Alzheimer's sufferer Ken Godward, 76, and cancer patient Roger Lamb, 79, died after they were beaten by 70-year-old Harry Bosomworth with a walking stick at St James's University
Hospital in Leeds in February 2015.
The inquest at Wakefield heard mentally ill cancer patient Mr Bosomworth had been acting aggressively and attacked the men on a hospital ward after waking up following sedation.
He later told security staff he believed he had attacked burglars who had broken into his home.
Mr Bosomworth's stepdaughter Rita Martin told an inquest into Mr Godward and Mr Lamb's deaths that he was denied his anti-psychotic medication in hospital, despite her
repeated requests for him to be given it.
Mrs Martin, of Swarcliffe, Leeds, told the inquest at Wakefield that Mr Bosomworth was diagnosed with schizophrenia in 1962, had been stable for 53 years while taking anti-psychotic
Mrs Martin said Mr Bosomworth should have been given anti-psychotic medication olanzapine while he was at St James's Hospital.
Mr Bosomworth was admitted to Sr James's on January 27 2015 and suffered a seizure on February 2.
The inquest was told On February 12 he was discharged to a care home without his stepdaughter's knowledge and suffered a psychotic episode while there.
He was re-admitted to St James's Hospital on February 19 and assessed by mental health services on February 22.
The inquest heard he was not given olanzapine in hospital until February 24, when he was given a lower dose then he had previously taken.
Mr Bosomworth refused to take the medication the following day.
The attack happened on February 28 2015.
Mrs Martin told he inquest: "Not one single person I spoke to throughout his whole stay had any comprehension of the nature of paranoid schizophrenia let alone mental health problems.
"They didn't place any value on his suffering. If he was pain they gave him painkillers, if he was sick they gave him ant-sickness tablets, but his mental suffering and torture, it meant
nothing, it didn't matter. It was just, oh, give him a sedative that will calm him down."
Mrs Martin said she believes the attack that led to the deaths of Mr Lamb and Mr Godward was "not only preventable but predictable".
The inquest heard Mr Bosomworth received "outstanding" care from social workers while being treated at St. James's in June 2014.
An arrangement was later made which saw a Co-op chemist bring a package with tables for the week out to Mr Bosomworth's home.
But around six weeks before Mr Bosomworth was admitted to hospital on January 27, 2015, it became apparent he was not taking his medication, the inquest heard.
Mrs Martin, whose mother married Mr Bosomworth, found tablets stashed in an old-fashioned coffee tin.
She then began to make regular visits to his home to make sure he took the medication.
On February 25 during a hospital visit, Mrs Martin told the inquest she was cornered by Mr Bosomworth, who made a rude gesture towards her.
She said: "To take anti-psychotic medication for 50 odd years and then to cut it dead has got to have some devastating effects on the brain and body.
"I could not convince anybody that was not the case. It was an ongoing nightmare.
"Everyone I spoke to seemed to misinterpret everything I said."
Mr Bosomworth died of throat cancer in June 2015 after being diagnosed around two years previously.
The inquest was previously told Mr Lamb had stepped in to help Mr Godward when he was being attacked.
Mr Godward's daughter-in-law Lisa Dixon told the inquest she spoke to Mr Lamb in hospital before he died and commended his bravery.
Mr Godward died on March 3, 2015, from sepsis due to pneumonia with underlying Alzheimer's.
Mr Lamb died on March 5 from a chest infection due to a fracture of the right hip which ultimately occurred as a result of blunt force trauma.
The inquest continues.