Flecainide Acetate

— THERAPEUTIC CATEGORIES —
  • CHF and arrhythmias
PAGE CONTENTS
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  • Generic Name & Formulations
  • Indications
  • Dosage and Administration
  • Contraindications
  • Boxed Warnings
  • Warnings/Precautions
  • Pharmacokinetics
  • Interactions
  • Adverse Reactions
  • Clinical Trials
  • Note
  • Patient Counseling

    • Flecainide Acetate Generic Name & Formulations

    Legal Class

    Rx

    General Description

    Flecainide acetate 50mg, 100mg+, 150mg+; tabs; +scored.

    Pharmacological Class

    Class IC antiarrhythmic.

    How Supplied

    Contact supplier.

    Storage

    Store at 20° to 25°C (68° to 77°F).

    Manufacturer

    Various generic manufacturers

    Generic Availability

    YES

    Flecainide Acetate Indications

    Indications

    Documented, life-threatening ventricular arrhythmias. Paroxysmal supraventricular tachycardias (PSVT), paroxysmal atrial fibrillation/flutter (PAF) in patients without structural heart disease.

    Flecainide Acetate Dosage and Administration

    Prior to Treatment Evaluations

    Patients with pacemakers: Pacing threshold should be determined prior to instituting therapy with flecainide, again after 1 week of administration and at regular intervals thereafter.

    Correct preexisting hypokalemia or hyperkalemia before administration of flecainide.

    Adult

    Sustained ventricular tachycardia: Initiate in hospital; initially 100mg every 12 hrs; may increase by 50mg twice daily at 4 day intervals; max 400mg/day. PSVT or PAF: 50mg every 12 hrs; may increase by 50mg twice daily at 4 day intervals; max 300mg daily. CrCl ≤35mL/min per 1.73m2: Initially 100mg once daily or 50mg every 12hrs.

    Adult

    Flecainide has a long half-life. Steady state levels may not be achieved until 3-5 days of treatment has been received. During the first 2-3 days, the optimal effect of a given dose may not be achieved. Increases in dosage should be made no more frequently than once every 4 days.

    Paroxysmal supraventricular tachycardia (PSVT) and paroxysmal atrial fibrillation/flutter (PAF): 50mg every 12 hours; increase in increments of 50mg twice daily every 4 days until efficacy is achieved.

    For PAF patients: A substantial increase in efficacy without a substantial increase in discontinuations for adverse reactions may be achieved by increasing the dosage from 50 to 100mg twice daily.

    Max recommended dose for paroxysmal supraventricular arrhythmias is 300mg/day.

    Sustained ventricular tachycardia (VT): 100mg every 12 hours; may be increased in increments of 50mg twice daily every 4 days until efficacy is achieved. Most patients do not require more than 150mg every 12 hours; max dose recommended is 400mg/day. 

    For sustained VT, a loading dose is not recommended. Higher initial doses and more rapid dosage adjustments have resulted in an increased incidence of proarrhythmic events and CHF, particularly during the first few days of dosing.

    Patients not adequately controlled by, or intolerant to, a dose given at 12 hour intervals may be dosed at 8-hour intervals.

    Once control of arrhythmia has been achieved, consider reducing dose to minimize side effects on conduction if possible.

    Transferring from another antiarrhythmic agent to flecainide: Allow 2-4 plasma half-lives to elapse for the drug being discontinued before starting flecainide at the usual dosage. Consider hospitalization in patients where withdrawal of a previous antiarrhythmic drug is likely to produce life-threatening arrhythmias.

    Majority of patients successfully treated were found to have trough plasma levels between 0.2 and 1mcg/mL. Periodic monitoring may be useful for management and is required for patients with severe renal or hepatic disease. Monitoring is strongly recommended with concurrent amiodarone.

    Children

    <18yrs: not established.

    Children

    Use should be directly supervised by a cardiologist skilled in treatment of arrhythmias in children. Specialized literature should be consulted due to the evolving nature of information in this area.

    <6months of age: Initial starting dose is approximately 50mg/m2 body surface area daily, divided into 2 or 3 equally spaced doses.

    >6months of age: Initial starting dose may be increased to 100mg/m2 per day.

