A middle-aged man died after being injected with four doses of the former "legal high" drug mephedrone resulting in the second highest ever concentration of the substance experts had ever recorded, an inquest heard today.

Pathologist David Wright found that Mr Smith had suffered coronary artery disease as well as mephedrone poisoning, but said: “It seems unlikely he would have died when he did without mephedrone.”

The 46-year-old suffered a cardiac arrest at his home in The Drive, Hove, East Sussex, in the early hours of February 7.

An inquest at Brighton County Court heard that Mr Smith, a part-time sales assistant, was also HIV positive, suffered from chronic renal disease and high blood pressure, and was an insulin-dependent diabetic.

The hearing was told he had spent the evening at his home with two men, having sex and injecting themselves and each other with mephedrone.

Christopher Sarson said he saw Mr Smith suddenly fall on to his side and he realised he was having some kind of seizure.

He said: "It was as though he was trying to breathe. We knew there was something wrong."

Mr Sarson said the other man, Ian Turner, rushed outside to call an ambulance while he started performing CPR on Mr Smith.

He had to wipe blood away from his mouth which he believed had been caused by him biting down on his tongue.

Mr Turner told the inquest: "I saw that John's lips had gone purple. He was gargling and he was trying to - he appeared to be clutching his chest."

He said he believed around an hour had passed between this happening and when Mr Smith had taken his last dose of mephedrone.

Note: This story originally used copy filed by an agency, which read: "But pathologist Dr David Wright, who conducted a post-mortem examination on John Sterling Smith, said it was "unlikely" that this alone killed him as he was also suffering from severe coronary artery disease."

However, The Argus also had a reporter in court, who filed the copy on which our later story here was based.

This made it clear the accurate quote was: “It seems unlikely he would have died when he did without mephedrone,” and so the story has now been amended.