Principal investigator of the clinical trial is Prof Paul Glue, head of psychological medicine at the Dunedin School of Medicine, whose off-label prescribing of ketamine at Dunedin Hospital prompted complaints leading to investigations by two government agencies. Prof Glue received permission for the trial late last year from the Ministry of Health's Lower South Regional Ethics Committee.
On Thursday, the National Health Board released terms of reference for an investigation into whether mental health patients unwittingly took part in medical research last year. The Health and Disability Commissioner, having previously rejected a complaint, this month started to examine ketamine use at Dunedin Hospital.
Mr Bunton said research trials at the hospital were subject to stringent ethical controls, including the DHB's own ethics committee, but in the mental health service ketamine had been used off-label with consent and not in a trial. Off-label use of drugs was not rare.
Specialists assess ethics approval requirements by referring to international medical literature, Mr Bunton said. Ketamine had definitely been trialled in severely depressed people, but its use was probably not supported in literature for use in cancer patients.
"[Ketamine] may have never been used for [depression] in cancer patients before. I don't know, but I presume that would be the reason."
Ketamine, licensed by Medsafe as a fast-acting general anaesthetic, was also used for pain relief in milder doses. It is a Class C controlled drug, used recreationally for its hallucinogenic effects.
Dunedin Hospital medical oncologist Dr David Perez, a co-investigator in the cancer trial, said one patient was taking part so far, with promising early results.
A lack of reported clinical data meant the use of ketamine was experimental for depression in cancer patients, although the drug was commonly used as pain relief for cancer patients, Dr Perez said.
National Health Board service improvement manager Jill Lane said hospital staff, as well as the Otago Mental Health Support Trust, raised concerns about ketamine when interviewed for the general systems assessment being carried out at the hospital.
The NHB appointed a subcommittee to investigate, comprising Ms Lane and Capital and Coast DHB psychiatrist, Dr Greg Young. Two new members who were not part of the general review team join them: Auckland University Prof Graham Mellsop, and consumer adviser Fiona Clapham Howard.
The group will interview patients, review medical notes, and talk to clinical and management staff. The group will consider the quality of hospital processes used to determine where off-label prescribing in mental health is appropriate. They will also look at whether the hospital handled information requests about off-label prescribing "transparently."
Hospital processes allowing off-label prescribing in mental health are to be scrutinised.
The group's report will be delivered later, as an addition to the main assessments review, which is due next month.
When the NHB review was announced, Prof Glue indicated he would not comment while the matter was investigated.
