Hank McKinnell, who engineered two megamergers as chairman and chief executive of Pfizer Inc. before walking away with more than $100 million when he retired in 2006, has taken over as chairman of Optimer Pharmaceuticals Inc. just a few months after becoming its lead independent director.

McKinnell and the board forced out Optimer's previous chairman, Michael Chang, claiming conflicts of interest, improper record keeping and other issues related to a stock grant awarded by an Optimer subsidiary in Taiwan.

The company's chief financial officer, John D. Prunty, and a vice president, Youe-King Shue, also were sent packing in the shake-up. Shue headed up Optimer Biotechnology, which has been working on a new breast-cancer treatment.

The Optimer stock grant was "potentially for the benefit of a third party," the company said.

Chang, quoted on Minyanville.com, blamed McKinnell for engineering the ouster.

- Lee Howard