The FDA has issued a complete response letter regarding Merck's new drug application for ezetimibe (Zetia) and atorvastatin (Lipitor) tablets, an investigational combination medicine.

In the letter, the agency advised Merck that it has completed its review of the submission and stated that additional data are needed. The experimental drug, still known as MK-0653C, would combine generic Lipitor with the cholesterol drug, Zetia.

The Whitehouse Station, N.J.-based Merck said it plans to discuss next steps with the agency in the near future, including new data that are expected to be available later this year, "which may address the FDA's comments."