    Max dose: 200mg/m2 per day; this should not be exceeded. Small changes in dose may lead to disproportionate increases in plasma levels.

    Obtain plasma trough levels and electrocardiograms at presumed steady state (after at least 5 doses) either after initiation or change in dose.

    First year on therapy: 12-lead electrocardiogram and plasma trough levels should be obtained during follow-up.

    Usual therapeutic level of flecainide in children: 200 to 500ng/m; levels as high as 800ng/mL may be required for control in some cases.

    Flecainide Acetate Contraindications

    Contraindications

    2nd- or 3rd-degree AV block or right bundle branch block associated with left hemiblock, unless paced. Cardiogenic shock. Recent MI.

    Flecainide Acetate Boxed Warnings

    Boxed Warning

    Study findings showed an excessive mortality or nonfatal cardiac arrest rate with flecainide in patients with asymptomatic non-life-threatening ventricular arrhythmias who had an MI >6 days but <2 years previously. Ventricular pro-arrhythmic effects in patients with atrial fibrillation/flutter.

    Flecainide Acetate Warnings/Precautions

    Warnings/Precautions

    Verify benefits outweigh risks; see full labeling. Increased risk of pro-arrhythmic effects. Chronic atrial fibrillation: not recommended. History of CHF or myocardial dysfunction. Sick sinus syndrome. Pacemaker patients. Correct potassium imbalances before use. Severe renal or hepatic impairment, concomitant amiodarone or reduced myocardial function: monitor plasma level. Discontinue if heart block occurs unless paced. Discontinue if liver dysfunction, blood dyscrasias occur. Pregnancy (Cat.C). Nursing mothers: not recommended.

    Warnings/Precautions

    Proarrhythmic Effects

    • Flecainide can cause new or worsened supraventricular or ventricular arrhythmias.
    • In studies of ventricular arrhythmia patients treated with flecainide acetate, three-fourths of proarrhythmic events were new or worsened ventricular tachyarrhythmias, the remainder being increased frequency of premature ventricular contractions (PVCs) or new supraventricular arrhythmias.
    • In patients treated with flecainide for sustained ventricular tachycardia (VT), 80% (51/64) of proarrhythmic events occurred within 14 days of the onset of therapy.
    • Flecainide is not recommended for use in patients with chronic atrial fibrillation; wide complex tachycardia and ventricular fibrillation have been reported in these patients.
    • Among patients treated for sustained VT, the incidence of proarrhythmic events was 13% when dosage was initiated at 200mg/day with slow upward titration, and did not exceed 300mg/day in most patients. 
    • In patients with sustained VT initiated at 400mg/day, the incidence of proarrhythmic events was 26%; in about 10% of the patients treated proarrhythmic events resulted in death, despite prompt medical attention. 
    • With lower initial doses, the incidence of proarrhythmic events resulting in death decreased to 0.5% of these patients.
    • Treatment of patients with sustained VT should be started in the hospital due to the relatively high frequency of proarrhythmic events in these patients and the need for careful titration and monitoring.

    Heart Failure

    • May cause or worsen CHF, particularly in patients with cardiomyopathy, preexisting severe heart failure (NYHA functional class III or IV) or low ejection fractions (<30%).
    • Exacerbation of preexisting CHF occurred more frequently in studies that included patients with class III or IV failure.
    • Use cautiously in patients with a history of CHF or myocardial dysfunction; initial dosage should be no more than 100mg twice daily and monitor carefully.
    • CHF has been observed to develop or worsen with flecainide from a few hours to several months after starting treatment.
    • Consider monitoring flecainide levels if feasible; attempts should be made to keep trough plasma levels below 0.7 to 1mcg/mL. 

    Effects on Cardiac Conduction

    • Flecainide slows cardiac conduction to produce dose-related increases in PR, QRS, and QT intervals.
    • Rare cases of torsades de pointes-type arrhythmia with flecainide have been reported.
    • Manage patients on the lowest effective dose to minimize the effects.
    • If second- or third-degree AV block, or right bundle branch block associated with a left hemiblock occur, discontinue flecainide unless a temporary or implanted ventricular pacemaker is in place.

    Sick Sinus Syndrome

    • Use with caution in patients with sick sinus syndrome because it may cause sinus bradycardia, sinus pause, or sinus arrest.

