Reporting on Adverse Clinical Events

An 80-year-old Caucasian male patient developed worsening confusion, irritability, delusions, persecution, and slurred speech approximately 3 weeks after starting melatonin (1 mg daily). Concurrent medications included enalapril, atenolol, chlortalidone, gliclazide, esomeprazole, atorvastatin, dutasteride, and silodosin. No other herbal-type medications were ingested. On admission, abnormal laboratory tests included a decreased serum sodium level (110 mEq/L). Other laboratory levels were in normal. Hematological and urinary screenings for infectious etiologies were negative. Based on these results, both melatonin and chlortalidone were discontinued. Treatment was initiated with hypertonic saline (3%), haloperidol, and sodium valproate. Symptoms gradually resolved over several days and was associated with normalization of serum sodium levels. By the fourth day serum sodium levels were within normal levels. At a 2-month follow-up assessment, chlorthalidone was reinitiated with no further events noted; serum sodium and other electrolytes were within normal limits. Rechallenge with melatonin was not performed. The patient was advised to not restart melatonin therapy. Based on the results of this case report, the author concluded that this patient experienced syndrome of inappropriate antidiuretic hormone related to melatonin therapy based on the temporal relationship between the administration of the product and the onset of symptoms. Melatonin [Melatonin] Famularo G (G Famularo, San Camillo Hospital, Rome, Italy) Syndrome of inappropriate antidiuretic hormone secretion in a patient treated with melatonin. Ann Pharmacother 55:131-132 (Jan) 2021