After the mistake was reported to the pharmacy board, an investigator for the state checked 200 prescriptions at the Owasso pharmacy for accuracy and found a 9.5 percent error rate, according to the complaint. Some errors were minor — like portions of directions that were missing — but others were more significant. A patient was told to take the wrong dose, for instance: one tablet instead of one-half.

The board wrote in the complaint that it had received “several letters of concern from various CVS employees regarding the lack of adequate staffing” at the company’s pharmacies.

Across the country, pharmacists who work at CVS and elsewhere have reported that their corporate offices have cut the hours of technicians who help behind the counter, and have pared back or eliminated shifts with overlapping pharmacists.

The Oklahoma investigator, who was at the Owasso CVS for three and a half hours, noted that the phone rang “almost constantly, with rarely a five minute break in between calls and several instances of more than one line ringing at a time,” according to the complaint.

The investigator also observed “almost constant foot traffic” in the store and a routinely packed drive-through.

The complaint states that on the day of the error involving the anticonvulsant medication, the pharmacist on duty was responsible for checking 194 prescriptions in a six-hour shift — about one every two minutes.

The store’s lead pharmacist told the state board that he had no control over staffing. He had complained about staffing to his district leader, but the district leader also had no power to make changes, according to the complaint.