The discovery of the unpublished research comes as Merck and Schering are already under criticism for not yet releasing data from an important Zetia study, called Enhance, that they completed early last year, the Times notes. The Enhance data may also contain important info about Zetiaâ€™s liver risks. At least some patients were dropped from the Enhance study after testing revealed that they had elevated liver enzymes, a Schering-Plough spokesman confirmed this week. But a full report on that trial, including the number of patients who had liver problems, will not be available until March.
Doctors say that by failing to disclose promptly all their research, Merck and Schering-Plough may be leaving the public with a misleadingly favorable view of Zetiaâ€™s safety and benefits. â€œYou donâ€™t want to have data missing,â€ Bruce Psaty, a professor of medicine and epidemiology at the University of Washington, tells the paper. â€œWhen there have been adverse effects, when the benefits donâ€™t look impressive, those are the trials that historically donâ€™t make it to press.â€
Before the drug was approved in 2002, one FDA reviewer said it should not be cleared for use with statins because the combo had caused liver damage in animals. And in the last two years, scattered case reports of severe liver damage in patients taking Zetia in combination with statins have appeared in medical journals. In the US, the product label for Zetia contains only mild warnings about the drugâ€™s potential for liver damage. But since 2005 in Australia and Canada, regulators have issued a series of warnings about Zetiaâ€™s potential to cause hepatitis, pancreatitis and depression.
â€œWe keep telling people we want to practice evidence-based medicine, and what we keep finding out is that much of the evidence is obscured,â€ Harlan Krumholz, a cardiologist at Yale, tells the paper. â€œThere is important evidence, but itâ€™s not in public view. Itâ€™s hidden from investigators.â€
UPDATE: Here is a Public Citizen newsletter from December 2004 warning against the use of Zetia.