Chapter 52: Anticoagulant, Antiplatelet, and Thrombolytic Drugs

A patient with atrial fibrillation is receiving warfarin [Coumadin]. The nurse notes that the patient's INR is 2.7. Before giving the next dose of warfarin, the nurse will notify the provider and: a. administer the dose as ordered. b. request an order to decrease the dose. c. request an order to give vitamin K (phytonadione). d. request an order to increase the dose.

ANS: A This patient has an INR in the appropriate range, which is 2 to 3 for most patients and 2.5 to 3.5 for some, so no change in warfarin dosing is necessary. It is not correct to request an order to either decrease or increase the dose of warfarin. It is not necessary to give vitamin K, which is an antidote for warfarin toxicity.

The nurse has just received an order for tenecteplase [TNKase] for a patient experiencing an acute myocardial infarction. The nurse should administer this drug: a. by bolus injection. b. by infusion pump over 24 hours. c. slowly over 90 minutes. d. via monitored, prolonged infusion.

ANS: A Tenecteplase [TNKase] is given by bolus injection. Tissue plasminogen activator (tPA) must be infused over 90 minutes. Because tenecteplase [TNKase] is given by bolus injection, an infusion pump is not required. Although the patient should be monitored, tenecteplase [TNKase] does not require a prolonged infusion time.

A patient who is taking warfarin [Coumadin] has just vomited blood. The nurse notifies the provider, who orders lab work revealing a PT of 42 seconds and an INR of 3.5. The nurse will expect to administer: a. phytonadione (vitamin K1) 1 mg IV over 1 hour. b. phytonadione (vitamin K1) 2.5 mg PO. c. protamine sulfate 20 mg PO. d. protamine sulfate 20 mg slow IV push.

ANS: A Vitamin K1 is given for warfarin overdose and may be given IV in an emergency. To reduce the incidence of an anaphylactoid reaction, it should be infused slowly. In a nonemergency situation, it would be appropriate to give vitamin K1 orally. Protamine sulfate is used for heparin overdose.

A patient is admitted to the hospital with unstable angina and will undergo a percutaneous coronary intervention. Which drug regimen will the nurse expect to administer to prevent thrombosis in this patient? a. Aspirin, clopidogrel, omeprazole b. Aspirin, heparin, abciximab [ReoPro] c. Enoxaparin [Lovenox], prasugrel [Effient], warfarin [Coumadin] d. Heparin, alteplase, abciximab [ReoPro]

ANS: B Abciximab, combined with ASA and heparin, is approved for IV therapy for patients undergoing PCI.

A patient who has taken warfarin [Coumadin] for a year begins taking carbamazepine. The nurse will anticipate an order to: a. decrease the dose of carbamazepine. b. increase the dose of warfarin. c. perform more frequent aPTT monitoring. d. provide extra dietary vitamin K.

ANS: B Carbamazepine is a powerful inducer of hepatic drug-metabolizing enzymes and can accelerate warfarin degradation. The warfarin dose should be increased if the patient begins taking carbamazepine. Decreasing the dose of carbamazepine is not indicated. It is not necessary to perform more frequent aPTT monitoring or to add extra vitamin K.

A patient will begin taking dabigatran etexilate [Pradaxa] to prevent stroke. The nurse will include which statement when teaching this patient? a. Dabigatran should be taken on an empty stomach to improve absorption. b. It is important not to crush, chew, or open capsules of dabigatran. c. The risk of bleeding with dabigatran is less than that with warfarin [Coumadin]. d. To remember to take dabigatran twice daily, a pill organizer can be useful.

ANS: B Patients should be taught to swallow capsules of dabigatran intact; absorption may be increased as much as 75%, increasing the risk of bleeding, if the capsules are crushed, chewed, or opened. Dabigatran may be taken with or without food. The risk of bleeding is not less than that of warfarin. Dabigatran is unstable when exposed to moisture, so using a pill organizer is not recommended.

A postoperative patient will begin anticoagulant therapy with rivaroxaban [Xarelto] after knee replacement surgery. The nurse performs a history and learns that the patient is taking erythromycin. The patient's creatinine clearance is 50 mL/min. The nurse will: a. administer the first dose of rivaroxaban as ordered. b. notify the provider to discuss changing the patient's antibiotic. c. request an order for a different anticoagulant medication. d. request an order to increase the dose of rivaroxaban.

