Sotalol

Classification:

Amiodarone – the most effective anti-arrhythmic drug, but associated with the highest rate of adverse effects.
Dronedarone – similar to amiodarone, but less potent and associated with fewer adverse effects.
Sotalol – also a non-selective beta-blocker.
Ibutilide – may be used for acute cardioversion of pre-excited atrial fibrillation (AF).

Mechanism:

Prolongs the non-nodal action potential (AP) and effective refractory period (ERP) in the myocardium

≤ 160 mg/day → predominantly beta-blocker effect
160–320 mg/day → additional Class III anti-arrhythmic effect (K⁺ channel blockade)
> 320 mg/day → markedly increased risk (2–4 %) of proarrhythmia (QT prolongation → torsades de pointes)

Reverse use-dependent (greater effect at lower heart rates), rate-dependent effect:

Effect on AF:

Sotalol and atrial fibrillation (AF)
Brand names
Sotalol, Sotalex, Sotacor
Indications
Maintenance of sinus rhythm
Dosing
Chronic rhythm control – maintenance of sinus rhythm (oral) 80–160 mg twice daily Increase the dose every 3 days if QTc < 500 ms 80 mg twice daily → 120 mg twice daily → 160 mg twice daily
Onset of action
1–2 hours (oral)
Effect
Maintenance of sinus rhythm (paroxysmal or persistent AF) at 1 year 40–55 % (oral)
Duration of action
12–24 hours (oral)
Contraindications
Prolonged QTc interval > 450 ms Long QT syndrome Second- or third-degree AV block Bronchial asthma or other bronchospastic disorders Sinus bradycardia (< 50/min) Cardiogenic shock Decompensated heart failure Electrolyte imbalance (potassium, sodium, magnesium) Sick sinus syndrome (without pacemaker) Concomitant use of myocardial depressant anaesthetics Allergy to sotalol

Patient monitoring after initiation of sotalol:

Patient monitoring after initiation of sotalol
Time from initiation	What to monitor	Reason for treatment discontinuation
1–3 days (from initiation or after dose increase)	ECG (QTc) Blood pressure	QTc > 500 ms Bradycardia < 50/min Hypotension < 90/60 mmHg
7 days – 1 month	ECG (QTc) Blood pressure Laboratory tests (electrolytes, renal function)	QTc > 500 ms Bradycardia < 50/min Hypotension < 90/60 mmHg Severe electrolyte imbalance (Na⁺, K⁺, Mg²⁺)
6–12 months	ECG (QTc) Echocardiography Laboratory tests (electrolytes, renal function)	QTc > 500 ms Severe electrolyte imbalance (Na⁺, K⁺, Mg²⁺)

Adverse effects:

Sotalol vs. beta-blockers in atrial fibrillation (AF)
Property	Sotalol	Beta-blockers
Class	Class III + non-selective beta-blocker	Class II (pure beta-blockers)
Mechanism	K⁺ channel blockade + β-receptor blockade	β₁ blockade (reduction of heart rate and AV conduction)
Effect on QT interval	Prolongs QT (risk of TdP)	No effect on QT
Reverse use-dependence	Strong effect at HR < 60/min Weak effect at HR > 100/min	No
Dose dependence	< 160 mg/day → beta-blocker effect ≥ 160–320 mg/day → beta-blocker + Class III effect	Dose determines strength of beta-blocker effect, without Class III activity
Indication in AF	Maintenance of sinus rhythm (rhythm control)	Heart rate control
Adverse effects	Torsades de pointes (at QTc ≥ 500 ms)	Bronchospasm, fatigue, bradycardia, hypotension