NAPLEX Practice Exam 2026 – Comprehensive Test Preparation

Dofetilide is classified under Class III antiarrhythmic agents. Class III antiarrhythmics predominantly block the potassium channels, prolonging the action potential duration and increasing the refractory period of the myocardium. This class of medications is used to treat various types of cardiac arrhythmias, including atrial fibrillation and ventricular tachycardia.

Regarding the other options:

- Class I antiarrhythmic agents block sodium channels (e.g., lidocaine, flecainide).

- Class II antiarrhythmics are beta-blockers (e.g., metoprolol, propranolol).

- Class IV antiarrhythmics are calcium channel blockers (e.g., verapamil, diltiazem).