Pfizer sought to reassure investors that the unravelling of its “monolithic” structure would prepare it for the impending expiry of the patent for its blockbuster cholesterol drug Lipitor, worth some $12bn in annual sales.

Under pressure from Wall Street to retool Pfizer to boost sales and profit, Jeff Kindler, chief executive, gave a frank assessment of the disruption created by its $90bn Warner-Lambert and $60bn Pharmacia deals since 2000. He provided the most detailed evidence yet of Pfizer’s efforts to streamline its operations, change its culture and improve its research and science.