McKinsey denies illegally hiding work for opioid-maker Purdue Pharma while advising FDA

Consulting firm was protecting client confidentiality, chief says, and wasn't obliged to disclose work advising drug manufacturer

The head of the influential and secretive consulting firm McKinsey & Company has denied the company illegally hid work for Purdue Pharma, the drug-maker that kickstarted the opioid epidemic, while also advising for the Food and Drug Administration.

But Bob Sternfels, McKinsey's global managing partner, apologised for the company's work with Purdue, manufacturer of the powerful painkiller OxyContin that initially drove an epidemic that has claimed more than one million lives over the past two decades.