Schering-Plough Corp. apparently is allergic to anothercompany’s attempts to horn in on profits generated by its top-sellingClaritin allergy drug.

That’s why it filed a patent infringement suit in federal court inWilmington against Copley Pharmaceuticals Inc. last week over Copley’sbid to sell a generic version of Claritin, which generated $2.3 billionin sales in 1998, making Claritin the world’s best-sellingantihistamine.