Category:

• Cardiac

Description:

• Antidysrhythmic (class IA)

Indications:

• Life threatening ventricular dysrhythmias, less severe but symptomatic ventricular dysrhythmias in select patients

• Maintenance of sinus rhythm following cardioversion in atrial fibrillation and/or flutter (non FDA approved)

• Suppression of recurrent paroxysmal atrial fibrillation (non FDA approved)

Contraindications:

• Complete heart block, lupus erythematosus

• Torsade de pointes

 Precautions:

• Pregnancy category C; compatible with breast feeding; long-term effect on nursing infant unknown

• Post MI, 1^st degree AV block (unless ventricular rate controlled by pacemaker)

• Asymptomatic premature ventricular contractions, digitalis intoxication

• CHF, myasthenia gravis, renal insufficiency, children

Adverse Reactions (Side Effects):

• CNS: depression, dizziness, giddiness, hallucinations, headache, psychosis, weakness

• CV: hypotension, 2^nd degree heart block, ventricular arrhythmias

• GI: abdominal pain, anorexia, bitter taste, diarrhea, hepatomegaly, nausea, vomiting

• HEME: agranulocytosis, hemolytic anemia (rare), neutropenia, thrombocytopenia

• SKIN: angioneurotic edema, flushing, pruritus, rash, urticaria

• MISC: lupus erythematosus-like syndrome (arthralgia, plueral or abdominal pain, arthritis, pleural effusion, pericarditis, fever, chills, rash) in up to 30% on long-term therapy

Dosage:

Administered orally, intravenously, intramuscularly

• Adult:   PO 250-500mg every 3-6 hours; PO SR 500-1000mg every 6 hours, usual dose 50 mg/kg/day, max 4g daily; IM 0.5-1g every 4-8 hours until PO therapy possible; IV 1g INF over 25-30 minutes or 100-200mg daily repeated every 5 minutes as needed to total dose of 1g as a loading dose, followed by continuous INF of 1-6 mg/min, titrate to patient response

• Child:   PO 15-50 mg/kg/day divided every 3-6 hours, max 4g daily; IM 20-30 mg/kg/day divided every 4-6 hours, max 4g daily; IV 3-6 mg/kg INF over 5 minutes not to exceed 100mg daily as a loading dose, then 20-80 mcg/kg/minute as a continuous INF, max 4g daily