Two cholesterol drugs still taken by millions of Americans are the subject of concern for a second time, according to a new study.
In the study involving about 360 people, Zetia failed to shrink buildups in artery walls while a rival drug, Niaspan, did so significantly.
Ultrasound images of neck arteries showed that Niaspan shrank buildups by about 2 percent, while Zetia had no effect on this even though it lowered bad cholesterol as expected. The results were published by the New England Journal of Medicine.
Last year, a large study suggested that the combo pill Vytorin, which combines Zetia with a statin, was no more effective than Zocor alone, a statin now available as a cheap generic.
Niaspan is a slow-release version of niacin, a type of B vitamin. Both Zetia and Vytorin are sold by Merck & Co. Niaspan is made by Abbott Laboratories, which sponsored the latest study.
Merck says it stands behind its drugs, which accounted for billions in sales last year.