AN ELDERLY woman whose death was thought to have been down to heart disease was killed by an accidental drug overdose, an inquest heard.

Eileen Thomas, 78, from Glenwood Avenue, Westcliff, died soon after being fed by carers at her home, Chelmsford Coroners Court was told.

The frail wheelchair-bound woman was found unresponsive in her chair when careers returned after 10pm on November 11, 2011.

Police were called by her daughter, Linda, who was concerned a bottle of oramorph – a morphine-based drug or opioid – was missing. But officers ruled the death was not suspicious.

She had previously suffered from severe depression and brain damage following a haemorrhage which left her weak down one side.

The court heard Dr Simon Payne carried out a postmortem at Southend Hospital, which concluded she died of natural causes as her main artery had narrowed by 90 per cent.

But subsequent toxicology tests, which came back in August that year, showed there were fatal amounts of another type of painkiller, tramedol, in her blood.

There were also traces of tamazepam, a drug used for anxiety and insomnia.

The court heard tramedol is potentially lethal at 2 micrograms per milligram of blood, and was found in her system at a level of 2.5 micrograms.

The court heard medics felt that over time users became tolerant to the drug and it’s sideeffects and may “self medicate”.

The combination of the raised level plus the heart disease was “significant”, the court heard.

Coroner Caroline Beasley- Murray Drew drew a conclusion of accidental death. She said: “It was not a massive overdose, but within the fatal range. On the balance of probabilities, this was an accident.”