Propafenone Hydrochloride

What it is and how it works

Mechanism of Action Propafenone is a Class 1C antiarrhythmic drug with local anesthetic effects and a direct stabilizing action on myocardial membranes. The electrophysiological effect of propafenone manifests itself in a reduction of upstroke velocity (Phase 0) of the monophasic action potential. In Purkinje fibers, and, to a lesser extent, myocardial fibers, propafenone reduces the fast inward current carried by sodium ions. Diastolic excitability threshold is increased and effective refractory period prolonged. Propafenone reduces spontaneous automaticity and depresses triggered activity.

Indications

Propafenone Hydrochloride Tablets are indicated to: • prolong the time to recurrence of paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms in patients without structural heart disease. • prolong the time to recurrence of paroxysmal supraventricular tachycardia (PSVT) associated with disabling symptoms in patients without structural heart disease. • treat documented ventricular arrhythmias, such as sustained ventricular tachycardia that, in the judgment of the physician, are life-threatening. Initiate treatment in the hospital. Usage Considerations: • The use of Propafenone Hydrochloride Tablets in patients with permanent atrial fibrillation (AF) or in patients exclusively with atrial flutter or PSVT has not been evaluated. Do not use Propafenone Hydrochloride Tablets to control ventricular rate during AF. • Some patients with atrial flutter treated with propafenone have developed 1:1 conduction, producing an increase in ventricular rate.

Dosage and administration (summary)

The dose of Propafenone Hydrochloride Tablets must be individually titrated on the basis of response and tolerance. Initiate therapy with Propafenone Hydrochloride Tablets 150 mg given every 8 hours (450 mg per day). Dosage may be increased at a minimum of 3- to 4- day intervals to 225 mg every 8 hours (675 mg per day). If additional therapeutic effect is needed, the dose of Propafenone Hydrochloride Tablets may be increased to 300 mg every 8 hours (900 mg per day). The usefulness and safety of dosages exceeding 900 mg per day have not been established.

Contraindications

Propafenone hydrochloride tablets are contraindicated in the following circumstances: • Heart failure • Cardiogenic shock • Sinoatrial, atrioventricular, and intraventricular disorders of impulse generation or conduction (e.g., sick sinus node syndrome, AV block) in the absence of an artificial pacemaker • Known Brugada Syndrome • Bradycardia • Marked hypotension • Bronchospastic disorders or severe obstructive pulmonary disease • Marked electrolyte imbalance • Heart failure • Cardiogenic shock …

Warnings and precautions

• May cause new or worsened arrhythmias. Evaluate patients via ECG prior to and during therapy. • Propafenone Hydrochloride Tablets may unmask Brugada or Brugada-like Syndrome. ( 4 , 5.2 ) • Avoid use with other drugs that prolong the QT interval. • Avoid simultaneous use of propafenone with both a cytochrome P450 2D6 (CYP2D6) inhibitor and a 3A4 inhibitor (CYP3A4). • May provoke overt heart failure. • May cause dose-related first-degree AV block or other conduction disturbances. Only use in patients with conduction disorders who have pacemakers. • May affect artificial pacemakers.

Pregnancy

Pregnancy Risk Summary There are no studies of propafenone hydrochloride tablets in pregnant women. Available data from published case reports and several decades of postmarketing experience with use of propafenone hydrochloride tablets in pregnancy have not identified any drug-associated risks of miscarriage, birth defects, or adverse maternal or …

Storage and supply

Propafenone Hydrochloride Tablets USP are supplied as: 225 mg – White, biconvex, round, film-coated tablets debossed with “ANI” over “231” and scored on one side and plain on the other side. This strength is supplied in bottles of 100 tablets under NDC 63629-1988-1. S torage :Store at 20° to 25°C (68° to 77°F); .

Source: Propafenone Hydrochloride (Propafenone Hydrochloride) — US FDA prescribing information, 2023-11-13, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.