Lipitor(atorvastain calcium) tablets made by Pfizer and distributed by Parke-Davis are seen November 30, 2011 in Washington, DC. Pfizer's patent on the best-selling drug of all-time, the cholesterol-lowering medication Lipitor, expired on November 30, 2011, opening the path to generic competitors for America's most popular medication. Lipitor came on the market in 1997, and has raked in some $100 billion for Pfizer even in a crowded market that includes various other cholesterol-lowering statins, many of which have already gone generic. In the United States, anti-cholesterol drugs account for 255 million prescriptions a year, and about nine million people are taking Lipitor.
