Valeant Pharmaceuticals has entered into a definitive agreement to acquire Salix Pharmaceuticals in a transaction valued at approximately $14.5 billion. Salix has a leading gastrointestinal franchise with a portfolio of 22 products, including prescription brands Xifaxan, Uceris, Relistor, and Apriso, as well as a late stage pipeline of new assets.    The combination is expected to yield greater than $500 million in annual cost savings, primarily from reductions in corporate overhead and R&D ...