Propafenone is indicated for the management of paroxysmal atrial fibrillation/flutter (PAF) and paroxysmal supraventricular tachycardia (PSVT). It is also used in the treatment of documented ventricular arrhythmias.

Propafenone acts by reducing the influx of sodium ions into cardiac muscle cells, thereby decreasing cellular excitability. It has greater selectivity for rapidly firing cells but also affects normal cells more than class Ia or Ib agents. Unlike typical class Ic antiarrhythmics, Propafenone also possesses beta-adrenergic blocking activity, which may lead to bradycardia and bronchospasm.

The dosage of Propafenone should be individually adjusted based on patient response and tolerance. Treatment is usually initiated with 150 mg every 8 hours (total 450 mg/day). The dose may be increased at intervals of at least 3 to 4 days to 225 mg every 8 hours (675 mg/day), and if required, up to 300 mg every 8 hours (900 mg/day). The safety and effectiveness of doses exceeding 900 mg per day have not been established.

Propafenone is primarily metabolized by CYP2D6, with additional metabolism via CYP1A2 and CYP3A4. Drugs that inhibit CYP2D6 (e.g., desipramine, paroxetine, ritonavir, sertraline), CYP1A2 (e.g., amiodarone), and CYP3A4 (e.g., ketoconazole, ritonavir, saquinavir, erythromycin, and grapefruit juice) may increase plasma levels of propafenone. Additionally, propafenone itself inhibits CYP2D6. Concomitant use with drugs metabolized by CYP2D6 (such as desipramine, imipramine, haloperidol, and venlafaxine) may result in elevated plasma concentrations of these medications.

Propafenone is contraindicated in patients with uncontrolled congestive heart failure, cardiogenic shock, and disorders of impulse generation or conduction (including sinoatrial, atrioventricular, or intraventricular disorders such as sick sinus syndrome or AV block) in the absence of a functioning pacemaker. It should also not be used in patients with bradycardia, marked hypotension, bronchospastic disorders, significant electrolyte imbalance, or known hypersensitivity to the drug.

Adverse effects of propafenone most commonly involve the gastrointestinal, cardiovascular, and central nervous systems. These may include altered taste, constipation, diarrhea, dizziness, drowsiness, dry mouth, flatulence, headache, light-headedness, nausea, and fatigue. Severe allergic reactions have also been reported with propafenone.

Pregnancy: Propafenone is classified as pregnancy category C by the FDA. There are no well-controlled studies in pregnant women. Limited available data suggest that propafenone has been used during the third trimester without causing adverse effects to the mother or fetus. It should be used during pregnancy only if the potential benefit justifies the potential risk.

Nursing Mothers: It is not known whether propafenone is excreted in human breast milk. Since many drugs are excreted in breast milk and there is a potential for serious adverse reactions in nursing infants, a decision should be made either to discontinue nursing or to discontinue the drug, considering the importance of the drug to the mother.

Hepatic Dysfunction: Propafenone is extensively metabolized by the liver; therefore, it should be used with caution in patients with impaired hepatic function. In such patients, the dose should be reduced to approximately 20–30% of the dose used in individuals with normal liver function.

Renal Dysfunction: A significant proportion of propafenone metabolites (about 18.5% to 38% of the dose over 48 hours) is excreted in the urine. Until more data are available, caution should be exercised when administering propafenone to patients with impaired renal function.

Neuromuscular Dysfunction: Worsening of myasthenia gravis has been reported during treatment with propafenone.

Pediatric Use: The safety and effectiveness of propafenone in pediatric patients have not been established.

Geriatric Use: Clinical studies of propafenone did not include enough subjects aged 65 years and older to determine whether they respond differently from younger individuals. In general, dose selection in elderly patients should be made with caution.

Membrane stabilizing agent (Sodium channel blockers)

Store at 25°C. Keep in a cool, dry place, protected from light. Keep out of reach of children.