Sotalol

Sotalol is a 1st-generation, nonselective beta-blocker with additional Class III antiarrhythmic properties.

It blocks:

• β1 receptors • β2 receptors • Cardiac potassium channels (IKr)

Because of its potassium channel blockade, sotalol prolongs the QT interval.

Classification: • 1st Generation (Nonselective) • Also a Class III Antiarrhythmic • No intrinsic sympathomimetic activity (ISA)

→ Beta-Blockers Overview → Dysrhythmias Module

Beta-blocking effects:

• ↓ Heart rate • ↓ AV nodal conduction • ↓ Renin release

Class III antiarrhythmic effects:

• Blocks potassium channels • Prolongs action potential duration • Prolongs QT interval • Increases refractory period

Net Effect:

• Suppresses atrial and ventricular arrhythmias

Unlike most beta-blockers, sotalol significantly prolongs QT.

• Rhythm control (not just rate control)

• Suppression of ventricular tachycardia

Sotalol is NOT commonly used for hypertension.

Because sotalol prolongs QT:

• Risk of torsades de pointes • Risk increases with:

1. Renal impairment
2. Electrolyte abnormalities
3. High doses

Initiation often requires ECG monitoring.

QT prolongation is dose-dependent.

• Hydrophilic • Renally cleared • Minimal CNS penetration

Dose adjustment required in renal impairment.

Beta-blocker effects:

• Bradycardia • Hypotension • Fatigue • Bronchospasm

Class III effects:

• QT prolongation • Torsades de pointes

• Baseline prolonged QT • Severe bradycardia • High-grade AV block • Cardiogenic shock • Significant renal impairment • Hypokalemia or hypomagnesemia

Most beta-blockers: • Do NOT prolong QT • Used for rate control

Sotalol: • Used for rhythm control • Prolongs QT • Higher arrhythmia risk

Compare with:

• Metoprolol (rate control) • Propranolol (nonselective, no QT effect)

Amiodarone: • Also Class III • More effective but more toxic

Sotalol: • Cleaner systemic profile • Greater torsades risk

✔ Nonselective beta-blocker + Class III antiarrhythmic ✔ Prolongs QT interval ✔ Risk of torsades de pointes ✔ Requires renal dose adjustment ✔ Used for rhythm control, not simple rate control

Related:

→ Beta-Blockers Overview → Dysrhythmias Module → Return to Cardiovascular Modules