Propafenone

Maintenance of sinus rhythm
1. Prevention of Paroxysmal Atrial Fibrillation and Atrial Flutter
2. Prevention of Paroxysmal Supraventricular Tachycardia (PSVT)
Atrial Fibrillation Cardioversion (Not FDA approved)
1. See Intermittent Atrial Fibrillation Pill in the Pocket
2. Flecainide is typically used for "pill in the pocket" management instead
3. Time to Cardioversion: 3-8h
4. Conversion Rate: 51-76%
5. Chronic Efficacy: 50-60%

Structural Heart Disease (e.g. Acute Myocardial Infarction, LV Dysfunction)
1. Risk for lethal ventricular Arrhythmias and increased mortality
Intraventricular conduction disorders (e.g. AV Node Block) without a Pacemaker
Pulse generation disorders (e.g. Sick Sinus Syndrome) without a Pacemaker
Hemodynamic instability
Severe COPD or bronchospastic disorders
Uncorrected Electrolyte disorders (esp. Hypokalemia, Hyperkalemia, Hypomagnesemia)
Brugada Syndrome
Myasthenia Gravis
1. Propafenone may precipitate Myasthenia Gravis symptoms

Proarrhythmic
1. Risk for ventricular Arrhythmias and mortality, esp. in structural heart disease (Acute Myocardial Infarction, LV Dysfunction)
2. Combination with AV Nodal blocking medication (e.g. Metoprolol, Diltiazem) recommended
  1. Decreases risk of Atrial Flutter with 1:1 conduction (Heart Rate 300)
Monitoring
1. Electrolytes
  1. Correct Potassium and Magnesium before initiating Propafenone
2. Blood Pressure Monitoring
3. Electrocardiogram Monitoring
  1. Decrease dose if QRS Widening >20% over baseline or AV Block (second or third degree)

See Class Ic Antiarrhythmic Drug
Slows overall cardiac conduction
1. Also prolongs refractory period within atria and ventricles
Other effects
1. Weak B adrenergic blocking effects
2. Weak Calcium entry blocking effects

Prevention of Paroxysmal Atrial Fibrillation, Atrial Flutter or PSVT (maintenance of sinus rhythm)
1. Regular Release
  1. Start 150 mg orally every 8 hours
  2. May increase to 225 mg every 8 hours after 3 to 4 days
  3. Maximum 900 mg/day
2. Sustained Release
  1. Start 225 mg sustained release orally every 12 hours
  2. May increase to 325 mg every 12 hours after 5 days
  3. Maximum 425 mg every 12 hours
Cardioversion of acute Atrial Fibrillation
1. See Intermittent Atrial Fibrillation Pill in the Pocket
2. Weight <70 kg: 450 mg orally for single bolus dose
3. Weight >70 kg: 600 mg orally for single bolus dose
Hepatic Insufficiency
1. Decrease dose 70 to 80%

Bioavailability
1. Sustained Release 325 mg every 12 hours is equivalent to regular release 150 mg every 8 hours
Slow metabolism in 10% of U.S. population (CYP2D6 deficiency)
1. Risk of toxicity (esp during titration) with significantly prolonged Half-Life

Avoid with Amiodarone, Quinidine
CNS side effects when combined with Lidocaine
Increases plasma levels of other drugs
1. Propranolol (and other Beta Blockers)
2. Digoxin (increases levels >35%)
3. Warfarin
  1. Monitor INR
Other drugs that increase Propafenone levels
1. Cimetidine
2. Fluoxetine
3. Orlistat
4. Ritonavir
5. CYP2D6 Inhibitors
6. CYP3A4 Inhibitors
Other drugs that decrease Propafenone levels
1. Rifampin