Oral Tolvaptan (Samsca) Is Safe and Effective Treatment for Chronic Hyponatremia

Vasopressin antagonists increase the serum sodium concentration in patients who have euvolemia and hypervolemia with hyponatremia in the short term (30 days), but their safety and efficacy with longer term administration is unknown.

In a study, 111 patients with hyponatremia received oral tolvaptan (Samsca) for 700 days.

The most common adverse effects attributed to tolvaptan were pollakiuria, thirst, fatigue, dry mouth, polydipsia, and polyuria.

Mean serum sodium increased from 130.8 mmol/L at baseline to greater than 135 mmol/L throughout the observation period.

Responses were comparable between patients with euvolemia and those with heart failure but more modest in patients with cirrhosis.

In conclusion, prolonged administration of tolvaptan maintains an increased serum sodium with an acceptable margin of safety.

Samsca (tolvaptan) Black Box Warnings

Appropriate Use

Initiate and re-initiate tx only in hospital with serum Na monitoring.

Monitor Serum Sodium

Osmotic demyelination may occur w/ rapid correction of hyponatremia (faster than 12 mEq/L/24h), resulting in dysarthria, mutism, dysphagia, lethargy, affective changes, spastic quadriparesis, seizures, coma, and death; slower rates of correction advised in pts w/ severe malnutrition, alcoholism or advanced liver disease.

Cost comparison of conivaptan (Vaprisol) versus tolvaptan (Samsca)

Conivaptan is administered IV only, the average cost per day is $573.

Tolvaptan is administered PO only, the average cost per day is $300.


Oral Tolvaptan Is Safe and Effective in Chronic Hyponatremia. Journal of the American Society of Nephrology, 2010.
Lowest sodium I have ever seen http://goo.gl/QgJmf
Image source: Tolvaptan, Wikipedia, public domain.

Comments from Twitter and Facebook:

@kidney_boy: tolvaptan is safe for the patient but not their wallet at $250 per pill!

Neil Mehta: "It costs a king's ransom to keep the sodium level up! Maybe we should just say "Let them eat Salt"!"

Updated: 10/28/2010

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