New clinical trials have increased doubts about the efficiency of Merck and Schering-Plough's prized anti-cholesterol drug Vytorin and its ability to fight cardiovascular disease, according to medical data released here.
A group of distinguished cardiologists recommended taking high doses of statins to reduce bad cholesterol levels before prescribing only Vytorine or Zetia.
The clinical tests showed that Vytorin did not reverse arteriosclerosis, the hardening of the arteries, even if it did reduce cholesterol levels.
Vytorin produced no result, the study's chief author John Kastelein, of the Academic Medical Center in Amsterdam, told the 57th annual meeting of the American College of Cardiology (ACC) here Sunday.
Since it first went on sale in 2004, Vytorin has been prescribed to millions of Americans to aggressively reduce cholesterol levels. It costs four times as much as other generic anti-cholesterol drugs.
Vytorin combines Merck's Zocor (simivastatine), with Schering-Plough's Ezetimibe (Zetia), sold since 2002 to reduce cholesterol in the intestinal tract but not in the liver like statins do.
The target of the clinical trial in Europe with 720 patients that had genetic-linked high cholesterol levels was to determine whether Vytorin was more efficient than Zocor in reducing hardening of the arteries due to an atheromatous plaque.
Vytorin performed better at lowering blood cholesterol levels than Zocor alone, but neither drug was able to reduce atheromatous plaque in the patients' arteries.
Completed in 2006, the crucial results of the study were not disclosed by Merck and Schering until January 2008, after a series of newspaper articles reported noxiousness problems with Vytorin, which were later denied.
The clinical trial results published Sunday in the online edition of the New England Journal of Medicine questioned whether Zetia's method of reducing cholesterol levels provided greater benefits to patients.
In 2007, Merch and Schering-Plough began a separate clinical trial with 10,000 patients, increased to 18,000 on Friday, to show that Zetia's cholesterol-lowering effects resulted in fewer heart attacks and strokes than treatment with statins alone.
The results of that study will not be known until 2012.
On Sunday, the cardiology group named by the ACC president did not recommend any changes for the ongoing clinical trial.
One of its members, however, University of Yale medical professor Harlan Krumholz, was especially critical of Merck-Schering and the US Food and Drug Administration (FDA).
"We need to understand the effects of a new drug on people and rely on certain drug's effects may not tell the whole story," he said.
"We learned this lesson before, and it sems like we may be learning it again," Krumholz added, referring to the scandal with nonsteroidal anti-inflammatory drug Vioxx that Merck withdrew from he market in 2004 after it was linked to a few deaths.
Merck and Schering on Sunday explained the problem with the clinical trials by saying that the patients that took part in it had already been treated aggressively with statins, making any improvement difficult.
Sales of Vytorin and Zetia, bolstered by a major television advertisement blitz, netted some five billion dollars for the drug makers last year.
But after the results of the study became known in January, sales dropped by 10 percent and shares of Merck and Schering fell 30 percent.