Wyeth will promote its No. 2 executive, Bernard Poussot, to CEO effective Jan.1 under a planned succession, the drugmaker said.

Poussot will succeed current CEO Robert Essner, who will become non-executive chairman of the board during a transition period beginning in the new year.

Poussot has served as Wyeth’s president and vice chairman since April 2006. In January he added the role of chief operating officer.

Essner has worked at Wyeth since 1989 and has been CEO since May 2001.