Amiodarone use in patients with documented allergy to iodine-containing compounds

The popularity of amiodarone has grown due to its effectiveness in converting arrhythmia and its formulation availability. Formulations of the drug also contain iodine; the iodine content is 75 mg in a 200-mg tablet of amiodarone and 18.7 mg/ml in the intravenous solution. Approximately 10% of the iodine content of oral amiodarone is released into the circulatory system and may increase the risks of hypersensitivity reactions in iodine-sensitive patients. Documented allergies to contrast media or shellfish should not imply that a patient is allergic to iodine. Reactions to contrast media are likely due to the high osmolar or ionic content of the dye. The primary allergen in shellfish that stimulates allergic reactions is tropomyosin. Although amiodarone can cause thyroid disorders due to the high iodine load delivered to the body with each dose, no known association exists between amiodarone and reactions to contrast media or shellfish. Three patients whose medical charts listed an allergy to iodine were administered amiodarone for chemical cardioversion of arrhythmia to normal sinus rhythm. No anaphylactic or anaphylactoid reactions were observed in any of the patients during oral or intravenous amiodarone administration. In patients with true iodine hypersensitivity, however, the potential for such reactions exists.