Antiplatelet drugs MCQs With Answer

Antiplatelet drugs MCQs With Answer

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Antiplatelet drugs MCQs With Answer are essential for B. Pharm students to master pharmacology of antiplatelet agents, mechanisms, clinical uses, dosing, adverse effects and drug interactions. This focused set covers aspirin, P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor, cangrelor), glycoprotein IIb/IIIa inhibitors, PDE inhibitors (cilostazol, dipyridamole) and newer agents like vorapaxar. Questions emphasize mechanism of action, prodrug activation by CYP2C19, reversible versus irreversible inhibition, monitoring, perioperative management, bleeding risk and evidence-based indications such as acute coronary syndrome and stroke prevention. Detailed MCQs reinforce pharmacokinetics, toxicity (TTP, bleeding), drug interactions (PPIs, NSAIDs) and clinical decision-making. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which mechanism best describes how low‑dose aspirin exerts antiplatelet effects?

  • Reversible inhibition of P2Y12 receptor
  • Irreversible inhibition of cyclooxygenase-1 reducing thromboxane A2 synthesis
  • Competitive antagonism of glycoprotein IIb/IIIa
  • PDE3 inhibition increasing cAMP in platelets

Correct Answer: Irreversible inhibition of cyclooxygenase-1 reducing thromboxane A2 synthesis

Q2. How long does the antiplatelet effect of aspirin typically last after a single dose?

  • 2–4 hours
  • 24 hours
  • 7–10 days (duration of platelet lifespan)
  • One month

Correct Answer: 7–10 days (duration of platelet lifespan)

Q3. Clopidogrel is best described as which of the following?

  • Direct P2Y12 receptor antagonist with reversible action
  • Prodrug requiring hepatic CYP2C19 activation to an active metabolite
  • Monoclonal antibody against GP IIb/IIIa
  • PDE5 inhibitor used for antiplatelet therapy

Correct Answer: Prodrug requiring hepatic CYP2C19 activation to an active metabolite

Q4. Which statement correctly contrasts prasugrel and clopidogrel?

  • Prasugrel is less potent than clopidogrel and has slower onset
  • Prasugrel is a reversible P2Y12 inhibitor while clopidogrel is irreversible
  • Prasugrel is generally more potent and has greater bleeding risk, contraindicated in prior stroke/TIA
  • Both are not affected by CYP enzymes and have identical metabolism

Correct Answer: Prasugrel is generally more potent and has greater bleeding risk, contraindicated in prior stroke/TIA

Q5. Which antiplatelet agent is a reversible P2Y12 inhibitor and commonly causes dyspnea as a side effect?

  • Clopidogrel
  • Prasugrel
  • Ticagrelor
  • Cangrelor

Correct Answer: Ticagrelor

Q6. Which antiplatelet agent is an intravenous, rapidly acting, reversible P2Y12 inhibitor used during PCI?

  • Clopidogrel
  • Ticagrelor
  • Cangrelor
  • Prasugrel

Correct Answer: Cangrelor

Q7. Dipyridamole’s antiplatelet action primarily involves which mechanism?

  • Irreversible COX-1 inhibition
  • Phosphodiesterase inhibition increasing intracellular cAMP and inhibiting platelet aggregation
  • Blocking ADP binding to P2Y12 receptor
  • Antagonism of thrombin receptor PAR-1

Correct Answer: Phosphodiesterase inhibition increasing intracellular cAMP and inhibiting platelet aggregation

Q8. Cilostazol is contraindicated in which clinical condition due to its PDE3 inhibitory effects?

  • Peripheral arterial disease
  • Heart failure
  • Ischemic stroke secondary prevention
  • Intermittent claudication

Correct Answer: Heart failure

Q9. Glycoprotein IIb/IIIa inhibitors block platelet aggregation by preventing which final common pathway?

  • ADP-mediated platelet activation
  • TcA2 synthesis
  • Fibrinogen binding to GP IIb/IIIa receptors
  • Thrombin generation at surface of platelets

Correct Answer: Fibrinogen binding to GP IIb/IIIa receptors

Q10. Which of the following GP IIb/IIIa inhibitors is a monoclonal antibody fragment with long receptor occupancy?

  • Abciximab
  • Eptifibatide
  • Tirofiban
  • Cangrelor

Correct Answer: Abciximab

Q11. Vorapaxar exerts antiplatelet effects by antagonizing which receptor?

  • P2Y12 ADP receptor
  • PAR-1 (protease-activated receptor-1) thrombin receptor
  • GPIIb/IIIa receptor
  • Thromboxane A2 receptor

Correct Answer: PAR-1 (protease-activated receptor-1) thrombin receptor

Q12. What is a typical loading dose of ticagrelor used in acute coronary syndrome?

  • 75 mg
  • 300 mg
  • 180 mg
  • 60 mg

Correct Answer: 180 mg

Q13. A patient is a CYP2C19 poor metabolizer. Which antiplatelet’s effectiveness is most likely reduced?

  • Aspirin
  • Clopidogrel
  • Ticagrelor
  • Abciximab

Correct Answer: Clopidogrel

Q14. Which drug interaction can reduce clopidogrel activation and clinical efficacy?

  • Concurrent use of omeprazole (CYP2C19 inhibitor)
  • Concurrent use of aspirin (synergistic effect)
  • Concurrent heparin infusion
  • Concurrent use of atorvastatin (no interaction)

Correct Answer: Concurrent use of omeprazole (CYP2C19 inhibitor)

Q15. Which antiplatelet agent historically associated with thrombotic thrombocytopenic purpura (TTP) leading to limited use?

