Flecard50 mg

Flecard is a Class IC antiarrhythmic medicine used to prevent certain abnormal fast heart rhythms. Its use is classified below by strength of evidence.

Established / FDA-approved uses

• Prevention of paroxysmal supraventricular tachycardia (PSVT) associated with disabling symptoms in patients without structural heart disease, including AV-nodal re-entrant tachycardia and AV re-entrant tachycardia (e.g., via an accessory pathway).
• Prevention of paroxysmal atrial fibrillation/atrial flutter (PAF) associated with disabling symptoms in patients without structural heart disease.
• Prevention of documented, life-threatening sustained ventricular arrhythmias (e.g., sustained ventricular tachycardia). Because of an increased risk of proarrhythmia and death shown in patients with structural heart disease, Flecard for ventricular arrhythmias is reserved for patients with these severe, life-threatening rhythm disturbances, generally after other options have been considered.

Off-label / specialist uses

• Used by cardiac electrophysiologists as part of the diagnostic "flecainide challenge" test for suspected Brugada syndrome.
• Used as an adjunct, in combination with beta-blockers, in selected patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) who remain symptomatic despite beta-blocker therapy.
• Used in a supervised, physician-directed "pill-in-the-pocket" strategy for termination of infrequent, symptomatic paroxysmal atrial fibrillation in selected patients without structural heart disease (typically combined with an AV-nodal blocking agent).

These off-label uses should only be undertaken under the direct supervision of a cardiologist experienced with Flecard therapy.

Each tablet contains Flecainide Acetate INN as the active pharmaceutical ingredient, commonly available in strengths such as 50 mg, 100 mg, and 150 mg, formulated as an immediate-release oral tablet. Please check the product pack/leaflet for the exact strength and excipients of the specific brand dispensed.

Flecard is a Class IC antiarrhythmic agent that works by blocking cardiac sodium channels, slowing electrical conduction through the heart. It is used to prevent recurrence of certain fast, abnormal heart rhythms (arrhythmias) in carefully selected patients, most commonly those without significant underlying structural heart disease, and in patients with certain documented life-threatening ventricular arrhythmias.

Because Flecard itself carries a risk of causing new or worsened arrhythmias (a proarrhythmic effect), it is prescribed and monitored by a physician, typically a cardiologist, with periodic ECG and, where available, plasma level monitoring.

Class IC Antiarrhythmic Agent (Cardiac Sodium Channel Blocker)

Flecainide Acetate is a local-anesthetic-type (membrane-stabilizing) antiarrhythmic classified as Vaughan-Williams Class IC.

Mechanism

It blocks the fast inward sodium (Na⁺) current in cardiac cell membranes. This action is characterized by slow onset/offset kinetics ("slow" channel blocking kinetics), which produces a marked, use-dependent slowing of conduction velocity in atrial muscle, ventricular muscle, and the His-Purkinje conduction system.

Electrophysiologic effects

• Dose-related prolongation of the PR, QRS, and, to a lesser degree, QT intervals on the ECG.
• Little effect on action potential duration or refractoriness compared with other antiarrhythmic classes.
• Mild negative inotropic (heart-muscle-weakening) effect, which can be clinically relevant in patients with reduced heart function.

Pharmacokinetics

• Absorption: well absorbed orally; food does not significantly affect overall absorption.
• Metabolism: hepatic, mainly via CYP2D6, to two major (less active) metabolites.
• Elimination half-life: approximately 12-27 hours in healthy adults (longer in renal/hepatic impairment and in slow CYP2D6 metabolizers).
• Excretion: renal, with a substantial fraction (roughly one-quarter to one-half) excreted unchanged, making renal function an important determinant of dosing.

• Take Flecard tablets by mouth, swallowed whole with water.
• May be taken with or without food; however, once a consistent pattern (with or without food) is established, it should generally be maintained, as food can slightly affect absorption timing.
• Take doses at evenly spaced intervals (usually every 12 hours) exactly as prescribed to maintain steady blood levels.
• Do not stop, skip, or change the dose without consulting the prescribing physician, since abrupt changes can affect heart rhythm control.
• If a dose is missed, take it as soon as remembered unless it is close to the next scheduled dose; do not double the dose.

Only well-established, clinically significant interactions with Flecard are listed below.

• Amiodarone: significantly increases Flecard plasma levels; when co-administered, the flecainide dose should typically be reduced by about half, with close ECG and level monitoring.
• Other antiarrhythmic drugs (e.g., other Class I agents, disopyramide): additive negative inotropic and proarrhythmic effects; concurrent use is generally avoided.
• Beta-blockers and non-dihydropyridine calcium channel blockers (e.g., verapamil, diltiazem): additive negative inotropic and conduction-slowing effects; use with caution, particularly in patients with reduced heart function.
• CYP2D6 inhibitors (e.g., quinidine, fluoxetine, paroxetine, ritonavir): can substantially raise Flecard plasma concentrations, increasing the risk of toxicity; dose adjustment and monitoring may be required.
• Digoxin: Flecard can modestly increase digoxin plasma levels; monitor digoxin levels and for signs of toxicity.
• Urinary alkalinizing agents (e.g., acetazolamide, high-dose antacids, some diuretics): can reduce renal excretion of Flecard, raising plasma levels and toxicity risk.