    Effects on Pacemaker Thresholds

    • Flecainide increases endocardial pacing thresholds and may suppress ventricular escape rhythms; these effects are reversible if discontinued.
    • Use with caution in patients with permanent pacemakers or temporary pacing electrodes.
    • Unless suitable pacing rescue is available, flecainide should not be used in patients with existing poor thresholds or nonprogrammable pacemakers.
    • Patients with pacemakers: Pacing threshold should be determined prior to instituting therapy with flecainide, again after 1 week of administration and at regular intervals thereafter.

    Electrolyte Disturbances

    • Correct preexisting hypokalemia or hyperkalemia before administration of flecainide.

    Pregnancy Considerations

    No adequate and well-controlled studies in pregnant women. Flecainide acetate should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

    Nursing Mother Considerations

    Flecainide is excreted in human breast milk. The calculated daily dose to a nursing infant (assuming ~700mL of breast milk over 24 hours) is less than 3mg, when the maternal plasma level is at the top of the therapeutic range.

    Pediatric Considerations

    In children, safety and effectiveness have not been established in clinical trials. Use should be directly supervised by a cardiologist skilled in treatment of arrhythmias in children. Specialized literature should be consulted due to the evolving nature of information in this area.

    In pediatric patients with structural heart disease, flecainide has been associated with cardiac arrest and sudden death.

    Flecainide should be started in the hospital with rhythm monitoring.

    Renal Impairment Considerations

    See Dosage and Administration.

    Dosage increases should be made very cautiously when plasma levels have plateaued (after >4 days); observe closely for signs of adverse cardiac effects or other toxicity.

    May take longer than 4 days for these patients to reach steady-state plasma level after a dosage change.

    Hepatic Impairment Considerations

    Flecainide elimination is slower in patients with significant hepatic impairment. Do not use in patients with severe hepatic impairment unless the potential benefits outweigh the risks. Frequent and early plasma level monitoring is required to guide dosage.

    Flecainide Acetate Pharmacokinetics

    Absorption

    Peak plasma levels attained at about 3 hours (range, 1 to 6 hours).

    Distribution

    Binding to human plasma proteins is about 40%.

    Metabolism

    Hepatic (CYP2D6).

    Elimination

    Plasma half-life averages about 20 hours (range, 12 to 27 hours). Excreted in the urine; elimination of flecainide depends on renal function.

    Flecainide Acetate Interactions

    Interactions

    Increased digoxin toxicity. May potentiate negative inotropic effects of β-blockers. Potentiated by cimetidine. Antagonized by phenytoin, phenobarbital, carbamazepine. Avoid disopyramide, verapamil, nifedipine, diltiazem, other negative inotropics. ½ dose when given with amiodarone.

    Flecainide Acetate Adverse Reactions

    Adverse Reactions

    Dizziness, visual disturbances, dyspnea, headache, fatigue, palpitations, chest pain, asthenia, tremor, edema, GI upset, new or exacerbated arrhythmias, heart failure, cardiac arrest, conduction defects.

    Flecainide Acetate Clinical Trials

    Clinical Trials

    Paroxysmal Supraventricular Tachycardia

    • Two randomized, crossover, double-blind, placebo-controlled trials of 16 weeks duration.
    • Results showed 79% of patients with paroxysmal supraventricular tachycardia (PSVT) treated with flecainide were attack free vs 15% of patients in the placebo group.
    • Median time before recurrence of PSVT in placebo group: 11-12 days.
    • 85% of patients in the flecainide group had no recurrence at 60 days.

    Paroxysmal Atrial Fibrillation/Flutter

    • Two randomized, crossover, double-blind, placebo-controlled trials of 16 weeks duration.
    • Results showed 31% of patients with paroxysmal atrial fibrillation/flutter (PAF) treated with flecainide were attack free vs 8% of patients in the placebo group.
    • Median time before recurrence of PAF in flecainide arm vs placebo arm: 15 days vs 2-3 days.

    Flecainide Acetate Note

    Notes

    Formerly known under the brand name Tambocor.

    Flecainide Acetate Patient Counseling

    Patient Counseling

    Extremely important fo follow the recommended dosage schedule.

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