Mallinckrodt, the Hazelwood-based pharmaceuticals business being spun off from Covidien, said it has entered a co-promotion agreement with Horizon Pharma Inc. to promote Duexis, a proprietary single-tablet combination of ibuprofen and famotidine used to treat rheumatoid arthritis and osteoarthritis. The deal calls for Mallinckrodt’s U.S. sales force to sell Duexis through Dec. 31, 2014. Financial terms of the deal weren’t disclosed. Read More…