What is the recommended dosing for flecainide (antiarrhythmic medication)?

Flecainide Dosing Guidelines

The recommended initial dose of flecainide is 50 mg every 12 hours with gradual upward titration, with a maximum maintenance dose of 150 mg every 12 hours for most patients with supraventricular arrhythmias. 1, 2

Initial Dosing and Titration

• For paroxysmal supraventricular tachycardia (PSVT) and paroxysmal atrial fibrillation (PAF):

  • Start with 50 mg every 12 hours 3, 2
  • Increase in increments of 50 mg twice daily every four days until efficacy is achieved 2
  • Maximum recommended dose: 300 mg/day 2

• For sustained ventricular tachycardia (VT):

  • Start with 100 mg every 12 hours 2
  • Increase in increments of 50 mg twice daily every four days until efficacy is achieved 2
  • Most patients respond to 150 mg every 12 hours (300 mg/day) 2
  • Maximum recommended dose: 400 mg/day 2

• For pediatric patients:

  • Under six months: approximately 50 mg/m² body surface area daily, divided into 2-3 doses 2
  • Over six months: may increase to 100 mg/m² per day 2
  • Maximum recommended dose: 200 mg/m² per day 2

Dosing in Special Populations

• Renal impairment:

  • For severe renal impairment (creatinine clearance ≤35 mL/min): reduce dose to 100 mg once daily or 50 mg twice daily 1, 2
  • Frequent plasma level monitoring required 1

• Drug interactions:

  • When co-administered with amiodarone: reduce flecainide dose by 50% 1
  • Monitor digoxin concentrations when administered with flecainide 3

Monitoring Parameters

• Plasma levels:

  • Therapeutic range: 0.2-1.0 mcg/mL 1
  • Levels above 0.7-1.0 mcg/mL require close monitoring 1
  • In children: 200-500 ng/mL (up to 800 ng/mL may be required in some cases) 2

• ECG monitoring:

  • Regular ECG monitoring to assess PR interval, QRS duration, and QT interval 1
  • Reduce dose or discontinue if QRS widens >25% from baseline 1
  • QRS widening should not exceed 150% of pretreatment QRS duration 1

Important Contraindications and Precautions

• Absolutely contraindicated in:

  • Structural heart disease or coronary artery disease 1, 3
  • Cardiogenic shock 3
  • Sinus or AV conduction disease (without pacemaker) 3
  • Brugada syndrome 3, 1
  • Atrial flutter (unless concomitant AV nodal therapy is used) 3

• Use with caution in:

  • Renal dysfunction 3
  • Hepatic dysfunction 3
  • Patients taking QT-prolonging drugs 3

Potential Adverse Effects

• Cardiac:

  • Atrial flutter with 1:1 AV conduction 3
  • QT prolongation 3
  • Torsades de pointes 3
  • Worsening heart failure 3
  • Bradycardia 3
  • Proarrhythmic effects (7-8% of patients) 4

• Non-cardiac:

  • Dizziness 1, 4, 5
  • Visual disturbances 1, 4, 5
  • Gastrointestinal complaints 1, 6
  • Headache 5, 6

Clinical Pearls

• Steady-state plasma levels may not be achieved until after 3-5 days of therapy at a given dose 2
• Due to flecainide's long half-life (12-27 hours), dosage increases should be made no more frequently than once every four days 2
• An occasional patient not adequately controlled by 12-hour intervals may be dosed at 8-hour intervals 2
• Once adequate control is achieved, it may be possible to reduce the dose to minimize side effects 2
• In-hospital initiation with rhythm monitoring is recommended for patients with sustained VT 2

Remember that flecainide is highly effective but should only be used in carefully selected patients without structural heart disease to minimize the risk of serious proarrhythmic effects.