Pharmacology Chapter 45 - Anticoagulants, Antiplatelets, and Thrombolytics
clumping together of platelets to form a clot.
The formation of a clot in an arterial or venous vessel.
What is fibrinogen?
A glycoprotein that helps in the formation of blood clots.
Blood clot moving through the bloodstream
- Oral and parenteral anticoagulants (warfarin and heparin) act primarily to prevent?
- Antiplatelet drugs act to prevent?
- venous thrombosis
- arterial thrombosis
Used prophylactically to prevent new blood clots from forming. Used in patients with venous and arterial disorders that put them at high risk for clot formation:
- Deep vein thrombosis (DVT)
- Pulmonary embolism (PE)
- Coronary thrombosis
- Myocardial Infarction
- Presence of artificial heart valves
- CVA's or stroke
Used for rapid anticoagulant effect when a thrombosis occurs because of a DVT, PE, or an evolving stroke. The PRIMARY use of heparin is to prevent venous thrombosis, which can lead to pulmonary embolism or stroke.
Given subQ for prophylaxis or IV to treat acute thrombosis.
Heparin can decrease the platelet count causing thrombocytopenia.
If hemorrhage occurs during therapy, the anticoagulant antagonist protamine sulfate is given IV.
Before discontinuing heparin, oral therapy with warfarin is begun. The pt may be on both for up to 3 days because that is how long warfarin may take to be effective.
Partial thromboplastin time (PTT) and Activated partial thromboplastin time(aPTT)
Laboratory tests used to detect deficiencies of certain clotting factors, and these tests are used to monitor HEPARIN therapy.
Low Molecular Weight Heparin (LMWH)
LMWHs produce more stable responses with less risk of bleeding. As a result, frequent lab monitoring of aPTT is not required, so drugs can be administered at home. LMWHs are administered subQ once or twice daily for 7-10 days.
These agents are commonly prescribed to prevent DVT and acute pulmonary embolism after orthopedic or abdominal surgery.
OD is rare, but if bleeding occurs protamine sulfate is the anticoagulant antagonist used.
Contraindicated for pts. with strokes, peptic ulcers, and blood abnormalities. Should NOT be given to pts. having eye, brain, or spinal surgery
- enoxaparin (Lovenox)
- dalteparin (Fragmin)
Inhibit synthesis of vitamin K, thus affecting the clotting factors II, VII, IX, X. Oral anticoagulants prolong clotting time and are monitored by prothrombin time (PT) a tests that measures how long it takes for blood to clot. It's performed before administering the next dose until a therapeutic level has been reached.
International Normalized Ratio (INR): A normal INR is 1.3-2. Patients on warfarin are maintained at 2-3.
Has a long half life and very long duration. Drug accumulation can occur and lead to external or internal bleeding, so the nurse must observe for: petechiae, ecchymosis, tarry stools, hematemesis (blood in vomit) and teach the pt to do the same at home.
The antidote for warfarin (Coumadin) OD is Vitamin K, but it takes 24-48 hrs to be effective.
Warfarin is highly protein bound (and can be displaced) and can have cumulative effects, bleeding can occur esp if another highly protein bound drug is given at the same time.
Warfarin is effective for long term anticoagulant therapy.
SE: Bleeding is the major adv rxn.
Drug Interactions: Many: aspirin, NSAIDS, sulfonamides...see p. 655
Info from Nsg Process: Anticoagulants warfarin and heparin
- Warfarin is contraindicated for pts with blood dyscrasias, peptic ulcer, CVA, hemophilia, or severe hypertension
- An increased pulse rate followed by a decreased systolic pressure can indicate a fluid volume deficit resulting from external or internal bleeding.
- Monitor PT or INR for warfarin and aPTT for heparin BEFORE administration
- Keep anticoagulant antagonists (protamine sulfate for heparin and vitamin K for warfarin) available
- Warn pt to shave with electric razor
- Do not take aspirin with warfarin
- Advise pt to AVOID large amounts of green leafy veggies, broccoli, legumes, soybean oil, caffeine and COQ10 because they may decrease the effectiveness of warfarin.
Used to prevent thrombosis in the arteries by suppressing platelet aggregation. Mainly for prophylactic use in:
- prevention of MI or stroke for pts with familial history
- prevention of repeat MI or stroke
- prevention of stroke for pts having transient ischemic attacks (TIAs)
Effective and inexpensive treatment for suppressing platelet aggregation.
clopidogrel (Plavix )
frequently used after MI or stroke to prevent a second event. It may be prescribed singly or in combo with aspirin.
