A human trial of an anaesthetic used by some as a party drug could transform the lives of people living with depression where other treatments have failed.

The Royal Adelaide Hospital in partnership with the Central Adelaide Local Health Network, is seeking eligible volunteers to test the world-first, slow-release ketamine tablet.

People living with depression can access a wide array of treatments but up to half experience a form of treatment-resistant symptoms and don't respond well to current medications.

With its increasing popularity within the medical field, ketamine is starting to be used as an alternative to existing treatments.

The new tablet could be a game-changer with current depression treatments using ketamine requiring direct supervision in clinics, University of Adelaide's Psychiatry department head Scott Clark said.

"The slow-release tablet can be taken at home similar to current antidepressant medications, with regular support from a psychiatrist," he said.

Its properties provide pain relief and anaesthesia and along with its dissociative elements, can change the way people's brains perceive things.

The drug is also used and sold illegally as a hallucinogen in white powder form.

But the sporadic and sometimes faster-than-expected uptake within the body has led to some unpleasant side effects such as drowsiness, disorientation, and changes to blood pressure and heart rate.

Existing ketamine treatments are safe with adequate care and ongoing psychiatric support, the health network's Professor Guy Ludbrook said.

"What we have found from studies to date, is that the slow-release approach we are trialling appears to markedly reduce the risk of rapid bursts of unpleasant effects," he said.

The hospital is seeking people aged 18 and over in South Australia who have been unsuccessful with common antidepressant medications for the trial after clearing safety requirements.

Suitable participants will potentially stay overnight for the first dose, with medication then being able to be taken regularly at home over several weeks as the team closely monitors the patient's progress.