Pregnancy Risk Category D
How supplied
Tablets: 100 mg‡, 200 mg
Injection: 50 mg/ml
Action
Unknown. Thought to prolong the refractory period and action potential duration.
Indications & dosage
Recurrent ventricular fibrillation or recurrent hemodynamically unstable ventricular tachycardia nonresponsive to adequate doses of other antiarrhythmics or when alternative agents can't be tolerated--
Adults: loading dose is 800 to 1,600 mg P.O. daily divided b.i.d. for 1 to 3 weeks until initial therapeutic response occurs; then 600 to 800 mg P.O. daily for 1 month, followed by 200 to 600 mg P.O. daily for maintenance.
Or, give loading dose of 150 mg I.V. over 10 minutes (15 mg/minute); then 360 mg I.V. over next 6 hours (1 mg/minute), followed by 540 mg I.V. over next 18 hours (0.5 mg/minute). After first 24 hours, continue with maintenance I.V. infusion of 720 mg/24 hours (0.5 mg/minute).
Adverse reactions
CNS: peripheral neuropathy, ataxia, paresthesia, tremor, insomnia, sleep disturbances, headache, malaise, fatigue.
CV: bradycardia, hypotension, arrhythmias, heart failure, heart block, sinus arrest, edema.
EENT: asymptomatic corneal microdeposits, optic neuropathy or neuritis resulting in visual impairment, abnormal taste and smell, visual disturbances.
GI: anorexia, nausea, vomiting, constipation, abdominal pain.
Hepatic: elevated liver enzymes, hepatic dysfunction, hepatic failure.
Respiratory: adult respiratory distress syndrome, severe pulmonary toxicity.
Skin: photosensitivity, solar dermatitis.
Other: hypothyroidism, hyperthyroidism, coagulation abnormalities.
Interactions
Drug-drug. Antiarrhythmics: amiodarone may reduce hepatic or renal clearance of certain antiarrhythmics (especially flecainide, procainamide, quinidine). Use of amiodarone with other antiarrhythmics (especially mexiletine, propafenone, quinidine, disopyramide, procainamide) may induce torsades de pointes. Avoid concomitant use.
Antihypertensives: increased hypotensive effect. Use together cautiously.
Beta blockers, calcium channel blockers: increased cardiac depressant effects; may potentiate slowing of SA node and AV conduction. Use together cautiously.
Cyclosporine: increased serum creatinine levels. Serum creatinine level can remain elevated even after cyclosporine dose is reduced. Monitor closely.
Digoxin: increased serum digoxin levels (average of 70% to 100%). Monitor digoxin levels closely and adjust dosage as ordered. Digoxin dosage should be reduced by half or discontinued.
Phenytoin: may decrease phenytoin metabolism. Monitor serum phenytoin levels and adjust dosage as ordered.
Theophylline: increased theophylline levels with toxicity may occur. Monitor serum theophylline levels.
Warfarin: potentiation of anticoagulant response with the potential for serious or fatal bleeding. Decrease warfarin dosage 33% to 50% when amiodarone is initiated. Monitor patient closely.
Drug-herb. Pennyroyal: may change the rate of formation of toxic metabolites of pennyroyal. Avoid concurrent use.
Drug-lifestyle. Sun exposure: photosensitivity reaction may occur. Take precautions.
Effects on diagnostic tests
None reported.
Contraindications
Contraindicated in patients with hypersensitivity to drug. Also contraindicated in those with cardiogenic shock, second- or third-degree AV block, severe SA node disease resulting in preexisting bradycardia unless an artificial pacemaker is present, and in those in whom bradycardia has caused syncope.
Nursing considerations
I.V. administration
Patient teaching
*Liquid contains alcohol. **May contain tartrazine. †Canada ‡Australia §U.K. OTCOver the counter
Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE-THREATENING