Antiarrythmics

Question 1

Amiodarone

Answer 1

Class III
Potassium channel blocker

Amiodarone is a class III antiarrhythmic agent with a primary effect of blocking potassium channels. It also blocks calcium and sodium channels to a lesser effect as well as α- and β-adrenergic receptors. The approved clinical use of amiodarone is limited to refractory ventricular arrhythmias. It is also commonly used in sustained supraventricular tachycardias with accessory pathway conduction and atrial fibrillation/flutter/tachycardia with congestive heart failure (CHF). It may be an effective prophylaxis for atrial fibrillation postoperatively. Recall that amiodarone is still the antiarrhythmic agent of choice in the setting of CHF or low ejection fraction.

Important side effects of amiodarone include bradycardia, hypotension, hypothyroidism, life-threatening hyperthyroid storm, pulmonary toxicity (with a pulmonary fibrosis appearance), prolonged QT, and elevated liver function markers. Two of the most frequent cardiovascular side effects of amiodarone are bradycardia and hypotension, which occur in approximately 5 to 10% of the population.

Question 2

Class Ia

Answer 2

sodium channel blockers

e.g. procainamide

Question 3

Class III

Answer 3

potassium channel inhibitors

e.g. amiodarone

Question 4

Class IV

Answer 4

calcium channel blockers

e.g. verapamil, diltiazem