Flecainide

Class Ic Antiarrhythmic Drug
Blocks cardiac Sodium channels
Slows overall cardiac conduction velocity
1. Electrocardiogram demonstrates an increase over baseline in PR Interval, QRS Duration, QT Interval
Decreases cardiac contractility
Decreases both ectopic and SA Node automaticity
Prolongs refractory period in His bundle and Purkinje Fibers, ventricle and accessory pathways

Atrial Fibrillation Cardioversion
1. Time to Cardioversion: 3-8 hours
2. Conversion Rate: 68-91%
3. Chronic Efficacy: 40-74%

Proarrythmic
1. Higher mortality in history of Myocardial Infarction and non-life threatening ventricular Arrhythmia
  1. Seen with other Class Ic Antiarrhythmic Drug
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)
Narrow therapeutic range
Correct Potassium abnormalities (Hypokalemia, Hyperkalemia) before administration
Exercise caution in decreased Renal Function
Risk of toxicity (esp. in renal dysfunction)
1. Acute ingestion >1 gram
2. Chronic dosing error
Indications to discontinue
1. Electrocardiogram (EKG) Changes
  1. QRS Widening >20%
  2. Second or third degree AV Block

Background
1. Consider starting medication while on telemetry in hospital
Life Threatening ventricular Arrhythmia (without structural heart disease)
1. Start 100 mg orally every 12 hours
  1. Start at 50 mg orally every 12 hours if Creatinine Clearance <35 ml/min
2. Increase by up to 50 mg twice daily every 4 days
3. Maximum: 400 mg/day
Atrial Fibrillation Rhythm Control (maintenance of sinus rhythm)
1. Start 50 mg orally every 12 hours
2. Increase by up to 50 mg twice daily every 4 days
3. Maximum: 300 mg/day
Intermittent Atrial Fibrillation Pill in the Pocket (home use)
1. Take one 200 to 300 mg tablet orally at onset of Atrial Fibrillation
Atrial Fibrillation Chemical Cardioversion
1. Load: 300 mg orally single bolus dose
2. Maintenance: 50-150 mg orally twice daily (see rhythm control dose titration as above)

Oral Bioavailability: 90%
1. However absorption is highly variable between patients
Peak: 3 hours after ingestion
Volume of Distribution (Vd): 8 to 9 L/kg (high)
1. Not dialyzable
Half-Life: 12 to 24 hours
1. Steady state level reached 4 days after starting or dose change
Trough Level target: 0.2 to 1 mcg/ml
Metabolism: Hepatic
1. Up to 10% of patients metabolize Flecainide four fold slower than other patients
Renal excretion: 30% unchanged

Avoid other Antiarrhythmic use in combination (except on cardiology Consultation)
Flecainide increases the serum level of other medications
1. Digoxin (>13 fold increase)
Other medications that increase Flecainide levels
1. Amiodarone
  1. Decrease Flecainide dose by 50% if used in combination with Amiodarone
2. Cimetidine
3. Quinidine