Quinidine sulphate MCQs With Answer

Quinidine sulphate MCQs With Answer — This focused introduction reviews quinidine sulphate, an important Class IA antiarrhythmic, tailored for B. Pharm students. Learn about quinidine’s mechanism of action (Na+ and K+ channel blockade), electrophysiologic effects (widened QRS, prolonged QT), pharmacokinetics, therapeutic uses in atrial and ventricular arrhythmias, dosage forms (sulfate vs. gluconate), adverse effects including cinchonism and torsades de pointes, major drug interactions (notably with digoxin and CYP2D6 substrates), monitoring parameters and contraindications. The content emphasizes clinical pharmacology, safety, and exam-relevant points to deepen understanding and prepare you for assessments. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary Vaughan-Williams classification of quinidine?

• Class IB antiarrhythmic
• Class IC antiarrhythmic
• Class IA antiarrhythmic
• Class III antiarrhythmic

Correct Answer: Class IA antiarrhythmic

Q2. Quinidine’s antiarrhythmic effect is mainly due to blockade of which ion channels?

• Calcium and potassium channels
• Sodium and potassium channels
• Sodium and calcium channels
• Potassium channels only

Correct Answer: Sodium and potassium channels

Q3. Which ECG changes are typically seen with quinidine therapy?

• Shortened PR interval and shortened QT
• Widened QRS and prolonged QT interval
• ST-segment elevation only
• No change in QRS or QT intervals

Correct Answer: Widened QRS and prolonged QT interval

Q4. A classic adverse effect characterized by tinnitus, headache and visual disturbances with quinidine is called:

• Stevens-Johnson syndrome
• Cinchonism
• Serotonin syndrome
• Agranulocytosis

Correct Answer: Cinchonism

Q5. Quinidine interaction with digoxin commonly results in:

• Decreased digoxin serum levels due to induction
• No change in digoxin levels
• Increased digoxin serum levels due to reduced clearance and displacement
• Complete antagonism of digoxin effect

Correct Answer: Increased digoxin serum levels due to reduced clearance and displacement

Q6. Which enzyme system is notably inhibited by quinidine, affecting many drug interactions?

• CYP3A4
• CYP1A2
• CYP2D6
• CYP2C19

Correct Answer: CYP2D6

Q7. Quinidine is most appropriately indicated for which of the following?

• Acute myocardial infarction pain relief
• Treatment of ventricular and supraventricular arrhythmias such as atrial fibrillation
• Chronic hypertension management
• Immediate treatment of bradycardia

Correct Answer: Treatment of ventricular and supraventricular arrhythmias such as atrial fibrillation

Q8. Which formulation of quinidine is commonly used for oral therapy?

• Quinidine sulfate tablets
• Quinidine chloride injection
• Quinidine phosphate inhaler
• Quinidine nitrate topical gel

Correct Answer: Quinidine sulfate tablets

Q9. Which of the following is a serious proarrhythmic risk associated with quinidine?

• Torsades de pointes due to QT prolongation
• Atrial thrombus formation
• Complete reversal of conduction block
• Bradycardia due to strong beta-blockade

Correct Answer: Torsades de pointes due to QT prolongation

Q10. Quinidine’s effect on atrioventricular (AV) conduction is best described as:

• Decreases AV nodal conduction exclusively
• Increases AV conduction due to anticholinergic effect
• Has no effect on AV conduction
• Causes complete AV block in all patients

Correct Answer: Increases AV conduction due to anticholinergic effect

Q11. The pharmacokinetic property of quinidine that is clinically important is:

• It is not orally absorbed at all
• It has highly variable oral absorption and hepatic metabolism
• It is exclusively renally excreted unchanged
• It has no protein binding

Correct Answer: It has highly variable oral absorption and hepatic metabolism

Q12. Which monitoring parameter is most important during quinidine therapy?

• Serum potassium and ECG (QT interval)
• Liver enzymes only
• Respiratory rate only
• Fasting blood glucose only

Correct Answer: Serum potassium and ECG (QT interval)

Q13. Quinidine’s half-life is best described as:

• Extremely short (<30 minutes)
• Moderate and variable, often around several hours
• Extremely long (>7 days)
• Identical for all patients at 24 hours

Correct Answer: Moderate and variable, often around several hours

Q14. In quinidine overdose with wide QRS complex, an appropriate emergency intervention is:

• IV sodium bicarbonate to narrow QRS
• Oral activated charcoal only after 48 hours
• No treatment, observe only
• Immediate beta-blocker administration

Correct Answer: IV sodium bicarbonate to narrow QRS

Q15. Which patient condition is a contraindication to quinidine use?