Side effects of Flecard range from common and mild to rare but serious.

Common

• Dizziness or light-headedness
• Visual disturbances (blurred vision, spots before the eyes)
• Shortness of breath (dyspnea)
• Headache
• Nausea
• Fatigue or tiredness
• Tremor
• Palpitations

Serious (seek prompt medical attention)

• New or worsened abnormal heart rhythms (proarrhythmia), including fast or slow rhythms
• Worsening heart failure (swelling of legs/ankles, worsening shortness of breath)
• Heart block or marked slowing of the heart rate
• Fainting (syncope)

Pregnancy: Human data on Flecard in pregnancy are limited. Animal reproduction studies have shown adverse fetal effects at high doses. Flecard should be used during pregnancy only if clearly needed and only if the potential benefit to the mother justifies the potential risk to the fetus; use should be under close physician supervision.

Lactation: Flecard is excreted into human breast milk. A decision should be made, in consultation with the treating physician, whether to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother and monitoring the breastfed infant for any adverse effects.

Proarrhythmia and structural heart disease

Flecard can cause new or worsened ventricular arrhythmias. Large controlled trial data (CAST) showed increased mortality when Flecard was used for asymptomatic or mildly symptomatic ventricular ectopy in patients with structural heart disease after myocardial infarction. See Contraindications for the populations in whom this risk precludes use.

Heart failure

Flecard has a mild negative inotropic effect and can precipitate or worsen heart failure in susceptible patients; use with caution and close monitoring in patients with reduced cardiac function.

Monitoring

Regular ECG monitoring (PR, QRS, QTc intervals) is recommended, particularly at initiation of therapy and after each dose change, along with periodic plasma level monitoring where available. Excessive QRS widening (e.g., >25% above baseline) generally warrants dose reduction or discontinuation.

Electrolyte disturbances

Correct hypokalemia or hyperkalemia before starting Flecard, as electrolyte disturbances can alter the drug's effect and increase arrhythmia risk.

Renal and hepatic impairment

Requires dose reduction and closer monitoring; see Dosage and Administration.

Pacemaker/ICD patients

Use with caution, as Flecard can raise pacing thresholds; device function should be checked periodically.

Overdose with Flecard is potentially life-threatening and can cause severe cardiac toxicity, including marked slowing of conduction, heart block, very low blood pressure, dangerously slow or absent heartbeat, cardiac arrest, and central nervous system effects such as seizures.

There is no specific antidote. If an overdose is suspected, seek emergency medical attention immediately or contact a poison control center / emergency services without delay. Treatment requires continuous cardiac monitoring and supportive care in a hospital setting; do not attempt to manage a suspected overdose at home.

Store at room temperature (below 30°C), away from light and moisture. Keep out of reach of children.

Renal impairment

Reduced clearance of Flecard; use a lower starting dose with slower titration and close monitoring (see Dosage and Administration).

Hepatic impairment

Use with caution and reduced dosing, with plasma level monitoring where available, due to slowed metabolism.

Elderly

Clearance of Flecard may be reduced with age; start at the lower end of the dosing range and titrate slowly, with attention to renal function.

Pediatric patients

Safety and efficacy of Flecard have not been formally established in the general pediatric population in the original labeling. It is used off-label by pediatric cardiology specialists for certain supraventricular arrhythmias, with weight-based dosing and close ECG/level monitoring; such use should occur only under specialist supervision.

The duration of treatment with Flecard is individualized based on the underlying arrhythmia, response to therapy, and tolerability. It is generally used as a long-term, ongoing preventive therapy for recurrent arrhythmias rather than a short course, with periodic clinical review, ECG, and (where available) Holter monitoring to confirm continued benefit and to screen for proarrhythmia. Treatment should be continued, reduced, or stopped only on the advice of the prescribing physician.

Antiarrhythmic Agents; Class IC Antiarrhythmics; Cardiac Sodium Channel Blockers

Flecainide Acetate exerts its antiarrhythmic effect primarily by binding to and blocking voltage-gated fast sodium channels in cardiac myocytes. By reducing the rate of rise of the cardiac action potential (phase 0), it slows impulse conduction throughout the atria, ventricles, and specialized His-Purkinje conduction tissue.

Its blocking kinetics are slow to dissociate ("slow-offset"), meaning the effect accumulates at faster heart rates (use-dependence) — this underlies both its antiarrhythmic benefit and its potential to worsen arrhythmias (proarrhythmia), particularly in the presence of structural heart disease. Unlike Class IA agents, Flecainide Acetate has minimal effect on repolarization and the QT interval, and it lacks significant anticholinergic activity.

C

In its original approved labeling, the safety and efficacy of Flecard in children have not been formally established. Nonetheless, Flecard is used off-label in specialized pediatric cardiology practice for selected supraventricular arrhythmias (and occasionally other arrhythmias) that have not responded to other therapies, using weight-based dosing individualized by a pediatric cardiologist, with close ECG and, where available, plasma level monitoring. It should not be used in children outside specialist cardiology supervision.