Dipyridamole MCQs With Answer

Dipyridamole MCQs With Answer offers B. Pharm students a focused, exam-ready review of dipyridamole pharmacology, clinical uses, formulations, adverse effects, interactions and monitoring. These concise MCQs emphasize core concepts: mechanism of action (phosphodiesterase inhibition and adenosine uptake blockade), antiplatelet effects, vasodilatory properties, combined aspirin formulations, and implications in stroke prevention and cardiac stress testing. Questions also cover contraindications, common side effects, drug interactions (e.g., caffeine, nitrates, anticoagulants), and practical dosing considerations for clinical practice and exams. This set deepens understanding beyond basics and reinforces application for therapeutics and patient safety. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which of the following best describes the primary mechanism of action of dipyridamole?

• Inhibits phosphodiesterase and adenosine uptake, increasing intracellular cAMP and adenosine effects
• Irreversibly inhibits cyclooxygenase-1 in platelets
• Blocks P2Y12 ADP receptors on platelets
• Direct thrombin inhibition

Correct Answer: Inhibits phosphodiesterase and adenosine uptake, increasing intracellular cAMP and adenosine effects

Q2. Dipyridamole primarily reduces platelet aggregation by increasing levels of which intracellular mediator?

• cAMP
• cGMP
• Thromboxane A2
• Calcium ions

Correct Answer: cAMP

Q3. Which formulation combines dipyridamole with low-dose aspirin for secondary stroke prevention?

• Aggrenox (extended-release dipyridamole + aspirin)
• Plavix (clopidogrel)
• Effient (prasugrel)
• Ticlid (ticlopidine)

Correct Answer: Aggrenox (extended-release dipyridamole + aspirin)

Q4. For which indication is dipyridamole commonly used in nuclear cardiac stress testing?

• Pharmacologic vasodilation to detect reversible myocardial ischemia
• Direct thrombolysis of coronary thrombus
• Chronic angina prophylaxis as first-line monotherapy
• Prevention of infective endocarditis

Correct Answer: Pharmacologic vasodilation to detect reversible myocardial ischemia

Q5. A major adverse effect of dipyridamole that often limits tolerability is:

• Severe headache
• Hyperglycemia
• Neutropenia
• Renal failure

Correct Answer: Severe headache

Q6. Which of the following is a key contraindication for dipyridamole use in stress testing?

• Unstable angina or recent myocardial infarction due to risk of coronary steal
• Mild seasonal allergies
• Controlled hypertension on therapy
• Hypercholesterolemia only

Correct Answer: Unstable angina or recent myocardial infarction due to risk of coronary steal

Q7. Dipyridamole enhances the effects of which endogenous nucleoside by inhibiting cellular uptake?

• Adenosine
• Adenine

Correct Answer: Adenosine

Q8. Patients are advised to avoid caffeine before a dipyridamole stress test because caffeine:

• Antagonizes adenosine receptors and reduces vasodilator response
• Potentiates dipyridamole-induced bleeding
• Causes irreversible platelet inhibition
• Inhibits hepatic metabolism of dipyridamole

Correct Answer: Antagonizes adenosine receptors and reduces vasodilator response

Q9. Dipyridamole’s antiplatelet effect can be best detected by which laboratory change?

• Prolonged bleeding time with normal PT and aPTT
• Prolonged PT with normal bleeding time
• Marked prolongation of aPTT
• Increased platelet count

Correct Answer: Prolonged bleeding time with normal PT and aPTT

Q10. Which drug interaction is clinically significant with dipyridamole due to additive hypotension?

• Nitrates
• Beta-blockers
• Statins
• Thiazide diuretics

Correct Answer: Nitrates

Q11. The combination of dipyridamole with anticoagulants (e.g., warfarin) primarily increases the risk of:

• Bleeding due to additive antithrombotic effects
• Renal toxicity
• Platelet count elevation
• Hypercoagulability

Correct Answer: Bleeding due to additive antithrombotic effects

Q12. Which of the following statements about dipyridamole pharmacodynamics is true?

• It potentiates prostacyclin-mediated platelet inhibition indirectly by raising cAMP
• It directly blocks thromboxane receptors
• It irreversibly acetylates platelet proteins
• It acts by chelating calcium in plasma

Correct Answer: It potentiates prostacyclin-mediated platelet inhibition indirectly by raising cAMP

Q13. How is extended-release dipyridamole administered in the Aggrenox regimen for stroke prevention?

• Twice daily (BID)
• Once daily (QD)
• Three times daily (TID)
• Once weekly

Correct Answer: Twice daily (BID)

Q14. Which physiologic phenomenon explains dipyridamole-induced worsening of ischemia in some coronary disease patients?

• Coronary steal due to vasodilation of non-ischemic vessels
• Increased myocardial oxygen demand by dipyridamole
• Direct vasoconstriction of coronary arteries
• Platelet aggregation in coronary microvessels

Correct Answer: Coronary steal due to vasodilation of non-ischemic vessels

Q15. Typical acute effects during IV dipyridamole administration for stress testing include:

• Flushing, headache and transient hypotension
• Bradycardia and heart block in all patients
• Severe hyperglycemia
• Profound diuresis

Correct Answer: Flushing, headache and transient hypotension

Q16. Which statement about dipyridamole use in pregnancy is most appropriate for B. Pharm students to counsel clinicians?

