Merck/Schering-Plough says it plans to sell its Zetia cholesterol inhibitor in combination with a generic version of Pfizer’s Lipitor. The pill could be available once US and international patents expire for Lipitor (atorvastatin), which could be as early as 2010. Lipitor had 2006 global sales of about $12.9 billion, according to Pfizer. The MSP joint venture already markets Zetia in a combination pill with Zocor. That drug, Vytorin, had 2006 global sales of $1.96 billion. Vytorin uses a dual approach to the treatment of high cholesterol, blocking cholesterol absorption in the small intestine (Zetia) and lowering production in the liver (Zocor). Considering Lipitor is more widely prescribed and studies show it is more effective than Zocor, the planned pill could prove even more successful, notes Bloomberg. The companies said they tested a Zetia-Lipitor combination and found that co-administration of the drugs lowered LDL or “bad” cholesterol by an average of 53% to 61%, compared to average LDL cholesterol reductions of 37% to 54% with atorvastatin alone.