What do we know about Vytorin?

It looks like Merck and Schering-Plough failed to publish several nasty studies that raise questions about the safety of their new cholesterol drug, Vytorin. Zetia, one component of Vytorin, causes liver damage, according to a New York Times report.

The drug makers are already under scrutiny for delays in publicizing the results of an important trial called Enhance of Vytorin, a combination of the cholesterol-fighters Zetia and Zocor.

The safety data at issue now were from trials conducted between 2000 and 2003 that were designed to assess Zetia’s long term safety. Most of the published studies on Zetia have been 12 weeks long, probably too short for liver toxicity to show up. The unpublished trials were at least a year long.

Data from the Enhance study of Vytorin show that at least some patients dropped out because of elevated liver enzymes, but the full results won’t be revealed until March.

There have been questions by the FDA and in case reports in medical journals, about whether the combination of Zetia with statins heightens the risk of liver damage.

The discovery of these unpublished data raises questions about the accuracy of information on Zetia. Schering-Plough didn’t consider these data “scientifically important enough” to publish, a company executive told the NYT.

“We keep telling people we want to practice evidence-based medicine, and what we keep finding out is that much of the evidence is obscured,” said Harlan Krumholz, a cardiologist at Yale, told the NYT.