Flecainide Acetate

Approved Indications:

• Supraventricular Arrhythmias: Treatment and prevention of paroxysmal supraventricular tachycardia (PSVT), including atrioventricular reentrant tachycardia (AVRT).
• Atrial Fibrillation and Atrial Flutter: Maintenance of normal sinus rhythm after conversion to sinus rhythm.
• Ventricular Arrhythmias: Management of life-threatening ventricular arrhythmias such as ventricular tachycardia and premature ventricular contractions in patients without structural heart disease.

Off-label / Clinically Accepted Uses:

• Use as prophylaxis for symptomatic arrhythmias in select patients.
• Occasionally used in other arrhythmias where class IC antiarrhythmic agents are appropriate.

• Adults:
• Initial oral dose: 50 mg every 12 hours, titrated gradually based on clinical response and plasma concentration.
• Maintenance dose: Typically 100–150 mg every 12 hours, with a maximum dose up to 300 mg per day in divided doses.
• Intravenous administration (in hospital settings): Initial dose usually 50–100 mg over 10 minutes; maintenance infusion rates adjusted per response.
• Elderly:
• Start with lower doses and titrate cautiously due to increased risk of adverse effects and reduced clearance.
• Pediatrics:
• Use only if benefits outweigh risks; dosing based on weight, typically 2–6 mg/kg/day divided into 2–3 doses.
• Renal Impairment:
• Use caution; dose adjustment may be necessary due to reduced clearance.
• Hepatic Impairment:
• Dose adjustment may be necessary; monitor patient carefully.
• Administration:
• Oral tablets should be swallowed whole with water; can be taken with or without food.
• Duration:
• As directed by physician; long-term therapy often required for maintenance of sinus rhythm.

Flecainide acetate is a class IC antiarrhythmic agent that works by blocking the fast inward sodium channels (Na⁺ channels) during the cardiac action potential phase 0. This inhibition slows conduction velocity in atrial, ventricular, and His-Purkinje tissues without significantly affecting repolarization. Flecainide also has minor effects on potassium channels and may suppress arrhythmogenic automaticity. The net effect is suppression of abnormal electrical activity, prevention of reentry circuits, and maintenance of normal sinus rhythm.

• Absorption:
  Rapidly and almost completely absorbed orally, with bioavailability around 90%. Peak plasma levels occur within 1–3 hours post-dose.
• Distribution:
  Volume of distribution approximately 4 L/kg; about 40% plasma protein bound.
• Metabolism:
  Extensively metabolized in the liver primarily via CYP2D6 to inactive metabolites.
• Elimination:
  Half-life ranges from 12 to 27 hours depending on patient factors. Excreted via kidneys (~30% unchanged) and bile as metabolites.

• Pregnancy:
  FDA Category C. Use only if potential benefits justify the potential risk to the fetus. Animal studies have shown adverse effects at high doses.
• Lactation:
  Flecainide is excreted in breast milk; use with caution. Breastfeeding is generally not recommended during therapy.

• Primary class: Antiarrhythmic agent
• Subclass: Class IC sodium channel blocker

• Known hypersensitivity to flecainide or any formulation components
• Structural heart disease, including previous myocardial infarction with reduced left ventricular function
• Cardiogenic shock or second- or third-degree atrioventricular block without pacemaker
• Severe sinus node dysfunction without pacemaker
• Non-life-threatening arrhythmias that do not pose serious risk
• Concomitant use with other class I antiarrhythmic drugs

• Use with extreme caution in patients with ischemic heart disease or structural cardiac abnormalities due to proarrhythmic risk.
• Risk of life-threatening arrhythmias, especially in patients with prior myocardial infarction (CAST trial findings).
• Monitor ECG regularly during treatment.
• Adjust dosage carefully in renal or hepatic impairment.
• Monitor for signs of worsening arrhythmias or new arrhythmias.
• Avoid abrupt discontinuation; taper dose under supervision.
• May exacerbate heart failure.

Common Side Effects:

• Dizziness, headache
• Visual disturbances including blurred vision or diplopia
• Fatigue and weakness
• Nausea and gastrointestinal discomfort
• Tremor

Serious/Rare Side Effects:

• Proarrhythmia including ventricular arrhythmias
• Heart block or conduction disturbances
• Worsening of existing arrhythmias
• Hypotension
• Bradycardia
• Seizures (rare)

• CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): May increase flecainide plasma levels, increasing toxicity risk.
• Other antiarrhythmics (class I or III): Increased risk of proarrhythmia; generally contraindicated.
• Beta-blockers and calcium channel blockers: Additive cardiac conduction effects; monitor closely.
• Digoxin: Flecainide may increase digoxin levels; monitor digoxin levels.
• Amiodarone: May increase flecainide levels; dosage adjustment needed.

• Recent guidelines recommend flecainide primarily for patients without significant structural heart disease.
• Emphasis on ECG monitoring and patient selection to reduce proarrhythmic risks.
• Use discouraged in patients with ischemic heart disease due to increased mortality risk noted in trials.
• Monitoring of plasma levels is encouraged in cases of toxicity or suspected overdose.

• Store at controlled room temperature between 20°C and 25°C (68°F to 77°F).
• Protect from moisture and light.
• Keep in original container tightly closed.
• Do not freeze.
• Keep out of reach of children.