Canadian health officials warn that side effects of Promacta, which is used to treat patients with disorders resulting in a low blood platelet count, may increase the risk of potentially fatal liver toxicity.
In a statement issued on August 25, Health Canada warned about the risk of severe hepatoxicity from Promacta, which is sold in Canada under the brand name Revolade. Canada is requiring new label warning be added to the drug’s label a result of the risk of liver injury.
Promacta (eltrombopag) is a Novartis drug approved in the United States in 2008, for treatment of patients with low blood platelet counts caused by chronic immune thrombocytopenia and hepatitis C virus infection. In patients with HCV it is used to prepare them for interferon-based therapy.
“Revolade administration can cause severe hepatoxicity and potentially fatal liver injury,” the Canadian health agency warns. “Cases of severe drug-induced liver injury with Revolade have been reported in patients during clinical trials and post-marketing.”
Health Canada is advising healthcare professionals to measure liver functions every two weeks during the dose adjustment phase, and then switching to monthly testing after a stable dose has been established. Promacta should be discontinued if serum alanine aminotransferase (ALT) levels are more than three times the upper limit of normal in patients with normal liver function, or if they increase or are greater than three times the baseline or greater than five times the upper normal limit in patients who already had elevated ALT levels before treatment.
The warnings in Canada came following an analysis of several different clinical trials. That analysis found two cases of liver injury among adults with chornic immunme thrombocytopenia, three cases among patients treated for off-label purposes, and estimates that Promacta-induced liver injury occurs in 1% of all patients treated with the drug for chronic hepatitis C virus infections.
In the U.S. the drug carries a boxed warning that it can cause hepatic decompensation in patients with chronic hepatitis C. There is also a note in the “Warnings and Precautions” section which simply reads: “Hepatoxicity: Monitor liver function before and during therapy.”