DUBLIN – Amgen Inc. is picking up Celgene Corp.'s oral phosphodiesterase 4 (PDE4) inhibitor Otezla (apremilast) for $13.4 billion, in a move that strengthens its hand in inflammatory disease, while paving the way for Bristol-Myers Squibb Co. to complete its $74 billion cash-and-shares acquisition of Summit, N.J.-based Celgene.