Generics In a second law suit filed against it in a matter of days, US generic drugmaker Impax Laboratories (Nasdaq: IPXL) says that Alza Corp, a subsidiary of drug major Johnson & Johnson (NYSE: JNJ), has filed suit for patent infringement against Impax in the US District Court for the District of Delaware in connection with Concerta (methylphenidate hydrochloride) extended-release 54mg tablets, a treatment for attention-deficit hyperactivity disorder (ADHD). 1 December 2010