McKesson Corp. has promoted Alan Seelenfreund to...

McKesson Corp. has promoted Alan Seelenfreund to chairman and chief executive, replacing Thomas Field, who abruptly resigned in September. The San Francisco-based drug wholesale and distribution company also promoted Rex Malson, formerly executive vice president-operations, to president and chief operating officer. The two longtime McKesson executives will share responsibilities under a newly created office of the chief executive. Seelenfreund, 52, formerly was executive vice president and chief financial officer. He joined the company in 1975. Malson, 57, joined the company in 1973 and was named executive vice president in 1986 after serving as president of the company’s Drug and Health-Care Group.