Complex sentence: When Pfizer's patent on Lipitor expired on November 30,2011, generic atorvastatin became available in the United States, initially manufactured only by generic drugmakers Watson Pharmaceuticals and India's Ranbaxy Laboratories.
Split into simpler sentences: When Pfizer's patent on Lipitor expired on November 30,2011, generic Atorvastatin became available in the United States. Initially, Atorvastatin was manufactured only by generic drugmakers Watson Pharmaceuticals and India's Ranbaxy Laboratories.