Propafenone works by slowing the influx of sodium ions into the cardiac muscle cells, causing a decrease in excitability of the cells. Propafenone is more selective for cells with a high rate, but also blocks normal cells more than class Ia or Ib. Propafenone differs from the prototypical class Ic antiarrhythmic in that it has additional activity as a beta-adrenergic blocker which can cause bradycardia and bronchospasm.

Propafenone is indicated for the treatment of paroxysmal atrial fibrillation/flutter (PAF), paroxysmal supraventricular tachycardia (PSVT). Propafenone is also indicated for the treatment of documented ventricular arrhythmias.

The dose of Propafenone must be individually titrated on the basis of response and tolerance. It is recommended that therapy be initiated with Propafenone 150 mg given every eight hours (450 mg/day). Dosage may be increased at a minimum of 3 to 4 day intervals to 225 mg every 8 hours (675 mg/day) and if necessary, to 300 mg every 8 hours (900 mg/day). The usefulness and safety of dosages exceeding 900 mg per day have not been established.

Propafenone is contraindicated in the presence of uncontrolled congestive heart failure, cardiogenic shock, sinoatrial, atrioventricular and intraventricular disorders of impulse generation and/or conduction (e.g. sick sinus node syndrome, atrioventricular block) in the absence of an artificial pacemaker, bradycardia, marked hypotension, bronchospastic disorders, manifest electrolyte imbalance and known hypersensitivity to the drug.

Adverse reactions associated with propafenone occur most frequently in the gastrointestinal, cardiovascular and central nervous systems. Change in taste, constipation, diarrhea, dizziness, drowsiness, dry mouth, gas, headache, light-headedness, nausea, tiredness etc. may happen. Severe allergic reactions also reported with propafenone.

Hepatic Dysfunction: Propafenone is highly metabolized by the liver and should therefore, be administered cautiously to patients with impaired hepatic function. As a result, the dose of propafenone given to patients with impaired hepatic function should be approximately 20 to 30% of the dose given to patients with normal hepatic function.

Renal Dysfunction: A considerable percentage of propafenone metabolites (18.5% to 38% of the dose/48 hours) are excreted in the urine. Until further data are available, propafenone should be administered cautiously to patients with impaired renal function.

Neuromuscular Dysfunction: Exacerbation of myasthenia gravis has been reported during propafenone therapy.

Use in Special Populations

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

Geriatric Use: Clinical studies of propafenone did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, dose selection for an elderly patient should be cautious.

Pregnancy & Lactation

Pregnancy: Propafenone has been assigned to pregnancy category C by the FDA. There are no controlled data in human pregnancy. Limited data indicate that propafenone has been administered during the third trimester of pregnancy without adverse maternal or fetal effects. Propafenone should be given during pregnancy only when benefit outweighs risk.

Nursing Mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from propafenone, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.