Lehne - Ch. 52 - Anticoagulant, Antiplatelet, and Thrombolytic Drugs

The nurse is caring for a group of patients taking warfarin (Coumadin). Which patient or patients is/are at moderate to high risk for harm as a result of warfarin therapy? (Select all that apply.) A. A 79-year-old man with variant genes that code for VKORC1 and CYP2CP B. A 50-year-old woman with a current INR of 2.2 treated for deep vein thrombosis C. A 26-year-old pregnant woman with new onset of symptoms of a pulmonary embolus D. A 65-year-old man on day 4 after hip replacement with a new order for warfarin E. A young adult with a prosthetic heart valve, for whom an interacting drug is being deleted from the regimen

A, C, E Patients with genetic alterations in VKORC1 and CYP2CP are at increased risk of warfarin-induced bleeding. An INR of 2.2 indicates a therapeutic warfarin level. Warfarin can cause fetal hemorrhage and is listed as Pregnancy Risk Category X. Warfarin could be prescribed for the prevention of deep vein thrombosis after hip replacement surgery. The day of prescription would not likely be a day to expect a dangerous adverse effect from warfarin, because its half-life is 1.5 to 2 days. Warfarin interacts with many other agents. The greatest risk for harm is when an interacting drug is being added to or deleted from the regimen.

A patient with nonvalvular atrial fibrillation is to be discharged on dabigatran etexilate (Pradaxa). Which statement should the nurse include in the discharge teaching? A. "The medication must be stored in the manufacturer-supplied bottle." B. "Once a new bottle is opened, the capsules maintain efficacy for 90 days." C. "If you have difficulty swallowing the capsule, you can open it and mix it with food." D. "You will need to learn how to give yourself a subcutaneous injection in your abdomen."

A. "The medication must be stored in the manufacturer-supplied bottle." Dabigatran is unstable, especially when exposed to moisture, and should be stored in the manufacturer-supplied bottle, which has a desiccant cap. Current labeling of the pill bottle indicates that once the bottle is opened, the pills should be used within 30 days. However, recent evidence indicates that they maintain efficacy for 60 days, provided they have been stored in the original container. Capsules should be swallowed intact, because chewing, crushing, or opening enhances absorption by 75% and increases the risk of bleeding. The medication is administered orally, not subcutaneously.

The laboratory calls the nursing unit to report a drop in the platelet count to 90,000/mm3 for a patient receiving heparin for the treatment of postoperative deep vein thrombosis. Which action by the nurse is the most appropriate? A. Call the healthcare provider to discuss the reduction or withdrawal of heparin. B. Call the healthcare provider to discuss increasing the heparin dose to achieve a therapeutic level. C. Obtain vitamin K and prepare to administer it by intramuscular (IM) injection. D. Observe the patient and monitor the activated partial thromboplastin time (aPTT) as indicated.

A. Call the healthcare provider to discuss the reduction or withdrawal of heparin. Heparin-induced thrombocytopenia (HIT) is a potential immune-mediated adverse effect of heparin infusions that can prove fatal. HIT is suspected when the platelet counts fall significantly. A platelet count below 100,000/mm3 would warrant discontinuation of the heparin.

A patient diagnosed with a pulmonary embolism is receiving a continuous heparin infusion at 1000 units/hr. Which situation would warrant a call to the physician? (Select all that apply.) A. aPTT of 65 seconds B. aPTT of 40 seconds C. Nosebleeds D. aPTT of 100 seconds E. platelet count of 300,000/mcL

B, C, D Measurement of the aPTT is essential to determine whether the heparin infusion is having the desired effect. If the normal value of the aPTT is 40 seconds, the goal is to achieve a therapeutic range of a factor of 1.5 to 2 (60 to 80 seconds). Because 40 seconds is too short (increases the risk for clotting) and 100 seconds is too long (increases the risk for bleeding), the physician requires notification for adjustment of the infusion rate. Evidence of bleeding, such as nosebleeds, hematuria, and red or tarry stools, warrant a call to the physician. An aPTT of 65 seconds indicates that a therapeutic effect has been achieved, and a platelet count of 300,000/mcL is within normal limits, indicating no evidence of thrombocytopenia.

Which needle length and gauge should the nurse choose to administer subcutaneous heparin? A. 1/2 inch; 20 gauge B. 5/8 inch; 25 gauge C. 1.5 inch; 18 gauge D. 1 inch; 26 gauge

B. 5/8 inch; 25 gauge Heparin should be administered subcutaneously into the fatty layer of the abdomen with a 1/2- to 5/8-inch needle, 25 or 26 gauge. The only appropriate option for injection in the list shown is the 5/8-inch, 25-gauge needle.

