Usage
Sotalol is prescribed for the treatment of life-threatening ventricular arrhythmias such as sustained ventricular tachycardia and ventricular fibrillation, and for the maintenance of sinus rhythm in patients with atrial fibrillation/flutter. It’s pharmacologically classified as a non-selective beta-blocker with Class III antiarrhythmic properties. Sotalol acts by blocking beta-adrenergic receptors and prolonging the action potential duration of cardiac myocytes, thereby slowing heart rate and conduction velocity.
Alternate Names
Sotalol is the generic name. Brand names include Betapace and Betapace AF. Sotacor is a brand name for the intravenous formulation.
How It Works
Pharmacodynamics: Sotalol possesses both beta-blocking (Class II) and potassium channel blocking (Class III) antiarrhythmic actions. The L-isomer exhibits primarily beta-blocking activity, while both isomers contribute to the Class III effects. Beta-blockade reduces heart rate, myocardial contractility, and atrioventricular conduction. Class III action prolongs repolarization, increasing the effective refractory period.
Pharmacokinetics: Sotalol is well-absorbed orally (bioavailability > 90%) with peak plasma concentrations reached in 2.5 to 4 hours. It’s not metabolized by CYP enzymes and is primarily excreted unchanged via the kidneys. The elimination half-life is approximately 12 hours, allowing for twice-daily dosing. Steady-state plasma levels are achieved in 2-3 days. Sotalol doesn’t bind significantly to plasma proteins and has a volume of distribution of 1.6 to 2.4 L/kg.
Mode of Action: Sotalol exerts its beta-blocking effect by competitively binding to beta-1 and beta-2 adrenergic receptors. Its Class III action involves blocking potassium channels, particularly the delayed rectifier potassium current (IK), which prolongs cardiac repolarization.
Elimination Pathways: Primarily renal excretion.
Dosage
Standard Dosage
Adults:
Initial dose: 80 mg orally twice daily.
Maintenance dose: Adjustable, typically 160-320 mg/day divided twice daily.
Some patients with life-threatening arrhythmias may require up to 480-640 mg/day.
Dose adjustments should be made every 2-3 days to allow for steady-state plasma concentrations and QT interval monitoring.
Children:
For children aged 2 or older with normal renal function:
Initial dose: 1.2 mg/kg three times daily (3.6 mg/kg total daily dose).
Maximum dose: 2.4 mg/kg three times daily (7.2 mg/kg total daily dose, or maximum 360mg total daily dose).
Dose titration should be based on clinical response, heart rate, and QTc interval, preferably in a hospital setting.
Special Cases:
- Elderly Patients: Start at the low end of the adult range and monitor closely. Reduce dose to approximately 80% of the usual adult dose based on patient response and changes in vital signs.
- Patients with Renal Impairment: Reduce the dose based on creatinine clearance. If CrCl is between 40-60 mL/min, administer once daily. If less than 40 mL/min, sotalol is not recommended.
- Patients with Hepatic Dysfunction: No dosage adjustment is necessary.
- Patients with Comorbid Conditions: Use with caution in patients with diabetes (can mask hypoglycemia), sick sinus syndrome, and other cardiovascular diseases.
Clinical Use Cases
Dosing guidelines for these settings are not provided in the available sources.
- Intubation
- Surgical Procedures
- Mechanical Ventilation
- Intensive Care Unit (ICU) Use
- Emergency Situations (e.g., status epilepticus, cardiac arrest)
Dosage Adjustments
Adjust dose based on patient’s renal function, QTc interval prolongation, and clinical response. Monitor heart rate, QT interval, and electrolytes during dosage titration.
Side Effects
Common Side Effects:
Fatigue, dizziness, bradycardia, hypotension, dyspnea.
Rare but Serious Side Effects:
Torsades de pointes, new or worsened heart failure, bronchospasm.
Long-Term Effects:
No specific long-term effects are mentioned in the provided sources aside from potential progression of underlying heart conditions.
Adverse Drug Reactions (ADR):
Torsades de pointes, bradycardia, hypotension, bronchospasm.
