LETTER
Reevaluation of Amiodarone
Saeed Ahmad, MD
15 November 1995 | Volume 123 Issue 10 | Page 809
TO THE EDITOR:
I read with interest the recent article by Podrid [1]. Some important issues arising from this review warrant discussion. First, the mechanism of the observed toxicity may result from the accumulation of substances such as iodine or amiodarone, given that 37.5% of the weight of the drug is iodine. It has been postulated that because both amiodarone and angiographic dyes contain iodine, the combination may cause an additive toxic effect and subsequent death after pulmonary angiography [2]. In addition, Sadek and colleagues [3] recently described amiodarone-induced epididymitis and reviewed 12 additional cases in the literature.
Reports of endocrine testicular dysfunction have been published, including one in which 44 men had higher serum concentrations of follicle-stimulating hormone and luteinizing hormone. Serum total and unbound testosterone concentrations correlated inversely with the cumulative amiodarone dose, culminating in a higher incidence of atrophic testes [4].
Dr. Podrid states that warfarin, digoxin, other antiarrhythmic drugs, and anesthetic agents have shown drug interactions with amiodarone. Phenytoin and lithium, two important and widely used agents, should be added to that list. Amiodarone inhibits the metabolism of phenytoin, thereby causing phenytoin toxicity. The phenytoin dose should thus be halved [5].
Thyroid disorders are much more common when lithium and amiodarone are used concomitantly. Clinicians should also take note of patients who are receiving ophthalmic ß-blocker eye drops concomitantly with amiodarone. Amiodarone increases serum cholesterol concentrations, an effect that occurs independently of changes in thyroid function.
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Author and Article Information
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Cardio-Diagnostic Clinique; Fairmont, WV 26554
1. Podrid PJ. Amiodarone: reevaluation of an old drug. Ann Intern Med. 1995; 122:689-700.
2. Malden E, Gutierrez F. Acute fatality following pulmonary angiography in a patient on an amiodarone regimen—a case report. Angiology. 1993; 44:152-5.
3. Sadek I, Biron P, Kus T. Amiodarone-induced epididymitis: report of a new case and literature review of 12 cases. Can J Cardiol. 1993; 9:833-6.
4. Dobs A, Sarma P, Guarnieri T, Griffith L. Testicular dysfunction with amiodarone use. J Am Coll Cardiol. 1991; 18:1328-32.
5. Gore J, Haffajee C, Alpert J. Interaction of amiodarone and diphenyl-hydantoin. Am J Cardiol. 1984; 54:1145-56.
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