Ketamine is a dissociative drug, which means it acts on different chemicals in the brain to produce visual and auditory distortion, and a detachment from reality.
It is used medically for induction and maintenance of anaesthesia, a pain management tool, and as an illegal recreational drug. It can also be used as a treatment for depression.
In an editorial in the latest New Zealand Medical Journal, University of Otago (Christchurch) psychological medicine researchers Dr Ben Beaglehole, Associate Prof James Foulds and Prof Roger Mulder examined the use of ketamine to treat mental illness in New Zealand and how it is evolving.
In New Zealand, the drug is mainly used in research settings, although there is limited use by publicly funded specialty services.
Recently, treatment has been offered by private providers.
Dr Beaglehole said studies showed ketamine was associated with short-term improvements in depression symptoms, but it could lead to high rates of relapse when treatment ended.
Managing these relapses would be a challenge for clinicians, he said.
"Additionally, there are concerns about the abuse potential of ketamine and other adverse factors including bladder issues and possible memory side effects."
While most ketamine used recreationally was produced offshore, lessons learned from other medications indicated there may be some misuse and diversion of prescribed ketamine for illicit use, he said.
"Patients who undergo this treatment will need to be carefully selected and closely monitored for adverse outcomes.
"The potential offered by ketamine is exciting, but history suggests tempering our enthusiasm, given lessons learned from other exciting treatments in our past."
The Royal Australian and New Zealand College of Psychiatrists recommends restricting use to treatment-resistant depression (outside of research settings) and ensuring its use only occurs in services where clinicians are familiar with the drug, and support structures are in place.
Dr Beaglehole said ketamine was best initiated by specialty services for the primary indication of treatment-resistant depression, although careful attention to equity of access was required.
