Overview
Propafenone is a class IC antiarrhythmic agent used to prolong time to recurrence of symptomatic atrial fibrillation in patients with episodic AF without structural heart disease. It works by blocking sodium channels to slow cardiac conduction and stabilize myocardial membranes. The extended-release formulation allows twice-daily dosing for maintenance therapy.
Mechanism of Action
Propafenone is a class IC antiarrhythmic that blocks cardiac sodium channels, slowing conduction velocity in the atria, ventricles, and accessory pathways. It has additional weak beta-adrenergic blocking properties and mild calcium channel blocking effects, contributing to its antiarrhythmic activity.
Indications
- Prolong time to recurrence of symptomatic atrial fibrillation (AF) in patients with episodic (paroxysmal or persistent) AF without structural heart disease
Common Doses
- 225 mg
- 325 mg
- 425 mg
Dosage
Initiate with 225 mg every 12 hours, may increase at minimum 5-day intervals to 325 mg every 12 hours, then to 425 mg every 12 hours if needed. Take with or without food; do not crush or divide capsules. Reduce dose in hepatic impairment or with significant QRS widening or AV block.
Contraindications
- Heart failure
- Cardiogenic shock
- Sinoatrial, atrioventricular or intraventricular conduction disorders without pacemaker
- Brugada Syndrome
- Bradycardia
- Marked hypotension
- Bronchospastic disorders or severe obstructive pulmonary disease
- Marked electrolyte imbalance
Side Effects
- Dizziness
- Unusual taste
- Nausea
- Fatigue
- Constipation
- Headache
- Blurred vision
- Proarrhythmia
- Heart failure exacerbation
- Conduction abnormalities
- Bronchospasm
Interactions
- CYP2D6 inhibitors (quinidine, fluoxetine) increase propafenone levels
- CYP3A4 inhibitors (ketoconazole, ritonavir) increase propafenone levels
- Digoxin (increased levels)
- Warfarin (increased INR)
- Beta-blockers (additive effects)
- Local anesthetics (additive cardiac effects)
Counseling Points
- Take exactly as prescribed, usually twice daily
- Do not crush, chew, or open capsules
- Report any dizziness, palpitations, or shortness of breath
- Regular ECG monitoring required
- Avoid grapefruit juice
- Inform all healthcare providers about all medications
- Carry medical identification indicating propafenone use