NCLEX® Pharmacology Review of Blood Thinners

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Introduction to Blood Thinners

Anticoagulation is an essential service that is frequently provided in the healthcare field to a wide variety of clients. Blood thinners are clinically used for many reasons, including prophylaxis for surgery, arrhythmia conversion, and for clients in a hypercoagulable state. These medications are available in many different types of classes including warfarin, direct-oral anticoagulants (DOACs), heparin, aspirin, and PGy12 inhibitors. It is essential to develop a firm understanding of the different kinds of anticoagulants to prepare yourself for your future practice. This NCLEX® Review of Blood Thinners is designed to provide you a good overview of the various topics that may appear on the exam.

Indications for Blood Thinners

  • Treatment of acute ischemic stroke and transient ischemic attack (TIA)
  • Treatment of deep vein thrombosis (DVT)
  • Treatment of venous thromboembolism (VTE)
  • Treatment of pulmonary embolism (PE)
  • Treatment of myocardial infarction and acute coronary symptoms
  • Prophylaxis for surgical and elective procedures at high risk of clotting
  • Atrial fibrillation rhythm correction (cardioversion) prophylaxis
  • Anticoagulation for states associated with increased risk of clot (e.g. severe infections, cancer)

Types of Drugs for Class of Blood Thinners

Warfarin

  • MOA:
    • Vitamin K antagonist → deactivates coagulation factors II, VII, IX, and X which are vitamin K dependent.
    • Protein C and S also deactivated.
  • Side Effects:
    • Bleeding: Warfarin increases the risk of bleeding which can lead to serious and sometimes fatal bleeding. This can contribute to major hemorrhages in the brain or elsewhere in the body causing death. Increased bleed risk is associated with INR values that are generally > 2.5.
    • Hepatitis
    • Hypersensitivity: Anaphylaxis
    • Acute renal failure
  • Warnings:
    • Black Box Warning: Warfarin can cause major or fatal bleeding. Perform regular monitoring of international normalized ratio (INR). Drugs, dietary changes, and other factors can affect INR.
  • Nursing Considerations:
    • Key counseling point:
      • It is important to take these medications exactly as the prescriber has instructed – failure to do so may lead to difficulty maintaining a therapeutic INR.
      • Inform clients that changes in diet can alter their risk of bleeding and/or clotting.
      • When taking warfarin, try to eat a consistent diet as INR fluctuations are very likely following the consumption of certain foods.
      • This includes foods high in vitamin K (e.g. leafy green vegetables) that can reduce the anticoagulation effect (↑ clot risk).
      • Certain drugs can alter INR including chewing tobacco, oils, ethanol, and green tea.
      • Prescription drugs may also alter INR so consult with the pharmacy prior to warfarin initiation.
    • INR monitoring:
      • Essential for clients being treated with warfarin. Goal INR range usually between 2-3.
      • INR values > 3 puts clients at increased risk of bleeding
      • Elevated INR is usually managed by giving clients Kcentra (4F-PCC) or vitamin K via oral or parenteral route.
      • INR values > 10 often warrant emergency care.
  • Common Key Generics (Brands)
    • Warfarin (Coumadin, Jantoven)

Heparin and Low Molecular Weight Heparin (LMWH)

