LUNENBURG -- A Shirley woman was arrested on drugged-driving charges for allegedly getting behind the wheel after being observed using an intravenous drug in a local Walmart parking lot, according to court documents.

Kelly A. Schuster, 21, of 8 Lawton Road, is charged with operating a motor vehicle under the influence of drugs and possession of a Class E substance.

According to a police report included with court documents, Schuster and a male subject were allegedly observed administering an intravenous substance to themselves in the back seat of Schuster's car Wednesday evening.

A witness told police Schuster staggered around and "could hardly stand up" as she entered the store and returned to the car. When an officer arrived, he saw Schuster's car exiting the parking lot with her operating and pulled her over.

The officer said Schuster was allegedly unsteady on her feet and drowsy, and failed field sobriety tests. A search of the car turned up several prescription medications under another person's name, including Clonidine, Hydroxazine and Xanax, according to the report.

Schuster was released on personal recognizance and is due back in Fitchburg District Court May 5.