By MARLEY SEAMAN AP Business Writer ALLEGAN, Mich. (AP) — Perrigo Co. said Thursday it settled a patent-infringement lawsuit with Schering-Plough Corp., which will allow Perrigo to launch a generic version of allergy drug Clarinex on July 1, 2012. Perrigo asked the Food and Drug Administration to approve its generic drug in June 2006, and Schering-Plough responded that September by filing a suit alleging the Michigan company was infringing three of its patents on the drug. That prevented Perrigo from launching its generic — which is awaiting FDA approval — until the suit was resolved. Under the terms of the settlement, Perrigo said it will be able to sell Clarinex, or desloratadine, in 5 mg tablet form. The company said sales of those tablets totaled $300 million in the 12 month period ended in October.Two of the disputed patents were set to expire on Dec. 31, 2014. The third was scheduled to expire July 7, 2019.