Original sentence: With 2006 sales of US$12.9 billion, Lipitor is the largest-selling drug in the world
Edited sentence: There is an agreement with Ranbaxy Laboratories to begin selling Lipitor and Caduet  beginning in November 2011 in the US.US patent protection is scheduled to expire in June 2011.With 2008 sales of US$12.4 billion, Lipitor is likely the top-selling drug in the world