Matthew Perry, the “Friends” actor who publicly struggled with drinking and drug use for decades, died from “the acute effects of ketamine,” the Los Angeles County Medical Examiner said in an autopsy report that was released on Friday, months after he was found dead at his home.

Perry was found unresponsive in a hot tub on Oct. 28. He was 54.

The coroner’s office said Perry, who also had the opioid buprenorphine in his system, had drowned in an accident. The report said that he also had coronary artery disease. The medical examiner also listed the effects of the buprenorphine as a contributing factor in his death.

Ketamine is a powerful anesthetic that has become increasingly popular as an alternative therapy for depression, anxiety, post-traumatic stress disorder and other hard-to-treat mental health problems. The Food and Drug Administration issued an alert in October warning about the dangers of treating psychiatric disorders with compounded versions of the drug.

The autopsy report said that Perry had been “on ketamine infusion therapy” and that his most recent therapy was about a week and a half before he died. The report noted that the ketamine in his system when he died could not have been from that infusion therapy, since the drug’s half life is three to four hours, or less.