Generics Three prominent US Senators have sent letters to pharma behemoth Pfizer (NYSE: PF), as well as three companies that manage pharmaceutical benefits and two insurance firms, asking for information about agreements aimed at limiting the sale of atorvastatin, the generic equivalent of Pfizer's drug Lipitor, which lost patent protection in the USA on Wednesday. So-called 'authorized' copy versions - with 180 days of market exclusivity - of the all-time blockbuster cholesterol lowerer have already been launched by Watson Pharmaceuticals and Ranbaxy Laboratories (The Pharma Letter December 1). 2 December 2011