Forest Laboratories is suing generic-drug maker Teva Pharmaceutical Industries for infringing the basic patent on its antidepressant Lexapro, for which Forest recorded $480 million in global sales in its most recent quarter, Reuters reported. The patent allows Forest to retain exclusive rights to Lexapro, which represents half the company’s sales, until March 2012, including a six-month patent extension that Forest received for conducting pediatric studies.Teva claims the patent is invalid. The bench trial is expected to last until March 27, after which both sides could typically have about 60 days to file additional briefs, a Forest spokesperson told Reuters. Judge Joseph Farnan will preside over the case.Farnan is the same judge who ruled in favor of Pfizer in its patent battle against Ranbaxy over Pfizer’s cholesterol treatment Lipitor.