A nasal spray containing ketamine, a powerful general anaesthetic, has shown promise in treating symptoms of severe depression and suicidal thoughts, according to a new study.
Researchers compared the effects of two treatment options: the first was standard treatment with antidepressants in hospital plus a nasal spray containing esketamine (part of the ketamine molecule); while the other was standard treatment plus a placebo.
68 participants were randomly assigned a treatment, either receiving esketamine or placebo twice a week for four weeks. The researchers then analysed its effects four hours, 24 hours and 25 days after first treatment.
They found a significant improvement in depression scores and decreased suicidal thoughts in the esketamine group compared to the placebo group at four hours and at 24 hours. However effects levelled out at 25 days.
The Royal College of Psychiatrists told the BBC it was a “significant” study that brought the drug “a step closer to being prescribed on the NHS”.
Researchers said the results of the study support nasal spray esketamine as a possible effective rapid treatment for patients who are deemed at imminent risk for suicide. They said it could be an important treatment to bridge the gap that exists because of the delayed effect of most common antidepressants, which can take four to six weeks to become fully effective.
That said, the authors cautioned that more research is needed into the potential for abuse of ketamine. The study was a proof-of-concept study and the nassal spray must still go through a further study before possible approval for public use.
Researchers have previously questioned the safe use of ketamine nasal spray. A small study from March this year tested repeated doses of ketamine through a nasal spray on 10 participants with severe depression.
Ketamine tolerance varied from one person to the next, with half of the group experiencing adverse side effects such as high blood pressure, psychotic-like effects and motor incoordination, which left some participants unable to continue to self-administer the spray. In the end, the trial had to be suspended.
“It’s clear that the intranasal method of ketamine delivery is not as simple as it first seemed,” said lead author UNSW Professor Colleen Loo, from Black Dog Institute.
“Many factors are at play when it comes to nasal spray ketamine treatments. Absorption will vary between people and can fluctuate on any given day within an individual based on such things as mucous levels in the nose and the specific application technique used.”
Professor Loo added: “It remains unclear whether ketamine nasal sprays can be safely relied upon as a treatment for patients with severe depression.”