Daughter denies NSW nursing home murder

A woman accused of murdering her 92-year-old mother in a NSW nursing home has formally pleaded not guilty.

The role of a particular barbiturate in the death of Mary Elizabeth White is expected to be an issue at the trial of her 68-year-old daughter, Barbara Mary Eckersley.

Ms White died in an aged care facility in Bundanoon, in the Southern Highlands, on August 5, 2018.

Eckersley was charged with murder three days later.

"Not guilty, Your Honour," she told Justice Robert Allan Hulme in the NSW Supreme Court on Friday.

Eckersley's intentions and whether she had a substantial mental impairment at the time of the alleged offence were also possible defences to be heard at trial, her lawyer said.

The matter will return to court later in 2020.