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The ENHANCE Study, Bad News for Vytorin, or Not?
You are probably familiar with Vytorin's "food and family" advertisements, such as this one at U-Tube; they are really eye-catching in their colors and reflections of food in the choice of people in the ads. These advertisements are correct on at least one point; the body's different cholesterol levels are affected by both what one eats and genetics. The advertisements also state that when the Vytorin pill was compared to the cholesterol lowering ability of other statins alone that it was more effective at lowering LDL cholesterol, and their study evidence supports that statement.
Vytorin is a pill that combines the statin simvastatin (Zocor, produced by Merck Manufacturing) and ezetimibe (Zetia, produced by manufacturer Schering-Plough) into one pill. Ezetimibe's method of lowering cholesterol is to prevent the building blocks of cholesterol from being absorbed in the intestinal tract, rather than preventing their manufacture in the liver, which is how the statin drugs work. The ENHANCE study compared Vytorin alone to Zocor alone, and measured their effectiveness on plaque size in the carotid (large neck) arteries. This is where the real controversy lies for me. To my knowledge there is no evidence that plaque size alone will predict disease outcomes. There are a multitude of factors involved in disease development, including plaque make-up (the kind of cholesterol particles inside it), its stability and location, and a person's genetic factors that determine whether or not plaque becomes a problem in a given individual.
Dr. Michael Richman discusses the results of the ENHANCE study here in his blog. He's not ready to give up on Vytorin yet, because he believes that there is enough clinical evidence that lowering LDL cholesterol lowers the risk of developing cardiovascular diseases, including heart attack and stroke. I have to agree with him there; we certainly have years of evidence from Framingham alone to support this hypothesis.
Dr. Richmond sites Dr. Robert Harrington from the Duke Clinical Research Institute, who says that ENHANCE was not meant to be an "outcomes" study, meaning that the measurement of markers such as plaque size have never been proven to be equal to the risk of disease development or progression. In other words, there are other factors involved in the development of cardiovascular disease that are not measured by plaque size alone. One such example is the still-developing evidence that the one of the reasons that statins are effective is their anti-inflammatory properties. Dr. Harrington is involved in one of three large clinical outcomes studies of Vytorin currently underway, and he notes that until these results are known, we have to rest on our current knowledge that lower LDL equals lower disease rates.
Vytorin has certainly been shown to reduce LDL cholesterol, and it was on that basis, as well as its safety profile, that it was FDA approved for use in controlling cholesterol. If you are currently taking Vytorin because you could not control your LDL cholesterol level on a statin alone, and you and your health care provider are happy with your results, then I would not be in a rush to stop taking the drug.
In health,
Laurie
Related Topics: Technorati Tags: Vytorin, Zetia, statins, heart disease, cholesterol, LDL, plaque, health and wellness
