• Life-threatening ventricular arrhythmias, including ventricular tachycardia (immediate-release only).
• Prolongs the time to recurrence of symptomatic paroxysmal atrial arrhythmias, including paroxysmal atrial fibrillation/flutter and paroxysmal supraventricular tachycardia.

Unlabeled Uses:

• Single-dose treatment for atrial fibrillation.

Contraindicated in:

• Hypersensitivity
• Cardiogenic shock
• Conduction disorders including sick sinus syndrome and heart block (without a pacemaker)
• Bradycardia
• Severe hypotension
• Bronchospastic disorders or severe COPD
• Electrolyte disturbances
• Uncontrolled HF
• Brugada syndrome.

Use Cautiously in:

• Severe renal impairment (dose ↓ may be necessary)
• Severe hepatic impairment (dose ↓ may be necessary)
• OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk
• Lactation: Use while breastfeeding only if potential maternal benefit justifies potential risk to infant
• Pedi: Safety and effectiveness not established in children
• Geri: Lower doses may be necessary in older adults due to age-related ↓ in renal/hepatic/cardiovascular function, concurrent chronic illnesses and medications.

CV: conduction disturbances, angina, bradycardia, hypotension, SUPRAVENTRICULAR ARRHYTHMIAS, VENTRICULAR ARRHYTHMIAS.

Derm: rash.

EENT: blurred vision.

GI: altered taste, constipation, nausea, vomiting, diarrhea, dry mouth.

Hemat: AGRANULOCYTOSIS.

MS: joint pain.

Neuro: dizziness, shaking, weakness.

Drug-Drug:

• Any inhibitors of the CYP1A2, CYP2D6, or CYP3A4 enzyme systems may ↑ levels, including desipramine, paroxetine, ritonavir, sertraline, ketoconazole, and erythromycin (blood level monitoring recommended); concurrent use with CYP2D6 inhibitor and CYP3A4 inhibitor should be avoided.
• Quinidine is a strong inhibitor of CYP2D6 and significantly ↑ levels of propafenone; concurrent use not recommended.
• Propafenone is also an inhibitor of CYP2D6 and may ↑ levels of desipramine, imipramine, haloperidol, and venlafaxine.
• Significantly ↑ serum digoxin levels; blood level monitoring recommended; ↓ digoxin dose may be required.
• ↑levels of metoprolol and propranolol; ↓ dose may be required.
• Concurrent use of local anesthetics may ↑ risk of CNS adverse reactions.
• ↑effects of warfarin; ↓ warfarin dose if necessary; monitor INR.
• Concurrent use with amiodarone can adversely effect conduction/repolarization and should be avoided.
• May ↑ risk of CNS adverse reactions with lidocaine.
• May ↑ cyclosporine trough levels and risk of nephrotoxicity.
• Rifampin may ↓ levels and effectiveness.
• Cimetidine may ↑ levels.
• Orlistat may ↓ absorption.

Drug-Food:

• Grapefruit juice may ↑ levels.

(Generic available)

• Sustained-release capsules: 225 mg; 325 mg; 425 mg;
• Tablets: 150 mg; 225 mg; 300 mg;

• PO (Adults): 150 mg every 8 hr; may be gradually ↑ at 3–4-day intervals as required up to 300 mg every 8–12 hr. Single dose treatment of atrial fibrillation (unlabeled use): 450 or 600 mg; Sustained release: 225 mg every 12 hr; may be gradually ↑ at a minimum of 5-day intervals as required to 325 mg every 12 hr; if further ↑ is needed, may ↑ to 425 mg every 12 hr.

Rythmol SR

• Slows conduction in cardiac tissue by altering transport of ions across cell membranes.

• Suppression of ventricular arrhythmias.
• Prolonged time to recurrence of symptomatic paroxysmal atrial arrhythmias, including paroxysmal atrial fibrillation/flutter and paroxysmal supraventricular tachycardia.

Therapeutic Classification: antiarrhythmics (class IC)

Absorption: 3–11% absorbed following oral administration.

Distribution: Widely distributed to tissues.

Metabolism/Excretion: Extensively metabolized by the liver by the CYP1A2, CYP2D6, and CYP3A4 isoenzymes (some metabolites have antiarrhythmic activity); the CYP2D6 isoenzyme exhibits genetic polymorphism (7% of population may be poor metabolizers and may have significantly ↑ propafenone concentrations and an ↑ risk of adverse effects). .

Half-life: Extensive metabolizers: 2–10 hr; Slow metabolizers: 10–32 hr.

Rythmol

(antiarrhythmic effects)

†Chronic dosing.

• Instruct patient to take medication around the clock as directed, even if feeling better. Take missed doses as soon as remembered if within 4 hr; omit if remembered later. Gradual dosage reduction may be necessary.
• May cause dizziness. Caution patient to avoid driving and other activities requiring alertness until response to medication is known.
• Advise patient to notify health care professional of medication regimen prior to treatment or surgery.
• Instruct patient to notify health care professional if fever, sore throat, chills, or unusual bleeding or bruising occurs or if chest pain, shortness of breath, diaphoresis, palpitations, or visual changes become bothersome.
• Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
• Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.
• Advise patient to carry identification describing disease process and medication regimen at all times.
• Emphasize the importance of follow-up exams to monitor progress.

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