A woman with mental health problems died when she suffered heart failure as a result of having high levels of anti-psychotic drugs in her system, an inquest heard.

Barbara Norman, 53, who was being cared for at Lansdowne House in Warmley, was pronounced dead at Frenchay Hospital on July 7, 2006.

A jury at Flax Bourton Coroner's Court heard a post-mortem examination concluded Ms Norman's body had been unable to cope with the amount of prescription medication she had taken, which prompted her heart and respiratory system to fail.

The inquest heard Ms Norman's family complained to Bath and North East Somerset Primary Care Trust after her death, arguing the tragedy could have been avoided.

In a letter to the trust read out at the inquest, Ms Norman's sister Wendy Ferrari said her sibling started to suffer problems in 2001 and then in 2005 when she was taken off the drug thioridazine, which had helped with her with her schizophrenia for 25 years without ill effects.

She said switching Ms Norman between thioridazine and alternative drugs worsened her condition and culminated in her not walking or talking in the weeks leading up to her death.

Mrs Ferrari said her sister was told she could no longer take thioridazine because it was being withdrawn from sale, only for the health authorities to acquire the drug from abroad to reintroduce it to her in 2006.

In her statement, Mrs Ferrari said she believed that her sister "would still be alive today" if she had not been taken off thioridazine and another drug she had been prescribed.

The inquest was told Ms Norman was set to be transferred from Lansdowne House to a specialist psychiatric unit offering her more intensive treatment but was taken to Frenchay Hospital by ambulance on July 7, 2006, and pronounced dead at 4am.

Avon's deputy coroner Brian Whitehouse heard Ms Norman, who had been detained under the Mental Health Act, had suffered heart failure caused by a combination of high levels of thioridazine and olanzapine, both prescribed drugs.

Annette Parker, representing B&NES PCT, said Ms Norman, who used to live in Knowle, had taken both drugs before with no ill effects.

She said: "We are talking about someone who had been on these drugs and was monitored on them and there were no problems found."

The inquest heard thioridazine, which has been linked with causing heart problems, was withdrawn from sale in the UK in 2002 and worldwide in 2005 and is now only available to patients on a case-by-case basis after a clinical evaluation.

The inquest is expected to last three days.