IBHRE Pharmacology and Drug Therapy 2 — Questions and Answers
Question 1: Why does dofetilide require mandatory 3-day in-hospital initiation?
- Risk of severe bradycardia
- Risk of QT prolongation and torsades de pointes (Correct answer)
- Risk of hypertensive crisis
- Risk of acute renal failure
Correct answer: Risk of QT prolongation and torsades de pointes
Dofetilide causes dose-dependent QT prolongation and can precipitate torsades de pointes, requiring in-hospital QTc and renal monitoring during initiation.
Question 2: Which antiarrhythmic drug requires regular monitoring of thyroid and pulmonary function due to its molecular structure?
- Sotalol
- Flecainide
- Amiodarone (Correct answer)
- Dronedarone
Correct answer: Amiodarone
Amiodarone contains two iodine atoms and can cause thyroid dysfunction and pulmonary toxicity requiring periodic thyroid function tests and chest imaging.
Question 3: Sotalol combines the pharmacological actions of which two Vaughan Williams classes?
- Class I and Class IV
- Class II and Class III (Correct answer)
- Class I and Class II
- Class III and Class IV
Correct answer: Class II and Class III
Sotalol combines Class II (beta-blocking) and Class III (potassium channel blocking) actions, reducing heart rate and prolonging repolarization.
Question 4: Ranolazine's antiarrhythmic properties are primarily due to inhibition of which sodium current?
- Peak INa
- IKr
- Late INa (Correct answer)
- IKs
Correct answer: Late INa
Ranolazine inhibits the late (persistent) sodium current, reducing intracellular sodium and calcium overload that can trigger arrhythmias.
Question 5: Which drug should be avoided in Wolff-Parkinson-White syndrome with atrial fibrillation because it enhances accessory pathway conduction?
- Flecainide
- Procainamide
- Digoxin (Correct answer)
- Amiodarone
Correct answer: Digoxin
Digoxin can enhance conduction through the accessory pathway in WPW, potentially precipitating ventricular fibrillation during atrial fibrillation.
Question 6: How does dronedarone structurally differ from amiodarone?
- It has higher iodine content
- It is non-iodinated (Correct answer)
- It has a longer half-life
- It is a pure beta-blocker
Correct answer: It is non-iodinated
Dronedarone is a non-iodinated benzofuran derivative developed to retain antiarrhythmic efficacy while eliminating iodine-related thyroid and pulmonary toxicity.
IBHRE Pharmacology and Drug Therapy 2
Why does dofetilide require mandatory 3-day in-hospital initiation?