Contraindications
- Sinus bradycardia, second- or third-degree AV block (without a functioning pacemaker).
- Congenital or acquired long QT syndrome.
- Cardiogenic shock.
- Uncompensated heart failure.
- Bronchial asthma or related bronchospastic conditions.
- Hypersensitivity to sotalol.
- Creatinine clearance <40 mL/min.
Drug Interactions
Sotalol interacts with several medications, including:
- Class Ia and Ic antiarrhythmics (increased risk of proarrhythmia).
- Calcium channel blockers (increased risk of bradycardia and hypotension).
- Digoxin (additive bradycardic effect).
- Insulin and oral hypoglycemics (may mask signs of hypoglycemia).
- Catecholamine-depleting drugs (e.g., reserpine) (additive beta-blocking effects).
Pregnancy and Breastfeeding
Pregnancy Safety Category: B. While animal studies have shown no evidence of teratogenicity, there’s limited human data. Use during pregnancy only if the potential benefit outweighs the risk to the fetus. Sotalol is excreted in breast milk, potentially causing bradycardia and hypoglycemia in the neonate. Monitor infants of breastfeeding mothers taking sotalol.
Drug Profile Summary
- Mechanism of Action: Non-selective beta-blocker with Class III antiarrhythmic properties.
- Side Effects: Fatigue, dizziness, bradycardia, hypotension, dyspnea, torsades de pointes, worsening heart failure, bronchospasm.
- Contraindications: Bradycardia, AV block, long QT syndrome, cardiogenic shock, uncompensated heart failure, bronchial asthma, hypersensitivity, renal impairment.
- Drug Interactions: Class Ia and Ic antiarrhythmics, calcium channel blockers, digoxin, insulin, catecholamine-depleting drugs.
- Pregnancy & Breastfeeding: Category B; use with caution; excreted in breast milk.
- Dosage: Adults: 80-320 mg/day divided BID; Children: 1.2-2.4 mg/kg TID. Special adjustments needed for renal impairment.
- Monitoring Parameters: ECG (QTc interval), heart rate, blood pressure, electrolytes.
Popular Combinations
Not specified in the provided sources.
Precautions
- Pre-existing cardiovascular conditions, diabetes, and renal/hepatic impairment.
- Monitor QTc interval during initiation and dosage adjustments.
- Caution with concurrent use of QT-prolonging drugs.
- Monitor for signs of heart failure.
- Electrolyte monitoring is essential.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Sotalol?
A: Adults: Initially 80 mg BID, adjustable to 160-320 mg/day divided BID. Children: 1.2-2.4 mg/kg TID. Renal adjustments are necessary.
Q2: What are the major side effects of Sotalol?
A: Bradycardia, hypotension, dizziness, fatigue, new or worsened heart failure, torsades de pointes, bronchospasm.
Q3: How does Sotalol work?
A: Sotalol blocks beta-adrenergic receptors and potassium channels, prolonging the action potential duration and slowing heart rate.
Q4: What are the contraindications for using Sotalol?
A: Bradycardia, AV block, long QT syndrome, cardiogenic shock, uncompensated heart failure, bronchial asthma, hypersensitivity to sotalol, renal impairment with CrCl <40 ml/min.
Q5: What medications interact with Sotalol?
A: Class Ia and Ic antiarrhythmics, calcium channel blockers, digoxin, insulin, catecholamine-depleting drugs.
Q6: Is Sotalol safe during pregnancy?
A: Pregnancy Category B. Use with caution if the benefits outweigh the potential fetal risks.
Q7: How should Sotalol be administered?
A: Orally, usually twice daily. Intravenous administration is available but mainly for hospital initiation or oral substitution when the patient cannot take oral medications.
Q8: How often should the QTc interval be monitored during Sotalol therapy?
A: Monitor closely during initiation and dose titration. Frequency should be based on clinical response and risk factors, but typically at baseline and within 2-4 hours after the first few doses.
Q9: What are the signs of Sotalol overdose?
A: Severe bradycardia, hypotension, bronchospasm, torsades de pointes, and potentially seizures.
