Antiarrhythmic Drugs Part 2

In this episode, we are going to review antiarrhythmic drugs that clinicians may encounter in practice: Digoxin, Propafenone, Dofetilide, and a few others. While these drugs are commonly used in the management of atrial fibrillation and other rhythm disturbances, they each come with important pharmacology and safety considerations that pharmacists and healthcare providers need to recognize.

Digoxin is a cardiac glycoside that increases contractility while also slowing AV node conduction through enhanced vagal tone, making it useful for rate control in atrial fibrillation, particularly in patients with heart failure. However, it has a narrow therapeutic index, and toxicity can occur if renal function declines or electrolyte abnormalities develop.

Propafenone is a Class IC sodium channel blocker used primarily for rhythm control in atrial fibrillation. A key clinical pearl with this medication is that it should generally be avoided in patients with structural heart disease due to the risk of proarrhythmia.

Dofetilide and sotalol are both Class III antiarrhythmics that work by blocking potassium channels and prolonging cardiac repolarization. Because of their ability to prolong the QT interval, both agents carry a risk of torsades de pointes and require careful monitoring. Dofetilide initiation typically requires hospitalization to monitor the QT interval and adjust dosing based on renal function. Sotalol also requires attention to renal function and ECG monitoring, and it has additional beta-blocking effects that can contribute to bradycardia and fatigue.

Throughout this episode, we will break down the mechanisms, common clinical uses, and key safety pearls for these medications to help you better understand how they fit into arrhythmia management.

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