Merck will consolidate media duties on all of its brands, including the newly acquired Schering-Plough portfolio, after a review.

The move puts the account—valued at approximately $600 million without digital spend, according to Nielsen—up for grabs, with Merck’s incumbents Draftfcb and Initiative participating. Schering-Plough incumbent Havas MPG is also in on the pitch, with final presentations planned for this March. Zenith Media will also participate in the review, according to an Adweek report. Merck is responsible for the bulk of the $600 million account, spending upward of $520 million from January-November 2009.