is the recommended course of action if a patient is experiencing severe bleeding due to warfarin overdose, and what is the expected outcome?
Transfusions of human plasma or clotting factor concentrates, and potential administration of Kcentra and Profiline; expected outcome is reversal of bleeding
What is the potential consequence of administering vitamin K to a patient who is taking warfarin, and how long does this effect last?
Warfarin resistance; up to 7 days
What is the key principle to keep in mind when ordering anticoagulant medications, and why is this important?
ALWAYS question an order if two anticoagulants are ordered; to prevent adverse effects and bleeding complications
What are some potential mechanisms of anticoagulant drug interactions, and what is the result of these interactions?
Enzyme inhibition of metabolism, displacement of the drug from inactive protein-binding sites, decrease in vitamin K absorption or synthesis, alteration in the platelet count or activity; increased risk of bleeding or thrombosis
What is the mechanism of action of Vitamin K antagonists, such as warfarin, and how do they prevent clot formation?
Vitamin K antagonists, such as warfarin, inhibit vitamin K synthesis by bacteria in the gastrointestinal tract, thereby inhibiting the production of vitamin K-dependent clotting factors II, VII, IX, and X, which are synthesized in the liver, preventing clot formation.
What is the primary indication for anticoagulant therapy in patients with atrial fibrillation?
The primary indication for anticoagulant therapy in patients with atrial fibrillation is to prevent stroke and systemic embolism.
How do Factor Xa inhibitors, such as rivaroxaban, prevent thrombosis?
Factor Xa inhibitors, such as rivaroxaban, prevent thrombosis by inhibiting the activity of factor Xa, a key enzyme in the coagulation cascade, thereby preventing the formation of thrombin and the subsequent formation of a blood clot.
What is the primary adverse effect of anticoagulant therapy, and how is it monitored?
The primary adverse effect of anticoagulant therapy is bleeding, which is monitored by measuring the international normalized ratio (INR) or activated partial thromboplastin time (aPTT) to assess the degree of anticoagulation.
What is the mechanism of action of direct thrombin inhibitors, such as dabigatran, and how do they prevent thrombosis?
Direct thrombin inhibitors, such as dabigatran, prevent thrombosis by directly inhibiting the activity of thrombin, which is a key enzyme in the coagulation cascade, thereby preventing the formation of a blood clot.
What is the primary indication for anticoagulant therapy in patients undergoing major orthopedic surgery?
The primary indication for anticoagulant therapy in patients undergoing major orthopedic surgery is to prevent venous thromboembolism (VTE) and pulmonary embolism (PE).
What is the contraindication for anticoagulant therapy in patients with a history of bleeding disorders?
The contraindication for anticoagulant therapy in patients with a history of bleeding disorders is the risk of exacerbating bleeding, which can be life-threatening.
What is the mechanism of action of fondaparinux, and how does it prevent thrombosis?
Fondaparinux is a factor Xa inhibitor that prevents thrombosis by inhibiting the activity of factor Xa, a key enzyme in the coagulation cascade, thereby preventing the formation of thrombin and the subsequent formation of a blood clot.
