(NaturalNews) The long-awaited release of the results from a clinical trial of Merck and Schering-Plough's cholesterol drug Vytorin has renewed allegations that the companies deliberately delayed in making the study data public.
"It is easy to conclude that Merck and Schering-Plough intentionally sought to delay the release of this data," said U.S. Rep. Bart Stupak of Michigan, who is involved in a Congressional inquiry into the study.
The drug trial, called ENHANCE, compared the effects of cholesterol drug Vytorin with the effects of Zocor alone.
Vytorin is a mix of a mix of Merck and Schering's cholesterol drug Zetia (ezetimibe) and the now-generic Zocor (simvastatin), originally marketed exclusively by Merck. Because Zetia works differently than the older of cholesterol drugs known as statins, which include Zocor, Lipitor and Crestor, the two kinds of drugs are often prescribed in tandem to create a greater increase in cholesterol levels.
Zetia interferes with the intestine's ability to absorb cholesterol, while statins increase the rate at which LDL ("bad") cholesterol is removed from the blood.
In ENHANCE, researchers tested both Vytorin and Zocor alone on 720 patients with a genetic disease known as heterozygous familial hypercholesterolemia, which causes dangerously high cholesterol levels and an elevated risk of heart attacks, stroke and death. In addition to measuring blood cholesterol levels, researchers used ultrasound images of arteries in the participants' thighs and necks to compare how well the drugs reduced plaque formation.
Initiated in 2002, ENHANCE was completed two years later, and the companies had analyzed all of the data by April 2006. Yet Merck and Schering did not publish or otherwise release the results, leading to speculation that Vytorin had failed the test. In spite of expectations by cardiologists, the companies failed to present the results at conferences in November 2006, March 2007 and November 2007.
As questions continued to mount as to the reason for the delay, the companies announced that they were having problems analyzing the data. Contrary to standard procedure, no committee had been set up ahead of time for dealing with problems that might arise in the ENHANCE study. So Merck and Schering-Plough announced on November 16 that they had put together an expert panel to help them decide how to analyze the ENHANCE data. On November 19, they announced a decision to only analyze neck arteries, and not both neck and thigh as had originally been planned.
The announcement drew fierce and instant criticism.
"You just don't change a primary endpoint in a major important trial partway through," said drug safety expert Bruce Psaty, from the University of Washington.
Further criticism arose from the fact that the lead ENHANCE researcher, John J. P. Kastelein of the University of Amsterdam, was not present when Merck and Schering decided to change the study's goals.
The drug companies backtracked on December 11, saying they would stick with the original procedure. But the antics attracted the attention of the House Committee on Energy and Commerce, which announced on the same day that it would be launching an investigation into "the delay in releasing the results of the study, the timing of ENHANCE trial registration and the apparent manipulation of trial data."
The results were finally released on January 14, confirming what many had long suspected: Vytorin provided no benefit over Zocor alone in preventing arterial plaque buildup. In fact, combining Zetia with Zocor might actually make plaque buildup worse.
"This drug doesn't work. Period. It just doesn't work," said renowned cardiologist Steven Nissen, head of cardiology at the Cleveland Clinic.
Researchers found that patients taking Vytorin experienced a 58 percent reduction in overall LDL cholesterol levels, a 40 percent greater decrease than that experienced by patients taking Zocor alone. The cholesterol levels of the Zocor patients went down by 41 percent.
But in spite of the fact that Vytorin delivered a greater decrease in cholesterol levels, there was no significant difference in arterial plaque buildup between the two groups. In fact, patients taking Vytorin had slightly more plaque buildup than patients taking only Zocor but the small sample size of the study made it impossible to tell if this difference was significant or due only to chance.
According to Robert Spiegel, chief medical officer for Schering, the plaque reduction may not have been large because all the participants had already been on cholesterol-lowering statins for many years, which might have already cleaned the plaque out from their arteries.
But according to Nissen, the ENHANCE participants should actually have been an ideal group to demonstrate Vytorin's benefits. In a different study conducted on a similar group of patients, the statin Lipitor was found to decrease the thickness of arterial plaque.
Other recent studies have shown no benefit from Zetia in preventing heart attacks and strokes, and also that plaque buildup in patients taking Vytorin can be twice that of patients taking Zocor alone.
Critics accuse Merck and Schering of concealing the ENHANCE data for so long in order to protect a major source of revenue. Between the two drugs, Zetia and Vytorin pull in $5 billion for the companies each year. Roughly 100,000 prescriptions for the two drugs are filled each day, and sales have increased 25 percent in the last year.
But the release of the ENHANCE data has renewed calls for decreased prescription of Zetia and Vytorin.
"If you're a physician and you use this drug in your practice, I think it might be worth reconsidering," said Allen Taylor, head of cardiology at Walter Reed Army Medical Center.
With Vytorin's reputation reeling, Merck and Schering have initiated a 10,000-patient study to determine whether it protects against heart attacks, strokes and death any better than Zocor alone. The results are not expected until 2011.
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