Generic Name

Sotalol

Mechanism

• β‑Blockade – Inhibits β₁ and β₂ adrenergic receptors, reducing sympathetic tone, slowing AV nodal conduction, and decreasing heart rate.
• Class III Activity – Prolongs repolarization by blocking potassium (K⁺) channels (IKr), lengthening the action potential and QT interval.
• Combined effect – Provides rate control in atrial fibrillation while preventing ventricular tachycardia via potassium‑channel blockade.

Pharmacokinetics

• Absorption – Oral bioavailability ≈ 90 %; peak plasma levels in 1–2 h.
• Distribution – Vd ≈ 0.7 L/kg; binds ≈ 10 % to plasma proteins.
• Metabolism – Minimal hepatic metabolism; primarily renal excretion.
• Half‑life – 12–18 h (IV) and 10–12 h (oral); dose accordingly in renal impairment.
• Drug interactions – Potentiation of β‑blocker β‑agonists; concomitant QT‑prolonging agents (e.g., erythromycin, azithromycin) ↑ arrhythmia risk.

Indications

• Atrial fibrillation/flutter – Maintenance of sinus rhythm, rate control in uncontrolled AF.
• Ventricular tachycardia – Prevents sustained monomorphic VT and degenerates into ventricular fibrillation.
• Post‑myocardial infarction – Secondary prevention of sudden cardiac death in high‑risk patients.

Contraindications

• Absolute contraindications
• Sick sinus syndrome (without pacemaker)
• Second‑ or third‑degree AV block (without pacemaker)
• Bradycardia < 50 bpm
• Severe hypotension or cardiogenic shock
• Warnings
• QT prolongation → torsades de pointes, especially with renal impairment or electrolyte abnormalities.
• Hypokalemia, hypomagnesemia, or hyperkalemia may compound QT changes.
• Concomitant use of other QT‑prolonging drugs.

Dosing

• Renal: Reduce maintenance dose by 50 % when CrCl < 30 mL/min.
• Administration: Oral tablets; IV infusion over 48 h with continuous ECG monitoring.

Adverse Effects

• Common
• Fatigue, dizziness, bradycardia, hypotension, sinus node dysfunction.
• Gastrointestinal upset, nausea, bloating.
• Sleep disturbances (insomnia).
• Serious
• Torsades de pointes (QT > 500 ms).
• Severe sinus bradycardia or AV block.
• Hypotensive crisis.
• Severe electrolyte imbalance (esp. hypokalemia).
• Renal dysfunction (accumulation).

Monitoring

• Baseline
• ECG (QTc), electrolytes (K⁺, Mg²⁺, Ca²⁺), renal function.
• During therapy
• Twice daily ECG until QTc stabilizes < 450 ms (men) / < 460 ms (women).
• Renal function every 2–3 days for the first week, then every 2–4 weeks.
• Serum electrolytes when symptomatic or if QTc increases.
• Long‑term
• Annual ECG or sooner if symptoms develop.

Clinical Pearls

• Torsades Check – If the QTc > 500 ms, hold the drug, correct electrolytes, and consider alternative anti‑arrhythmic.
• Pacemaker Guidance – Patients with a pacing system may tolerate higher doses; nevertheless, monitor ECG closely for bradyarrhythmia.
• Renal Adjustment – Reduce the dose early; remember sotalol’s half‑life extends in CKD, raising systemic exposure.
• Drug‑Drug Caution – Avoid combining with other β‑blockers or K⁺‑channel blockers (e.g., amiodarone) unless on a carefully monitored regimen.
• Patient Education – Counsel patients on signs of bradycardia (dizziness, fainting) and to avoid sudden caffeine or alcohol cessation during initiation.

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• *For further reading, consult the latest guidelines from the American College of Cardiology/American Heart Association and UpToDate entries on sotalol therapy.*