McKinsey will pay at least $550m to settle US states’ claims that its advice to pharmaceutical companies contributed to the country’s deadly opioid crisis, under an agreement that could be announced on Thursday. 

People familiar with its negotiations with the attorneys-general of 47 states, the District of Columbia and several US territories said the consultancy was not expected to admit wrongdoing or liability but would agree to court-ordered restrictions including retaining documents relating to its opioids work. 

A spokesman for McKinsey declined to comment. 

The authorities had brought the civil claims after details emerged of McKinsey’s advice to Purdue Pharma, owned by members of the billionaire Sackler family, on how to boost sales of OxyContin, its potent prescription opioid. 

Its consultants had urged Purdue directors to consider whether to “turbocharge the sales engine”, according to a lawsuit brought by the Massachusetts attorney-general, encouraging them to direct sales representatives to visit doctors with a record of prescribing large amounts and pitching opioids as giving patients “the best possible chance to live a full and active life”.

One July 2019 email disclosed in the litigation showed a McKinsey partner discussing talking to its risk committee about “eliminating all our documents and emails”.

In December, McKinsey pushed back at the idea that it had sought to worsen the public health crisis but admitted that it “fell short” of its responsibility to take account of the possible consequences of its work.

The consultancy has long pitched itself as a trusted adviser to the world’s largest companies, several of which are run by McKinsey alumni. But its reputation has taken a series of costly hits over unrelated assignments that have prompted it to review how it chooses which clients to take on.

Purdue agreed last October to pay more than $8bn in a criminal and civil settlement with the US Department of Justice, but the company remains in negotiations with several states, counties and cities. Sackler family members agreed to pay $225m while denying the allegations against them.

McKinsey has also come under fire for its past advice to other drug manufacturers, including Johnson & Johnson, which previously made opioids and owned an opioid ingredient maker. The consultancy said it stopped work on “any opioid-specific business” in 2019.

According to the US Centers for Disease Control and Prevention, the number of deaths each year from overdoses involving prescription opioids rose fourfold between 1999 and 2018. More than 232,000 Americans died from prescription opioid overdoses in that period.