Anticoagulants Flashcards
Which anticoagulant has a delayed onset of action?
Warfarin
D. Inhibits epoxide reductase to decrease Vitamin K.
C. Vitamin K and FFPD
C. Factor VII
A. Erythromycin.
D. Rifampin
A. Apixaban
Each of the following anticoagulants decreases factor Xa activity EXCEPT?
A. Apixaban
B. Dabigatran
C. Fondaparinux
D. Unfractionated Heparin
B. Dabigatran is a direct thrombin inhibitor and directly binds and inhibits thrombin/factor II and does not decrease the activity of factor Xa.
Which of the following anticoagulants requires monitoring of the PTT (partial thromboplastin time)?
A. Abciximab
B. Enoxaparin
C. Rivaroxaban
D. Unfractionated heparin
D. Unfractionated heparin is monitored with PTT or aPTT.
Which of the following is a contraindication to the administration of enoxaparin for DVT treatment?
A. Inability to take oral meds
B. Pregnancy
C. Recent major trauma
D. Renal failure
D. Renal Failure. Enoxaparin is a LMWH and is renally eliminated and has a longer hal-life, therefore contraindicated in renal failure patients.
Which of the following clinical signs is the most appropriate for initiating aspirin therapy?
A. Acute ischemic stroke.
B. Acute MI
C. Closure of a patent ductus arteriosus
D. Initial Tx of PE
B. Acute MI
A patient receiving heparin for treatment of deep vein thrombosis (DVT) has an elevated activated partial thromboplastin time (aPTT) slightly over the therapeutic range. He has no evidence of bleeding. Which action is recommended to reduce risk for bleeding and achieve a therapeutic level?
A. Temporarily holding the drug and reducing the dose
B. Administering protamine sulfate 1 mg for every 100 units
C. Administering vitamin K
D. Administering platelets
A. Because heparin’s half-life is short, heparin overdose is usually treated with withdrawal of the drug.
A patient taking warfarin for a history of deep vein thrombosis presents with an international normalized ratio (INR) of 4.2. His examination shows no evidence of bleeding. Which action taken by the APN is most appropriate?
A. Stop the warfarin and begin treatment with a direct factor Xa inhibitor.
B. Treat with 2 mg of vitamin K and adjust the dose accordingly.
C. Treat with protamine sulfate and adjust the dose accordingly.
D. Hold one or more doses, recheck the INR and adjust the dose accordingly
D. Toxicity and overdose are usually treated by withholding one or two doses of warfarin.
Which agent is categorized as a direct thrombin inhibitor?
A. Fondaparinux (Arixtra)
B. Dabigatran (Pradaxa)
C. Rivaroxaban (Xarelto)
D. Low molecular weight heparin (LMWH)
B. Dabigatran works as a direct thrombin inhibitor to prevent conversion of fibrinogen to fibrin to prevent thrombus formation. Fondaparinux is a selective antithrombin III inhibitor and factor Xa inhibitor. Rivaroxaban is a factor Xa inhibitor and selectively inactivates circulating factor Xa, reducing thrombin formation. LMWH potentiates activity of antithrombin III and inactivates factors Xa and IIa (thrombin).
An elderly patient with a history of atrial fibrillation on dabigatran presents with gastrointestinal bleeding. The APN reviews the patient’s current medications. Which medication is most likely to cause a significantly increased risk for bleeding when combined with dabigatran?
A. Hydrochlorothiazide taken to reduce blood pressure
B. Metoprolol taken for heart rate control
C. Aspirin taken for arthritis pain
D. Diltiazem used for heart rate control
C. Drugs that affect platelet functioning, including aspirin, increase risk for bleeding with any anticoagulant.
Which patient taking warfarin should be considered for “bridging” with heparin in the perioperative period?
A. A patient having a skin biopsy
B. A patient with history of stroke with atrial fibrillation
C. A patient with remote history of deep vein thrombosis
D. A patient having cataract surgery
B. This patient is at high risk for recurrent stroke, and anticoagulation should be continued.
A patient presents with a transient ischemic attack (TIA) and needs long-term anticoagulation. He reports an allergy to aspirin. Which other medication is recommended by the American College of Chest Physicians (ACCP)?
