Class III Antiarrythmics - Sotalol
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Summary
Sotalol is Class III antiarrhythmic medication that works by blocking potassium channels in cardiomyocytes, which increases the refractory period. Sotalol primarily targets arrhythmias in non-nodal cardiac myocytes, which makes it good for rhythm control. Sotalol is also a beta blocker, and has mild class II antiarrhythmic properties. A dangerous side effect of sotalol and all class 3 antiarrhythmics is QT prolongation leading to Torsades de pointes.
Key Points
- Sotalol
- Mechanism
- Acts as Class 2 and 3 Antiarrhythmic
- Causes Beta-blocker Activity
- Reduces cAMP and calcium influx at nodal tissue
- Slows down heart rate, AV conduction (PR interval)
- Blocks Potassium (K+) channels
- Prolongs phase 3 repolarization by blocking potassium outflow, mainly in non-nodal tissue
- Increases AP duration and effective refractory period (ERP)
- Prolonged QT creates risk for early after-depolarizations and Torsades de Pointes
- Causes Beta-blocker Activity
- Acts as Class 2 and 3 Antiarrhythmic
- Clinical Use
- Treats Atrial flutter/fibrillation
- Treats Ventricular tachycardia
- Adverse Effects
- Causes Long QT (Torsades de Pointes risk)
- All drugs that increase QT interval increase the risk of early after-depolarizations causing ventricular arrhythmias like Torsades de Pointes
- Avoid in patients with congenital or acquired long QT syndrome
- Causes Long QT (Torsades de Pointes risk)
- Mechanism