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Pronunciation:

(fle KAY nide)

U.S. Brand Names:

Tambocor™

Synonyms:

Flecainide Acetate

Generic Available:

Yes

Canadian Brand Names:

Tambocor™

Use:

Prevention and suppression of documented life-threatening ventricular arrhythmias (eg, sustained ventricular tachycardia); controlling symptomatic, disabling supraventricular tachycardias in patients without structural heart disease in whom other agents fail

Pregnancy Risk Factor:

Lactation:

Enters breast milk/compatible

Contraindications:

Hypersensitivity to flecainide or any component of the formulation; pre-existing second- or third-degree AV block or with right bundle branch block when associated with a left hemiblock (bifascicular block) (except in patients with a functioning artificial pacemaker); cardiogenic shock; coronary artery disease (based on CAST study results); concurrent use of ritonavir or amprenavir

Warnings/Precautions:

Not recommend for patients with chronic atrial fibrillation. A worsening or new arrhythmia may occur (proarrhythmic effect). Use caution in heart failure (may precipitate or exacerbate CHF). Dose-related increases in PR, QRS, and QT intervals occur. Use with caution in sick sinus syndrome or with permanent pacemakers or temporary pacing wires (can increase endocardial pacing thresholds). Pre-existing hypokalemia or hyperkalemia should be corrected before initiation (can alter drug's effect). Cautious use in significant hepatic impairment.

Adverse Reactions:

>10%:

Central nervous system: Dizziness (19% to 30%)

Ocular: Visual disturbances (16%)

Respiratory: Dyspnea (~10%)

1% to 10%:

Cardiovascular: Palpitations (6%), chest pain (5%), edema (3.5%), tachycardia (1% to 3%), proarrhythmic (4% to 12%), sinus node dysfunction (1.2%), syncope

Central nervous system: Headache (4% to 10%), fatigue (8%), nervousness (5%) additional symptoms occurring at a frequency between 1% and 3%: fever, malaise, hypoesthesia, paresis, ataxia, vertigo, somnolence, tinnitus, anxiety, insomnia, depression

Dermatologic: Rash (1% to 3%)

Gastrointestinal: Nausea (9%), constipation (1%), abdominal pain (3%), anorexia (1% to 3%), diarrhea (0.7% to 3%)

Neuromuscular & skeletal: Tremor (5%), weakness (5%), paresthesia (1%)

Ocular: Diplopia (1% to 3%), blurred vision

<1% (Limited to important or life-threatening): Bradycardia, paradoxical increase in ventricular rate in atrial fibrillation/flutter, heart block, increased P-R, QRS duration, ventricular arrhythmia, CHF, flushing, AV block, angina, hyper-/hypotension, amnesia, confusion, decreased libido, depersonalization, euphoria, apathy, nervousness, twitching, neuropathy, weakness, taste disturbance, urticaria, exfoliative dermatitis, pruritus, alopecia, flatulence, xerostomia, blood dyscrasias, possible hepatic dysfunction, paresthesia, eye pain, photophobia, bronchospasm, pneumonitis, swollen lips/tongue/mouth, arthralgia, myalgia, polyuria, urinary retention, leukopenia, granulocytopenia, thrombocytopenia, metallic taste, alters pacing threshold

Postmarketing and/or case reports: Tardive dyskinesia, corneal deposits

Overdosage/Toxicology:

Flecainide has a narrow therapeutic index and severe toxicity may occur slightly above the therapeutic range, especially if combined with other antiarrhythmic drugs. (Acute single ingestion of twice the daily therapeutic dose is life-threatening). Symptoms of overdose include increase in P-R, QRS, or QT intervals and amplitude of the T wave, AV block, bradycardia, hypotension, ventricular arrhythmias (monomorphic or polymorphic ventricular tachycardia), and asystole. Other symptoms include dizziness, blurred vision, headache, and GI upset. Treatment is supportive.

Drug Interactions:

Substrate of CYP1A2 (minor), 2D6 (major); Inhibits CYP2D6 (weak)

Amiodarone increases in flecainide plasma levels; consider reducing flecainide dose by 25% to 33% with concurrent use.

