Propafenone hydrochloride
Propafenone hydrochloride (Rythmol)
Propafenone hydrochloride
(proh-pah- FEN-ohn)
Pregnancy Category: C Rythmol (Rx)

Classification: Antiarrhythmic, class IC

Action/Kinetics: Manifests local anesthetic effects and a direct stabilizing action on the myocardium. Reduces upstroke velocity (Phase O) of the monophasic action potential, reduces the fast inward current carried by sodium ions in the Purkinje fibers, increases diastolic excitability threshold, and prolongs the effective refractory period. Also, spontaneous activity is decreased. Slows AV conduction and causes first-degree heart block. Has slight beta-adrenergic blocking activity. Peak plasma levels: 3.5 hr. Therapeutic plasma levels: 0.5-3 mcg/mL. Significant first-pass effect. Most metabolize rapidly ( t 1/2: 2-10 hr) to two active metabolites: 5-hydroxypropafenone and N-depropylpropafenone. However, approximately 10% (as well as those taking quinidine) metabolize the drug more slowly ( t 1/2: 10-32 hr). Because the 5-hydroxy metabolite is not formed in slow metabolizers and because steady-state levels are reached after 4-5 days in all clients, the recommended dosing regimen is the same for all clients.

Uses: Documented life-threatening ventricular arrhythmias, such as sustained ventricular tachycardia where the benefits outweigh the risks. Paroxysmal atrial fibrillation or flutter and paroxysmal supraventricular tachycardia associated with disabling symptoms. Do not use in less severe ventricular arrhythmias even if the client is symptomatic. Antiarrhythmic drugs have not been shown to improve survival in clients with ventricular arrhythmias. Investigational: Arrhythmias associated with Wolff-Parkinson-White syndrome.

Contraindications: Uncontrolled CHF, cardiogenic shock, sick sinus node syndrome or AV block in the absence of an artificial pacemaker, bradycardia, marked hypotension, bronchospastic disorders, electrolyte disorders, hypersensitivity to the drug. MI more than 6 days but less than 2 years previously. Lactation.

Special Concerns: There is an increased risk of death in those with non-life-threatening arrhythmias. Use with caution during labor and delivery. Safety and effectiveness have not been determined in children. Use with caution in clients with impaired hepatic or renal function. Geriatric clients may require lower dosage.

Side Effects: CV: New or worsened arrhythmias. First-degree AV block, intraventricular conduction delay, palpitations, PVCs, proarrhythmia, bradycardia, atrial fibrillation, angina, syncope, CHF, ventricular tachycardia, second-degree AV block increased QRS duration, chest pain, hypotension, bundle branch block. Less commonly, atrial flutter, AV dissociation, flushing, hot flashes, sick sinus syndrome, sinus pause or arrest, SVT, cardiac arrest. CNS: Dizziness, headache, anxiety, drowsiness, fatigue, loss of balance, ataxia, insomnia. Less commonly, abnormal speech, abnormal dreams, abnormal vision, confusion, depression, memory loss, apnea psychosis/mania, vertigo, seizures, coma numbness, paresthesias. GI: Unusual taste, constipation, nausea and/or vomiting, dry mouth, anorexia, flatulence, abdominal pain, cramps, diarrhea, dyspepsia. Less commonly, gastroenteritis and liver abnormalities (cholestasis, hepatitis, elevated enzymes, hepatitis). Hematologic: Agranulocytosis increased bleeding time, anemia, granulocytopenia, bruising, leukopenia, purpura, anemia, thrombocytopenia. Miscellaneous: Blurred vision, dyspnea, weakness, rash, edema, tremors, diaphoresis, joint pain, possible decrease in spermatogenesis. Less commonly, tinnitus, unusual smell sensation, alopecia, eye irritation, hyponatremia, inappropriate ADH secretion, impotence, increased glucose, kidney failure, lupus erythematosus, muscle cramps or weakness, nephrotic syndrome, pain, pruritus.

Laboratory Test Alterations: ANA titers.

Overdose Management: Symptoms: Bradycardia, hypotension, IA and intraventricular conduction disturbances, somnolence. Rarely, high-grade ventricular arrhythmias and seizures. Treatment: To control BP and cardiac rhythm, defibrillation and infusion of dopamine or isoproterenol. If seizures occur, diazepam, IV, can be given. External cardiac massage and mechanical respiratory assistance may be required.

Drug Interactions: Beta-adrenergic blockers / Plasma levels of beta blockers metabolized by the liver Cimetidine / Propafenone plasma levels Cyclosporine / Blood trough levels; renal function Digoxin / Plasma levels digoxin dose Local anesthetics / May risk of CNS side effects Quinidine / Propafenone serum levels in rapid metabolizers possible effect Rifampin / Propafenone effect R/T clearance Warfarin / May warfarin plasma levels; warfarin dose

How Supplied: Tablet: 150 mg, 225 mg, 300 mg

Dosage
?Tablets
Adults, initial: 150 mg q 8 hr; dose may be increased at a minimum of q 3-4 days to 225 mg q 8 hr and, if necessary, to 300 mg q 8 hr.