Hypokalemia With Venlafaxine

Letter to the Editor

Sir: The antidepressant venlafaxine has the desirable quality of being selective for both serotonin and norepinephrine reuptake inhibition. Venlafaxine-induced hyponatremia has been reported, and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) has been proposed as the possible mechanism. Serotonin has been observed to increase concentrations of vasopressin in rats, and an increased level of vasopressin is the underlying cause of SIADH.