LINDA A. JOHNSON Associated Press Writer TRENTON, N.J. (AP) — Drugmakers Johnson & Johnson and Watson Pharmaceuticals Inc., locked in a patent dispute over J&J’s blockbuster attention deficit drug Concerta, are weighing their options after a federal court ruled a key patent is invalid. According to the companies, the U.S. District Court in Wilmington, Del., ruled the primary patent patent on the popular drug for attention deficit hyperactivity disorder is invalid and that Watson’s planned generic version of the stimulant therefore does not infringe on the patent. Watson did not immediately return calls Wednesday seeking comment about when it might launch a generic version, but its chief executive, Paul Bisaro, said in a statement, “we will continue to evaluate the court’s opinion as we contemplate our next steps.” Concerta, which had global sales of $1.25 billion last year, can cost $90 to $160 a month without insurance, depending on the dose. Generic drugs generally cost about one-third as much as brand-name ones. Corona, Calif.-based Watson is awaiting Food and Drug Administration approval to sell generic Concerta, extended-release methylphenidate that is taken once a day, in four different dosages. The company already sells short-acting methylphenidate, or generic Ritalin, which must be taken two or three times a day — an inconvenience and stigma for children because schools require it to be dispensed by a school nurse. The stimulant drugs are meant to increase attentiveness and decrease hyperactivity and impulsive behavior, but can be abused and can cause dependence, heart problems and other side effects. New Brunswick, N.J.-based J&J, which markets Concerta, and subsidiary Alza Corp., which developed the drug, sued Andrx Corp. in 2005 over its planned generic version of Concerta. Andrx was bought by Watson in 2006. Watson said in its statement that a ruling on the validity of a second Concerta patent remains in litigation, but that it believes it also is invalid. “We’re looking at the court decision, and we’re looking at the next steps,” Tricia Geoghegan, a spokeswoman for J&J’s McNeil Pediatrics unit, said Wednesday. The ruling, from U.S. District Judge Joseph Farnan Jr., was issued Monday.