I ran across this handy pdf file from the website of Prof. Njardason at Cornell. It is a graphic compilation of the top selling drugs (in the USA?). Just click on the image and a pdf will download. The site has compilations for the last several years as well.
A few of the drugs on the list are protected under patents that will expire in the next few years- Lipitor, Crestor, Lexapro, Advair, Singulair, Plavix, etc. Hours after the license to print money expires, the generic barbarians and visigoths will storm the gates and unceremoniously slaughter these cash cows. The horror, the horror.