Syndrome of inappropriate antidiuretic hormone secretion induced by amiodarone therapy

We describe a case of amiodarone induced hyponatremia consistent with the syndrome of inappropriate antidiuretic hormone (SIADH) that developed during amiodarone loading, similar to three prior reports. The hyponatremia improved after a lower maintenance dose was initiated. This episode was reported online to the FDA (http://www.fda.gov/medwatch), and future amiodarone labeling will include SIADH as a potential side effect (personal communication, Wyeth Medical Science). Clinicians should be aware of this rare but serious complication, especially in light of the neurological effect of profound hyponatremia. Amiodarone induced SIADH may develop during the loading phase, and may respond to dose reduction without termination of drug.