The FDA rejected the pharmaceutical giant's new combination cholesterol drug asking Merck (NYSE:MRK - News) to perform more tests before approval. The medication combines generic Lipitor, Pfizer's best-selling drug, with Merck's cholesterol medicine Zetia. Approval could boost its cholesterol pill sales by replacing its weaker combo pill, Vytorin. The news had little effect on investors as the FDA has routinely asks for more data before approval. Shares rose 1.4% to 38.45.