A low-cost version of the common drug for anaesthesia and sedation, ketamine has shown promising results as an effective treatment for severe depression.
It's the largest study ever of its kind - a collaboration between clinical mood disorder units in Australia and New Zealand.
Commonly known as Special K, or Horse tranq, it's used as an illegal party drug but when used by doctors or veterinarians the applications of ketamine are practical.
Now it's increasingly known to be effective for treating severe depression.
"It is transformative," lead researcher Prof Colleen Loo said.
The study took place across Australia and here in New Zealand with the University of Otago. It involved 179 people with treatment-resistant depression.
Some were given a generic form of ketamine and others a placebo, with participants receiving two injections a week for a month in the double-blind trial.
"Our study found ketamine was much, much, much more effective than the placebo medication," Prof Loo said.
More than one in five participants were in total remission from their symptoms. While a third had their symptoms improve by at least 50 percent.
A benefit of this trial method is that it's far cheaper compared to other forms approved for use overseas. In Australia, the generic ketamine is around $5. However, patients need to pay for the skill and time in the clinic, including a two-hour observation for side effects - costing $350 per session.
The use of ketamine for treating depression has been explored and researched for more than 20 years.
In New Zealand, Douglas Pharmaceuticals Ltd is currently developing a slow-release ketamine tablet that is proving successful in trials.
"It can be very easily and safely taken at home. It really cuts out all the clinic costs. it still has clinical trials to complete," University of Otago Psychological Medicine Professor Paul Glue said.
The latest research also has many hoops to get through, including its legal classification as it is currently considered a class C controlled drug.
