Party woman died after taking 'legal high' drug cocktail

Miss Waters, 24, took the substance – also known as M-Cat and Meow Meow – at a party with friends in the early hours of March 20 this year, just weeks before the so-called legal high was outlawed.

When she later complained of feeling unwell friends just thought she was tired after staying up all weekend. But just 48 hours later she was found dead in bed.

An inquest was told yesterday Miss Waters, of Wood Street, Norton, North Yorkshire, had taken the drug "many times before" – never realising she suffered from an undetected medical condition which restricted the flow of blood to her heart.

The inquest heard that Mephedrone had become the latest craze after Ecstasy and other young people were being offered it at the party.

The heart defect, combined with the Mephedrone – which an expert classed as similar to Ecstasy – and two anti-depressants she was taking was likely to have caused her death.

After falling asleep at her friend Sarah Ford's house in Riverside View, Norton, Miss Waters was found dead by her friend in the early hours of May 22, the inquest at Scarborough County Court was told.

Miss Ford said: "I saw her take the M-Cat and I did it with her. People were offering it to other people at this house we were all at. I had seen Lois take it before many times."

She had offered her friend a bed for the night on March 21.

"The day before she died she said she had a headache and was feeling unwell, but she had been up for the whole weekend so I put it down to that," she added.

Forensic toxicologist Dr Simon Elliott told the hearing: "Mephedrone is quite an unknown substance in terms of toxicology. We have only known about it in the late 2000s.

"Designer drugs are constantly prevalent in our society. After Ecstasy there was always going to be something to follow it. It is related to amphetamines so it is likely to be a stimulant where users feel a euphoria, a rush."

He found 0.15mg per litre of Mephedrone in Miss Waters's blood, which he considered relatively low. But he believed the Mephedrone could have worked in combination with the anti-depressants to affect the heart even though the dose was only "recreational".

He said he had studied 17 deaths of Mephedrone users – although many were victims of accidents, suicides and other causes.

Miss Waters had taken sick leave from Malton Bacon Factory during a bout of depression in late 2009 and had been prescribed anti-depressants but was getting over it and was looking for another job.

The inquest heard that the cause of death was reduced blood supply to the heart muscle, usually associated with coronary artery disease, and pneumonia, contributed to by Mephedrone and anti-depressant medication.

Recording a verdict of misadventure, Coroner Michael Oakley said: "The drugs she had been taking could have affected her heart, most particularly Mephedrone possibly working in conjunction with the anti-depressants."