Flecainide Drug Profile

What is Flecainide?

Flecainide is a prescription medication belonging to the class IC antiarrhythmic drugs used to treat certain types of irregular heart rhythms. It is primarily prescribed for patients with specific arrhythmias including atrial fibrillation, atrial flutter, and certain ventricular arrhythmias. This medication works by blocking sodium channels in heart muscle cells to restore normal heart rhythm.

Uses

Flecainide is approved for several cardiac rhythm disorders:

• Atrial fibrillation: Used to convert abnormal rapid, irregular heartbeats back to normal rhythm and prevent recurrence
• Atrial flutter: Helps restore regular heart rhythm when the upper chambers beat too rapidly in a regular pattern
• Paroxysmal supraventricular tachycardia (PSVT): Treats episodes of rapid heartbeat originating above the ventricles
• Ventricular tachycardia: Used in specific cases of life-threatening rapid heartbeats from the lower heart chambers, but only in patients without structural heart disease
• Wolff-Parkinson-White syndrome: Helps manage arrhythmias associated with this congenital heart condition

How it works

Flecainide blocks sodium channels in heart muscle cells, which slows down the electrical conduction system of the heart. By reducing the speed at which electrical impulses travel through heart tissue, it helps prevent abnormal rapid or irregular heartbeats from occurring. This mechanism allows the heart to maintain a more stable, regular rhythm.

Side effects

Common side effects include:

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• Dizziness or lightheadedness
• Visual disturbances (blurred vision, seeing spots)
• Headache
• Nausea
• Fatigue or weakness
• Tremor
• Constipation
• Shortness of breath

Serious side effects requiring immediate medical attention:

• New or worsening irregular heartbeats (proarrhythmic effects)
• Severe chest pain or heart attack symptoms
• Fainting or severe dizziness
• Severe shortness of breath or heart failure symptoms
• Severe allergic reactions with rash, swelling, or difficulty breathing

Warnings and precautions

• Structural heart disease: Flecainide should not be used in patients with significant heart disease, previous heart attack, or heart failure, as it may increase risk of sudden cardiac death
• Pregnancy and breastfeeding: Should only be used when benefits clearly outweigh risks; the drug passes into breast milk and requires careful monitoring
• Kidney function: Dosage adjustments are necessary for patients with reduced kidney function, as the drug is partially eliminated through the kidneys
• Liver disease: Patients with liver impairment may require dose modifications and closer monitoring
• Electrolyte imbalances: Low potassium or magnesium levels can increase the risk of dangerous arrhythmias and should be corrected before starting treatment

Interactions

• Digoxin: Flecainide can increase digoxin blood levels, potentially leading to digoxin toxicity
• Beta-blockers: Combined use may increase risk of heart rhythm problems and require careful monitoring
• Calcium channel blockers: May enhance the heart rhythm effects and blood pressure lowering effects of both medications
• CYP2D6 inhibitors (fluoxetine, paroxetine): These antidepressants can increase flecainide levels by blocking its metabolism
• Amiodarone: Another antiarrhythmic that can significantly increase flecainide blood concentrations
• Quinidine: Can increase flecainide levels and enhance cardiac effects
• Cimetidine: This acid reducer can increase flecainide blood levels
• Urinary alkalinizers: Substances that make urine less acidic can reduce flecainide elimination from the body

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Dosage

Typical adult dosages vary based on the specific condition being treated and individual patient factors. For atrial fibrillation and flutter, the usual starting dose is 50-100 mg twice daily, which may be increased to a maximum of 150 mg twice daily. For ventricular arrhythmias, starting doses are typically 100 mg every 12 hours, with possible increases to 150 mg twice daily. Treatment should always begin in a hospital setting with continuous heart monitoring. Dosage adjustments are necessary for patients with kidney disease, and all dosing decisions should be made by a qualified healthcare provider based on individual patient assessment and response to treatment.

Sources: FDA DailyMed drug labels (public domain), BNF, WHO Essential Medicines List. This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting or stopping any medication.

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