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Last Updated: Jun 30, 2008 - 11:14:37 AM |
MONDAY MARCH 31, 2008 (foodconsumer.org) -- Ezetimibe is commonly used alone (under brand name Zetia) or along with simvastatin (Zocor) in a common combined therapy (Vytorin) for cholesterol management. But the lowering of cholesterol by Ezetimibe does not seem to reduce the risk of cardiovascular disease, according to a new study published on March 30, 2008 in the New England Journal of Medicine.
Simvastatin is a robust statin that lowers low density lipoprotein or bad cholesterol by preventing it from being synthesized in the liver. Zetia lowers cholesterol levels by preventing the intestine from absorbing dietary low-density lipoprotein or LDL. A combined therapy with both drugs is intended to deliver a maximum cholesterol-lowering effect with hopes that it can reduce the cardiovascular risk further.
But the new trial showed that although the combo treatment with Zocor and Zetia or simply Vytorin did lower cholesterol levels in patients, evidence suggested that the further lowering of cholesterol attributed to Zetia may not help reduce cardiovascular disease further. Researchers suggested that the action of Zetia may differ from that of statins, which can not only lower LDL, but also heart attack and stroke risk.
The study of 720 patients with familial hypercholesterolemia was a randomized, double-blind, active-comparator, multi-center trial sponsored by Merck and Schering-Plough, the companies that make Vytorin and Zetia. The trial was conducted at 18 ambulatory care centers in the United States, Canada, South Africa, Spain, Denmark, Norway, Sweden, and the Netherlands during the period of August 2002 through April 2006.
In the trial, Dr. John Kastelein and colleagues assigned one group of patients 80 mg of simvastatin or Zocor alone as controls and another group 80 mg of simvastatin plus 10 mg of ezetimibe (Zetia). The purpose is to see the addition of Zetia to the treatment with Zocor would provide any further help in reducing cardiovascular risk. All patients used a placebo for six weeks and then had their intima-media thickness of the walls of the carotid and femoral arteries measured. The measurements were repeated at 6, 12, 18, and 24 months.
The results showed that adding ezetimine to simvastatin (the Vytorin treatment) did not reduce the intima-media thickness of the carotid-artery wall in the patients with familial hypercholesterolemia in spite of significant incremental reductions in levels of both LDL and C-creative protein.
Reduction in the intima-media thickness of the carotid artery has been inversely associated strongly with stroke, angina spectoris and myocardial infarction in large epidemiologic studies. One study found an increase of 0.2 mm in the mean carotid-artery intima-media thickness was linked with an increase in relative risk for myocardial infarction and stroke of 33% and 28% respectively, according to the researchers in the trial. This means that ezetimibe (Zetia) may not help reduce the cardiovascular risk even though it helped lower LDL levels.
The trial secondary outcome measurements showed use of ezetimibe may actually do more harm than good. Regression in the mean carotid-artery intima-media thickness was found in 44.4% in the simvastatin group and 45.3% in the simvastatin/ezetimibe group. New plaque formation was found in 2.8% of the patients on simvastatin only, but in 4.7% of the patients receiving the combined-therapy. But no significant change was seen in the mean maximum carotid-artery intima-media thickness, the mean measures of the intima-media thickness of the common carotid artery, the carotid bulb, the internal carotid artery and the femoral artery.
The trial results were discussed at a major cardiology conference in Chicago. Dr. Steven Nissen, a distinguished cardiology specialist at the famous Cleveland Clinic said of ezetimibe used in Zetia and Vytorin, cited by The New York Times, "We've got a drug that has no clinical outcome trials" and "I advise my colleagues essentially to use this drug only as a last resort."
Outcome trials are those involving 10,000 or more patients and lasting multiple years. Statins such as Lipitor and Zocor have been subject to such outcome trials and they have proved to help patients reduce risk of heart disease. But the trials have not been conducted for Vytorin and Zetia.
According to the New York Times, Merck and Schering-Plough only rushed to start their own outcomes study in 2006, four years after Zetia reached the market to compare the effects of Vytorin (Zetia plus Zocor) and Zetia alone and the results had been expected in 2011 and may be available only after 2012 or later.
In spite of the negativity of the published trial known as the Ezetimibe and Simvastatin in Hypercholesterolemia Enhances Atherosclerosis Regression (ENHANCE) trial, Merck and Schering-Plough defended Zetia and Vytorin that earned the companies $5 billion last year in sales saying that they would continue to promote their medications as first-line treatments for high cholesterol. As estimated, four millions Americans take the drugs.
Dr. Harlan Krumholz, a cardiologist at Yale University was cited by the Times as saying that there is no evidence at the moment to show that Vytorin and Zetia help patients. He made such a comment when speaking on a panel on Sunday discussing the trial at the American College of Cardiology annual conference in Chicago.
"Just because you know what a drug does to cholesterol doesn't mean you know what it does to patients," Dr. Krumholz was quoted as saying.
Web links:
Trial report:
Simvastatin with or without Ezetimibe in Familial Hypercholesterolemia
Editorials:
Does ENHANCE Diminish Confidence in Lowering LDL
or in Ezetimibe?
Cholesterol Lowering and Ezetimibe
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