The nurse is beginning a heparin infusion for a patient with evolving stroke. The baseline activated partial thromboplastin time (aPTT) is 40 seconds. Which aPTT value indicates that a therapeutic dose has been achieved? A. 50 B. 70 C. 90 D. 110

B. 70 The therapeutic level of heparin is achieved when the aPTT reaches 1.5 to 2 times normal. Thus, a range of 60 to 80 seconds would be appropriate for this patient.

A patient with deep vein thrombosis is receiving an intravenous (IV) heparin infusion. He asks the nurse how this medication will help him. The nurse's response is accurately based on which concept? A. Heparin prevents the activation of vitamin K and thus blocks synthesis of some clotting factors. B. Heparin suppresses coagulation by helping antithrombin perform its natural functions. C. Heparin works by converting plasminogen to plasmin, which in turn dissolves the clot matrix. D. Heparin inhibits the enzyme responsible for platelet activation and aggregation within vessels.

B. Heparin suppresses coagulation by helping antithrombin perform its natural functions. Heparin is an anticoagulant that works by helping antithrombin inactivate thrombin and factor Xa, reducing the production of fibrin and thus decreasing the formation of clots.

A patient admitted with deep vein thrombosis (DVT) and subsequent pulmonary embolism (PE) requires immediate anticoagulation. What would be appropriate in this situation, given that the patient has a history of heparin-induced thrombocytopenia (HIT)? A. Warfarin (Coumadin) B. Lepirudin (Refludan) C. Bivalirudin (Angiomax) D. Eptifibatide (Integrilin)

B. Lepirudin (Refludan) Lepirudin (Refludan) and argatroban are indicated for the treatment of thrombosis in patients with a history of HIT. Because these medications are given as an initial IV bolus followed by a continuous infusion, the desired effect of direct thrombin inhibition is achieved more quickly. Because of warfarin's delayed onset of effects, it is not useful in emergency situations, such as pulmonary embolism (PE). Intravenous bivalirudin given in combination with aspirin helps prevent clot formation in patients undergoing coronary angioplasty. Eptifibatide (Integrilin), a glycoprotein IIb/IIIa receptor inhibitor, is an antiplatelet drug that is used short term to prevent ischemic events in patients who have acute coronary syndrome or who are undergoing percutaneous coronary intervention.

The nurse is caring for a patient receiving clopidogrel (Plavix) to prevent blockage of coronary artery stents. Which other drug on the patient's medication administration record may reduce the antiplatelet effects of clopidogrel? A. Aspirin (Bayer) B. Omeprazole (Prilosec) C. Acetaminophen (Tylenol) D. Warfarin (Coumadin)

B. Omeprazole (Prilosec) Omeprazole and other proton pump inhibitors may reduce the antiplatelet effects of clopidogrel. Patients sometimes take them to reduce gastric acidity and the risk of gastrointestinal (GI) bleeding.

The nurse knows that which statement is accurate for enoxaparin (Lovenox)? A. It equally reduces the activity of thrombin and factor Xa. B. It has selective inhibition of factor Xa and no effect on thrombin. C. It reduces the activity of factor Xa more than the activity of thrombin. D. It has a lower bioavailability and shorter half-life than unfractionated heparin.

C. It reduces the activity of factor Xa more than the activity of thrombin. Enoxaparin acts primarily on factor Xa and also but to a lesser degree on thrombin. Unfractionated heparin equally reduces the action of thrombin and factor Xa. Fondaparinux (Arixtra) causes selective inhibition of factor Xa. Low-molecular-weight (LMW) heparins, such as enoxaparin, have greater bioavailability and a longer half-life than those of unfractionated heparin.

Which instruction about clopidogrel (Plavix) should be included in the discharge teaching for a patient who has received a drug-eluting coronary stent? A. "Constipation is a common side effect of clopidogrel, so take a stool softener daily." B. "If you see blood in your urine or black stools, stop the clopidogrel immediately." C. "Check with your healthcare provider before taking any over-the-counter medications for gastric acidity." D. "Keep the amounts of foods containing vitamin K, such as mayonnaise, canola and soybean oil, and green, leafy vegetables, consistent in your diet."

