The death of Friends star Matthew Perry has been ruled an accident from the “acute effects of ketamine”, the County of Los Angeles Department of Medical Examiner confirmed.

Perry, who played Chandler Bing in the hit US sitcom, was found “unresponsive in the pool at his residence” on October 28 before he was pronounced dead at the age of 54.

A post-mortem examination concluded Perry died from the “acute effects of ketamine” while contributing factors included “drowning, coronary artery disease and the effects of buprenorphine” – which is described as an “opioid-like drug used in the treatment of opioid addiction as well as acute and chronic pain”.

“The manner of death is accident,” The County of Los Angeles Department of Medical Examiner confirmed.

Senior deputy medical examiner Raffi Djabourian’s summary said: “At the high levels of ketamine found in his post-mortem blood specimens, the main lethal effects would be from both cardiovascular overstimulation and respiratory depression.

“Drowning contributes due to the likelihood of submersion into the pool as he lapsed into unconsciousness; coronary artery disease contributes due to exacerbation of ketamine induced myocardial effects on the hearts.”

The report summary said Perry was receiving “ketamine infusion therapy for depression and anxiety”, with his last known treatment one-and-a-half weeks prior to his death.

The medical examiner ruled that “the ketamine in his system at death could not be from that infusion therapy”, but was not able to specify the “exact method of intake” in Perry’s case.

The report suggests Perry had been “reportedly clean for 19 months” from drug use.

During his life, Perry was open about his battle with substance abuse and addiction – and also set up a sober living facility for men with similar issues.

Following his death, a foundation was set up in his name to help those struggling with addiction.

Friends co-star Jennifer Aniston, who played Rachel Green in the sitcom, was among those urging support of the foundation which was set up to “honour his legacy”.

Perry’s cause of death comes days after Aniston revealed she had been messaging him on the morning of his passing, describing him as “happy and healthy”.

“I want people to know he was really healthy, and getting healthy. He was on a pursuit. He worked so hard. He really was dealt a tough one,” she told Variety.