Usual Adult Dose for Atrial Fibrillation

Immediate-release Tablets:
Initial dose: 150 mg orally every 8 hours; may increase dose after at least 3 to 4 days to 225 mg orally every 8 hours; if additional therapeutic effect is needed, may increase dose to 300 mg orally every 8 hours.
Maximum dose: 900 mg/day

Uses:

• To prolong time to recurrence of paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms in patients without structural heart disease.
• To prolong time to recurrence of paroxysmal supraventricular tachycardia (PSVT) associated with disabling symptoms in patients without structural heart disease.
• To treat documented ventricular arrhythmias, such as sustained ventricular tachycardia that, in the judgment of the physician, are life-threatening.

Extended-release Capsules:
Initial dose: 225 mg orally every 12 hours; may increase dose after at least 5 days to 325 mg orally every 12 hours; if additional therapeutic effect is needed, may increase dose to 425 mg orally every 12 hours.

Use: To prolong time to recurrence of symptomatic atrial fibrillation (AF) in patients with episodic (most likely paroxysmal or persistent) AF who do not have structural heart disease.

Usual Adult Dose for Atrial Flutter

Immediate-release Tablets:
Initial dose: 150 mg orally every 8 hours; may increase dose after at least 3 to 4 days to 225 mg orally every 8 hours; if additional therapeutic effect is needed, may increase dose to 300 mg orally every 8 hours.
Maximum dose: 900 mg/day

Uses:

• To prolong time to recurrence of paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms in patients without structural heart disease.
• To prolong time to recurrence of paroxysmal supraventricular tachycardia (PSVT) associated with disabling symptoms in patients without structural heart disease.
• To treat documented ventricular arrhythmias, such as sustained ventricular tachycardia that, in the judgment of the physician, are life-threatening.

Extended-release Capsules:
Initial dose: 225 mg orally every 12 hours; may increase dose after at least 5 days to 325 mg orally every 12 hours; if additional therapeutic effect is needed, may increase dose to 425 mg orally every 12 hours.

Use: To prolong time to recurrence of symptomatic atrial fibrillation (AF) in patients with episodic (most likely paroxysmal or persistent) AF who do not have structural heart disease.

Usual Adult Dose for Ventricular Tachycardia

Immediate-release Tablets:
Initial dose: 150 mg orally every 8 hours; may increase dose after at least 3 to 4 days to 225 mg orally every 8 hours; if additional therapeutic effect is needed, may increase dose to 300 mg orally every 8 hours.
Maximum dose: 900 mg/day

Uses:

• To prolong time to recurrence of paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms in patients without structural heart disease.
• To prolong time to recurrence of paroxysmal supraventricular tachycardia (PSVT) associated with disabling symptoms in patients without structural heart disease.
• To treat documented ventricular arrhythmias, such as sustained ventricular tachycardia that, in the judgment of the physician, are life-threatening.

Extended-release Capsules:
Initial dose: 225 mg orally every 12 hours; may increase dose after at least 5 days to 325 mg orally every 12 hours; if additional therapeutic effect is needed, may increase dose to 425 mg orally every 12 hours.

Use: To prolong time to recurrence of symptomatic atrial fibrillation (AF) in patients with episodic (most likely paroxysmal or persistent) AF who do not have structural heart disease.

Usual Adult Dose for Paroxysmal Supraventricular Tachycardia

Immediate-release Tablets:
Initial dose: 150 mg orally every 8 hours; may increase dose after at least 3 to 4 days to 225 mg orally every 8 hours; if additional therapeutic effect is needed, may increase dose to 300 mg orally every 8 hours.
Maximum dose: 900 mg/day

Uses:

• To prolong time to recurrence of paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms in patients without structural heart disease.
• To prolong time to recurrence of paroxysmal supraventricular tachycardia (PSVT) associated with disabling symptoms in patients without structural heart disease.
• To treat documented ventricular arrhythmias, such as sustained ventricular tachycardia that, in the judgment of the physician, are life-threatening.

Extended-release Capsules:
Initial dose: 225 mg orally every 12 hours; may increase dose after at least 5 days to 325 mg orally every 12 hours; if additional therapeutic effect is needed, may increase dose to 425 mg orally every 12 hours.

Use: To prolong time to recurrence of symptomatic atrial fibrillation (AF) in patients with episodic (most likely paroxysmal or persistent) AF who do not have structural heart disease.

Renal Dose Adjustments

Use with caution

Liver Dose Adjustments

Dose reduction may be required; however, no specific guidelines have been suggested. Caution recommended.

Dose Adjustments

Patients with significant widening of the QRS complex or second- or third-degree atrioventricular (AV) block: Dose reduction may be required; however, no specific guidelines have been suggested. Caution recommended.

Precautions

CONTRAINDICATIONS:

• Heart failure, cardiogenic shock, or marked hypotension
• Sinoatrial, atrioventricular, and intraventricular disorders of impulse generation or conduction (e.g., sick sinus syndrome, atrioventricular block) in the absence of a pacemaker
• Known Brugada Syndrome
• Bradycardia
• Bronchospastic disorders and severe obstructive pulmonary disease
• Marked electrolyte imbalance

US BOXED WARNING:

• MORTALITY: An increased rate of death or reversed cardiac arrest rate was seen in patients treated with encainide or flecainide (Class IC antiarrhythmics) compared with that seen in patients assigned to placebo. At present it is prudent to consider any IC antiarrhythmic to have a significant risk of provoking proarrhythmic events in patients with structural heart disease. Given the lack of any evidence that these drugs improve survival, antiarrhythmic agents should generally be avoided in patients with non-life-threatening ventricular arrhythmias, even if the patients are experiencing unpleasant, but not life-threatening, signs or symptoms.

Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

• If a dose is missed, the next dose should be taken at the usual time (and not doubled).
• Extended-release capsules: Do not crush or further divide the contents of the capsule.

General:

• Use in patients with permanent atrial fibrillation (AF) or with atrial flutter or paroxysmal supraventricular tachycardia (PSVT) has not been evaluated. Do not use this drug to control ventricular rate during AF.
• In patients with atrial fibrillation and atrial flutter, use of this drug with other drugs that increase the functional atrioventricular (AV) nodal refractory period is recommended.
• Due to its proarrhythmic effects, use of this drug with lesser ventricular arrhythmias is not recommended.
• The effect of this drug on mortality has not been determined.

Monitoring:

• Cardiovascular: ECG (before and during treatment); blood pressure
• Other: Plasma concentrations; implanted pacemakers and defibrillators (during and after treatment)

Patient advice:

• Instruct patients to promptly report any signs of infection, such as chills, fever, or sore throat.
• Instruct patients to report symptoms that may be associated with altered electrolyte balance (e.g., excessive or prolonged diarrhea, sweating, vomiting, or loss of appetite or thirst).
• Inform male patients regarding the possibility of decreased sperm count.