Amprenavir and ritonavir may increase cardiotoxicity of flecainide (decrease metabolism).

Cimetidine may decrease flecainide's metabolism; monitor cardiac status or use an alternative H2 antagonist.

CYP2D6 inhibitors: May increase the levels/effects of flecainide. Example inhibitors include chlorpromazine, delavirdine, fluoxetine, miconazole, paroxetine, pergolide, quinidine, quinine, ritonavir, and ropinirole.

Digoxin's serum concentration may increase slightly.

Propranolol (and possibly other beta-blockers) increases flecainide blood levels, and propranolol blood levels are increased with concurrent use; monitor for excessive negative inotropic effects.

Quinidine may decrease flecainide's metabolism; monitor cardiac status.

Urinary alkalinizers (antacids, sodium bicarbonate, acetazolamide) may increase flecainide blood levels.

Ethanol/Nutrition/Herb Interactions:

Food: Clearance may be decreased in patients following strict vegetarian diets due to urinary pH 8. Dairy products (milk, infant formula, yogurt) may interfere with the absorption of flecainide in infants; there is one case report of a neonate (GA 34 weeks PNA >6 days) who required extremely large doses of oral flecainide when administered every 8 hours with feedings ("milk feeds"); changing the feedings from "milk feeds" to 5% glucose feeds alone resulted in a doubling of the flecainide serum concentration and toxicity.

Mechanism of Action:

Class Ic antiarrhythmic; slows conduction in cardiac tissue by altering transport of ions across cell membranes; causes slight prolongation of refractory periods; decreases the rate of rise of the action potential without affecting its duration; increases electrical stimulation threshold of ventricle, His-Purkinje system; possesses local anesthetic and moderate negative inotropic effects

Pharmacodynamics/Kinetics:

Absorption: Oral: Rapid

Distribution: Adults: Vd: 5-13.4 L/kg

Protein binding: Alpha1 glycoprotein: 40% to 50%

Metabolism: Hepatic

Bioavailability: 85% to 90%

Half-life elimination: Infants: 11-12 hours; Children: 8 hours; Adults: 7-22 hours, increased with congestive heart failure or renal dysfunction; End-stage renal disease: 19-26 hours

Time to peak, serum: ~1.5-3 hours

Excretion: Urine (80% to 90%, 10% to 50% as unchanged drug and metabolites)

Dosage:

Oral:

Children:

Initial: 3 mg/kg/day or 50-100 mg/m²/day in 3 divided doses

Usual: 3-6 mg/kg/day or 100-150 mg/m²/day in 3 divided doses; up to 11 mg/kg/day or 200 mg/m²/day for uncontrolled patients with subtherapeutic levels

Adults:

Life-threatening ventricular arrhythmias:

Initial: 100 mg every 12 hours

Increase by 50-100 mg/day (given in 2 doses/day) every 4 days; maximum: 400 mg/day.

Use of higher initial doses and more rapid dosage adjustments have resulted in an increased incidence of proarrhythmic events and congestive heart failure, particularly during the first few days. Do not use a loading dose. Use very cautiously in patients with history of congestive heart failure or myocardial infarction.

Prevention of paroxysmal supraventricular arrhythmias in patients with disabling symptoms but no structural heart disease:

Initial: 50 mg every 12 hours

Increase by 50 mg twice daily at 4-day intervals; maximum: 300 mg/day.

Dosing adjustment in severe renal impairment: Clcr<35 mL/minute: Decrease initial dose to 50 mg every 12 hours; increase doses at intervals >4 days monitoring ECG levels closely.

Dialysis: Not dialyzable (0% to 5%) via hemo- or peritoneal dialysis; no supplemental dose necessary.

Dosing adjustment/comments in hepatic impairment: Monitoring of plasma levels is recommended because of significantly increased half-life.

When transferring from another antiarrhythmic agent, allow for 2-4 half-lives of the agent to pass before initiating flecainide therapy.

