After riding a career arc that took him to the top of Biogen Idec over a 21-year stint--ending in a battle royale with Carl Icahn that opened the door to his departure--James Mullen is moving on to the next chapter in his biotech odyssey. Toronto-based contract drug developer and manufacturer Patheon ($PTI) announced this morning that Mullen has been named its new CEO. Over the course of his work at Biogen Mullen helped craft the big merger with Idec and brought major new drugs to the market. But intense criticism from Icahn and others over Biogen's spotty R&D record led to his departure last summer. Patheon has more than 4,000 employees in Europe and the U.S. Pantheon release