Venlafaxine hyponatraemia: incidence, mechanism and management.
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Roxanas M, Hibbert E, Field M
Venlafaxine hyponatraemia: incidence, mechanism and management.
Aust N Z J Psychiatry. 2007 May;41(5):411-8. doi: 10.1080/00048670701261202.
- PubMed ID
- 17464733 [ View in PubMed]
- Abstract
OBJECTIVE: This prospective study was performed on patients aged >65 years commencing therapy with venlafaxine, in order to determine the incidence of hyponatraemia induced by the drug, to investigate the underlying pathophysiological mechanisms, and to evaluate a simple approach to management of this condition. METHOD: All patients aged >65 years seen by one author (MR) from all referral sources were entered into the study. Baseline biochemical tests were ordered, and if hyponatraemia developed (plasma Na <130 mmol L(-1)) additional tests were performed to ascertain the mechanism, while the patient continued on venlafaxine and fluid restriction was instituted. RESULTS: A total of 58 patients were seen, of whom 10 developed hyponatraemia, giving an incidence of 17.2%. Of these 10 patients, five were excluded from prolonged observation because of either severe medical illness, side-effects from the antidepressant or being lost to follow up. When hyponatraemia developed, it invariably did so within a few days of starting venlafaxine, and was associated with non-suppression of antidiuretic hormone in the face of a low serum osmolality. Fluid restriction (800 mL day(-1)) was effective in raising the plasma sodium to the normal range within 2 weeks, after which the fluid restriction could be relaxed without relapse occurring. These patients remained well for the follow-up period of up to 6 months. CONCLUSIONS: Patients >65 years of age should have their electrolytes measured 3-5 days after starting venlafaxine therapy. If hyponatraemia develops, it can be managed with modest fluid restriction without discontinuing drug treatment, subject to close continued clinical observation and biochemical monitoring.