Fluoxetine and hyponatraemia--a potential hazard in the elderly.

AIMS

To review reports of the association between fluoxetine and hyponatraemia.

METHODS

Reports of hyponatraemia associated with fluoxetine received over a four-year period in the New Zealand Intensive Medicines Monitoring Programme have been examined and these and other case reports in the literature, discussed.

RESULTS

Seven patients, all women aged 68-88 years on fluoxetine 20 mg daily, developed hyponatraemia (serum sodium 114-128 mmol/L, five within 19 days of commencement of fluoxetine. The reported rate for women over 65 years was 8.5 per thousand. Withdrawal of fluoxetine was associated with recovery in all cases.

CONCLUSIONS

Fluoxetine is associated with a significant incidence of hyponatraemia in the elderly, especially during the first weeks of therapy. It is advisable to monitor electrolytes in older patients during this period.