(Reuters) - Washington state on Thursday sued OxyContin maker Purdue Pharma LP, becoming the latest state or local government to file a lawsuit seeking to hold pharmaceutical companies accountable for a national opioid addiction epidemic.

FILE PHOTO: A pharmacist holds prescription painkiller OxyContin, 40mg pills, made by Purdue Pharma L.D. at a local pharmacy, in Provo, Utah, U.S. on April 25, 2017. REUTERS/George Frey/File Photo

The city of Seattle also filed a separate lawsuit against Purdue as well as units of Teva Pharmaceutical Industries Ltd, Johnson & Johnson, Endo International Plc and Allergan plc.

The lawsuit by Washington Attorney General Bob Ferguson accused Purdue of deceptive marketing of OxyContin and convincing doctors and the public that its drugs had a low-risk of addiction and were effective for treating chronic pain.

He said he would be seeking to force Purdue to pay a “significant” sum for engaging in marketing practices that downplayed the addictiveness of its drugs, allowing it to earn billions of dollars while fuelling the opioid crisis.

“I don’t know how executives at Purdue sleep at night,” Ferguson told reporters.

Stamford, Connecticut-based Purdue said in a statement it was “deeply troubled” by the opioid crisis and that its U.S. Food and Drug Administration-approved products account for just 2 percent of all opioid prescriptions.

“We vigorously deny these allegations and look forward to the opportunity to present our defense,” Purdue said.

According to the U.S. Centers for Disease Control and Prevention, opioids were involved in over 33,000 deaths in 2015, the latest year for which data is available. The death rate has continued rising, according to estimates.

The lawsuits followed a wave of cases against opioid manufacturers and distributors by Louisiana, West Virginia, New Mexico, Oklahoma, Mississippi, Ohio, Missouri, New Hampshire and South Carolina, as well as several cities and counties.

Purdue and three executives pleaded guilty in 2007 to federal charges related to the misbranding of OxyContin, which is used to relieve pain, and agreed to pay a total of $634.5 million to resolve a U.S. Justice Department probe.

That year, the privately held company also reached a $19.5 million settlement with 26 states and the District of Columbia. It had agreed in 2015 to pay $24 million to resolve a lawsuit by Kentucky.

In filing his lawsuit in King County Superior Court in Seattle on Thursday, Ferguson said he was breaking off from an ongoing multi-state probe by various attorneys general into companies that manufacture and distribute opioids.

While Ferguson said looked forward to seeing its results, “we felt we had a case ready to go.”