BOSTON (AP) – An elderly man at Brockton Hospital died after he was given 60 times the recommended dose of a sedative, according to a report.

State investigators say even after a nurse discovered the error, the hospital mistakenly gave the patient, who was not identified, other sedatives and antidepressants for two days as the man’s blood pressure dropped.

Nurses also administered two doses of antibiotics more than six hours late.

The man, who was alert when he entered the hospital on April 9, died four days later on April 13.

Investigators faulted the hospital’s own probe for not uncovering all the mistakes. The state also said Brockton Hospital has failed to put into place all the improvements it had promised.

Asked if the medication errors contributed to the death, Brockton Hospital spokesman Rich Copp told The Patriot Ledger an autopsy concluded that he died of pneumonia.

“When the error was found the doctor and the patient’s family were immediately notified,” Copp said. “Brockton Hospital immediately launched an investigation and has taken several steps to ensure that this will not happen again.”

The errors began when a pharmacist ordered Librium, an antianxiety sedative, instead of the similar-sounding Lithium, the medicine the patient was supposed to take for his bipolar disorder.

Patients can safely take up to 600 milligrams of Lithium a day, but the recommended dose of Librium for elderly people is 5 milligrams two to four times a day.

The pharmacist immediately realized his mistake, and telephoned a nurse to correct it, but the nurse wasn’t there and the pharmacist told investigators he “forgot to follow through.”

The next morning the man got 300 milligrams of Librium, 60 times the safe dose.

A nurse discovered the mistake a day later when she checked on the patient and found him lethargic.

More than 7,000 people die each year from medication errors, according to a 1999 report by the Institute of Medicine.

The state has investigated other cases of medication mistakes at area hospitals this year, including a report that three patients at South Shore Hospital in Weymouth were given higher-than-prescribed doses of medication. However, those patients went sent home with no ill effects, the Ledger reported.