Jan. 25, 2017 -- Newer drugs to cure hepatitis C may put patients at risk for liver failure and other severe side effects, according to a new study from a U.S. nonprofit group that examines drug safety.
The study by the Institute for Safe Medication Practices is based on an analysis of U.S. Food and Drug Administration data and reports from doctors worldwide on adverse events possibly caused by the nine widely used antiviral drugs, The New York Times reported.
Two of the drugs, Sovaldi and Harvoni, are so-called blockbusters made by Gilead Sciences and priced at $1,000 a pill. Sovaldi was approved in 2013 and Harvoni in 2014. These and other antiviral drugs can cure hepatitis C in 12 weeks in many patients.
The number of adverse events is fairly small and the findings are not conclusive, but experts say the study published online Wednesday should serve as a warning, The Times reported.
The study said about 250,000 people worldwide took the newer drugs in 2015. Among patients treated with the drugs during the year ending June 30, 2016, 524 suffered liver failure, and 165 of those patients died. Another 1,058 patients experienced severe liver injury. The study also said the drugs appeared ineffective in 761 patients.
But there is no proof the drugs were to blame for the patients' liver problems, The Times reported.
Gilead's drugs were approved for people with severe liver disease from hepatitis C and some will inevitably suffer liver failure despite the best treatment, according to company spokesman Mark Snyder.
"We closely assess both post-marketing safety reports as well as safety data from our clinical trials on an ongoing basis and have found no suggestion of a causal relationship between Sovaldi or Harvoni and liver failure," he wrote in an email, The Times reported.
There have been other accounts of problems with the new drugs and further investigation is required, said Dr. Robert S. Brown, director of the Center for Liver Disease and Transplantation at NewYork-Presbyterian/Columbia. He was not involved in the study.
"We don't want people to ignore it and lead to risks to patients," he told The Times. "We don't want people to overreact and not treat patients who should be treated. A lot of doctors are unclear about it, and if doctors are unclear, patients are, too."
He said problems with the new drugs might be due to incorrect prescribing by some doctors, giving the drugs to patients with liver function too poor to tolerate or benefit from the medicines.