CHICAGO (Reuters) - A disappointing study of the heart drug Vytorin has led some doctors to reconsider what makes statin drugs so effective at fighting heart disease.
Merck and Schering-Plough are already feeling the effects of last week’s long-awaited study, which found that the $5 billion combination drug Vytorin did no better than one of its components — a statin drug called Zocor — at preventing fatty build-up in high-risk patients.
Shares of both companies have fallen sharply. New prescriptions of Vytorin have plunged, while prescriptions for Pfizer Inc’s popular statin Lipitor have risen.
The companies have been accused by activists and politicians of dragging their feet in announcing the results, and on Tuesday they pulled popular television ads for Vytorin.
What has rattled some doctors about the Vytorin study, dubbed Enhance, is that Vytorin did not appear to reduce artery-clogging plaque better than a statin even though it lowered cholesterol.
It lowered levels of low-density lipoprotein, so-called LDL or “bad” cholesterol, better than the statin alone. It cut LDL by 58 percent compared with a 41 percent reduction for those who took Zocor, known generically as simvastatin.
“That gives us cause for pause in the sense that all forms of cholesterol lowering may not be equally effective at preventing hardening of the arteries,” said Dr. Samuel Dudley of the University of Illinois Medical Center at Chicago.
“My intuition is telling me we are missing something,” Dudley said in a telephone interview. “It is probably not so simple as just lowering bad cholesterol and raising good cholesterol. It probably also matters how you do it.”
Millions of people take statins to lower cholesterol in the hope of preventing heart attack or stroke. The drugs work by cutting the amount of cholesterol made by the liver. Statins also can raise high-density lipoprotein, or HDL — the so-called “good” cholesterol — and they reduce inflammation.
Vytorin fights cholesterol in two ways. It combines the statin Zocor with the drug Zetia, which blocks cholesterol from being absorbed in the gut.
“What we don’t know is whether or not reducing cholesterol that way is associated with benefit for the patient,” said Dr. Harlan Krumholz, cardiology professor at Yale University.
“There is reason to believe it might. We do think maybe the main way that drugs like statins may be beneficial is their effect on lowering cholesterol. But we don’t know for sure.”
Krumholz said the Enhance study was not designed to prove what patients really need to know: whether Vytorin can prevent heart attacks and strokes. Those studies are under way.
But until those results are in, Krumholz said Vytorin should only be used as a second choice.
Dr. Andrew Feiring, a cardiologist at Columbia-St Mary’s Medical Center in Milwaukee, said the Enhance study has refocused attention on choosing therapies that are proven to reduce heart attacks and strokes.
And he said Merck and Schering-Plough’s decision to voluntarily pull their TV advertising makes sense until the company can resolve these scientific questions.
Editing by Maggie Fox and Eric Beech