RYTHMOL- propafenone hydrochloride tablet, film coated
GlaxoSmithKline LLC
WARNING: MORTALITY
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In the National Heart, Lung, and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST), a long-term, multi-center, randomized, double-blind trial in subjects with asymptomatic non-life-threatening ventricular arrhythmias who had a myocardial infarction more than 6 days but less than 2 years previously, an increased rate of death or reversed cardiac arrest rate (7.7%; 56/730) was seen in patients treated with encainide or flecainide (Class IC antiarrhythmics) compared with that seen in subjects assigned to placebo (3.0%; 22/725). The average duration of treatment with encainide or flecainide in this trial was 10 months.
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The applicability of the CAST results to other populations (e.g., those without recent myocardial infarction) or other antiarrhythmic drugs is uncertain, but at present, it is prudent to consider any IC antiarrhythmic to have a significant proarrhythmic risk 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, symptoms or signs.
1 INDICATIONS AND USAGE
RYTHMOL is indicated to:
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prolong the time to recurrence of paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms in patients without structural heart disease.
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prolong the time to recurrence of paroxysmal supraventricular tachycardia (PSVT) associated with disabling symptoms in patients without structural heart disease.
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treat documented ventricular arrhythmias, such as sustained ventricular tachycardia that, in the judgment of the physician, are life-threatening. Initiate treatment in the hospital.
Usage Considerations:
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The use of RYTHMOL in patients with permanent atrial fibrillation (AF) or in patients exclusively with atrial flutter or PSVT has not been evaluated. Do not use RYTHMOL to control ventricular rate during AF.
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Some patients with atrial flutter treated with propafenone have developed 1:1 conduction, producing an increase in ventricular rate. Concomitant treatment with drugs that increase the functional atrioventricular (AV) nodal refractory period is recommended.
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The use of RYTHMOL in patients with chronic atrial fibrillation has not been evaluated.
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Because of the proarrhythmic effects of RYTHMOL, its use with lesser ventricular arrhythmias is not recommended, even if patients are symptomatic, and any use of the drug should be reserved for patients in whom, in the opinion of the physician, the potential benefits outweigh the risks.
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The effect of propafenone on mortality has not been determined [see Boxed Warning].
2 DOSAGE AND ADMINISTRATION
The dose of RYTHMOL must be individually titrated on the basis of response and tolerance. Initiate therapy with RYTHMOL 150 mg given every 8 hours (450 mg per day). Dosage may be increased at a minimum of 3- to 4- day intervals to 225 mg every 8 hours (675 mg per day). If additional therapeutic effect is needed, the dose of RYTHMOL may be increased to 300 mg every 8 hours (900 mg per day). The usefulness and safety of dosages exceeding 900 mg per day have not been established.