Hyponatremia in relation to treatment with antidepressants: a survey of reports in the World Health Organization data base for spontaneous reporting of adverse drug reactions.

To determine the risk factors associated with the development of hyponatremia during treatment with antidepressant drugs, we conducted a retrospective register study of the World Health Organization (WHO) data base for spontaneous reporting of adverse drug reactions. From the start of the WHO Collaborating Centre for International Drug Monitoring in 1968 until the end of 1993, 668 reports of antidepressant-associated hyponatremia disorders were submitted. Seventy-eight percent of them concerned women, compared with 69% for all other adverse drug reactions with antidepressants (p < 0.0005). The mean age of all patients was 66.6 years, compared with 48.6 years for the other adverse drug reactions (p < 0.0001). In 51.3% of the patients the reaction occurred within the first 2 weeks of treatment. Significantly more cases occurred during the summer than during the other seasons (p < 0.02). The risk for hyponatremia during treatment with antidepressants seems to be highest in women, in the elderly, during the summer, and during the first weeks of treatment.