The opioid manufacturer Insys Therapeutics filed for bankruptcy protection Monday, days after agreeing to pay $225 million to settle a federal investigation into the marketing practices for its powerful fentanyl painkiller.

The company said it would continue operating while it comes up with a plan to pay its creditors, including the Justice Department, under Chapter 11 of the federal bankruptcy code. Under an agreement released last week with the federal government, the company has promised to divest of Subsys, its lead product and the painkiller that had come under scrutiny.

The company was accused of bribing doctors to prescribe its product and misleading insurers about patients’ need for the drug. Subsys, an under-the-tongue spray, was approved only for cancer patients who were already taking round-the-clock opioid painkillers.

“We determined that a court-supervised sale process is the best course of action to maximize the value of our assets and address our legacy legal challenges in a fair and transparent manner,” Andrew G. Long, the chief executive of Insys, said in a statement Monday.