(Reuters) — Drugmaker Insys Therapeutics Inc. filed for Chapter 11 bankruptcy protection on Monday, about a week after agreeing to pay $225 million to settle a U.S. probe into bribes it paid to doctors for prescribing a powerful opioid medication.

The filing in U.S. Bankruptcy Court in the District of Delaware made Insys the first drug manufacturer to turn to bankruptcy due to legal expenses brought on by accusations of responsibility in the deadly U.S. opioid epidemic. Shares of the company fell nearly 60% to 52 cents in premarket trading.

Insys said it intends to continue operating its business, while it pursues the sale of substantially all its assets under a court-supervised sale process.

Chandler, Arizona-based Insys, which manufactured the fentanyl spray Subsys, agreed on June 5 to settle the U.S. Justice Department probe and have a subsidiary plead guilty to fraud charges.

A month earlier, a federal jury in Boston found Insys founder John Kapoor and four other former executives and managers guilty of engaging in a vast racketeering conspiracy.

Subsys is an under-the-tongue spray the U.S. Food and Drug Administration approved in 2012 only for treating pain in cancer patients. Its main ingredient, fentanyl, is an opioid 100 times stronger than morphine.

Prosecutors alleged that while Mr. Kapoor served as Insys’ chairman, the company from 2012 to 2015 paid doctors and other medical practitioners bribes in exchange for prescribing Subsys to their patients, often to those who did not have cancer.

Insys did so by paying medical practitioners to act as speakers at sham events ostensibly meant to educate clinicians about Subsys.

Prosecutors said the scheme helped boost sales of Subsys, whose net revenue grew from $8.6 million in 2012 to $329 million in 2015. Insys went public in 2013 with what became the best-performing initial public offering of that year.

The Justice Department probe led to multiple people being charged including Mr. Kapoor, the company’s majority shareholder, in October 2017 on the same day U.S. President Donald Trump declared the opioid crisis a public health emergency.

Opioids were involved in a record 47,600 U.S. overdose deaths in 2017, the U.S. Centers for Disease Control and Prevention has said.

The investigation took a toll on Insys, and sales of Subsys declined. In May, Insys said it had just $87.6 million in cash at the end of the first quarter and $240.3 million in liabilities.

The company said on Monday it intends to pay vendors and suppliers in full for goods and services provided after the filing date of June 10.

Other opioid manufactures face lawsuits by state and local governments seeking to hold them responsible for the epidemic, including OxyContin maker Purdue Pharma. Purdue has also considered filing for bankruptcy to address potentially significant liabilities from roughly 2,000 lawsuits, sources told Reuters in March.