Study Notes
Anticoagulants and Thrombolytic Agents
Bridge Therapy
- Exception: Bridge therapy with heparin or enoxaparin and PO warfarin
Argatroban
- Synthetic direct thrombin inhibitor
- Used for active HIT (heparin-induced thrombocytopenia) and percutaneous coronary intervention procedures in patients at risk for HIT
- Only given IV
Dabigatran (Pradaxa)
- First oral direct thrombin inhibitor approved for prevention of strokes and thrombosis in patients with non-valvular atrial fibrillation
- Prodrug that becomes activated in the liver
- Specifically and reversibly binds to both free and clot-bound thrombin
- Dose dependent on renal function
- Adverse effects: bleeding, GI bleeding
- No coagulation monitoring is required
Enoxaparin (Lovenox)
- Prototypical LMWH (low-molecular-weight heparin)
- Greater affinity for factor Xa than for factor IIa
- Higher degree of bioavailability and longer elimination half-life
- Lab monitoring is not necessary
- Injectable form
- Used for prophylaxis and treatment
- Pre-filled syringes: do not expel air bubble
Heparin
- Natural anticoagulant obtained from the lungs or intestinal mucosa of pigs
- 10 to 40,000 units/mL
- DVT prophylaxis: 5000 units subcutaneously two or three times a day; aPTT does not need to be monitored when used for prophylaxis
- When heparin is used therapeutically (for treatment), continuous IV infusion; measurement of aPTT (usually every 6 hours until therapeutic effects are seen) is necessary
Alteplase (Activase)
- t-PA made through recombinant DNA techniques
- Fibrin specific, so does not produce a systemic lytic state
- Present in the body in a natural state
- Very short half-life (5 minutes)
- Indications: MI, strokes
- Smaller doses to flush clogged IV or arterial lines (CathFlo Activase)
Antifibrinolytic Drugs
- Prevent the lysis of fibrin
- Result in promoting clot formation
- Used for prevention and treatment of excessive bleeding resulting from hyperfibrinolysis or surgical complications
- Treatment of hemophilia or von Willebrand’s disease
- Examples: Aminocaproic acid (Amicar), Tranexamic acid (Cyklokapron), Desmopressin (DDAVP)
Adverse Effects
- Uncommon and mild
- Rare reports of thrombotic events
- Others: Dysrhythmia, orthostatic hypotension, bradycardia, headache, dizziness, fatigue, nausea, vomiting, abdominal cramps, diarrhea, etc.
Aminocaproic Acid (Amicar)
- Synthetic antifibrinolytic drug
- Prevents and controls excessive bleeding that results from surgery or overactivity of fibrinolytic system
- Oral or parenteral
Desmopressin (DDAVP)
- Synthetic polypeptide
- Similar to vasopressin, which is an antidiuretic hormone
- Indications: diabetes insipidus, hemophilia
- Nasal spray: used for nocturnal enuresis
Nursing Implications
- Assess: patient history, medication history, allergies, contraindications, baseline vital signs, laboratory values, potential drug interactions, history of abnormal bleeding conditions
- IV doses of heparin are usually double-checked with another nurse
Treatment of Toxic Effects of Warfarin
- Caution: when vitamin K is given, warfarin resistance will occur for up to 7 days
- Severe bleeding: transfusions of human plasma or clotting factor concentrates
- Life-threatening bleeding from warfarin: Kcentra and Profiline
- IV vitamin K: risk of anaphylaxis
Idarucizumab (Praxbind)
- Specific antidote for dabigatran
- Reverses the anticoagulant effects of dabigatran for emergency surgery or in life-threatening or uncontrolled bleeding
Andexxa (Coagulation Factor Xa [recombinant] Inactivated-zhzo)
- Specific antidote for factor Xa inhibitor
- Used for life-threatening or uncontrolled bleeding
- Black Box Warning for thromboembolic events: MI, ischemic stroke, cardiac arrest, sudden death
Drug Interactions: Anticoagulants
- Enzyme inhibition of metabolism
- Displacement of the drug from inactive protein-binding sites
- Decrease in vitamin K absorption or synthesis by the bacterial flora of the large intestines
- Alteration in the platelet count or activity
- ALWAYS question an order if two anticoagulants are ordered!
Antiplatelet Drugs
- Work to prevent platelet adhesion at the site of blood vessel injury
- Prevent platelet adhesion: Aspirin, Cilostazol (Pletal), Clopidogrel (Plavix), Prasugrel (Effient), Ticagrelor (Brilinta), Treprostinil (Remodulin), Abciximab (ReoPro), Eptifibatide (Integrilin), Tirofiban (Aggrastat), Anagrelide (Agrylin), Dipyridamole (Persantine), Vorapaxar (Zontivity)
Thrombolytic Drugs
- Break down, or lyse, preformed clots
- Older drugs: Streptokinase and urokinase
- Current drugs: t-plasminogen activators (tPa)
- Examples: Alteplase (Activase, Cathflo Activase), Tenecteplase (TNKase)
Mechanism of Action
- Activate the fibrinolytic system to break down the clot in the blood vessel quickly
- Activate plasminogen and convert it to plasmin, which can digest fibrin
- Reestablish blood flow to the heart muscle via coronary arteries, preventing tissue destruction
This quiz covers the use of heparin, enoxaparin, warfarin, argatroban, and dabigatran in bridge therapy and direct thrombin inhibition, including their applications in HIT and percutaneous coronary intervention.
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