McKesson Corp., the largest distributor of pharmaceutical and health-care products in North America, said it named Mark Pulido to succeed Alan Seelenfreund as chief executive on April 1. Pulido, 44, is president and chief operating officer. He joined McKesson in May from Novartis unit Sandoz Pharmaceuticals Corp., where he was president and chief executive. Seelenfreund, 60, will remain chairman of San Francisco-based McKesson. He has been chairman and CEO since November 1989. "Mark Pulido is a dynamic executive fully committed to our vision, with the qualities to guide our company into the next century," Seelenfreund said. McKesson stock rose 12.5 cents to close at $56.50 on the New York Stock Exchange.