[A case of hyponatremia associated with combination therapy of systemic chemotherapy and paroxetine].

A 65-year-old woman with relapsed non small cell lung cancer, who had no prior chemotherapy, was admitted to our hospital. She was initially treated with paroxetine, a selective serotonin-reuptake inhibitor antidepressant, and received cisplatin-based chemotherapy three days after the initiation of the paroxetine. She developed hyponatremia on day 5 after the start of chemotherapy. Based on the laboratory examinations, the syndrome of inappropriate secretion of antiduretic hormone was suggested. Her plasma sodium concentration returned to normal after paroxetine withdrawal and appropriate fluid restriction. Cisplatin-based chemotherapies were subsequently continued without paroxetine and there were no further episodes of electrolyte disturbance. Paroxetine has been used widely for treatment of depressed patients with malignancies. However, careful monitoring of plasma sodium is needed following cisplatin-based chemotherapy in patients taking paroxetine.