Study Casts Doubts on Vytorin, Zetia
Cholesterol-Lowering Drugs May Not Reduce Plaque Buildup
WebMD News Archive
Jan. 15, 2008 -- Disappointing results from a long-awaited trial of the
best-selling cholesterol drug Vytorin drew mixed reactions
from some of the nation's leading cardiologists.
Vytorin, which combines the unique cholesterol drug Zetia with the traditional
statin drug simvastatin, was found to be no better than simvastatin alone for
reducing plaque buildup in the carotid arteries. The carotid arteries run
through both sides of the neck to the brain.
In fact, patients taking Vytorin actually had slightly more plaque buildup
during the trial than those taking simvastatin alone.
The findings were revealed Monday morning in a news release issued by the
drug companies Merck and Schering-Plough, which jointly market Vytorin and
In an interview with WebMD, cardiologist Steven E. Nissen, MD, called the
results "a stunning reversal for Zetia and Vytorin."
Nissen is chairman of the department of cardiovascular medicine at the
Cleveland Clinic, and is a past president of the American College of
"Zetia works only by blocking the absorption of cholesterol, but it has
not been shown to produce any health benefits," he says. "I have been
skeptical of these drugs from the beginning because I wasn't sure that Zetia's
mechanism of cholesterol lowering would produce the same benefits that we see
But P.K. Shah, MD, who directs the cardiology department at Cedars-Sinai
Medical Center in Los Angeles, tells WebMD that the trial results do not mean
that the millions of patients taking Zetia or Vytorin derive no benefit from
"I don't think this is a call for a moratorium on Zetia. That would be
overreaching," he says. "This was a small study and it is not the last
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Congressional Probe of Zetia, Vytorin Research
The release of the results came just weeks after the announcement of a
congressional investigation into the drug companies' actions surrounding the
study, which ended nearly two years ago.
In addition to delays in presenting the results, critics had accused the
companies of attempting to change the endpoints of the study, known as the
ENHANCE trial, in an effort to present the results in a more favorable
In a news release issued Monday afternoon, the two congressmen leading the
investigation had harsh words for Merck and Schering-Plough.
"Today's announcement that the ENHANCE study failed to find any positive
benefit from the addition of Zetia to a common, inexpensive, generic therapy
raised concerns that attempts were made to mask the minimal value of this new
drug," Committee on Energy and Commerce chairman John Dingell, D-Mich.,
Rep. Bart Stupak, D-Mich., who chairs the oversight subcommittee, said the
investigation will continue.
"In light of today's results, which were released nearly two years after
the ENHANCE trial ended, it is easy to conclude that Merck and Schering-Plough
intentionally sought to delay the release of this data," Stupak said.
"It's currently unclear whether these companies knew that adding a new
expensive drug accomplished nothing more than an established cheaper generic.
But it is clear that our investigation is far from over."