Rx for Uncertainty
Does a popular cholesterol-lowering drug do what it's supposed to?
A new study has raised questions about the effectiveness of the cholesterol drug Zetia and its sister drug Vytorin, which combines Zetia with another drug, Zocor. Research released in January found that Vytorin did no better at slowing artery plaque build-up than Zocor alone, although patients on Vytorin dropped their LDL, or "bad," cholesterol almost 20 percent more than those taking only Zocor. Currently, roughly a million prescriptions are written each week for Zetia and Vytorin, and they are relatively pricey drugs, at three times the cost of simvastatin, Zocor's generic version.
After the study results were made public in a press release from the drug company, the American Heart Association (AHA) and American College of Cardiology issued a joint statement advising people taking the drug to consult their physicians, adding that the study was not large or long enough to reach definite conclusions-and that data from larger studies are still to come from manufacturer Merck/Schering-Plough. (The company's press release can be viewed at www.sch-plough.com/schering_plough/news/release.jsp?releaseID=1095943.)
A Contested Approach
Some critics of the two-year study question its use of artery thickening as a measure of the drug's effectiveness. "The study was done over a short interval and did not look at real disease events, like heart attacks," says University of Colorado endocrinologist Robert Eckel, MD, a former AHA president, "so we can't say from the results how taking Zetia will play out over time." The study of just over 700 patients with a hereditary high-cholesterol condition was also quite small, notes Eckel. He points to three current and much larger studies involving 20,000 patients that should provide more telling results. However, those results aren't expected for at least four years, says Steven Nissen, MD, chief of cardiology at Cleveland Clinic. In the meantime, he asks, "Why would you use an expensive drug like this when it doesn't show a positive result?"
Reducing LDL, which Vytorin did better than Zocor alone, is critical to staving off heart disease, Nissen concedes. But, he says, so are reducing other blood fats and raising "good," or HDL, cholesterol-all done by Zocor and others in its class of "statin" drugs. "It doesn't make sense to use Vytorin in place of higher doses of more potent statins," Nissen says. However, says Eckel, some patients can't tolerate statin side effects, such as muscle pain and numbness. Zetia, by comparison, has fewer side effects.
Adding to the controversyis the fact that Merck/Schering-Plough released the study data later than the scientific community expected. Congress has launched an investigation of the delay.
Bridget Murray Law is a Washington, D.C.-based writer and editor.