Flecainide (Tambocor) Dosage and Administration Protocol for Arrhythmia
For patients with atrial fibrillation, the recommended starting dose of flecainide (Tambocor) is 50 mg twice daily, 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
Dosing Protocol for Different Arrhythmias
Paroxysmal Atrial Fibrillation (PAF) and Paroxysmal Supraventricular Tachycardia (PSVT)
- Initial dose: 50 mg every 12 hours
- Titration: Increase by 50 mg twice daily every four days until efficacy is achieved
- Maximum dose: 300 mg/day (150 mg twice daily)
- A substantial increase in efficacy without significant increase in adverse effects may be achieved by increasing from 50 mg to 100 mg twice daily 1
Sustained Ventricular Tachycardia (VT)
- Initial dose: 100 mg every 12 hours
- Titration: Increase by 50 mg twice daily every four days until efficacy is achieved
- Maximum dose: 400 mg/day
- Most patients with sustained VT do not require more than 300 mg/day (150 mg twice daily) 1
- For VT patients, flecainide should be initiated in-hospital with rhythm monitoring 1
Administration Considerations
Timing and Steady State
- Flecainide has a long half-life (12-27 hours in patients)
- Steady-state plasma levels may not be achieved until 3-5 days of therapy at a given dose
- Therefore, dosage increases should not be made more frequently than once every four days 1
Special Populations
Patients with Renal Impairment
- For severe renal impairment (creatinine clearance ≤35 mL/min/1.73 m²):
- Initial dose: 100 mg once daily or 50 mg twice daily
- Frequent plasma level monitoring required to guide dosage adjustments 1
Pediatric Patients
- Under 6 months: Initial dose approximately 50 mg/m² body surface area daily, divided into 2-3 equally spaced doses
- Over 6 months: Initial dose may be increased to 100 mg/m² per day
- Maximum dose: 200 mg/m² per day
- Pediatric use should be directly supervised by a cardiologist skilled in treating arrhythmias in children 1
Monitoring Requirements
Plasma Level Monitoring
- Therapeutic plasma levels: 200-500 ng/mL (in children)
- In some cases, levels up to 800 ng/mL may be required for control
- Plasma trough levels should be obtained at steady state (after at least 5 doses) 1
ECG Monitoring
- Regular ECG monitoring is essential, particularly after initiation or dose changes
- Monitor for QRS widening, PR interval prolongation, and QT prolongation
- If QRS width increases by 50%, the remainder of the dose should be held 2
Precautions and Contraindications
Contraindications
- Structural heart disease (including ischemic heart disease)
- Cardiogenic shock
- Sinus or AV conduction disease (in absence of pacemaker)
- Brugada syndrome 2
Use with Caution
- History of CHF or myocardial dysfunction
- Hepatic dysfunction
- Atrial flutter (unless concomitant AV nodal therapy is used to avoid 1:1 conduction) 2, 1
Potential Adverse Effects
- Hypotension
- Atrial flutter with high ventricular rate (1:1 conduction)
- QT prolongation (though rare)
- Torsades de pointes (rare)
- Worsening heart failure
- Bradycardia
- Visual disturbances (28%)
- Dizziness (30%)
- Headache, nausea (6-9%) 2, 3
Drug Interactions
Flecainide interacts with several medications, including:
- Amiodarone
- Digoxin
- Ritonavir
- Saquinavir
- Tipranavir 2
Efficacy Considerations
- Flecainide is more effective for conversion of recent-onset AF than long-standing AF
- Conversion rates are higher in patients with smaller atria and shorter duration of AF 4
- For acute cardioversion of AF, flecainide can be administered intravenously at 1.5-3.0 mg/kg over 10-20 minutes 2
Important Safety Considerations
- Proarrhythmic effects can occur even in patients with structurally normal hearts
- Regular ECG monitoring is essential, even if the patient reports subjective improvement
- Consider 24-hour Holter monitoring to detect asymptomatic ventricular arrhythmias 5
- If 50% QRS widening or hypotension occurs during administration, hold the remainder of the dose 2
Flecainide is an effective medication for treating atrial arrhythmias but requires careful dosing, monitoring, and patient selection to maximize benefits while minimizing risks.