Samsca Side Effects Linked to Potential Liver Injury Risk: FDA

Federal health regulators are warning that the hyponatremia drug Samsca may cause severe and potentially fatal liver damage.

According to a safety communication issued by the FDA on January 25, at least three patients involved in a clinical trial suffered liver damage after taking Samsca.

Although all recovered from the liver injury once they stopped taking the drug, side effects of Samsca could cause other users to suffer permanent injury or death.

Samsca (tolvaptan) is an Otsuka Pharmaceutical Co. drug approved for the treatment of clinically significant hypervolemic and euvolemic hyponatremia, a condition that results in critically low salt levels. It belongs to a family of drugs known as selective vasopressin V2-receptor antagonists.

According to the FDA warning, 1,400 human test subjects were undergoing a 3-year, placebo-controlled, double blind clinical trial to test Samsca as a possible treatment for Autosomal Dominant Polycystic Kidney Disease (ADPKD). During the trial, patients were given much higher doses of Samsca than they would have been for the treatment of hyponatremia. Three of the patients developed significant increases in serum alanine aminotransferase (ALT) with concomitant, clinically significant increases in serum total bilirubin; typically a sign of liver injury.

They were taken off the medication and their conditions improved. An external panel of experts concluded that the liver damage was most likely caused by Samsca.

In a Dear Healthcare Provider letter (PDF) letter sent out by Otsuka on January 22, the drug maker warned that doctors should be aware that liver injury from Samsca could be permanent and fatal, despite the recovery of the three patients.

“The ability to recover from liver injury may be impaired in patients with hyponatremia in the setting of underlying liver disease, including cirrhosis,” the letter states.

The FDA now believes that Samsca can cause serious and fatal liver injury. The agency warned doctors to look for signs of liver injury among patients taking Samsca. Symptoms of a Samsca liver injury can include:

• Anorexia
• Dark Urine
• Fatigue
• Jaundice
• Right Upper Abdominal Discomfort

Doctors who have patients on Samsca who are suspected of having liver damage should be taken off the drug immediately and only placed back on it if it can be definitively established that the liver injury was not caused by Samsca.

The FDA asks doctors and patients who experience Samsca liver injury to file a report with the MedWatch Safety Information and Adverse Event Reporting Program.