Select therapeutic use:
Indications for RYTHMOL SR:
To prolong recurrence of symptomatic atrial fibrillation in patients without structural heart disease.
Individualize. Not interchangeable on a mg-to-mg basis with immediate-release form (see literature). Swallow whole. Initially 225mg every 12hrs. May increase at 5-day intervals to 325mg every 12hrs; max 425mg every 12hrs. When switching from 150mg three times daily of the immediate-release form, start Rhythmol SR at 325mg twice daily. QRS widening, 2nd or 3rd degree heart block, or hepatic impairment: reduce dose.
Heart failure. Cardiogenic shock. SA, AV and intraventricular disorders of impulse generation or conduction (eg, sick sinus syndrome, AV block), unless paced. Known Brugada Syndrome. Bradycardia. Marked hypotension. Bronchospastic disorders. Marked electrolyte imbalance.
Significant proarrhythmic risk in structural heart disease. Avoid in patients with non-life-threatening ventricular arrhythmias. Monitor ECG, pacemakers before and during therapy. Discontinue if ECG changes are suggestive of Brugada Syndrome or if CHF worsens; reduce dose if 2nd- or 3rd- degree AV block or QRS widening occurs. Monitor for agranulocytosis. Hepatic or renal dysfunction. Elderly. Labor & delivery. Pregnancy (Cat.C). Nursing mothers: not recommended.
Class IC antiarrhythmic.
Local anesthetics may increase CNS effects. Avoid drugs that may prolong the QT interval (eg, antiarrhythmics, phenothiazines, cisapride, bepridil, tricyclic antidepressants, macrolides). Avoid concomitant quinidine, amiodarone. Potentiates β-blockers, warfarin, digoxin (consider reducing their doses when starting propafenone), desipramine, cyclosporine, theophylline. Antagonized by rifampin. Monitor and adjust dose with CYP2D6, CYP1A2, and CYP3A4 inhibitors.
Dizziness, palpitations, chest pain, dyspnea, taste disturbance, nausea, fatigue, anxiety, constipation, upper respiratory tract infection, edema, influenza, angina pectoris, atrial flutter, 1st degree AV block, heart failure, bradycardia, headache, blurred vision; new or exacerbated arrhythmias, conduction defects, elevated ANA titer, exacerbation of myasthenia gravis.