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AHA: Tolvaptan Can Relieve Hyponatremia

Side effects include dry mouth, increased thirst and increased urination

WEDNESDAY, Nov. 15 (HealthDay News) -- The vasopressin V2-receptor antagonist tolvaptan is effective in relieving hyponatremia, according to the results of a study published online Nov. 14 in the New England Journal of Medicine. The findings were reported at the American Heart Association's Scientific Sessions in Chicago.

Robert W. Schrier, M.D., of the University of Colorado Health Sciences Center in Denver, and colleagues randomly assigned 448 patients with hyponatremia (serum sodium less than 135 mmol per liter) to placebo or 15-mg oral tolvaptan daily. The tolvaptan dose was increased to 30-mg or 60-mg daily as needed based on serum sodium concentration. Changes in the serum sodium average daily area under the curve were monitored from baseline to day 4 and baseline to day 30.

There was a significant increase in serum sodium at both day 4 and day 30 in patients taking tolvaptan, although hyponatremia returned once tolvaptan was discontinued after day 30. Patients taking tolvaptan reported increased thirst, increased urination and dry mouth, the report indicates.

"The study is encouraging in terms of the efficacy of tolvaptan as a V2-receptor antagonist and its use, at least during a limited period, in the outpatient setting," Richard M. Hays, M.D., from the Albert Einstein College of Medicine, Bronx, New York, writes in an accompanying editorial. But, he adds, "careful oversight of the use of this agent is required."

The study was supported by the Otsuka Maryland Research Institute.

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