In 2007, the company and three of its top executives pleaded guilty to federal criminal charges that Purdue had misrepresented the dangers of OxyContin, and they paid $634.5 million in fines. The Sacklers were not accused of any wrongdoing and have not faced personal legal consequences over the drug.

But last June, Maura Healey, the Massachusetts attorney general, sued eight members of the Sackler family, along with the company and numerous executives and directors, alleging that they had misled doctors and patients about OxyContin’s risks. The suit also claimed that the company aggressively promoted the drug to doctors who were big prescribers of opioids, including physicians who later lost their licenses.

The court filing released on Tuesday also asserts that Sackler family members were aware that Purdue Pharma repeatedly failed to alert authorities to scores of reports the company had received that OxyContin was being abused and sold on the street. The company also used pharmacy discount cards to increase OxyContin’s sales and Richard Sackler, who served as Purdue Pharma’s president from 1999 to 2003, led a company strategy of blaming abuse of the drug on addicts, the suit claimed.

In 1995, when the Food and Drug Administration approved OxyContin, it allowed Purdue Pharma to claim that the opioid’s long-acting formulation was “believed to reduce” its appeal to drug abusers compared with traditional painkillers such as Percocet and Vicodin.

At a gathering shortly afterward to celebrate the drug’s launch, Mr. Sackler boasted that “the launch of OxyContin tablets will be followed by a blizzard of prescriptions that will bury the competition. The prescription blizzard will be so deep, dense, and white,” according to a document cited in the legal complaint.

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Company sales representatives told doctors that OxyContin couldn’t be abused and were trained to say that the drug had an addiction risk for patients of “less than one percent,” a claim that had no scientific backing. Within a few years, Purdue Pharma was selling more than $1 billion worth of OxyContin annually.