Administration:

Administer around-the-clock to promote less variation in peak and trough serum levels

Monitoring Parameters:

ECG, blood pressure, pulse, periodic serum concentrations, especially in patients with renal or hepatic impairment

Reference Range:

Therapeutic: 0.2-1 mcg/mL; pediatric patients may respond at the lower end of the recommended therapeutic range

Patient Education:

Take exactly as directed, around-the-clock. Do not discontinue without consulting prescriber. You will require frequent monitoring while taking this medication. You may experience lightheadedness, nervousness, dizziness, visual disturbances (use caution when driving or engaging in tasks requiring alertness until response to drug is known); or nausea, vomiting, or loss of appetite (small, frequent meals may help). Report palpitations, chest pain, excessively slow or rapid heartbeat; acute nervousness, headache, or fatigue; unusual weight gain; unusual cough; respiratory difficulty; swelling of hands or ankles; or muscle tremor, numbness, or weakness. Pregnancy precaution: Inform prescriber if you are or intend to become pregnant.

Nursing Implications:

Monitor ECG

Anesthesia and Critical Care Concerns/Other Considerations:

Based on adverse outcomes noted with flecainide in the CAST trial, the FDA recommends that use of flecainide be limited to patients with life-threatening ventricular arrhythmias.

Cardiovascular Considerations:

Flecainide is a Class Ic antiarrhythmic with a very narrow therapeutic index and with considerable proarrhythmic properties. The CAST trial, evaluating flecainide in the treatment of asymptomatic ventricular extrasystoles after myocardial infarction, showed a significant increase in mortality. In lower doses, flecainide has sometimes been used for maintenance of sinus rhythm in patients with severe refractory atrial fibrillation, without structural heart disease.

Dental Health: Effects on Dental Treatment:

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions:

No information available to require special precautions

Mental Health: Effects on Mental Status:

Dizziness is common; may cause sedation; may rarely cause nervousness

Mental Health: Effects on Psychiatric Treatment:

Use beta-blockers with caution; may produce additive negative inotropic effect; use caution with TCAs; may affect cardiac conduction; CYP2D6 substrate; use caution with the SSRIs

Dosage Forms:

Tablet, as acetate: 50 mg, 100 mg, 150 mg

Extemporaneously Prepared:

A 5 mg/mL suspension compounded from tablets and an oral flavored commercially available diluent (Roxane®) was stable for up to 45 days when stored at 5°C or 25°C in amber glass bottles. Flecainide 20 mg/mL was found stable for up to 60 days at 5°C and 25°C in a 1:1 preparation of Ora-Sweet® and Ora-Plus®, in Ora-Sweet® SF and Ora-Plus® and in cherry syrup

Allen LV and Erickson III MA, "Stability of Baclofen, Captopril, Diltiazem, Hydrochloride, Dipyridamole, and Flecainide Acetate in Extemporaneously Compounded Oral Liquids,"Am J Health Syst Pharm, 53:2179-84.

Wiest DB, Garner SS, and Pagacz LR, "Stability of Flecainide Acetate in an Extemporaneously Compounded Oral Suspension,"Am J Hosp Pharm, 1992, 49(6):1467-70.

International Brand Names:

Almarytm® (IT); Apocard® (ES, NO); Apocard Orifarm® (DK); Aristocor® (AT); Diondel® (AR); Flecadura® (DE); Flécaïne® (FR); Flecainid Alpharma® (DK); Flecainide® (GB); Flecainid-Isis® (DE); Flecatab® (AU); Tambocor® (AR, AU, BE); Tambocor™ (CA); Tambocor® (CH, CL, CR, DE, DK, DO, FI, GB, GT, HK, HN, IE, IL, JP, LU, MA, MX, NL, NO, NZ, PA, RO, SE, SG, SV, TH, ZA)

References

Flaker GC, Blackshear JL, McBride R, et al, "Antiarrhythmic Drug Therapy and Cardiac Mortality in Atrial Fibrillation. The Stroke Prevention in Atrial Fibrillation Investigators,"J Am Coll Cardiol, 1992, 20(3):527-32.

"Preliminary Report: Effect of Encainide and Flecainide on Mortality in a Randomized Trial of Arrhythmia Suppression After Myocardial Infarction. The Cardiac Arrhythmia Suppression Trial (CAST) Investigators,"N Engl J Med, 1989, 321(6):406-12.

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