Merck and Schering-Plough conducted several studies of their cholesterol treatment Zetia that raise questions about its risks to the liver but never published the results to those studies, The New York Times reports.
Results of the studies alluded to on the FDA's website raise questions about whether Zetia can cause liver damage when used long-term with other statins.
The discovery of the unpublished research comes as Merck and Schering-Plough are under criticism for not releasing data from a Zetia study completed last year called Enhance, which may also contain information about the drug's liver risks. A full report on that trial is not expected until March.
Zetia is on track to earn $5 billion in sales this year.
Dr. Robert J. Spiegel, chief medical officer of the Schering-Plough Research Institute, said in The Times report that the companies had not considered the studies scientifically important enough to publish their findings. Some may eventually be published, he said.
“We're pretty comfortable that people don't have trouble tolerating Zetia,” he said.
But some critics argue that by failing to disclose promptly all their research, Merck and Schering-Plough may be leaving the public with a misleadingly favorable view of Zetia's safety and benefits.
“You don't want to have data missing,” Dr. Bruce Psaty, a professor of medicine and epidemiology at the University of Washington told The Times. “When there have been adverse effects, when the benefits don't look impressive, those are the trials that historically don't make it to press.”