• History of stable controlled hypertension
• Complete heart block without pacemaker
• Seasonal allergic rhinitis
• Mild acne vulgaris

Correct Answer: Complete heart block without pacemaker

Q16. Quinidine may aggravate which neuromuscular disorder?

• Myasthenia gravis
• Osteoarthritis
• Tension headache
• Plantar fasciitis

Correct Answer: Myasthenia gravis

Q17. Which of the following best describes quinidine’s action potential duration (APD) effect?

• Shortens APD markedly
• Prolongs APD and effective refractory period
• No effect on APD
• Prolongs APD only in the AV node

Correct Answer: Prolongs APD and effective refractory period

Q18. Quinidine produces which effect on cardiac conduction velocity?

• Increases conduction velocity in ventricles
• Decreases conduction velocity (widens QRS)
• No effect on conduction velocity
• Only affects sinus node automaticity

Correct Answer: Decreases conduction velocity (widens QRS)

Q19. Which laboratory adverse effect can occur with quinidine therapy?

• Thrombocytopenia
• Marked hyperglycemia
• Elevated hemoglobin exclusively
• Increased creatinine kinase only

Correct Answer: Thrombocytopenia

Q20. Which clinical feature suggests cinchonism from quinidine toxicity?

• Persistent cough and hemoptysis
• Tinnitus and headache
• Jaundice and ascites
• Peripheral neuropathy only

Correct Answer: Tinnitus and headache

Q21. How does quinidine affect digoxin clearance mechanistically?

• Induces renal P-glycoprotein leading to increased digoxin excretion
• Inhibits digoxin renal clearance and displaces tissue-bound digoxin, raising levels
• Directly metabolizes digoxin via CYP3A4
• Has no interaction with digoxin at all

Correct Answer: Inhibits digoxin renal clearance and displaces tissue-bound digoxin, raising levels

Q22. Which adverse cardiac arrhythmia may be precipitated by quinidine therapy?

• Sinus bradycardia only
• Torsades de pointes
• Wolff-Parkinson-White resolution
• Stable atrial flutter suppression without risk

Correct Answer: Torsades de pointes

Q23. Which patient factor increases the risk of quinidine-induced torsades?

• Hypokalemia
• Hypercalcemia
• Elevated hemoglobin
• Low body temperature only

Correct Answer: Hypokalemia

Q24. Quinidine’s use-dependent sodium channel blockade means:

• Blockade is greater at slower heart rates
• Blockade is greater at higher heart rates due to more frequent channel opening
• Blockade is independent of heart rate
• Blockade occurs only in atrial tissue

Correct Answer: Blockade is greater at higher heart rates due to more frequent channel opening

Q25. Which of the following is true regarding quinidine and pregnancy?

• It is absolutely contraindicated in pregnancy
• Classified as pregnancy category C; use only if benefits justify risks
• Safe and recommended as first-line in pregnancy without caution
• Causes guaranteed fetal malformations

Correct Answer: Classified as pregnancy category C; use only if benefits justify risks

Q26. Which electrolyte abnormality should be corrected before starting quinidine?

• Hypernatremia
• Hypokalemia
• High bicarbonate
• Hypermagnesemia

Correct Answer: Hypokalemia

Q27. Compared with procainamide, quinidine is distinguished by:

• Less anticholinergic activity
• Greater anticholinergic effects and more pronounced cinchonism risk
• No effect on AV nodal conduction
• Exclusive IV administration only

Correct Answer: Greater anticholinergic effects and more pronounced cinchonism risk

Q28. Which pharmacologic property explains quinidine’s potential to cause hypotension?

• Strong beta-2 agonist effect
• Alpha-adrenergic blockade and vasodilation
• Excessive sodium retention
• Direct increase in blood viscosity

Correct Answer: Alpha-adrenergic blockade and vasodilation

Q29. What is a key counseling point when dispensing quinidine sulfate to patients?

• Advise to avoid sunlight due to photosensitivity only
• Report symptoms of tinnitus, palpitations, dizziness, or syncope and have periodic ECG monitoring
• No monitoring required and take with antacids freely
• Stop all other cardiac medications immediately

Correct Answer: Report symptoms of tinnitus, palpitations, dizziness, or syncope and have periodic ECG monitoring

Q30. Which antidote or supportive therapy is specifically useful for quinidine-induced torsades de pointes?

• IV magnesium sulfate
• High-dose vitamin K
• Oral calcium carbonate
• Subcutaneous insulin

Correct Answer: IV magnesium sulfate

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