ALLEGAN, Mich. (AP) — Perrigo Co. said Tuesday it received Food and Drug Administration approval to market a generic version of Schering-Plough Corp.’s laxative MiraLAX. Perrigo said it expects to start shipping its version of the over-the-counter constipation treatment immediately. The Perrigo version will be marketed under store brand labels. U.S. sales of MiraLAX totaled $200 million in the year ended Aug. 28, Perrigo said.