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Monday, July 28, 2025

Sotalol


Generic name: Sotalol
Drug class: Antiarrhythmic (Class II and Class III)
Formulation: Oral tablets, oral solution, intravenous injection
Strengths available: 80 mg, 120 mg, 160 mg, 240 mg tablets
Route of administration: Oral, Intravenous
Prescription status: Prescription-only medication
Uses:
– Management of life-threatening ventricular arrhythmias
– Maintenance of normal sinus rhythm in patients with atrial fibrillation or flutter
– Not intended for treating asymptomatic arrhythmias in patients without structural heart disease

Sotalol is a non-selective beta-blocker with additional potassium channel-blocking activity. It is used as both a beta-adrenergic antagonist and a cardiac rhythm stabilizer.

2. Mechanism of Action

Sotalol exhibits dual electrophysiological effects:

Class II (beta-blocker activity):

  • Inhibits β1 and β2 adrenergic receptors

  • Reduces heart rate

  • Decreases myocardial oxygen demand

  • Slows AV nodal conduction

Class III (antiarrhythmic activity):

  • Inhibits cardiac potassium channels (IKr current)

  • Prolongs action potential duration and refractory period

  • Stabilizes cardiac electrical activity and reduces the likelihood of reentrant tachyarrhythmias

These combined actions suppress abnormal heart rhythms and prevent recurrence of arrhythmia in susceptible individuals.

3. Pharmacokinetics

Absorption:

  • Rapid and complete oral absorption with ~100% bioavailability

  • Peak plasma concentration occurs 2 to 4 hours after oral dose

Distribution:

  • Volume of distribution is moderate

  • Does not bind significantly to plasma proteins

  • Limited central nervous system penetration

Metabolism:

  • Not metabolized in the liver

  • Exists as a racemic mixture of d- and l-enantiomers

Elimination:

  • Excreted unchanged in urine

  • Renal clearance accounts for entire elimination

  • Elimination half-life is about 12 hours in healthy adults

  • Prolonged in renal impairment

4. Indications

1. Ventricular arrhythmias
– For symptomatic, sustained ventricular tachycardia
– For patients at high risk of sudden cardiac death

2. Supraventricular arrhythmias
– For maintenance of normal sinus rhythm after conversion of atrial fibrillation or atrial flutter

3. Off-label uses (under clinical discretion):
– Certain pediatric arrhythmias
– AV reentrant tachycardia in structurally normal hearts
– Some cases of premature ventricular contractions in symptomatic patients

5. Dosage and Administration

Adults (oral):

  • Initial dose: 80 mg twice daily

  • May be increased incrementally every 3 days based on clinical response and ECG findings

  • Usual maintenance dose: 160 to 320 mg daily in divided doses

  • Maximum dose: 640 mg/day in selected patients under strict monitoring

Pediatrics:

  • Dosing based on body surface area or weight

  • Initiated under specialized cardiac care with ECG monitoring

Renal impairment:

  • Requires dose adjustment based on creatinine clearance

  • CrCl <60 mL/min: reduce dose or increase dosing interval

  • CrCl <10 mL/min: avoid use unless under cardiac supervision

Intravenous administration:

  • Used when oral therapy is not feasible

  • Requires cardiac monitoring during infusion

6. Contraindications

  • Second- or third-degree AV block without pacemaker

  • Sinus bradycardia (<50 bpm)

  • Congenital or acquired long QT syndrome

  • QTc interval >450 ms before initiation

  • Severe renal impairment without dosage adjustment

  • Uncontrolled heart failure

  • Cardiogenic shock

  • Bronchial asthma or severe chronic obstructive pulmonary disease

  • Known hypersensitivity to sotalol

7. Precautions

  • Must be initiated in a hospital setting where continuous ECG and renal function can be monitored

  • Risk of torsades de pointes increases with higher doses, renal impairment, electrolyte imbalances, and prolonged QT

  • Correct hypokalemia and hypomagnesemia before starting treatment

  • Withdraw other QT-prolonging agents before initiating sotalol

  • Avoid abrupt discontinuation to reduce the risk of rebound arrhythmias or angina

  • Not first-line in patients with recent myocardial infarction or heart failure

8. Warnings

  • Proarrhythmia is a serious risk, particularly torsades de pointes, which can be life-threatening

  • ECG monitoring is essential during initiation and dose titration

  • Avoid use with other QT-prolonging medications

  • May exacerbate bradycardia, hypotension, and conduction abnormalities

  • Use with caution in patients with diabetes as it may mask hypoglycemia symptoms

  • Can worsen bronchospasm in patients with reactive airway disease

  • May reduce exercise tolerance and provoke fatigue in some patients

9. Adverse Effects

Common (>10%):

  • Bradycardia

  • Dizziness

  • Fatigue

  • Palpitations

  • Dyspnea

  • Nausea

Less common (1–10%):

  • Torsades de pointes

  • Ventricular tachycardia

  • Headache

  • Insomnia

  • Depression

  • Cold extremities

  • Chest pain

  • Asthma exacerbation

Rare (<1%):

  • Syncope

  • Prolonged QT leading to ventricular fibrillation

  • Visual disturbances

  • Severe hypotension

  • Allergic skin reactions

10. Drug Interactions

  • Do not use concurrently with other QT-prolonging drugs (e.g., amiodarone, erythromycin, haloperidol)

  • Additive bradycardia with other beta-blockers or calcium channel blockers (e.g., verapamil, diltiazem)

  • Increased risk of proarrhythmia with diuretics that lower potassium or magnesium

  • Risk of hypotension when combined with antihypertensive agents

  • May mask symptoms of hypoglycemia in diabetic patients on insulin or sulfonylureas

  • Use with digoxin may increase the risk of bradyarrhythmia

11. Use in Specific Populations

Pregnancy:

  • Limited human data available

  • Use only if benefits outweigh risks

Lactation:

  • Excreted in breast milk

  • Avoid breastfeeding or monitor infant for bradycardia

Geriatrics:

  • Increased risk of bradycardia, hypotension, and renal impairment

  • Dose selection should be cautious and renal function monitored

Renal impairment:

  • Main route of elimination

  • Requires strict adjustment of dose and interval

Pediatrics:

  • Use under specialized care

  • Requires individualized dosing and continuous ECG monitoring

12. Monitoring Parameters

  • Baseline ECG and QTc interval before initiating

  • Regular ECG monitoring during dose initiation and changes

  • Serum creatinine and estimated glomerular filtration rate (eGFR)

  • Potassium and magnesium levels

  • Heart rate and blood pressure monitoring

  • Watch for symptoms of torsades de pointes: syncope, palpitations, dizziness

  • Ongoing assessment of therapeutic response and adverse effects



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