The study pitted extended-release niacin, sold as Niaspan, which works by boosting levels of HDL "good" cholesterol, against ezetimibe. Ezetimibe, sold as Zetia, lowers levels of LDL "bad" cholesterol.
"The question is whether ezetimibe works at all," says researcher Allen Taylor, MD, of the Washington Hospital Center in Washington, D.C. "Niacin has been around for 50 years. It's a well-understood drug, and in this trial it was clearly superior."
Peter Kim, president of Merck Research Laboratories, which makes Zetia, says the new study was limited due to its small size and short length. "It would be very unfortunate if a flawed analysis led patients to discontinue their cholesterol treatment."
The new findings were released at the annual American Heart Association (AHA) meeting and published online by TheNew England Journal of Medicine.
Niacin Slows Plaque Buildup
The new study, funded by Abbott, the maker of Niaspan, involved 363 people who had heart disease or were at high risk of heart disease. All the patients were on statin drugs that had brought their LDL cholesterol below 100 mg/dL. However, they all had suboptimal HDL levels.
About half of the patients were given Niaspan and the other half were given Zetia, in addition to their usual statin drugs.
The study was halted in July, about four months early, when investigators concluded that one group was clearly doing better than the other -- although they did not say which group was doing better at the time; 208 patients completed the trial.
At a news conference at the AHA meeting Sunday night, Taylor reported that the "winner" was Niaspan.
Ultrasound images of neck arteries showed that Niaspan reduced artery plaque by about 2%. Zetia did not slow plaque buildup, although it did lower cholesterol.
"This trial doesn't quite put the nail in the coffin for ezetimibe, but it pushes it way down on the list of medications for cholesterol-lowering therapy," Anthony DeMaria, MD, editor-in-chief of the Journal of the American College of Cardiology, says in a statement.
Two editorials accompanying the findings in The New England Journal of Medicine raised questions about the findings.
"Unfortunately, the premature termination of the trial, the small number of patients studied and the limited duration of follow-up preclude us from conclusively declaring niacin the adjunctive agent of choice," write Roger Blumenthal, MD, and Erin Michos, MD, both of Johns Hopkins.
Still, Vytorin and Zetia should probably be reserved for patients whose cholesterol isn’t controlled with statins and niacin, Blumenthal tells WebMD.
That said, some patients have trouble tolerating niacin, whose main side effects are itching and flushing, he says. Thirty-six percent of patients taking niacin in the trial reported flushing.
Blumenthal adds that several large clinical trials of niacin and Zetia that are in progress should offer more guidance.