Flecainide Dosage and Usage for Irregular Heartbeat
For patients with supraventricular tachyarrhythmias (SVT), the recommended starting dose of flecainide is 50 mg every 12 hours, which may be increased in increments of 50 mg twice daily every four days until efficacy is achieved, with a maximum recommended dose of 300 mg/day. 1
Initial Dosing and Titration
- Starting dose: 50 mg every 12 hours for paroxysmal supraventricular tachycardia (PSVT) and paroxysmal atrial fibrillation (PAF) 1
- Dose titration: Increase in increments of 50 mg twice daily every four days until efficacy is achieved 1
- Maximum dose: 300 mg/day for supraventricular arrhythmias 1
- Dosing interval: Typically every 12 hours; occasionally every 8 hours may be considered for patients not adequately controlled on twice-daily dosing 1
Monitoring and Considerations
- Steady state: Requires 3-5 days of therapy at a given dose due to flecainide's long half-life (12-27 hours) 1
- Plasma levels: Therapeutic range is 200-500 ng/mL in most patients; levels up to 800 ng/mL may be required in some cases 1
- ECG monitoring: QRS widening should not exceed 150% of pretreatment QRS duration 2
- Renal impairment: For patients with severe renal impairment (creatinine clearance ≤35 mL/min/1.73 m²), the initial dosage should be 100 mg once daily (or 50 mg twice daily) with frequent plasma level monitoring 1
Efficacy
- Flecainide has shown 85-90% efficacy in preventing recurrent episodes of SVT in patients without structural heart disease 2
- Adding a beta-blocker increases efficacy to >90% for abolishing symptomatic tachycardia 2
- In clinical trials, 87% of PSVT patients and 73% of PAF patients showed symptomatic improvement with flecainide therapy 3
- Long-term studies show 89% of patients remained free of symptomatic SVT over a mean follow-up period of 3.9 years 4
Contraindications and Precautions
- Absolute contraindications: Structural heart disease, recent myocardial infarction, significant ventricular dysfunction, and congenital heart disease with ventricular dysfunction 2
- Caution: Flecainide should be used cautiously in patients with a history of congestive heart failure or myocardial dysfunction 1
- Initiation setting: For patients with sustained ventricular tachycardia, flecainide should be initiated in-hospital with rhythm monitoring 1
- Proarrhythmic risk: Higher initial doses and more rapid dosage adjustments have resulted in increased incidence of proarrhythmic events and CHF, particularly during the first few days of dosing 1
Common Side Effects
Special Populations
- Children: Initial starting dose approximately 50 mg/m² body surface area daily for children under six months, up to 100 mg/m² per day for children over six months, with maximum recommended dose of 200 mg/m² per day 1
- Elderly: May require lower doses due to decreased renal function and increased sensitivity to antiarrhythmic effects
Flecainide is particularly effective for patients with PSVT, with somewhat lower efficacy and higher side effect rates in patients with chronic atrial fibrillation 3. When used appropriately in patients without structural heart disease, flecainide offers an effective option for managing supraventricular arrhythmias with a relatively favorable side effect profile.