tion 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 patients assigned to placebo (3.0%; 22/725). The average duration of treatment with encainide or flecainide in this study was 10 months.
•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 proarrythmic 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 SR® is indicated to prolong the 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.
Usage Considerations:
•The use of RYTHMOL SR in patients with permanent AF or in patients exclusively with atrial flutter or paroxysmal supraventricular tachycardia (PSVT) has not been eva luated. Do not use RYTHMOL SR to control ventricular rate during AF.
•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.
•The effect of propafenone on mortality has not been determined [see Boxed Warning].
2 DOSAGE AND ADMINISTRATION
RYTHMOL SR can be taken with or without food. Do not crush or further divide the contents of the capsule.
The dose of RYTHMOL SR must be individually titrated on the basis of response and tolerance. Initiate therapy with RYTHMOL SR 225 mg given every 12 hours. Dosage may be increased at a minimum of 5 day interval to 325 mg given every 12 hours. If additional therapeutic effect is needed, the dose of RYTHMOL SR may be increased to 425 mg given every 12 hours.
In patients with hepatic impairment or those with significant widening of the QRS complex or second or third degree AV block, consider reducing the dose.
The combination of CYP3A4 inhibition and either CYP2D6 deficiency or CYP2D6 inhibition with the simultaneous administration of propafenone may significantly increase the concentration of propafenone and thereby increase the risk of proarrhythmia and other adverse events. Therefore, avoid simultaneous use of RYTHMOL SR with both a CYP2D6 inhibitor and a CYP3A4 inhibitor [see Warnings and Precautions (5.2) and Drug Interactions (7.1)].
3 DOSAGE FORMS AND STRENGTHS
RYTHMOL SR (propafenone HCl) capsules are supplied as white, opaque, hard gelatin capsules containing either 225 mg, 325 mg, or 425 mg of propafenone HCl and imprinted in red with the Reliant logo and strength. The 325 mg strength is also imprinted with a single red band around ¾ of the circumference of the body; the 425 mg strength is imprinted with three bands around ¾ of the circumference of the body.
4 CONTRAINDICATIONS
RYTHMOL SR is contraindicated in the following circumstances:
•Heart failure
•Cardiogenic shock
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