Intravenous
amiodarone was approved in 1995 for the treatment of malignant and resistant ventricular
arrhythmia. Although it is an "old
drug," much has been learned recently about this complex
drug and its application in a variety of
cardiac arrhythmias. The objectives of this review were to summarize what is known about intravenous
amiodarone, including its pharmacologic and electrophysiologic effects, to review its efficacy for the treatment of patients with highly malignant ventricular
arrhythmia and to provide specific information about its clinical use for this and other indications. The studies that were reviewed were selected on the basis of time published (from 1983 to 1995) and the completeness of information provided regarding patient clinical characteristics,
drug dosing and methods of evaluation, efficacy analyses, long-term follow-up and complications. The full data from the three controlled trials that formed the basis of the
drug's approval are contained in published reports that were also extensively reviewed. Intravenous
amiodarone has demonstrable efficacy for the treatment of frequently recurrent destabilizing
ventricular tachycardia and
ventricular fibrillation, with suppression rates of 63% to 91% in uncontrolled trials. The three pivotal trials confirmed these findings and demonstrated a dose-response relation, with at least comparable efficacy to
bretylium, a
drug with a similar indication. The safety profile has also been well described; cardiovascular adverse effects are the most frequent, especially
hypotension. Intravenous
amiodarone is a useful addition to the drugs available for the treatment of patients with very severe ventricular
arrhythmia. Its use in patients with other rhythm disorders appears promising, but final recommendations must await development of definitive data from ongoing clinical trials.