MUMBAI, India Ranbaxy Laboratories has decided to drop its bid to sell generic versions of Schering-Plough allergy medicine Clarinex (desloratadine).

Schering-Plough sued a dozen generic drug companies last year to block their versions of generic Clarinex. The agreement between Ranbaxy and Schering-Plough will end if another company is successful in challenging the validity of the patent, according to court records.

This announcement comes after recent news from Merck and Schering-Plough, which plan on creating a combination drug of their respective drugs, Singulair and Claritin. Claritin generated $455 million in global sales in the first six months.