Contraindicated: intracranial hemorrhage, peptic ulcer, GI bleeding
Highly protein bound
Stop 7d prior to surgery
occlusion of an artery or vein caused by thrombus or embolus resulting in ischemia (deficient blood flow) that causes necrosis (death).
Promote the converting of plasminogen to plasmin which destroys the fibrin in the blood clot.
- streptokinase: acts systemically to promote conversion of plasminogen to plasmin
- alteplase: aka plasminogen activator (tPA) and it is clot specific and binds to the fibrin surface of a clot promoting the conversion of plasminogen to plasmin.
- urokinase: acts systemically to promote conversion of plasminogen to plasmin
These drugs induce fibrinolysis (fibrin breakdown).
prototype p. 660
SE: bleeding, nausea, vomiting, fever
ADV RXN: anaphylactoid rxn., laryngeal edema, angioedema, intracerebral hemorrhage, pulmonary edema, stroke
Contraindicated: Internal bleeding, blood disorders, recent CVA, surgery or trauma, severe liver dysfunction, brain tumor, severe uncontrolled HTN
Anticoagulants should be avoided until the thrombolytic effect has passed.
Info from NSG Process
- Report if pt takes NSAIDS or aspirin
- Observe for S/S of active bleeding from mouth or rectum. Hemorrhage is a serious complication of thrombolytic treatment. aminocaproic acid (Amicar) can be given as an intervention to stop bleeding.
- Observe for S/S of reaction to thrombolytics: itching, hives, flush, fever, dyspnea, bronchospasm, hypotension and or cardiovascular collapse.
- Avoid venipuncture/arterial sticks
A patient is recovering from surgery to replace her right hip. In the early postoperative phase, the nurse anticipates administration of which drug to prevent deep vein thrombosis?
D.Anagrelide HCl (Agrylin)
Rationale: Low-molecular-weight heparins are derivatives of standard heparin and were introduced to prevent venous thromboembolism. The other drugs are platelet inhibitors. Antiplatelets are used to prevent thrombosis in the arteries by suppressing platelet aggregation.
The patient develops a deep vein thrombosis. The nurse anticipates administration of which medication?
D.Protamine sulfate (Protamine)
Rationale: Intravenous heparin is indicated for rapid anticoagulant effect when a thrombosis occurs because of a deep vein thrombosis (DVT), pulmonary embolism (PE), or an evolving stroke. The effects of subcutaneous heparin take longer to occur.
Clopidogrel (Plavix) is an antiplatelet drug that is mainly for prophylactic use in
The patient is being discharged home on warfarin (Coumadin) therapy. Which information will the nurse include when teaching the patient?
A.Results of activated partial thromboplastin time (aPTT) will determine if the medication is effective.
B.International normalized ratio (INR) results should be between 2 to 3.
C.A normal response to warfarin (Coumadin) is for your stools to look tarry.
D.Increase the amount of green leafy vegetables in your diet.
Rationale: Today, international normalized ratio (INR) is the laboratory test most frequently used to report PT results; a value of 2 to 3 is considered acceptable. Partial thromboplastin time (PTT) and activated partial thromboplastin time (aPTT) are laboratory tests to detect deficiencies of certain clotting factors, and these tests are used to monitor heparin therapy. Tarry stools indicate GI bleeding. Green leafy vegetables contain vitamin K, which is the antidote for warfarin (Coumadin).
A patient is prescribed aspirin, 81 mg, and clopidogrel (Plavix). The nurse identifies the drug classification of clopidogrel as
Rationale: Clopidogrel is an antiplatelet drug.
A patient arrived in the emergency department 2 hours after an acute ischemic stroke. The patient is given an intravenous (IV) injection of alteplase tPA (Activase). It is most important for the nurse to monitor what? (Select all that apply.)
Answer: A, B, D, E
Rationale: The nurse should monitor the patient receiving thrombolytics for adverse effects, such as bleeding, allergic reactions, and cardiac dysrhythmias. An increased heart rate with a decreased BP usually indicates blood loss from bleeding.
Which information will the nurse include when teaching a patient about warfarin (Coumadin) therapy?
A.Increase the amount of green, leafy vegetables in your diet.
B.Rinse your mouth instead of brushing your teeth.
C.Follow up with laboratory tests such as PT or INR to regulate warfarin (Coumadin) dose.
D.Use a new razor blade each time you shave.
Rationale: Laboratory tests such as PT or INR are performed to regulate warfarin (Coumadin) dose. The patient should avoid consuming large amounts of green, leafy vegetables; broccoli; legumes; soybean oil; coffee; tea; cola; excessive alcohol, and certain nutritional supplements such as coenzyme Q10. Patients are encouraged to perform oral hygiene and use a soft tooth brush to prevent gums from bleeding. Patients should be instructed to use an electric razor when shaving.
