TRENTON, N.J. – Drugmaker Merck & Co. said Thursday it is shutting down eight manufacturing plants and eight research sites around the world, including two domestic locations, in the latest phase in its strategic pruning of excess capacity.

The moves will include consolidating some small offices into larger facilities with multiple functions.

The announcement is part of ongoing restructuring following Merck’s acquisition of Schering-Plough Corp. last November.

Late Thursday, the company said in a regulatory filing that it also plans to eliminate 2,500 vacant positions, mainly duplicative positions in sales, administrative and headquarters organizations, as well as some from the 16 sites being sold or closed.