In December 2007, clinical study evidence was released proving that Merck and Schering-Plough never published full results of studies of Zetia, their popular cholesterol medicine, which raised questions about Zetia’s link to liver damage. While partial results of the studies were released, questions about long-term use of Zetia with statins, and consequent effects on the liver, were never answered.

The discovery comes as Merck and Schering face critical attacks for not yet releasing data from another Zetia study, called Enhance, which was completed in 2006.

Most patients who use Zetia also use other cholesterol drugs, called statins, such as Lipitor, Crestor, or Zocor.

Doctors allege that the failure of these companies to release all information could be perceived as misleading the public into a favorable perception of Zetia. But the companies counter they did not consider the studies scientifically significant enough to publish.

Before Zetia was approved by the Food and Drug Administration (FDA) in 2002, one reviewer said it should not be approved for use with statins because the combination caused liver damage in animals. In the last two years, reports have surfaced of Zetia patients suffering from severe liver damage.

“We keep telling people that we want to practice evidence-based medicine, and what we keep finding out is that much of the evidence is obscured,” said Dr. Harlan Krumholz. “There is important evidence, but it’s not in public view. It’s hidden from investigators.”

Another doctor, Beatrice A. Golomb from the University of California, said the purpose of cholesterol-lowering drugs is to reduce the number of deaths and heart attacks in patients. Without data to prove that Zetia accomplishes this, she said, doctors cannot be sure they are helping patients when they prescribe the drug.

Source: Alex Berenson, “Data about Zetia risks was not fully revealed,” New York Times, December 21, 2007.