A patient manifests symptoms of a thrombolic stroke. The emergency department nurse is aware that thrombolytics need to be administered in this situation within how many hours of the onset of symptoms?
Rationale: A thrombolytic drug should be administered within 3 hours of a thrombolic stroke.
A patient is on heparin therapy secondary to deep vein thromboses. The nurse has which medication on hand as an antidote in case it is needed?
D.Aminocaproic acid (Amicar)
Rationale: Vitamin K is the antidote for warfarin (Coumadin), not heparin, therapy; warfarin (Coumadin) is an anticoagulant, and aminocaproic acid (Amicar) is a plasminogen inactivator used to control excessive bleeding from hyperfibrinolysis.
Four patients are considered as potential candidates for thrombolytic therapy. Which patient is most likely to receive thrombolytic therapy?
A.The patient who recently used acetaminophen (Tylenol)
B.The patient with a history of severe hypertension
C.The patient who recently had spinal surgery
D.The patient with a history of warfarin (Coumadin) use
Rationale: Acetaminophen (Tylenol) does not interfere with the coagulation system. Contraindications for use of thrombolytics include a recent CVA, active bleeding, severe hypertension, recent history of traumatic injury, especially head injury, and anticoagulant therapy. The nurse should report if the patient takes aspirin or NSAIDs.
The nurse is caring for a patient who received alteplase tPA (Activase) for treatment of acute coronary syndrome. The patient starts to bleed. The nurse anticipates administration of which medication?
A.Protamine sulfate (protamine)
B.Vitamin K (phytonadione)
D.Aminocaproic acid (Amicar)
Rationale: Aminocaproic acid (Amicar) is used to stop bleeding by inhibiting plasminogen activation, which inhibits thrombolysis.
A patient visits an outpatient clinic. The patient has been noncompliant with anticoagulation therapy and states, “I don’t like having to have blood work all of the time.” The nurse anticipates prescription of which medication?
Rationale: Two oral anticoagulants form a new anticoagulant category called Xa inhibitors. Rivaroxaban (Xarelto) was FDA-approved in July 2011, and apixaban (Eliquis) was FDA-approved in December 2012. These drugs do not require routine coagulation monitoring and are given q.d. or b.i.d. The other medications are administered intravenously.
A patient is receiving an intravenous heparin drip. Which laboratory value requires immediate action by the nurse?
- Platelet count of 150,000
- Activated partial thromboplastin time (aPTT) of 120 seconds
- INR of 1.0
- Blood urea nitrogen (BUN) level of 12 mg/dL
The aPTT value of 120 seconds is too prolonged. The heparin drip should be shut off for an hour. The typical aPTT normal reference range for a patient on anticoagulant therapy is 30 to 85 seconds (range may vary slightly depending on the laboratory used). The normal range for BUN is 7 to 20 mg/dL, and the normal platelet range is 150,000 to 450,000.
A patient who has been taking warfarin (Coumadin) is admitted with coffee-ground emesis. What can the nurse anticipate being prescribed for this patient?
- Vitamin E
- Vitamin K
- Protamine sulfate
- Calcium gluconate
Vitamin K is the antagonist for warfarin.
The patient has an international normalized ratio (INR) value of 1.5. In response to this, the nurse could anticipate the health care provider placing which order?
- Administer an additional dose of warfarin (Coumadin).
- Hold the next dose of warfarin (Coumadin).
- Increase the heparin drip rate.
- Administer protamine sulfate.
A therapeutic INR is 2 to 3. The patient needs more warfarin to reach a therapeutic level
A patient is receiving warfarin (Coumadin) for a chronic condition. Which patient statement requires immediate action by the nurse?
- “I will avoid contact sports.”
- “I will take my medication in the early evening each day.”
- “I will increase dark-green, leafy vegetables in my diet.”
- “I will contact my health care provider if I develop excessive bruising.”
Dark-green, leafy vegetables are rich in vitamin K, which would antagonize the effects of warfarin. Rather than increase the intake of these, it is important to maintain a consistent daily intake of vitamin K. The patient should monitor his or her incidence of bruising carefully. The medication will usually be ordered for the patient to take in the morning.
A nurse is preparing to administer enoxaparin sodium (Lovenox) to a patient for prevention of deep vein thrombosis. Which is an essential nursing intervention?
- Draw up the medication in a syringe with a 22-gauge, 1½-inch needle.
- Utilize the Z-track method to inject the medication.
- Administer the medication into subcutaneous tissue.
- Rub the administration site after injecting.
