Asante Rogue Regional Medical Center faces a $303 million medical malpractice and wrongful death lawsuit over allegations that a former registered nurse swapped patients’ prescribed fentanyl with tap water.

The lawsuit was filed in Jackson County Circuit Court on Tuesday on behalf of 18 former patients of the Medford hospital.

An Asante spokesperson declined to comment.

The plaintiffs — who include nine patients of Asante and family members of nine patients who died — allege that the hospital failed to recruit, train and supervise employees so as to prevent drug diversion, and that the hospital failed to protect patients from unsafe tap water.

Asante contacted Medford police in December over concerns of “theft and misuse of controlled substances by a former Asante nurse that resulted in infections in multiple patients.”

The hospital began contacting an unknown number of patients during the same month. Patients and patients’ families interviewed by the Rogue Valley Times said they were first contacted in December and told that a hospital nurse was removing fentanyl from IV bags and replacing it with tap water, resulting in bacterial infections.

Tuesday’s case is the largest to date. A civil suit filed in late February by Central Point attorney Justin Idiart first named former Asante nurse Dani Marie Schofield as a co-defendant along with the hospital.

In that case, which seeks $11.5 million in damages, Schofield is alleged to have caused the death of 65-year-old Horace “Buddy” Wilson by replacing the fentanyl in his IV with tap water.

In addition to the pair of civil suits filed to date, Schofield, who was arrested at her home near Eagle Point on June 13, faces 44 criminal counts of second-degree assault — one count for each of the 44 victims named in the criminal case.

Schofield pleaded not guilty to all counts during her first court appearance June 14. She posted a $400,000 bond — 10% of her $4 million bail — one week later.

A pre-trial appearance for Schofield’s criminal trial is set for 9 a.m. Monday. Schofield’s attorneys have requested a stay in civil proceedings for the case filed in February while her criminal case proceeds.

While Asante officials have declined to comment on the civil or criminal proceedings, Asante Senior Vice President and Chief Financial Officer Heather Rowenhorst, during a presentation before the city of Medford Hospital Facilities Authority Board in March, said the health care provider was creating a “pool of funds” in anticipation of potential payouts as a result of the drug-diversion investigation.