(Adds background, comments from FDA)
Aug 28 (Reuters) - The U.S. Food and Drug Administration said on Wednesday it had identified 63 cases of worsening liver function in certain patients taking hepatitis C medicines made by drugmakers Merck & Co Inc, Gilead Sciences and AbbVie Inc.
The agency said that while the treatments are safe and effective, it had received reports of rare but serious instances of worsening liver function or failure when they were taken by patients with advanced liver disease. (https://reut.rs/2Zu2xoN)
Hepatitis C, a liver disease caused by a blood-borne virus, can be cured with antiviral medicines. Given this, the market for such drugs in the United States has been steadily shrinking as the impact of the disease lessens. If left untreated, the virus can cause cirrhosis or liver cancer.
The World Health Organization estimates that 71 million people suffer from chronic hepatitis C virus infection globally.
The FDA said it had received reports from submissions to the agency as well as other sources, which helped identify cases of worsening liver function, including some cases of liver failure or death in patients that used AbbVie's Mavyret, Merck's Zepatier and Gilead's Vosevi.
In most patients, symptoms resolved or liver function improved after stopping the medicine, the agency said.
These medicines are not indicated for use in patients with moderate to severe liver impairment, but are safe and effective in patients with no or mild liver impairment, the FDA said.
The companies did not immediately respond to Reuters requests for comment. (Reporting by Tamara Mathias in Bengaluru; Editing by Shailesh Kuber)