The US government missed the opportunity to curb sales of the drug that kickstarted the opioid epidemic when it secured the only criminal conviction against the maker of OxyContin a decade ago.

Purdue Pharma hired Rudolph Giuliani, the former New York mayor and now Donald Trump’s lawyer, to head off a federal investigation in the mid-2000s into the company’s marketing of the powerful prescription painkiller at the centre of an epidemic estimated to have claimed at least 300,000 lives.

While Giuliani was not able to prevent the criminal conviction over Purdue’s fraudulent claims for OxyContin’s safety and effectiveness, he was able to reach a deal to avoid a bar on Purdue doing business with the federal government which would have killed a large part of the multibillion-dollar market for the drug.

The former New York mayor also secured an agreement that greatly restricted further prosecution of the pharmaceutical company and kept its senior executives out of prison.