NYT: Merck, Schering-Plough may be concealing Zetia risks

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Are Merck, Schering-Plough hiding clinical trial results? Source: Innovation Australia

New evidence shows that Merck and Schering-Plough have conducted several studies of their popular cholesterol medicine Zetia, raising questions about its risks to the liver, but the companies have never published those results, according to The New York Times.

The NY Times reported that partial results of the studies have appeared on the FDA’s website, raising questions about whether Zetia can cause liver damage when used long term with statins.

The unpublished studies, conducted from 2000 to 2003 according to the FDA documents, were not listed on the industry websites where companies are supposed to register the results of all drug trials that were ongoing after October 2002, the NY Times reported.

The discovery of the new unpublished research comes as Merck and Schering are already under criticism for not yet releasing data from Zetia’s ENHANCE study, that was completed early last year. Merck, which markets cholesterol-lowering Vytorin in a joint effort with Schering-Plough, decided to delay the results of the long-awaited ENHANCE study, until rumors begin in the medical community word that the parameters of the study were to be changed. The results of the study will have a tremendous impact on both pharmaceutical companies. Vytorin is a single pill that combines the companies’ Zetia with simvastatin, the active ingredient in Merck’s Zocor statin.  

According to the Wall Street Journal, if ENHANCE produces a favorable result for Vytorin, it would strengthen the case for Vytorin in high-risk heart patients over the generic form of Zocor alone, but a negative finding could encourage insurers to reduce coverage for the more expensive medicine.

The ENHANCE data also may contain important information about Zetia’s liver risks, the NY Times reported. At least some patients were dropped from the ENHANCE study after testing revealed that they had elevated liver enzymes, a Schering-Plough spokesman confirmed to the NY Times.

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, according to medical professionals.

The U.S. product label for Zetia contains only mild warnings about the drug’s potential for liver damage, but in Australia and Canada, regulators have placed more stringent warnings on the drug.

Also, the NY Times reported that despite its widespread use, there is no evidence proving that Zetia can reduce heart attacks and strokes, while there is extensive medical evidence showing that Lipitor and other statins provide such protection.

As a result of the recent questions that have arisen, Reps. John Dingell, D-Mich., and Bart Stupak, D-Mich., asked Merck and Schering-Plough to explain their delay in releasing data from a clinical trial of Vytorin, according to the Washington Drug Letter.

Merck and Schering have said that a full report on the trial, including the number of patients who had liver problems, will be made available until March due to pressure from Congress and the cardiology community.