  • MOA:
    • Binds to antithrombin and indirectly deactivates coagulation factors by enhancing the effect of antithrombin.
  • Side Effects:
    • Increased risk of major bleeding – intracranial hemorrhage and GI bleeding
    • Heparin-induced thrombocytopenia (HIT)
    • Skin reactions
    • Osteoporosis with long-term use
  • Warnings:
    • Increased risk of major bleeding including intracranial hemorrhage as well as gastrointestinal bleeding. Use with caution in clients suspected of having a high risk of bleeding or those who are actively bleeding.
    • Heparins can cause heparin-induced thrombocytopenia (HIT). This is an immune mediated collapse in platelet count that can be serious and potentially fatal – drastically increasing the risk of serious bleeding. This reaction is rare but should be monitored carefully in all clients – especially clients using heparin products for the first time.
  • Nursing Considerations:
    • Key counseling points:
      • Increased risk of thrombocytopenia with these medications – counsel clients on increased risk of bleeding which can suddenly progress to a severe state.
      • At home regimens involving low-molecular weight heparins should be taken exactly as instructed to ensure adequate anticoagulation.
    • Monitor platelet count (thrombocytes) at baseline and periodically after to assess for the possibility of thrombocytopenia.
    • Low molecular weight heparins are injected subcutaneously – commonly used in clients following surgical procedures but growing out of favor given the superior safety profile of DOACs.
    • Heparins can be reversed with a medication called protamine.
    • Fondaparinux is a synthetic heparin which has a lower risk of HIT compared to unfractionated heparin and LMWH
  • Common Key Generics (Brands)
    • Unfractionated Heparin
    • LMWH
      • Enoxaparin (Lovenox)
      • Dalteparin (Framin)
    • Fondaparinux – synthetic heparin

Direct Thrombin Inhibitors

  • MOA:
    • Direct thrombin inhibitor → binds and deactivates thrombin to stop the coagulation cascade.
  • Side Effects:
    • Risk of major bleeding – including intracranial hemorrhage and gastrointestinal bleeding
  • Warnings:
    • Increased risk of major bleeding including intracranial hemorrhage as well as gastrointestinal bleeding. Use with caution in clients suspected of having a high risk of bleeding or those who are actively bleeding.
  • Nursing Considerations:
    • Key counseling point:
      • Dabigatran is the only oral version of these medications – the others are only administered via parenteral route.
      • No risk of heparin-induced thrombocytopenia
      • Dabigatran toxicity can be reversed via Idarucizumab (Praxbind)
    • These medications are generally reserved for heart attacks and strokes – less frequently used than alternative anticoagulants (e.g. heparin, LMWH, DOACs)
  • Common Key Generics (Brands)
    • Bivalrudin
    • Argatroban
    • Desirudin
    • Dabigatran (Pradaxa) – oral direct thrombin inhibitor

Direct Oral Anticoagulants (DOACs)

  • MOA:
    • Direct factor Xa inhibitors → prevents the cleaving of prothrombin to thrombin halting the coagulation cascade.
  • Side Effects:
    • Risk of bleeding
  • Warnings:
  • Increased risk of major bleeding including intracranial hemorrhage as well as gastrointestinal bleeding. Use with caution in clients suspected of having a high risk of bleeding or those who are actively bleeding.
  • Nursing Considerations:
    • Key counseling point:
      • Emphasize the importance of proper adherence to these medications as this can lead to inadequate anticoagulation and/or increased risk of bleeding.
      • Xarelto (rivaroxaban) should be taken with food to ensure proper absorption.
    • These drugs are excreted through the kidneys. Use with caution in clients with renal dysfunction – poor renal function may warrant dosage reduction or changing to another anticoagulant.
    • These medications require much less monitoring and have less risk of serious bleeding when compared to warfarin.
    • These medications can be reversed with Andexanet alfa (AndexXa) in the event of major bleeding
  • Common Key Generics (Brands)
    • Apixaban (Eliquis)
    • Rivaroxaban (Xarelto)
    • Edoxaban (Savaysa)
    • Betrixaban (Bevyxxa)

P2y12 Inhibitors

  • MOA:
    • Irreversibly blocks the P2Y12 component of ADP receptors on the platelet surface → preventing platelet aggregation
  • Side Effects:
    • Increased risk of bleeding (minor and major hemorrhage)
  • Contraindication:
    • Contraindicated in clients with active bleeding including peptic ulcers and intracranial hemorrhage
  • Nursing Considerations:
    • Key counseling point:
      • Take these medications exactly as instructed to ensure proper anticoagulation.
      • Inform your provider if there are any changes to your medications as they can interfere with these medications.
      • These medications are generally used as addons to other anticoagulants for those who are at very high risk of clotting. They increase the anticoagulation effect by acting on a different mechanism than heparins, warfarin, and DOACs by acting as platelet inhibitors.
      • Cangrelor is only administered via intravenous route – will be seen more in the hospital setting.
  • Common Key Generics (Brands)
    • Clopidogrel (Plavix)
    • Prasugrel (Efient)
    • Ticagrelor (Brilique)
    • Cangrelor (Kengreal)

