Cephalon Inc. has hit Apotex Corp. with a lawsuit that accuses the rival drug manufacturer of infringing a pair of patents for Nuvigil®, in an attempt to block a generic version of the stimulant from entering the market. Apotex infringed the two patents by submitting an abbreviated new drug application (ANDA) to make and sell the Nuvigil® generic armodafinil to the U.S. Food and Drug Administration, according to a complaint filed Thursday in the U.S. District Court for the Southern District of Florida. The patents-in-suit involve methods for producing drugs used to treat daytime sleepiness associated with sleep apnea, narcolepsy, and work shift sleep disorder. Cephalon is represented by Finnegan.