A 69-year-old woman developed severe mental health problems after taking part in trials of a cannabis-based treatment and died five months later, an inquest heard today.

Rene Anderson, a diabetic, began to become "confused and intoxicated" just three days after starting to take the drug Sativex, which is derived from cannabis.

A coroner was told how Mrs Anderson, of Silkstone Close, Sheffield, was admitted to hospital after her mental state had deteriorated so much "she was not the same person".

The inquest, which could have far-ranging implications for the use of drugs derived from the cannabis plant, heard how retired supermarket supervisor Mrs Anderson’s physical condition declined in hospital until she died on March 3 last year from acute kidney failure.

She had been taking part in a trial supervised by diabetes expert Dr Solomon Tesfaye, who told the court he wanted to investigate whether cannabis could provide useful relief from the severe pain experienced by diabetic neuropathy sufferers.

He said Sativex, which is not yet licensed in the UK but has been granted a licence in Canada, had shown good results in Multiple Sclerosis sufferers.

The consultant told the inquest he asked the drug firm GM Pharmaceuticals to supply Sativex for the Sheffield trial in diabetic neuropathy patients, and the research was funded by Diabetes UK.

Dr Tesfaye said he was first aware of Mrs Anderson’s case when her family complained about her mental problems, just days after her treatment began. He said: "My understanding was that there was some confusion and intoxication, as if being drunk."

The doctor said the dose of the drug, which is taken using an oral spray, was reduced on advice from GM Pharmaceuticals, but Mrs Anderson’s daughter, Jackie Sadler, rang back two weeks later to tell his colleague of her mother’s deterioration.

Dr Tesfaye added: "She said to him that her mother was not the same person. He used those words."

Sheffield Coroner Chris Dorries, sitting at the city’s Medico-Legal Centre, heard how Mrs Anderson suffered a series of physical problems after she was admitted to hospital, including pneumonia, culminating in her death at another city hospital, the Northern General.

Pathologist John Shortland told the inquest kidney failure had followed respiratory problems which had been caused by a number of factors relating to her illness. He agreed that the immobility caused by her illness could have played a part in her decline.

The coroner said the purpose of the inquest was to examine what links there were, if any, between the experimental treatment and the physical deterioration which led to Mrs Anderson’s death. He said it would "try to establish whether there is a clear and direct link or, indeed a clear and indirect link between the drug that was taken on trial and the death."

Mr Dorries said he was aware of academic literature which suggested some people may have a genetic predisposition to mental health problems after taking cannabis. He said that consideration of this debate would form part of the inquest, but that he was not sure at this stage what relevance it had to Mrs Anderson’s death.

Speaking before today’s hearing, the Anderson family’s solicitor Richard Starkie said: "If it is found that Sativex did in fact play a part in her illness or death, it would clearly raise some very important questions as to the safety of the drug."

He declined to say whether Mrs Anderson had a previous history of mental illness, but added: "There is no disputing that Mrs Anderson did get pain relief from the drug, but it also raises the question of who should not have this drug."

Ms Sadler said: "Our mother was a wonderful woman who still had a great deal of life in her. We are still in the dark as to how she became so ill and why she died and none of the medical experts involved have yet been able to answer our questions."

But a spokesman for GM Pharmaceuticals said he was surprised and disappointed that Mr Starkie had pre-empted the conclusion of the inquest. He added: "This is a complex case involving a patient with a serious and long-standing illness, who finally succumbed to pneumonia and kidney failure. She was taking a wide range of medicine both before and after her brief involvement in the Sativex trial."

The inquest is expected to last five to six days.

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