A former sales representative for a major drug manufacturer has admitted to charges she helped fuel the opioid addiction crisis by bribing doctors to prescribe a potent painkiller, authorities said.

Michelle Breitenbach, who worked for the pharmaceutical company Insys Therapeutics, Inc., pleaded guilty Wednesday to a second-degree charge of conspiracy to commit commercial bribery, according to the state Division of Criminal Justice, which brought the charges.

Michelle Breitenbach, 38, of Middletown.

Breitenbach's guilty plea comes after state authorities filed a civil lawsuit against her former employer, accusing Insys of "evil" practices that pushed doctors to prescribe its painkiller Subsys for conditions it was never intended to treat. The civil case is ongoing.

Attorney General Gurbir Grewal said Wednesday that a "primary cause of the devastating opioid epidemic gripping the country has been overprescribing of prescription opioids, driven by the greed of manufacturers."

State authorities say the company gave kickbacks to doctors in the form of phony "speaker's fees" that really served as payments for "off-label" prescriptions that gave patients the painkillers for purposes not approved by the federal Food and Drug Administration.

An NJ Advance Media investigation published last year found many doctors across the state received lucrative payments from drug companies. From 2013 to 2015, doctors in New Jersey were paid at least $1.67 million by pharmaceutical companies marketing various forms of of the synthetic opioid fentanyl, including Insys.

Last year, the state Board of Medical Examiners cracked down on doctors with relationships with Insys. In court filings, Breitenbach was quoted as telling one doctor who had allegedly prescribed Subsys to multiple patients to "keep them rolling."

As part of a plea deal, Breitenbach, 38, "admitted that the payments made to the doctors as 'speakers' were actually rewards for prescribing more Subsys," the Attorney General's Office said Wednesday.

The Middletown resident now faces up to five years in prison. Sentencing is scheduled for July 6. Her attorney did not immediately return a message seeking comment.

S.P. Sullivan may be reached at ssullivan@njadvancemedia.com. Follow him on Twitter. Find NJ.com on Facebook.