What is the recommended dosage and usage of Flecainide for treating irregular heartbeat?

Flecainide Dosage and Usage for Irregular Heartbeat

For patients with paroxysmal supraventricular tachycardia (PSVT) or paroxysmal atrial fibrillation (PAF), the recommended starting dose of flecainide is 50 mg every 12 hours, which can 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 1
• Titration: Increase by 50 mg twice daily every four days as needed 1
• Maximum dose: 300 mg/day for supraventricular arrhythmias 1
• Steady state: Achieved after 3-5 days of therapy at a given dose due to flecainide's long half-life (12-27 hours) 1

For patients with PSVT, a substantial increase in efficacy without significant increase in adverse effects may be achieved by increasing the dose from 50 mg to 100 mg twice daily 1. Most patients respond well to a maintenance dose of 100-200 mg twice daily 2, 3.

Patient Selection and Contraindications

Flecainide should only be used in patients without structural heart disease. Absolute contraindications include:

• Structural heart disease
• Recent myocardial infarction
• Significant ventricular dysfunction
• Congenital heart disease with ventricular dysfunction 2

Monitoring Requirements

• Initial monitoring: QRS duration should not exceed 150% of pretreatment QRS duration 2
• Plasma levels: Therapeutic range is 200-500 ng/mL (up to 800 ng/mL may be required in some cases) 1
• Follow-up: Regular ECG monitoring and plasma level checks are recommended, especially after dose adjustments 1

Special Populations

1. Renal impairment: For patients with severe renal impairment (creatinine clearance ≤35 mL/min/1.73m²), the initial dosage should be 100 mg once daily (or 50 mg twice daily) with frequent plasma level monitoring 1

2. Children:

   • Under six months: Initial dose of approximately 50 mg/m² body surface area daily
   • Over six months: Initial dose may be increased to 100 mg/m² per day
   • Maximum dose: 200 mg/m² per day 1

Efficacy and Safety

Flecainide has demonstrated high efficacy rates in treating supraventricular arrhythmias:

• 87% of PSVT patients showed symptomatic improvement 4
• 73% of PAF patients showed symptomatic improvement 4
• 89% of patients remained free of symptomatic SVT over a mean follow-up period of 3.9 years 3

The addition of a beta-blocker to flecainide increases efficacy to >90% for abolition of symptomatic tachycardia 2.

Common Side Effects

• Visual disturbances (blurred vision)
• Dizziness
• Headache
• Nausea 4, 3

Important Considerations

• Flecainide should be initiated in-hospital with rhythm monitoring for patients with sustained ventricular tachycardia 1
• Outpatient initiation may be appropriate in selected cases without structural heart disease 2
• For patients with occasional but prolonged episodes, a single oral dose (approximately 3 mg/kg) may be effective for terminating acute episodes 2
• Flecainide should be used cautiously in patients with a history of congestive heart failure or myocardial dysfunction 1

Alternative Dosing Schedule

An occasional patient not adequately controlled by (or intolerant to) a dose given at 12-hour intervals may be dosed at eight-hour intervals. Once adequate control of the arrhythmia has been achieved, it may be possible in some patients to reduce the dose to minimize side effects 1.

By following these dosing guidelines and monitoring protocols, flecainide can be an effective and safe treatment option for patients with supraventricular arrhythmias who do not have structural heart disease.