• Use only if clearly needed and benefits justify potential risks
• It is absolutely safe and recommended for all pregnant patients
• It is a first-line agent for pregnancy-associated thrombosis
• Administration is contraindicated only in the first trimester

Correct Answer: Use only if clearly needed and benefits justify potential risks

Q17. Dipyridamole’s antiplatelet action is generally considered:

• Reversible and short-acting compared with aspirin or clopidogrel
• Irreversible and life-long for platelets
• Dependent on renal replacement therapy for reversal
• Due to covalent modification of platelet receptors

Correct Answer: Reversible and short-acting compared with aspirin or clopidogrel

Q18. Which monitoring parameter is most relevant when initiating dipyridamole therapy for stroke prevention?

• Blood pressure and signs of bleeding
• Serum potassium levels weekly
• Routine coagulation profile changes daily
• Urine protein excretion monthly

Correct Answer: Blood pressure and signs of bleeding

Q19. Which patient characteristic increases risk of adverse events with dipyridamole?

• History of unstable angina or recent myocardial infarction
• Controlled hypothyroidism on replacement therapy
• Remote history of seasonal allergic rhinitis
• Hyperopia corrected with glasses

Correct Answer: History of unstable angina or recent myocardial infarction

Q20. The clinical benefit of adding dipyridamole to aspirin for some stroke patients is primarily due to:

• Synergistic antiplatelet effects reducing recurrent ischemic stroke
• Direct fibrinolytic activity dissolving clots
• Significant lipid-lowering properties
• Antihypertensive effects that control blood pressure

Correct Answer: Synergistic antiplatelet effects reducing recurrent ischemic stroke

Q21. During a dipyridamole stress test, which agent is used to reverse vasodilation and symptoms if needed?

• Aminophylline (an adenosine receptor antagonist)
• Propranolol
• Nitroglycerin
• Intravenous aspirin

Correct Answer: Aminophylline (an adenosine receptor antagonist)

Q22. Which adverse effect would most likely prompt dose reduction or discontinuation of dipyridamole?

• Intolerable, persistent severe headaches
• Mild transient thirst
• Asymptomatic slight weight gain
• Occasional dry cough

Correct Answer: Intolerable, persistent severe headaches

Q23. Which statement about dipyridamole and platelet aggregation is correct?

• It inhibits ADP- and collagen-induced platelet aggregation via cAMP elevation
• It selectively inhibits fibrinogen binding to GPIIb/IIIa receptors irreversibly
• It stimulates thromboxane production to inhibit aggregation
• It depletes platelet serotonin stores to prevent aggregation

Correct Answer: It inhibits ADP- and collagen-induced platelet aggregation via cAMP elevation

Q24. In elderly patients, what precaution is most relevant when prescribing dipyridamole?

• Start at recommended dose but monitor for hypotension and headaches
• Double the dose because of slower metabolism
• No special precautions are necessary compared with young adults
• Prohibit all concomitant antihypertensive agents

Correct Answer: Start at recommended dose but monitor for hypotension and headaches

Q25. Which of the following is an important counseling point for patients taking Aggrenox (dipyridamole + aspirin)?

• Take doses twice daily and report any unusual bleeding or severe headache
• It can be stopped abruptly and restarted without concern
• There is no interaction with over-the-counter NSAIDs
• It must be taken only once weekly

Correct Answer: Take doses twice daily and report any unusual bleeding or severe headache

Q26. Which pharmacologic property of dipyridamole contributes to its vasodilatory effect?

• Increased extracellular adenosine concentrations leading to coronary vasodilation
• Direct activation of alpha-1 adrenergic receptors
• Inhibition of beta-2 receptors
• Blocking calcium channels in skeletal muscle only

Correct Answer: Increased extracellular adenosine concentrations leading to coronary vasodilation

Q27. Which clinical trial outcome is associated with dipyridamole plus aspirin compared to aspirin alone in some stroke patients?

• Reduced risk of recurrent ischemic stroke in certain patients
• Clear mortality benefit in all stroke subtypes
• Increased cholesterol lowering compared with aspirin alone
• Elimination of need for blood pressure control

Correct Answer: Reduced risk of recurrent ischemic stroke in certain patients

Q28. Which of the following best describes dipyridamole’s effect on coagulation tests?

• Bleeding time may be prolonged but PT and aPTT typically remain normal
• PT is markedly prolonged while bleeding time is unchanged
• aPTT becomes significantly shortened
• Fibrinogen levels rise substantially

Correct Answer: Bleeding time may be prolonged but PT and aPTT typically remain normal

Q29. Which practical step should be taken before performing a pharmacologic dipyridamole stress test?

• Instruct the patient to avoid caffeine for at least 24 hours
• Ensure the patient takes their morning caffeine to enhance test sensitivity
• Administer aspirin immediately before the test to prevent adverse effects
• Stop all antihypertensive drugs permanently

Correct Answer: Instruct the patient to avoid caffeine for at least 24 hours

Q30. Which statement about dipyridamole’s place in therapy is most accurate?

• It is useful as an adjunct antiplatelet agent and pharmacologic vasodilator with defined roles in stroke prevention and cardiac imaging
• It is the first-line agent for all types of acute coronary syndromes
• It replaces anticoagulants in atrial fibrillation management
• It has no role in modern cardiovascular practice

Correct Answer: It is useful as an adjunct antiplatelet agent and pharmacologic vasodilator with defined roles in stroke prevention and cardiac imaging

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com