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Pharmacology · chapter 20 · Anticoagulant, Antiplatelet, and Thrombolytic Drugs

Antiplatelets

The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.

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Key points

  1. What antiplatelets do

    Antiplatelet drugs work by decreasing platelet activation and/or platelet adhesion. They are used for various indications including prevention and treatment of cardiovascular disease and prevention of ischemic stroke.

  2. Aspirin and Reye syndrome

    Aspirin should not be routinely used in pediatric clients due to the risk of Reye syndrome.

  3. Aspirin and the stomach

    However, in addition to the effect on platelets, aspirin can also increase the risk of gastric ulcer formation through inhibition of gastric prostaglandin synthesis. Subsequently, gastrointestinal effects are a major adverse effect, and it has additive gastrointestinal bleeding risk beyond its antiplatelet effect.

  4. Chew aspirin during a heart attack

    Clinical Tip Chew Aspirin for Faster Absorption If acute effects of aspirin are needed, such as during a heart attack, it is recommended that aspirin be chewed and swallowed for faster absorption (Mayo Clinic, n.d.)

  5. Stop P2Y12 inhibitors before surgery

    Because of their effect on bleeding, it is recommended that P2Y12 inhibitors be discontinued 5–7 days prior to surgery, depending on the agent.

  6. Clopidogrel needs activation

    Clopidogrel is a prodrug, meaning it must be metabolized to become biologically active. This activation is accomplished through the enzyme CYP2C19.

  7. CYP2C19 inhibitors can cause failure

    If clients without any genetic alteration take a concomitant drug that inhibits CYP2C19, the enzyme will not be available to activate clopidogrel, which could lead to therapeutic failure.

  8. Clopidogrel without a loading dose

    Initiating clopidogrel without a loading dose will result in a delayed effect up to several days, putting the client at risk for a thromboembolic event.

  9. Prasugrel bleeding and contraindications

    However, prasugrel has a comparatively higher risk of bleeding and the highest risk of fatal bleeding of these agents. It is also contraindicated in clients with a history of a stroke or transient ischemic attack, clients who are older than 75 years of age unless they are at very high risk of thromboembolism, and clients who weigh less than 60 kg.

  10. Ticagrelor causes dyspnea

    A noteworthy side effect of ticagrelor is dyspnea, which can limit activities of daily living. It also has a boxed warning from the FDA regarding concomitant aspirin doses, which should not exceed 100 mg orally per day.

  11. Cangrelor works and wears off fast

    The advantage of cangrelor is that it inhibits platelets nearly immediately upon administration, and platelet function recovers within an hour of medication discontinuation.

  12. Eptifibatide and platelet count

    The major side effect of eptifibatide is profound thrombocytopenia. Nurses should monitor the client’s platelet count closely and discontinue eptifibatide if the platelet count decreases to under 100,000/mm 3.

  13. Drugs that add bleeding risk

    Concomitant medications that further increase bleeding risk such as non-steroidal anti-inflammatory drugs (e.g., ibuprofen and naproxen) or antiplatelet agents (e.g., aspirin) may also be considered contraindicated with antiplatelet medications.

  14. Do not stop ticagrelor for bleeding if possible

    If possible, manage bleeding without discontinuing ticagrelor since discontinuation will increase the risk of subsequent cardiovascular events.

Terms to know

prodrug
Clopidogrel is a prodrug, meaning it must be metabolized to become biologically active.
Thromboxane A2
Thromboxane A2 is a substance that activates platelets.
P2Y12 inhibitors
P2Y12 Inhibitors P2Y12 inhibitors are potent antiplatelet agents that work as antagonists at the P2Y12 subunit of the ADP receptor on the platelet surface, which decreases platelet activation at the site of vessel injury.

Practice questions

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Every question here, with the answer

  1. A client with crushing chest pain at home calls a nurse advice line and has aspirin available. Which instruction is appropriate?

    1. Take it only after the pain has lasted an hour.
    2. Swallow the tablet whole with a full glass of water.
    3. Chew the aspirin and swallow it.
    4. Dissolve it under the tongue without swallowing.

    Answer: Chew the aspirin and swallow it.

    When acute effects of aspirin are needed, such as during a heart attack, chewing and swallowing gives faster absorption. Swallowing it whole is slower, and the other options are not supported and delay treatment.

  2. A client receiving eptifibatide during an acute coronary syndrome has a platelet count of 85,000/mm3. What should the nurse do?

    1. Stop the eptifibatide per guidelines and notify the provider.
    2. Increase the infusion rate.
    3. Continue the infusion and recheck tomorrow.
    4. Give aspirin to protect the platelets.

    Answer: Stop the eptifibatide per guidelines and notify the provider.

    Eptifibatide can cause profound thrombocytopenia, and it is discontinued if the platelet count falls under 100,000/mm3. Continuing, increasing, or adding another antiplatelet raises bleeding risk.

  3. Which clients should the nurse recognise as having a contraindication to prasugrel? Select all that apply.

    1. A client with stable angina and no other history
    2. A client who weighs less than 60 kg
    3. A client with active pathological bleeding
    4. A client with a previous transient ischemic attack
    5. A client with a history of stroke

    Answer: A client who weighs less than 60 kg, A client with active pathological bleeding, A client with a previous transient ischemic attack, A client with a history of stroke

    Prasugrel is contraindicated after stroke or TIA, in clients under 60 kg, and in active pathological bleeding. Stable angina alone is not a listed contraindication.

  4. A client started on clopidogrel is also prescribed a drug that inhibits the CYP2C19 enzyme. What concern should the nurse have?

    1. The client will develop dyspnea.
    2. Clopidogrel levels will rise and cause toxicity.
    3. There is no concern because clopidogrel is already active.
    4. Clopidogrel may not be activated, so it may not work.

    Answer: Clopidogrel may not be activated, so it may not work.

    Clopidogrel is a prodrug activated by CYP2C19, so a drug that inhibits this enzyme can lead to therapeutic failure. It is not already active, and dyspnea is a side effect of ticagrelor.

  5. A nurse is teaching a client who is starting an antiplatelet drug. Which points should be included? Select all that apply.

    1. Take ibuprofen for any pain.
    2. Head injuries may be more serious while taking this drug.
    3. Report blood in the urine or dark, tarry stools right away.
    4. Wear a medical alert bracelet.
    5. Avoid working on rooftops or tall ladders.

    Answer: Head injuries may be more serious while taking this drug., Report blood in the urine or dark, tarry stools right away., Wear a medical alert bracelet., Avoid working on rooftops or tall ladders.

    Clients should report bleeding signs, avoid fall risks, know that head injuries may be more severe, and wear medical identification. NSAIDs such as ibuprofen add bleeding risk and may be contraindicated.

  6. A client taking ticagrelor reports new shortness of breath that makes daily activities harder. How should the nurse interpret this?

    1. It means the drug is not being activated.
    2. It is caused by chewing the tablet.
    3. It is a sign of Reye syndrome.
    4. It is an expected side effect of ticagrelor worth reporting.

    Answer: It is an expected side effect of ticagrelor worth reporting.

    Dyspnea is a noteworthy side effect of ticagrelor and can limit activities of daily living. Reye syndrome relates to aspirin in children, and ticagrelor does not need activation.

Where every quote comes from

Section 20.3 Antiplatelets of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.

The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.