Chris Viehbacher, one of the most senior executives at GlaxoSmithKline, the pharmaceuticals group, is to quit for a top job at a rival group, heralding a shake-up in the troubled drugs sector.

Mr Viehbacher, president for North American Pharmaceuticals at GSK and a board director, leaves at the start of December after an approach to run another pharmaceuticals group, say people close to the situation.