A. Clopidogrel 75 mg daily
B. Warfarin daily
C. Dipyridamole 200 mg daily
D. Low molecular weight heparin
A. Clopidogrel is a recommended option instead of aspirin.
A cancer patient with a long-term implanted venous access device is being considered for anticoagulation. Which condition would exclude the patient from having any anticoagulant prescribed?
A. Renal insufficiency
B. Hyperkalemia
C. Stage 4 hypertension
D. Hypersensitivity to NSAIDs
C. All anticoagulants are contraindicated in severe hypertension.
A patient taking warfarin for treatment of deep vein thrombosis (DVT) presents to the clinic with a fungal infection requiring treatment with antifungal agent. The APN recognizes that there is an interaction between many antifungal agents and warfarin. Which action by the APN is most appropriate?
A. Discontinue the warfarin and start a different anticoagulant for the time the patient is taking the antifungal medication.
B. Increase the dose of warfarin to counteract the effects of the new medication.
C. Hold the warfarin until the patient completes the new medication.
D. Adjust the dose of warfarin and monitor the patient’s international normalized ratio (INR) more frequently while the patient is taking the new medication.
D. Data suggest that these drugs potentiate the action of warfarin, causing increased risk for bleeding. Increasing the dose of warfarin without evidence of need based on international normalized ratio (INR) is not a safe practice.
Which drug is recommended for anticoagulation in a patient with a prosthetic heart valve?
A. Low molecular weight heparin (LMWH)
B. Warfarin (Coumadin)
C. Clopidogrel (Plavix)
D. Aspirin
B. Warfarin is the drug of choice for patients with prosthetic heart valves as well as those with recurrent embolism. Clopidogrel is beneficial in prevention of myocardial infarction in patients with coronary artery disease, but it is not recommended for anticoagulation in patients with mechanical heart valves. Aspirin is used as antithrombotic therapy in patients with atrial fibrillation but low risk for stroke; thus, it is not appropriate for anticoagulation in the presence of a mechanical heart valve.
Which statement provides the best explanation for why NSAIDs are contraindicated when anticoagulants are prescribed?
A. There is inference with platelet aggregation.
B. There is direct inhibition of thrombin.
C. There is acceleration of antithrombin III.
D. There is inhibition of hepatic synthesis of clotting factors.
A. Aspirin and NSAIDs disrupt the cyclooxygenase pathway interfering with platelet aggregation.
A patient with atrial fibrillation, as well as a prosthetic heart valve, is to be anticoagulated. Which is the optimal international normalized ratio (INR) range for this patient?
A. 2.5 to 3.5
B. 1.5 to 3.0
C. 2.0 to 3.0
D. 3.0 to 4.0
A. Patients with additional risk factors, in addition to having a prosthetic heart valve, should have an INR level that is maintained above 2.0 to 3.0.
Interference of the effectiveness of factor Xa inhibitors such as rivaroxaban (Xarelto) can occur when given with some drugs. Which drug should be avoided when rivaroxaban is in use?
A. Penicillin
B. Phenytoin
C. Acetaminophen
D. Digitalis
B. Phenytoin and carbamazepine are strong inducers of CYP3A4 and should be avoided when rivaroxaban is prescribed. Penicillin can alter platelet aggregation, causing increased risk for bleeding when used in combination with heparin, not rivaroxaban. Concomitant use of acetaminophen with warfarin may potentiate its action causing increased risk for bleeding. Digitalis may interfere with the anticoagulation effects of heparin
Which regimen is American College of Chest Physicians (ACCP)-recommended for prevention of myocardial infarction (MI) for a patient who has had acute coronary syndrome (ACS) and placement of a stent?
A. Aspirin 100 mg daily
B. Clopidogrel (Plavix) 75 mg daily
C. Ticagrelor (Brilinta) 90 mg twice daily and aspirin 75 to 100 mg daily
D. Warfarin with target international normalized ratio (INR) of 2.0 to 3.0
C. Ticagrelor and aspirin in combination is the preferred treatment recommendation for prevention of MI in patients who have had ACS. Clopidogrel alone is inadequate in this situation.
