By | January 29 2013 2:21 PM

Patent expirations for lucrative blockbuster drugs eroded fourth-quarter sales for top drugmakers Pfizer Inc. (NYSE:PFE), Eli Lilly & Co. (NYSE:LLY) and Bristol-Myers Squibb Co. (NYSE:BMY) as they faced competition from low-cost generic drugs. Big pharmaceutical companies have been cutting costs and working to bring new products to market to soften the hit from patent expirations.