Montana is suing the makers of the pain medication OxyContin following a multistate investigation into opioid manufacturers' marketing practices.
Montana Attorney General Tim Fox says the legal action accuses Purdue Pharma of misrepresenting the risk of long-term use of its drug leading to addiction and falsely claiming it's safe for treating chronic pain.
"Our investigation has revealed and our complaint alleges that executives at Purdue knew exactly what they were doing," Fox said during a news conference.
Purdue did not immediately respond to a request for comment. It has denied similar allegations, saying its medications are approved by the US Food and Drug Administration for long-term use and carry warning labels about their addiction risks.
Opioids were involved in over 33,000 deaths in 2015, according to the US Centers for Disease Control and Prevention.
