40 Questions
What is the primary indication for argatroban, and how is it administered?
Active HIT and percutaneous coronary intervention procedures in patients at risk for HIT, and it is only given IV.
What is the mechanism of action of dabigatran, and what is its approved indication?
Dabigatran is a prodrug that becomes activated in the liver, and it specifically and reversibly binds to both free and clot-bound thrombin. It is approved for prevention of strokes and thrombosis in patients with non-valvular atrial fibrillation.
What is the main difference between enoxaparin and unfractionated heparin, and why is lab monitoring not necessary for enoxaparin?
Enoxaparin has a higher degree of bioavailability and a longer elimination half-life than unfractionated heparin. Lab monitoring is not necessary because of its predictable dose-response and low interpatient variability.
How is heparin typically administered for DVT prophylaxis, and why is aPTT monitoring not necessary in this setting?
Heparin is administered subcutaneously two or three times a day, and aPTT monitoring is not necessary for prophylaxis because the dose is fixed and not adjusted based on lab results.
What is the difference in heparin administration and monitoring between prophylactic and therapeutic uses?
For prophylaxis, heparin is administered subcutaneously two or three times a day, and aPTT monitoring is not necessary. For therapeutic use, heparin is administered as a continuous IV infusion, and aPTT monitoring is necessary to adjust the dose.
What are the potential adverse effects of dabigatran, and how does its dose depend on renal function?
The potential adverse effects of dabigatran include bleeding and GI bleeding. The dose of dabigatran depends on renal function, and the dose should be adjusted in patients with renal impairment.
What is the difference between enoxaparin and unfractionated heparin in terms of their affinity for factor Xa and thrombin?
Enoxaparin has a higher affinity for factor Xa than for thrombin, whereas unfractionated heparin has a higher affinity for thrombin.
What is the mechanism of action of Factor Xa inhibitors in preventing thrombosis?
They inhibit thrombosis by their specific action against factor Xa.
When is coagulation monitoring required for anticoagulant therapy, and what lab test is typically used?
Coagulation monitoring is required for heparin therapy, and the aPTT is typically used to monitor the therapeutic effect.
What is the primary goal of antithrombotic prophylaxis in patients undergoing major orthopedic surgery?
To prevent venous thromboembolism and pulmonary embolism.
What is the difference between unfractionated heparin and low-molecular-weight heparins (LMWHs) in terms of their effects on bleeding times?
Unfractionated heparin requires frequent laboratory monitoring of bleeding times, whereas LMWHs have a more predictable anticoagulant response and do not require frequent monitoring.
What is the mechanism of action of warfarin in preventing clot formation?
Warfarin inhibits the production of vitamin K-dependent clotting factors II, VII, IX, and X, which are necessary for clot formation.
What is the primary advantage of direct oral anticoagulants (DOACs) compared to warfarin?
DOACs have a more predictable anticoagulant response and do not require frequent laboratory monitoring.
What is the primary indication for anticoagulant therapy in patients with atrial fibrillation?
To prevent stroke and systemic embolism.
What is the primary contraindication for anticoagulant therapy?
Any acute bleeding process or high risk for such an occurrence.
What is the primary advantage of factor Xa inhibitors over vitamin K antagonists?
Factor Xa inhibitors have a more rapid onset of action and a shorter half-life, making them more suitable for acute thrombotic events.
What is an essential aspect of patient education for anticoagulant therapy?
Importance of regular laboratory testing
What should patients taking warfarin (Coumadin) be advised to consume consistently?
Foods high in vitamin K
What is a crucial nursing consideration when administering thrombolytic drugs?
Following strict manufacturer's guidelines for preparation and administration
What is a key concern for patients receiving antiplatelet therapy?
Drug-drug interactions
What should the nurse monitor for when converting a patient from IV heparin to oral warfarin (Coumadin) therapy?
INR
Why is overlapping therapy of IV heparin and warfarin necessary?
To ensure continued anticoagulation
What is a sign of abnormal bleeding that the nurse should monitor for in a patient receiving thrombolytic drugs?
Bleeding from gums, mucous membranes, nose, and injection sites
What should the nurse emphasize in patient education for patients taking anticoagulants?
Measures to prevent bruising, bleeding, and tissue injury
What is the specific antidote for dabigatran and what is its purpose?
Idarucizumab (Praxbind) is the specific antidote for dabigatran, and it is used to reverse the anticoagulant effects for emergency surgery or in life-threatening or uncontrolled bleeding.
What is therisk of administering IV vitamin K and how can it be minimized?
The risk of administering IV vitamin K is anaphylaxis, and it can be minimized by diluting it and giving it over 30 minutes.
What is the specific antidote for factor Xa inhibitors and what are the associated risks?
Andexxa (Coagulation Factor Xa [recombinant] Inactivated-zhzo) is the specific antidote for factor Xa inhibitors, such as rivaroxaban and apixaban, and it carries a risk of thromboembolic events, including MI, ischemic stroke, cardiac arrest, and sudden death.
What is the caution when giving vitamin K to a patient taking warfarin?
The caution when giving vitamin K to a patient taking warfarin is that warfarin resistance will occur for up to 7 days.
What are the potential mechanisms of drug interactions with anticoagulants?
The potential mechanisms of drug interactions with anticoagulants include 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, and alteration in the platelet count or activity.
What is the crucial consideration when ordering two anticoagulants?
The crucial consideration when ordering two anticoagulants is to always question the order, as it may increase the risk of adverse interactions and bleeding complications.
What is the treatment for severe bleeding due to warfarin overdose?
The treatment for severe bleeding due to warfarin overdose includes transfusions of human plasma or clotting factor concentrates, and in life-threatening bleeding, Kcentra and Profiline may be used.
