A bid by a generic company in Largo, Fla, to produce a generic version of the allergy medication Clarinex (desloratadine) has been blocked by a lawsuit from Schering-Plough Corp, makers of the brand drug. The pharmaceutical company has sued GeoPharma Inc and its subsidiary, Belcher Pharmaceuticals, in federal court in New Jersey for patent infringement. The suit is tied to Belcher's filing for a generic version of Clarinex 5-mg tablets with the FDA.

Schering's lawsuit also names 12 other pharmaceutical companies that filed for rights to generic Clarinex at the same time as Belcher. Sales of Clarinex in 2005 reached $325 million, and, although competition was expected to be tight, Mihir Taneja, chief executive of GeoPharma, was surprised that so many others were lining up to make generic Clarinex as well. He and the other defendants are claiming that their versions of the allergy drug are bioequivalent to the brand version but do not infringe on Schering's patent, which expires in June 2007. The FDA can approve the generic filings if the complaint is not resolved in 30 months.