A prosecutor says five people have been charged in connection with Matthew Perry's death from a ketamine overdose last year, including the actor's assistant and two doctors.

US Attorney Martin Estrada announced the charges Thursday, saying the doctors supplied Perry with a large amount of ketamine and even wondered in a text message how much the former “Friends” star would be willing to pay.

“These defendants took advantage of Mr Perry's addiction issues to enrich themselves. They knew what they were doing was wrong," Estrada said.

Perry died in October due to a ketamine overdose and received several injections of the drug on the day he died from his live-in personal assistant. The assistant, Kenneth Iwamasa, is the one who found Perry dead later that day.

Two of the people, including one of the doctors charged, have been arrested, Estrada said. Two of the defendants, including Iwamasa, have pleaded guilty to charges already, and a third person has agreed to plead guilty.

Iwamasa's attorneys did not immediately return a message seeking comment.

The prosecutor said the defendants exchanged messages soon after Perry's death referencing ketamine as the cause of death. Estrada said they tried to cover up their involvement in supplying Perry ketamine, a powerful anesthetic that is sometimes used to treat chronic pain and depression.

Los Angeles police said in May that they were working with the US Drug Enforcement Administration and the US Postal Inspection Service with a probe into why the 54-year-old had so much of the surgical anesthetic in his system.

Iwamasa found the actor face down in his hot tub on Oct 28, and paramedics who were called immediately declared him dead.

His autopsy, released in December, found that the amount of ketamine in his blood was in the range used for general anesthesia during surgery.

The decades-old drug has seen a huge surge in use in recent years as a treatment for depression, anxiety and pain. People close to Perry told coroner's investigators that he was undergoing ketamine infusion therapy.

But the medical examiner said Perry's last treatment 1 1/2 weeks earlier wouldn't explain the levels of ketamine in his blood. The drug is typically metabolised in a matter of hours. At least two doctors were treating Perry, a psychiatrist and an anesthesiologist who served as his primary care physician, the medical examiner's report said. No illicit drugs or paraphernalia were found at his house.

Ketamine was listed as the primary cause of death, which was ruled an accident with no foul play suspected, the report said. Drowning and other medical issues were contributing factors, the coroner said.

Perry had years of struggles with addiction dating back to his time on “Friends,” when he became one of the biggest television stars of his generation as Chandler Bing alongside Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc and David Schwimmer for 10 seasons from 1994 to 2004 on NBC's megahit sitcom.

Drug-related celebrity deaths have in other cases led authorities to prosecute the people who supplied them.

After rapper Mac Millerdied from an overdose of cocaine, alcohol and counterfeit oxycodone that contained fentanyl, two of the men who provided him the fentanyl were convicted of distributing the drug. One was sentenced to more than 17 years in federal prison, the other to 10 years.

And after Michael Jackson died in 2009 from a lethal dose of propofol, a drug intended for use only during surgery and other medical procedures, not for the insomnia the singer sought it for, his doctor, Conrad Murray, was convicted of involuntary manslaughter in 2011. Murray has maintained his innocence.