Health insurer Anthem Inc. filed a lawsuit against Insys Therapeutics Inc., alleging the drugmaker fraudulently obtained reimbursements for its opioid painkiller Subsys.

U.S. Attorney General Jeff Sessions will unveil a major crackdown on healthcare fraud involving opioid treatment programs, Bloomberg News reported, citing two people familiar with the matter.

Mallinckrodt Plc, one of the largest manufacturers of the generic opioid painkiller oxycodone, will pay $35 million to resolve allegations that it failed to report suspicious drug orders, the U.S. Justice Department said.

Oklahoma joined growing litigation over claims drugmakers misrepresented the risks of opioid painkillers, as New Hampshire cleared a hurdle in its own probe of the role played by companies in the national addiction epidemic.

Missouri became the third U.S. state to accuse major drug manufacturers of fraudulently misrepresenting the risks of opioid painkillers.