ANS: B Patients with impaired renal function who are taking macrolide antibiotics will experience increased levels of rivaroxaban, increasing the risk of bleeding. It is correct to discuss using a different antibiotic if possible. The nurse should not administer the dose without discussing the situation with the provider. The patient's renal impairment is minor; if it were more severe, using a different anticoagulant might be appropriate. It is not correct to increase the dose of rivaroxaban.

A nurse caring for a patient receiving heparin therapy notes that the patient has a heart rate of 98 beats per minute and a blood pressure of 110/72 mm Hg. The patient's fingertips are purplish in color. A stat CBC shows a platelet count of less than 100,000 mm3. The nurse will: a. administer oxygen and notify the provider. b. discontinue the heparin and notify the provider. c. request an order for protamine sulfate. d. request an order for vitamin K (phytonadione).

ANS: B This patient is showing signs of heparin-induced thrombocytopenia, so the heparin should be discontinued immediately and the provider should be notified. The purplish color of the fingertips is caused by thrombosis, not hypoxia, so oxygen is not indicated. This patient may need continued anticoagulation therapy, so a request for protamine sulfate is not correct. Heparin is not a vitamin K inhibitor.

A patient is admitted to the emergency department with chest pain. An electrocardiogram shows changes consistent with an evolving myocardial infarction. The patient's cardiac enzymes are pending. The nurse caring for this patient will expect to: a. administer aspirin when cardiac enzymes are completed. b. give alteplase [Activase] within 2 hours. c. give tenecteplase [TNKase] immediately. d. obtain an order for an INR.

ANS: B When alteplase is given within 2 hours after symptom onset, the death rate for MI has been shown to be 5.4%, compared with 9.4% if given 4 to 6 hours after symptom onset. ASA may be given at the first sign of MI; it is not necessary to wait for cardiac enzyme results. Tenecteplase may be given more than 2 hours after onset of symptoms. Obtaining an order for an INR is not indicated.

A postoperative patient reports pain in the left lower extremity. The nurse notes swelling in the lower leg, which feels warm to the touch. The nurse will anticipate giving which medication? a. Aspirin b. Clopidogrel [Plavix] c. Enoxaparin [Lovenox] d. Warfarin [Coumadin]

ANS: C Enoxaparin is a low-molecular-weight heparin and is used in situations requiring rapid onset of anticoagulant effects, such as massive DVT. Aspirin, clopidogrel, and warfarin are useful for primary prevention but are not used when rapid anticoagulation is required.

A patient has been receiving heparin while in the hospital to treat deep vein thromboses and will be discharged home with a prescription for enoxaparin [Lovenox]. The nurse provides teaching for the nursing student who asks about the advantages of enoxaparin over heparin. Which statement by the student indicates a need for further teaching? a. "Enoxaparin does not require coagulation monitoring." b. "Enoxaparin has greater bioavailability than heparin." c. "Enoxaparin is more cost-effective than heparin." d. "Enoxaparin may be given using a fixed dosage."

ANS: C Low-molecular-weight (LMW) heparins have higher bioavailability and longer half-lives, so routine coagulation monitoring is not necessary and fixed dosing is possible. LMW heparins are more expensive, however, so this statement indicates a need for further teaching.

A patient who is taking clopidogrel [Plavix] calls the nurse to report black, tarry stools and coffee-ground emesis. The nurse will tell the patient to: a. ask the provider about using aspirin instead of clopidogrel. b. consume a diet high in vitamin K. c. continue taking the clopidogrel until talking to the provider. d. stop taking the clopidogrel immediately.

ANS: C Patients who experience bleeding should be warned not to stop taking the clopidogrel until the prescriber says they should, since abrupt withdrawal may precipitate a thrombotic event. Taking aspirin with an active GI bleed is contraindicated. Warfarin is a vitamin K inhibitor; consuming extra vitamin K will not reverse the effects of clopidogrel.

A nursing student who is preparing to care for a postoperative patient with deep vein thrombosis asks the nurse why the patient must take heparin rather than warfarin. Which response by the nurse is correct? a. "Heparin has a longer half-life." b. "Heparin has fewer adverse effects." c. "The onset of warfarin is delayed." d. "Warfarin prevents platelet aggregation."

ANS: C Warfarin is not useful for treating existing thromboses or for emergencies because the onset of action is delayed. Heparin has a shorter half-life and has more side effects. Warfarin does not prevent platelet aggregation.

