Hamish Hardie, 30, died at his home in Wisborough Green, Billinghurst in August last year, after accidentally overdosing on medication for severe back pain, he received at Loxwood Medical Practice.
An inquest, which was opened in January, continued at Crawley Coroner's Court today (Wednesday, November 25).
The inquest heard how an 'unfortunate' human error led to confusion over the correct dosage Hamish should have taken.
Hamish was given a prescription of oramorph, dihydrocodeine and diazepam but the dosage was not written on the oramorph bottle, with 'use as directed' instead written on the bottle.
Dr Oliver Starr, a general practitioner (GP) based in Hertfordshire, gave evidence as an impartial witness.
He stated that it was initially a computer error which led to the vague instruction on the bottle but it was the responsibility of third-year trainee GP, Dr Carlos Novo, to manually fix this error.
"It was unfortunate," he said. "It's an error we've all made, and I've made, to leave it as use as directed.
"The GP would have been left to free text the prescription when we are used to just printing and signing.
"It was 5.30 in the afternoon after a long day. It's not excusable but understandable."
Dr Mark Piper, a GP at Loxwood Medical Practice who had consultations with Hamish in early July, also gave evidence.
He said it was 'not unreasonable' to add oramorph to morphine due to the 'challenges when dealing with patients in severe pain'.
However, he admitted that it 'wasn't best practice' to say use as directed.
"Wholesale changes have now been made in the dispensary," he said. "It would have been best practice for them to challenge it but it doesn't question their competence.
"It's an anomaly. We have done an awful lot of training with the dispensary team and we have employed a pharmacist."
The inquest heard how Mr Hardie, a public relations consultant, was 'on the road to recovery' after a history of drug addiction — which his GP was unaware of.
Karen Henderson, the assistant coroner for West Sussex, asked if Hamish's previous history of cocaine use should have been clearly highlighted when the prescription was given.
"That's not usual practice, it's done on an individual basis," Dr Starr said. "It would have been helpful in this case as I think Dr Novo would have been more cautious if he had of known."
Dr Starr said that this was an important factor as 'you wouldn't want' someone with a history of drug dependence 'to take too much'.
He added: "It's a warning sign for me as a doctor. It's possible that their old habits might come back and they might take more than they need."
Dr Piper said it was 'clearly visible' that Hamish had a history of drug dependency. He said, that following Hamish's death, there has been changes to the system so previous medical records will be disclosed before consultations.
'I trusted my son and he was on the road to recovery'
Dr Robert Forrest, a professor in law and formally in forensic toxicology, led an independent review of the toxicological issues in Hamish's case.
Professor Forrest said that, on the balance of probabilities, the dosage itself didn't cause Hamish's death. He said it was instead likely to have been caused by the mixture of medical drugs taken.
He said it would have been 'common sense' for the provider to ensure Hamish knew what we was taking.
However, he said he would have been 'unhappy' if he received medication with a use as directed note, so would have read the 'package insert' and checked with the surgery.
Hamish's mother, Mary-Anne Hardie, was asked by the coroner if, in retrospect, she would have checked the dosage independently, following his 'recent relapse' in addiction issues.
"I relied on him to tell me what the dosage was," she said.
"I trusted my son and he was on the road to recovery. He was in a good place, going to job interviews.
"Hamish told me there was no point ringing the surgery as they wouldn't speak to me [due to patient confidentiality].
"I didn't and I will live with that every day."
Mrs Hardie said she did not believe she was misled by her son over the instructed dosage. She added that there was no way of him accessing the bottle as it was 'locked every night' and the keys were hidden 'where there was no way of him finding them'.
In her conclusion, in which she offered her condolences to the Hardie familly, Ms Henderson ruled a verdict of an accidental overdose on prescribed medication.
She said: "This was a clinical error, compounded by a further lack of clarity in how much was given."
However, Ms Henderson did note that there was no evidence to suggest that the surgery had been negligent, due to the 'prompt assessment and thorough treatment' given to Hamish.
On the subject of preventing future deaths, the coroner said she was satisfied the surgery had implemented procedures to ensure the same mistakes would not be repeated.
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