TRENTON, N.J. -- Merck has decided to abandon efforts to market a closely watched experimental cholesterol medicine after mediocre test results.

Merck's decision Wednesday to not seek regulatory approval after years of testing marks the fourth time this type of once-promising drug has been scrapped. Merck had continued to study its drug, a so-called CETP inhibitor called anacetrapib, long after rivals had given up on similar drugs.

Merck raised hopes when it announced in June that anacetrapib not only lowered cholesterol, but also reduced heart attacks, deaths and other heart disease complications. But in August it disclosed the pill only cut those risks 9 per cent.

That would have limited sales of the drug, if it had won regulatory approval, in part because cheap, genetic statin drugs lower cholesterol well for most people.