A prescription version of niacin beat out a popular cholesterol-lowering drug in reducing the buildup of plaque in artery walls, researchers report at the annual American Heart Association meeting.
The study compared extended-release niacin, a B-vitamin, sold as Niaspan against Zetia (ezetimibe). Niacin, which has been used as a heart medication for about 50 years, works by boosting levels of HDL "good" cholesterol, while Zetia, lowers levels of LDL "bad" cholesterol by blocking the absorption of cholesterol in the intestines.
The study, which was funded by Abbott, the maker of Niaspan, found that Zetia failed to shrink plaque buildups in artery walls, while Niaspan did so significantly.
Zetia users also suffered a few more heart attacks and other problems, although the numbers of these events were small.
The small study, published online by the New England Journal of Medicine, involved 363 people with heart disease or a high risk for it who had been taking statins for six years on average. Half were given Niaspan and the rest, Zetia.
Researchers stopped the study in June, after participants had been on the medicines for 14 months, because it was clear the Niaspan group was faring much better than the other.
Ultrasound images of neck arteries showed that Niaspan shrank plaque buildups by about two per cent, while Zetia had no effect on plaque. That was despite the fact that Zetia did lower bad cholesterol, as expected.
Dr. Roger Blumenthal, a preventive cardiology chief at Johns Hopkins University who wrote an NEJM editorial accompanying the results, suggested that even though Zetia has been on the market for about seven years, it's still not clear that it improves outcomes for people with high cholesterol.
But Blumenthal said the study had "too many limitations" for physicians to change the way they treat high-risk patients.
"Although study results are provocative, I am not convinced," Blumenthal said in a news release. "These early results offer no conclusive evidence that niacin along with a statin will actually lower the number of deaths and incidents of heart attack from coronary artery disease down the road."
Merck, the maker of Zetia, also said the study and especially the number of heart attacks and other problems, were too small to be conclusive.
"The results of the small Arbiter-6 study do not, in any way, change our view of Zetia and Vytorin as effective medicines for fighting high LDL cholesterol," said Peter S. Kim, president of Merck Research Laboratories in a news release.
"We encourage patients to continue taking their medication as prescribed by their physicians, and of course to speak to their physician if they have concerns."
Merck insisted the study was skewed to favour Niaspan, because the patients selected to take it had well-controlled LDL cholesterol and relatively low HDL cholesterol.
Nevertheless, these findings are the second recent setback for Zetia. Last year, another study showed that Vytorin, a pill that combines Zetia and the statin Zocor, worked no better than Zocor alone.
In August, Merck and Schering-Plough agreed to pay $41.5 million to settle lawsuits claiming they delayed unfavourable study results on the drugs because they would hurt sales.
Merck is currently conducting a large study called Improve-It designed to determine whether Zetia can help prevent heart attacks, strokes and death. Those results may still be years away.
