Novartis is losing its respected head of global development Trevor Mundel to the Bill & Melinda Gates Foundation, creating a temporary gap at the top of its new-drugs machine. Novartis said on Tuesday a successor for Mundel, who will stay with the Swiss drugmaker until December 1, would be named shortly. Mundel, 51, is to replace another one-time pharmaceutical executive, GlaxoSmithKline’s former research head Tachi Yamada, as executive director for global health at the charity established by Microsoft founder and chairman Bill Gates.