Enoxaparin (Lovenox) is a low-molecular-weight heparin that is administered subcutaneously. The site should not be rubbed after injection, and the Z-track method also should never be used to administer enoxaparin sodium (Lovenox). The use of 22-gauge, 1½-inch needle is more appropriate for administration of an IM injection.
The patient asks the nurse to explain the difference between dalteparin (Fragmin) and heparin. Which response by the nurse is accurate?
- “There is no real difference. Dalteparin is preferred because it is less expensive.”
- “Dalteparin is a low-molecular-weight heparin that is more predictable in its effect and has a lower risk of bleeding.”
- “I’m not sure why some health care providers choose dalteparin and some heparin. You should ask your doctor.”
- “The only difference is that heparin dosing is based on the patient’s weight.”
A low-molecular-weight heparin is more predictable in its effect than regular heparin. Dalteparin (Fragmin) is more expensive than heparin and is dosed based on the patient’s weight. It is not appropriate to provide the patient with no instruction other than to simply refer to the health care provider.
A patient has arrived at the emergency department and requires immediate surgery. He has been receiving heparin. Which intervention is essential?
- Teach the patient about the phenytoin.
- Administer protamine sulfate.
- Assess the INR before surgery.
- Administer vitamin K.
Protamine sulfate binds with heparin in the bloodstream to inactivate it and thus reverse its effect. Allowing the patient to undergo surgery while receiving heparin would be life-threatening. The situation should be reversed immediately, without the nurse taking the time to assess the INR or administer vitamin K. It is not appropriate to teach the patient about phenytoin since it has not been ordered for the patient.
Which nursing intervention is essential for the patient receiving alteplase (Activase)?
- Assess for reperfusion dysrhythmias.
- Monitor liver enzymes.
- Administer prescribed vitamin K if bruising is observed.
- Monitor blood pressure and stop the medication if blood pressure drops below 110 systolic.
Alteplase (Activase) can cause bleeding as well as reperfusion dysrhythmias. Alteplase does not directly affect liver enzymes. Vitamin K will not reverse the effects of alteplase. Vital sign changes can alert the nurse to complications; however, a blood pressure below 110 systolic is not, in itself, cause for alarm.
A patient taking warfarin (Coumadin) asks for an aspirin for a headache. What is the nurse’s best action?
- Administer 650 mg of acetylsalicylic acid (ASA) and reassess pain in 30 minutes.
- Teach the patient of potential drug interactions with anticoagulants.
- Explain to the patient that ASA is contraindicated and administer ibuprofen as ordered.
- Explain that the headache is an expected side effect and will subside shortly.
Patients taking an anticoagulant should not use medications that would further increase the risk of bleeding, which includes aspirin as well as ibuprofen. Aspirin should not be administered to the patient taking other anticoagulants, unless it is ordered specifically as a low-dose daily therapy. Ibuprofen is not the best choice of medication for the patient receiving Coumadin. Tylenol (acetaminophen) would be preferred for pain relief. Headache is not an expected side effect of Coumadin therapy.
A patient is started on warfarin (Coumadin) therapy while also receiving intravenous heparin. The patient is concerned about the risk for bleeding. What will the nurse tell the patient?
- “Your concern is valid. I will call the doctor to discontinue the heparin.”
- “It usually takes about 3 days to achieve a therapeutic effect for warfarin, so the heparin is continued until the warfarin is therapeutic.”
- “Because of your valve replacement, it is especially important for you to be anticoagulated. The heparin and warfarin together are more effective than one alone.”
- “Because you are now up and walking, you have a higher risk of blood clots and therefore need to be on both medications.”
Warfarin works by decreasing the production of clotting factors. However, it takes approximately 3 days for the body to metabolize present clotting factors and thus achieve a therapeutic anticoagulant effect. Because of this, heparin is continued until this is achieved.
The nurse evaluates that the patient has understood discharge teaching regarding warfarin (Coumadin) based on which statement?
- “I will double my dose if I forget to take it the day before.”
- “I should keep taking ibuprofen for my arthritis.”
- “I should decrease the dose if I start bruising easily.”
- “I should use a soft toothbrush for dental hygiene.”
This statement is accurate and will reduce the risk of bleeding. Ibuprofen will potentiate bleeding. The patient should call the health care provider if experiencing excessive bruising.
Which intervention is essential before the nurse administers tenecteplase (TNKase)?
- Perform all necessary venipunctures.
- Administer aminocaproic acid (Amicar).
- Have the patient void.
- Assess for allergies to iodine.
TNKase is a thrombolytic agent that can interfere with the body’s clotting ability. Therefore, all invasive procedures should be completed before administering this drug.