Merck and Schering-Plough said on Monday they were beginning development on a cholesterol-lowering product that would combine their Zetia drug with Pfizer's Lipitor.
The development program is timed so the combination product could be available when the patent for Lipitor, known generically as atorvastatin, expires in the U.S. and
internationally, the companies said.
Lipitor, the world's largest-selling drug, is expected to face generic competition in the U.S. in 2010 or 2011.
Schering-Plough and Merck already have a joint venture to market Zetia and Vytorin, which combines Zetia with Merck's Zocor.