Aspirin

  • MOA:
    • Inhibits thromboxane A2 to prevent platelet aggregation
  • Side Effects:
    • Increased risk of bleeding (especially gastrointestinal)
    • Risk of peptic ulcer formation
    • Hypersensitivity (anaphylaxis)
    • Rash
    • Agitation
  • Warnings:
    • This medication is an NSAID – avoid in clients with proven NSAID allergies
    • Avoid these medications in the elderly (> 70 years)
    • Aspirin should never be used in clients under the age of 18
  • Nursing Considerations:
    • Key counseling points:
      • The normal dosage of aspirin used is 81mg – this is called low-dose aspirin
      • These medications can be harsh on the stomach – avoid in peptic ulcer disease
    • No longer used for primary prevention – in clients who have not yet had a major CV event (e.g. MI, TIA, stroke)
    • Low-dose aspirin is often referred to as “baby aspirin” – healthcare providers should avoid this label as it can result in children and infants being given this medication mistakenly.
  • Common Key Generics (Brands)
    • Asprin (Bayer)

Key Nursing Tips for Blood Thinners

  • Monitor for signs and symptoms of bleeding with all these medications:
    • Clinical findings:
      • ↓ hematocrit
      • ↓ red blood cells
      • ↓ hemoglobin
    • Physical findings:
      • Bloody stools
      • Blood in urine
      • Bruising
  • Prior to initiating anticoagulants in clients – assess baseline clotting factors, INR, or for signs and symptoms of bleeding prior to administration.
  • Clients on warfarin should be counseled on avoiding significant dietary changes (especially those that contain a lot of vitamin K; e.g. green leafy vegetables)
  • Many of these medications are renally excreted – initiate anticoagulants with caution in clients with chronic kidney disease.
  • All anticoagulants should be taken as prescribed to ensure proper anticoagulation and to avoid the risk of major bleeding.

Example NCLEX® questions for NCLEX® Review of Blood Thinners:

Conclusion for Blood Thinners

Anticoagulants are used frequently and for a wide variety of indications in clients every day in the healthcare setting. They are commonly used for surgical prophylaxis to prevent the risk of serious clotting as well as in clients who have experienced major CV events (e.g. heart attack, stroke), or in clients at high risk of serious clotting. The different classes come with an array of safety profiles – with DOACs being among the safest to administer in most healthy adults. Major bleeding is the primary adverse effect to monitor for in all clients on anticoagulants. Hopefully, this NCLEX® Review of Blood Thinners served as a nice overview of the different classes and types of blood thinners used clinically today.

References

  1. Warfarin: Drug Information. In: Post T, ed. UpToDate. Waltham, MA.: UpToDate; 2020. www.uptodate.com. Accessed April 21st, 2020.
  2. Garcia D, Crowther M. Management of bleeding in clients receiving direct oral anticoagulants. In: Post T, ed. UpToDate. Waltham, MA.: UpToDate; 2020. www.uptodate.com. Accessed April 21st, 2020.
  3. Hull R, Garcia D, Burnett A. Heparin and LMW heparin Dosing and adverse effects. In: Post T, ed. UpToDate. Waltham, MA.: UpToDate; 2020. www.uptodate.com. Accessed April 21st, 2020.
  4. Leung L. Direct oral anticoagulants (DOACs) and parenteral direct-acting anticoagulants: Dosing and adverse effects. In: Post T, ed. UpToDate. Waltham, MA.: UpToDate; 2020. www.uptodate.com. Accessed April 21st, 2020.
  5. Clopidogrel: Drug Information. In: Post T, ed. UpToDate. Waltham, MA.: UpToDate; 2020. www.uptodate.com. Accessed April 21st, 2020.
  6. Aspirin: Drug Information. In: Post T, ed. UpToDate. Waltham, MA.: UpToDate; 2020. www.uptodate.com. Accessed April 21st, 2020.