B vitamin outperforms another drug in keeping arteries clear
The findings led to an early halt of a small study comparing Niaspan and Zetia, two compounds commonly used along with statins to reduce heart attack risk
By Laura Beil
ORLANDO, Fla. — Adding a pharmaceutical form of the B vitamin niacin — but not the drug ezetimibe — to a cholesterol-lowering statin drug appears to reduce artery plaque buildup in patients with coronary artery disease, according to much-anticipated results announced at a press conference November 15.
The results were from a study that was relatively small — only 208 patients — but provided a head-to-head comparison of niacin and ezetimibe, known by the brand name Zetia. Despite studies last year that questioned its effectiveness, Zetia remains a blockbuster drug for Merck & Co. Inc. The form of niacin used in the study is an extended-release, prescription-only formulation of niacin called Niaspan, made by Abbott, which funded the new trial.
The new findings were simultaneously published online by the New England Journal of Medicine and presented during the American Heart Association’s Scientific Sessions 2009. Niacin has been shown to raise levels of HDL, the type of cholesterol that protects against heart disease. Zetia is designed to work differently, by lowering levels of LDL, the cholesterol that contributes to heart disease. Niacin also lowers LDL, but is better known for raising HDL. Zetia’s performance fell flat in two recent trials, leading many doctors to question its usefulness.
For the new study, researchers enrolled 363 patients from Walter Reed Army Medical Center in Washington, D.C., and Washington Adventist Hospital in Takoma Park, Md. The patients were randomly assigned to take their prescribed statin drug with the addition of either Niaspan or Zetia. The drugs’ effects were gauged by measuring plaque buildup in each participant’s carotid arteries.
Investigators stopped the study in June when it became clear that one group was not faring as well as the other. Among 208 patients analyzed after 14 months, those receiving Niaspan experienced a significant shrinkage in artery wall thickness, while the patients taking Zetia had no measurable change in plaque buildup — despite the fact that, overall, people in the Zetia group experienced a 19 percent drop in levels of LDL cholesterol.
“This has raised concerns about ezetimibe’s mechanism of action,” said Allen Taylor, who is now with the Medstar Research Institute in Washington, D.C. However, safety concerns were not what halted the study, and other scientists — while acknowledging that niacin proved superior — questioned the decision to stop the study early. “I would have seen no problem running this trial another four to five months,” said John Kastelein of the University Medical Center Utrecht in the Netherlands. Writing in a commentary also published online in the journal, he called the premature termination of the study “a missed opportunity to enhance precision and power” of the research.
While these and other data raise questions about the future of Zetia, niacin has never looked better as a tool for heart disease treatment. Knowing that some patients experience heart attacks while taking statins, researchers have searched for ways to improve cholesterol further. The ability to protect patients by raising HDL levels “is exciting news,” said Roger Blumenthal of the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, who also has a commentary appearing online in the journal. “This is one medicine people should talk to their doctors about,” he said, though he remained cautious about the results. Stopping the trial early might have exaggerated the benefits of Niaspan, Blumenthal noted. Two other large studies testing niacin’s effectiveness are under way, but won’t be completed for at least two years, he said.
While niacin is available in pharmacies and health food stores, doctors aren’t recommending that patients start trying to treat themselves. The U.S. Food and Drug Administration does not oversee the production of dietary supplements, so the supplements’ quality and safety can’t be guaranteed, Taylor said. With off-the-shelf niacin, doctors can’t even be sure the doses listed on the labels are accurate. “Over-the-counter niacin is not considered useful,” he said.