C. "Check with your healthcare provider before taking any over-the-counter medications for gastric acidity." Proton pump inhibitors (PPIs), such as omeprazole (Prilosec), and CYP2C1 inhibitors, such as cimetidine (Tagamet), can be purchased over the counter to treat heartburn. However, patients taking clopidogrel should consult their healthcare provider before using them. PPIs and CYP2C1 inhibitors can reduce the antiplatelet effects of clopidogrel. Diarrhea (5% incidence), not constipation, is a side effect of clopidogrel. Patients should immediately contact the healthcare provider if signs of bleeding occur, such as bloody urine, stool, or emesis. The drug should not be stopped until the prescriber advises it, because this could lead to coronary stent restenosis. Consistency of vitamin K intake is indicated while taking warfarin (Coumadin).

A 52-year-old male patient presents to the emergency department with symptoms of acute myocardial infarction. After a diagnostic workup, the healthcare provider prescribes a 15-mg IV bolus of alteplase (tPA), followed by 50 mg infused over 30 minutes. In monitoring this patient, the nurse understands that which symptom, if present, indicates the most likely adverse reaction to this drug? A. Urticaria, itching, and flushing B. Blood pressure of 90/50 mm Hg C. Decreasing level of consciousness D. Potassium level of 5.5 mEq/L

C. Decreasing level of consciousness Unlike streptokinase, alteplase does not cause an allergic reaction or hypotension. The greatest risk with this drug is bleeding, with intracranial bleeding being the greatest concern. A decreasing level of consciousness indicates intracranial bleeding. Thrombolytic agents, such as alteplase, do not typically cause an elevated potassium level.

A 63-year-old male patient has been receiving a heparin infusion for 2 days for treatment of pulmonary embolism. Which symptom most clearly relates to an adverse effect of heparin? A. Heart rate of 60 beats per minute B. Blood pressure of 160/88 mm Hg C. Discolored urine D. Wheezing

C. Discolored urine The primary and most serious adverse effect of heparin is bleeding. Bleeding can occur from any site and may be manifested in various ways, including reduced blood pressure, increased heart rate, bruises, petechiae, hematomas, red or black stools, cloudy or discolored urine, pelvic pain, headache, and lumbar pain.

A patient admitted with atrial fibrillation is receiving a continuous heparin infusion as well as daily warfarin (Coumadin). What is an appropriate action by the nurse? A. Contact the healthcare provider for an order to stop the heparin, because the aPTT is 60 seconds. B. Contact the healthcare provider to request discontinuation of the heparin, because the patient is receiving Coumadin. C. Notify the healthcare provider that the INR is 3 and anticipate that the heparin will be discontinued. D. Prepare to administer protamine sulfate, because the patient has received two anticoagulants at the same time.

C. Notify the healthcare provider that the INR is 3 and anticipate that the heparin will be discontinued. The INR is within a therapeutic range (2 to 3), so the nurse should call the health care provider to get the heparin infusion discontinued. An aPTT of 60 indicates the heparin is therapeutic with no indication that the patient has achieved the therapeutic effect of warfarin. The patient will be on a combination of heparin and warfarin until the therapeutic effect of warfarin has been achieved, and this may take several days. The patient will have no protective effect against clotting if the heparin is reversed with protamine sulfate and the INR is not within a therapeutic range.

The nurse is caring for a patient who takes warfarin (Coumadin) for prevention of deep vein thrombosis. The patient has an international normalized ratio (INR) of 1.2. Which action by the nurse is most appropriate? A. Prepare to administer protamine sulfate. B. Continue with the current prescription. C. Prepare to administer vitamin K. D. Call the healthcare provider to increase the dose.

D. Call the healthcare provider to increase the dose. An INR in the range of 2 to 3 is considered the level for warfarin therapy. For a level of 1.2, the nurse should contact the healthcare provider to discuss an order for an increased dose.

Fondaparinux (Arixtra) is not approved for use in which circumstance? A. Prevention of deep vein thrombosis (DVT) after knee replacement B. Treatment of acute pulmonary embolism (PE) (in conjunction with warfarin) C. Prevention of deep vein thrombosis (DVT) after abdominal surgery D. Prevention of ischemic complications in patients with unstable angina

D. Prevention of ischemic complications in patients with unstable angina Enoxaparin (Lovenox), not Arixtra, is approved for use in preventing ischemic complications in patients with unstable angina, non-Q-wave myocardial infarction (MI), and ST-segment elevation myocardial infarction (STEMI). Arixtra is approved for (1) preventing DVT after hip surgery, knee replacement, and abdominal surgery; and (2) treating acute PE and acute DVT in conjunction with warfarin.