The family that owns Purdue Pharma, maker of Oxycontin, has rejected a demand that they give up $4.5 billion of their personal wealth to settle opioid claims against the firm, according to state attorneys general negotiating with the company.

As a consequence, talks toward a national settlement with members of the Sackler family reached an impasse over the weekend, according to an email obtained by NPR.

Two attorneys general directly involved in the talks predicted in the email that the company will now file for bankruptcy "imminently."

"States have already begun preparations for handling the bankruptcy proceedings," wrote Josh Stein, North Carolina's state attorney general, and Herbert Slatery, attorney general for the state of Tennessee.

"The Sacklers refused to budge," the email concluded, "and have declined to offer any counterproposal."

The email, first reported by the Associated Press, was sent Saturday to other state attorneys general. It details an offer made to the Sacklers that would have forced them to pay billions of dollars to compensate states for their role helping to fuel the prescription opioid epidemic.

The deal would also have forced Purdue Pharma into bankruptcy proceedings while dissolving the Sacklers' overseas opioid business.

But in a statement emailed to NPR Sunday night, the drug firm suggested a deal might still be possible.

"Purdue Pharma believes a settlement that benefits the American public now is a far better path than years of wasteful litigation and appeals," the statement said. "Those negotiations continue and we remain dedicated to a resolution that genuinely advances the public interest."

Overdose deaths linked to prescription opioids have killed more than 218,000 Americans since the addiction crisis began in the late 1990s, according to the Centers for Disease Control and Prevention.

State and local governments have filed more than 2,000 lawsuits claiming Purdue Pharma played a central role marketing opioid medications, while downplaying the risks.

Over two decades, opioid sales generated billions of dollars in profits for the company, making the Sacklers one of the richest families in the U.S.

A spokesperson for Purdue Pharma declined an interview request by NPR and wouldn't say whether the company is, in fact, considering an immediate bankruptcy filing. Last March, company officials acknowledged that filing for Chapter 11 protection is one strategy being considered.

If Purdue Pharma does file for bankruptcy without first reaching some kind of structured deal, it could take years to sort out the remaining value of the company's assets and then determine who's first in line for compensation.

Pressure to reach a settlement is also intensifying because a federal opioid trial involving Purdue Pharma and more than twenty other drug makers, distributors and pharmacy chains is set to begin next month in Cleveland.

While that legal process moves forward, state attorneys general have promised to continue pursuing the Sacklers personally to recoup profits the family received from opioid sales, even if Purdue Pharma seeks Chapter 11 protection.

"I won't let them get away with their crimes," wrote Pennsylvania Attorney General Josh Shapiro Saturday on Twitter. "I will sue them personally, so that we can dig into their personal pocketbooks."

The Wall Street Journal also reported Friday that the U.S. Justice Department is involved in separate talks with Purdue Pharma.

According to the newspaper, those negotiations involve possible civil penalties tied to federal probes of Oxycontin sales, but could also include criminal charges using statutes normally used to prosecute drug dealers.

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