What is the specific antidote for life-threatening bleeding due to warfarin?
The specific antidote for life-threatening bleeding due to warfarin is Kcentra and Profiline.
What is the primary mechanism of action of Rivaroxaban (Xarelto)?
Inhibiting factor Xa
What is the therapeutic INR range for patients with atrial fibrillation on warfarin therapy?
2-3.5
Why is heparin often used in combination with warfarin therapy?
To provide anticoagulation until therapeutic levels of warfarin are reached
What genetic factors can affect warfarin dosing?
Variations in CYP2CP and VKORC1 genes
What is the primary indication for Rivaroxaban (Xarelto) in orthopedic surgery?
Post-operative thromboprophylaxis
What is the potential consequence of not monitoring the PT/INR in patients on warfarin therapy?
Bleeding or thrombosis
What is the mechanism of action of warfarin?
Inhibition of vitamin K-dependent clotting factors
What is the primary advantage of factor Xa inhibitors over warfarin?
Fixed dosing and no need for INR monitoring
Study Notes
Anticoagulants and Antiplatelet Drugs
Treatment of Toxic Effects of Warfarin
- Caution: Vitamin K administration can cause warfarin resistance for up to 7 days
- Severe bleeding: treat with transfusions of human plasma or clotting factor concentrates
- Life-threatening bleeding: use Kcentra and Profiline
- IV vitamin K administration: risk of anaphylaxis, minimize by diluting and giving over 30 minutes
Idarucizumab (Praxbind)
- Specific antidote for dabigatran
- Reverses anticoagulant effects of dabigatran for emergency surgery or life-threatening/uncontrolled bleeding
Andexxa (Coagulation Factor Xa [recombinant] Inactivated-zhzo)
- Specific antidote for factor Xa inhibitors
- Used for life-threatening or uncontrolled bleeding
- Black Box Warning: thromboembolic events, MI, ischemic stroke, cardiac arrest, sudden death
Drug Interactions: Anticoagulants
- Enzyme inhibition of metabolism
- Displacement of drug from inactive protein-binding sites
- Decrease in vitamin K absorption or synthesis by bacterial flora of the large intestine
- Alteration in platelet count or activity
Argatroban
- Synthetic direct thrombin inhibitor
- Used for active HIT 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 required
Enoxaparin (Lovenox)
- Prototypical LMWH
- Greater affinity for factor Xa than for factor IIa
- Higher degree of bioavailability and longer elimination half-life
- No lab monitoring required
- Injectable form
- Used for prophylaxis and treatment
- Pre-filled syringes, do not expel air bubble
Heparin
- Natural anticoagulant obtained from lungs or intestinal mucosa of pigs
- 10 to 40,000 units/mL
- DVT prophylaxis: 5000 units subcutaneously two or three times a day, no need to monitor aPTT
- Therapeutic use: continuous IV infusion, monitor aPTT every 6 hours until therapeutic effects seen
- Numerous factors can affect action
Coagulation Modifier Drugs
- Anticoagulants: inhibit action or formation of clotting factors, prevent clot formation
- Antiplatelet drugs: inhibit platelet aggregation, prevent platelet plugs
- Hemorheologic drugs: alter platelet function without preventing platelet activity
- Thrombolytic drugs: lyse existing clots
- Antifibrinolytic or hemostatic drugs: promote blood coagulation
Anticoagulants
- Also known as antithrombotic drugs
- No direct effect on already formed blood clots
- Prevent intravascular thrombosis by decreasing blood coagulability
- Used prophylactically to prevent clot formation, thrombus, and embolus
Embolus
- Thromboembolic events
- Myocardial infarction (MI): embolus lodges in coronary artery
- Stroke: embolus obstructs brain vessel
- Pulmonary emboli: embolus in pulmonary circulation
- Deep vein thrombosis (DVT): embolus goes to vein in leg
Anticoagulants: Heparins
- Action: inhibit clotting factors IIa and Xa
- Unfractionated heparin: "heparin"
- Low-molecular-weight heparins (LMWHs): enoxaparin (Lovenox) and dalteparin (Fragmin)
Anticoagulants: Coumarins
- Action: inhibit vitamin K-dependent clotting factors II, VII, IX, and X
- Warfarin (Coumadin)
Anticoagulants: Factor Xa Inhibitors
- Fondaparinux (Arixtra)
- Direct oral anticoagulants: rivaroxaban (Xarelto), apixaban (Eliquis), edoxaban (Savaysa), betrixaban (Bevyxxa)
- Inhibit thrombosis by specific action against factor Xa
Anticoagulants: Direct Thrombin Inhibitors
- Action: inhibit thrombin (factor IIa)
- Natural: human antithrombin III (Thrombate)
- Synthetic: lepirudin (Refludan), argatroban (Argatroban), bivalirudin (Angiomax), dabigatran (Pradaxa) (oral)
Anticoagulants: Indications
- Used to prevent clot formation in settings where clot formation is likely
- MI, unstable angina, atrial fibrillation, indwelling devices, major orthopedic surgery
Anticoagulants: Contraindications
- Drug allergy
- Any acute bleeding process or high risk for such occurrence
Anticoagulants: Patient Education
- Importance of regular laboratory testing
- Signs of abnormal bleeding
- Measures to prevent bruising, bleeding, and tissue injury
- Wearing a medical alert bracelet
- Consistent intake of foods high in vitamin K
- Consulting physician before taking other drugs or OTC products, including herbals
Antiplatelet and Thrombolytic Drugs: Nursing Implications
- Concerns and teaching tips same as for anticoagulants
- Drug-drug interactions
- Adverse reactions to report
- Monitoring for abnormal bleeding
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