Dow Jones Newswires | Abbott Laboratories is suing Sun Pharmaceutical Industries Ltd. and Ranbaxy Laboratories Ltd. in separate infringement suits in the U.S. for challenging the patents of its cholesterol-lowering drugs, Niaspan and TriCor, respectively, the Business Standard reported on its website Thursday, without citing sources.

This type of patent litigation is common in the U.S., as an innovator company is required to sue a generic manufacturer which challenges a drug patent with a Para IV certification within 45 days of notice, the website said.