A recent study has raised doubts over the effectiveness of cholesterol drug Zetia, and its counterpart Vytorin, in reducing build ups in the walls of arteries and lowering cholesterol. Last year as well, a study was conducted and the role of these two medicines came under considerable doubt, millions of Americans, however, still continue to take it on a regular basis.

In the study conducted to test the effects of the drugs, Zetia failed to shrink the excess build up in artery walls, while Niaspan, a rival drug, effectively managed to, by a significant amount. Although the number reported are too small to actually base anything on them, but it has been noticed that Zetia users suffer more heart attacks and other cardiovascular and health problems.

"Zetia has been on the market for about seven years and we still haven't proven that it improves clinical outcomes", said Dr. Roger Blumenthal, Preventive Cardiology Chief at Johns Hopkins University, who is now convinced that the results of the study would mean more and more doctors turning to Niaspan.

The study, which involved analysis of 363 heart patients, was presented at the American Heart Association Conference on Sunday and has been published in the New England Journal of Medicine.