A 50-year-old female patient asks a nurse about taking aspirin to prevent heart disease. The patient does not have a history of myocardial infarction. Her cholesterol and blood pressure are normal, and she does not smoke. What will the nurse tell the patient? a. Aspirin is useful only for preventing a second myocardial infarction. b. She should ask her provider about using a P2Y12 ADP receptor antagonist. c. She should take one 81-mg tablet per day to prevent myocardial infarction. d. There is most likely no protective benefit for patients her age.

ANS: D ASA is used for primary prevention of myocardial infarction (MI) in men and in women older than 65 years. Aspirin for primary prevention may be used in women ages 55 to 79 years when the potential benefit of a reduction in MI outweighs the potential harm of increased GI hemorrhage. This patient has no previous history of MI, so the use of ASA is not indicated. ASA is useful for primary prevention, but only when indicated by cardiovascular risk, based on age, gender, cholesterol levels, blood pressure, and smoking status. A P2Y12 ADP receptor antagonist is used as secondary prevention. This patient should not begin taking ASA unless her risk factors change, or until she is 65 years old.

A patient is receiving heparin postoperatively to prevent deep vein thrombosis. The nurse notes that the patient has a blood pressure of 90/50 mm Hg and a heart rate of 98 beats per minute. The patient's most recent aPTT is greater than 90 seconds. The patient reports lumbar pain. The nurse will request an order for: a. a repeat aPTT to be drawn immediately. b. analgesic medication. c. changing heparin to aspirin. d. protamine sulfate.

ANS: D Heparin overdose may cause hemorrhage, which can be characterized by low blood pressure, tachycardia, and lumbar pain. Protamine sulfate should be given, and the heparin should be discontinued. An aPTT may be drawn later to monitor the effectiveness of protamine sulfate. Analgesics are not indicated because the lumbar pain is likely caused by adrenal hemorrhage. Aspirin will only increase the risk of hemorrhage.

A patient who takes warfarin [Coumadin] is brought to the emergency department after accidentally taking too much warfarin. The patient's heart rate is 78 beats per minute and the blood pressure is 120/80 mm Hg. A dipstick urinalysis is normal. The patient does not have any obvious hematoma or petechiae and does not complain of pain. The nurse will anticipate an order for: a. vitamin K (phytonadione). b. protamine sulfate. c. a PTT. d. a PT and an INR.

ANS: D This patient does not exhibit any signs of bleeding from a warfarin overdose. The vital signs are stable, there are no hematomas or petechiae, and the patient does not have pain. A PT and INR should be drawn to evaluate the anticoagulant effects. Vitamin K may be given if laboratory values indicate overdose. Protamine sulfate is given for heparin overdose. PTT evaluation is used to monitor heparin therapy.

A patient who takes warfarin for atrial fibrillation undergoes hip replacement surgery. On the second postoperative day, the nurse assesses the patient and notes an oxygen saturation of 83%, pleuritic chest pain, shortness of breath, and hemoptysis. The nurse will contact the provider to report possible ____ and request an order for ____. a. congestive heart failure; furosemide [Lasix] b. hemorrhage; vitamin K (phytonadione) c. myocardial infarction; tissue plasminogen activator (tPA) d. pulmonary embolism; heparin

ANS: D This patient is exhibiting signs of pulmonary embolism. Heparin is used when rapid onset of anticoagulants is needed, as with pulmonary embolism. The patient would have respiratory cracks and a cough with congestive heart failure. Hemorrhage involves a decrease in blood pressure, bruising, and lumbar pain. The patient has pleuritic pain, which is not consistent with the chest pain of a myocardial infarction.

A patient has been taking warfarin [Coumadin] for atrial fibrillation. The provider has ordered dabigatran etexilate [Pradaxa] to replace the warfarin. The nurse teaches the patient about the change in drug regimen. Which statement by the patient indicates understanding of the teaching? a. "I may need to adjust the dose of dabigatran after weaning off the warfarin." b. "I should continue to take the warfarin after beginning the dabigatran until my INR is greater than 3." c. "I should stop taking the warfarin 3 days before starting the dabigatran." d. "I will stop taking the warfarin and will start taking the dabigatran when my INR is less than 2."

ANS: D When switching from warfarin to dabigatran, patients should stop taking the warfarin and begin taking the dabigatran when the INR is less than 2. It is not correct to begin taking the dabigatran before stopping the warfarin. While warfarin is stopped before beginning the dabigatran, the decision to start taking the dabigatran is based on the patient's INR and not on the amount of time that has elapsed.