He is an American public affairs executive and public policy advocate.

He is an American public affairs executive and public policy advocate. He was the former president and chief executive officer of the Pharmaceutical Research and Manufacturers of America (PhRMA), a trade group representing U.S. pharmaceutical research and biopharmaceutical companies. Prior to joining PhRMA, Castellani led the Business Roundtable, a U.S. advocacy and lobbying group. Currently he is on the Pharmacist Partners Advisory Board.