Syndrome of inappropriate antidiuretic hormone with imipramine

Among the various medications that have been associated with the development of syndrome of inappropriate antidiuretic hormone secretion (SIADH) are the tricyclic antidepressants. A 69-year-old man admitted for treatment of a depressive disorder that had not responded to trazodone was prescribed imipramine. Twenty-two days after initiation of therapy, the patient developed hyponatremia. The patient also had depressed serum osmolality and elevated urine sodium concentrations consistent with SIADH. With the discontinuation of imipramine, fluid restriction, and several doses of furosemide, normal serum sodium concentrations were attained. As antidepressant therapy was indicated, doxepin was selected. The patient maintained normal electrolyte values and water balance over the next two months of follow-up. No reports of doxepin-related SIADH were found in the literature; therefore, this agent may be considered as an alternative therapy in patients developing SIADH during antidepressant drug therapy.