Chattem, Manufactures and sells health and beauty products, toiletries, proprietary drugs , fragrances and dietary supplements, is bought by Drug maker Sanofi-Aventis S.A for about $1.9 billion in cash in a deal it said would create the world’s fifth-largest consumer health-care company.

Sanofi-Aventis said that it will attempt to convert is popular antihistamine Allegra to an OTC product, which Chattem would then distribute. Sanofi-Aventis shares were mostly flat in premarket trading Monday.

“The acquisition of Chattem will be a significant milestone in Sanofi-Aventis’ transformation strategy and will provide us with the ideal platform in the U.S. consumer healthcare market, which represents 25 percent of the current worldwide opportunity,” the Sanofi chief executive Christopher A. Viehbacher said in a statement.