WHITEHOUSE STATION, N.J. (AP) — Merck & Co. said Friday that it received U.S. marketing approval for the new combination cholesterol drug Liptruzet, which combines the company’s drug Zetia with a generic version of the mega-blockbuster drug Lipitor.

The Food and Drug Administration approved the once-a-day medication to reduce low-density lipoprotein cholesterol, or “bad” cholesterol, in patients who can’t control their levels with a healthy diet alone.

The drug contains medicines that fight bad cholesterol in two different ways.

Lipitor, known chemically as atorvastatin, is part of the widely used class of drugs called statins that reduce the amount of cholesterol naturally produced in the liver. Pfizer’s branded version of the drug became the best-selling drug of all time, before its patent expired in 2011. The drug is now marketed in various generic forms.

Merck’s Zetia reduces the amount of cholesterol absorbed from the food the patient eats.

Despite Liptruzet’s two-pronged approach, the labeling approved by FDA notes that the drug has not been proven to reduce heart attack or death more than Lipitor alone.

The approval could boost Merck’s sagging cholesterol franchise by essentially replacing its existing combo pill, Vytorin, with one likely to be seen as more powerful. Vytorin sales have been dwindling for a few years due to concerns about how well it works, and now Merck has to contend with patients defecting to the generic versions of Lipitor.