Mallinckrodt plc and Questcor Pharmaceuticals Inc. announced that they have entered into a definitive merger agreement under which Mallinckrodt will acquire Questcor in a transaction valued at approximately $5.6 billion. It is expected that, following closing of the transaction, Mallinckrodt's Board of Directors will be increased to twelve members, with the addition of three directors from Questcor. The three directors will include Mr. Don M. Bailey and two current, independent directors of Questcor: Angus C. Russell and Virgil D.Thompson.

Melvin D. Booth, the current Chairman of Mallinckrodt's Board of Directors, will continue in that role after the transaction is completed.