  • Ticlopidine
  • Clopidogrel
  • Ticagrelor
  • Dipyridamole

Correct Answer: Ticlopidine

Q16. Which laboratory or point‑of‑care test is specifically used to assess P2Y12 inhibitor effect?

  • PT/INR
  • Bleeding time
  • VerifyNow P2Y12 assay
  • Serum troponin

Correct Answer: VerifyNow P2Y12 assay

Q17. In a patient with life‑threatening bleeding on clopidogrel, which immediate supportive measure is commonly used to restore platelet function?

  • Administer vitamin K
  • Platelet transfusion
  • Give protamine sulfate
  • Start hemodialysis

Correct Answer: Platelet transfusion

Q18. For most patients after percutaneous coronary intervention with a drug‑eluting stent, what is the commonly recommended duration of dual antiplatelet therapy (DAPT)?

  • 1 week
  • 1 month
  • 6–12 months, commonly 12 months
  • Indefinitely without assessment

Correct Answer: 6–12 months, commonly 12 months

Q19. Which scoring tool helps estimate benefit versus risk for prolonged DAPT after PCI?

  • CHA2DS2-VASc
  • HAS-BLED
  • DAPT score
  • APACHE II

Correct Answer: DAPT score

Q20. Which situation is an absolute contraindication to initiating antiplatelet therapy?

  • Recent elective surgery 2 months ago
  • History of peptic ulcer disease remote
  • Active major bleeding
  • Controlled hypertension

Correct Answer: Active major bleeding

Q21. Why does low‑dose aspirin preferentially inhibit platelet TXA2 over endothelial prostacyclin (PGI2)?

  • Platelets have higher COX-2 expression where aspirin acts
  • Aspirin concentrates in endothelial cells only
  • Platelets cannot resynthesize COX-1, whereas endothelial cells can regenerate COX and produce PGI2
  • Aspirin is selective for TXA2 receptor antagonism

Correct Answer: Platelets cannot resynthesize COX-1, whereas endothelial cells can regenerate COX and produce PGI2

Q22. Which P2Y12 inhibitor does NOT require metabolic activation and therefore has a more consistent platelet inhibition?

  • Clopidogrel
  • Prasugrel
  • Ticagrelor
  • Ticlopidine

Correct Answer: Ticagrelor

Q23. Ticagrelor’s primary metabolic pathway involves which enzyme system?

  • CYP2C19 activation to a prodrug
  • CYP3A4 metabolism, it is not a prodrug
  • Direct renal excretion without metabolism
  • CYP1A2 bioactivation

Correct Answer: CYP3A4 metabolism, it is not a prodrug

Q24. Which antiplatelet drug combination is evidence‑based for secondary stroke prevention in selected patients?

  • Aspirin plus ticagrelor long-term in all patients
  • Aspirin plus dipyridamole extended-release formulation
  • Clopidogrel plus vorapaxar routinely
  • Aspirin plus cilostazol immediately after hemorrhagic stroke

Correct Answer: Aspirin plus dipyridamole extended-release formulation

Q25. What common side effect is associated with cilostazol therapy for intermittent claudication?

  • Severe thrombocytopenia
  • Headache and palpitations
  • Neutropenia requiring monitoring
  • Marked renal toxicity

Correct Answer: Headache and palpitations

Q26. Short‑term dual antiplatelet therapy with aspirin plus clopidogrel is recommended for which early period after minor ischemic stroke or high‑risk TIA?

  • Indefinitely
  • First 21 days (short‑term, e.g., 21–90 days depending on protocol)
  • Only during hospitalization
  • Not recommended due to bleeding risk

Correct Answer: First 21 days (short‑term, e.g., 21–90 days depending on protocol)

Q27. Which laboratory parameter is most directly prolonged by effective antiplatelet therapy?

  • Prothrombin time (PT)
  • Activated partial thromboplastin time (aPTT)
  • Bleeding time or platelet function assays
  • Serum fibrinogen concentration

Correct Answer: Bleeding time or platelet function assays

Q28. Glycoprotein IIb/IIIa inhibitors are most appropriately used in which clinical scenario?

  • Long-term outpatient stroke prevention
  • Periprocedural high‑risk PCI or acute coronary syndromes with large thrombus burden
  • First-line for primary prevention of myocardial infarction
  • Chronic prevention of peripheral arterial disease progression

Correct Answer: Periprocedural high‑risk PCI or acute coronary syndromes with large thrombus burden

Q29. Which adverse effect should be monitored with ticagrelor therapy due to its known association?

  • Severe hyperglycemia
  • Bradycardia and conduction abnormalities
  • Dyspnea and transient ventricular pauses
  • Significant hepatotoxicity in all patients

Correct Answer: Dyspnea and transient ventricular pauses

Q30. Recommended perioperative discontinuation times for antiplatelet agents commonly include which of the following?

  • Stop clopidogrel 5 days before surgery, ticagrelor 5 days, prasugrel 7 days; continue aspirin when possible
  • Stop aspirin 1 day before surgery, clopidogrel 1 day before, continue prasugrel
  • All antiplatelets should be stopped 30 days before any surgery
  • No need to stop antiplatelets for any surgical procedure

Correct Answer: Stop clopidogrel 5 days before surgery, ticagrelor 5 days, prasugrel 7 days; continue aspirin when possible

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