By E.J. Mundell
Psychiatrists were cautiously optimistic about the anesthetic's potential for treating the mood disorder.
"This study only had 68 people enrolled, which is a limitation, so there really needs to be larger-scale studies before being able to confidently recommend ketamine as a first-line choice," said Dr. Matthew Lorber, a psychiatrist at Lenox Hill Hospital in New York City. He wasn't involved in the new study, which was funded by drug maker Janssen.
Longer-term studies also need to be conducted, Lorber added, "but ketamine is certainly an exciting option that holds a lot of promise, especially when traditional medications have failed."
Ketamine has a checkered history, and is perhaps best known as the recreational club drug "Special K." But researchers have also noted its effects in easing signs of depression.
So, a group led by Dr. Carla Canuso, of Janssen Research and Development in Titusville, N.J., conducted a study involving 68 people diagnosed with major depression. The participants were randomly assigned to receive either a "dummy" placebo nasal spray, or ketamine in a nasal spray form called esketamine.
All of the participants were deemed to have such severe depression that they were at "imminent suicide risk," the researchers said. They were already using standard antidepressants and continued to do so throughout the study.
Canuso's team then tracked the effects of esketamine at four hours after use, 24 hours later and 25 days later. The study was "double-blind," meaning that neither the researchers nor the participants knew which people were taking esketamine and which were taking the placebo.
The result: At the four-hour and 24-hour mark, there was "a significantly greater improvement" --- between 30 and 40 percent reductions -- in depression scores and a lowering of suicidal thoughts for those taking the esketamine nasal spray.
The effect did not last to the 25-day mark, however. Still, the study is "proof-of-concept" that "intranasal esketamine may be an efficacious treatment for rapid reduction of depressive symptoms, including suicidal ideation [thoughts] in patients assessed to be at imminent risk for suicide," Canuso's team concluded.
The study was published April 16 in The American Journal of Psychiatry.
The researchers noted that assessments of depression level and suicide risk were made by both the patients and their physicians.
Side effects did occur for some participants and included nausea, dizziness, dissociation (a sense of being disconnected from reality) and headache, the researchers said.
And while the benefits seen in this small study are encouraging, Canuso's team stressed that ketamine does come with a potential for abuse.
In an accompanying editorial, journal editor Dr. Robert Freedman stressed that "protection of the public's health is part of our responsibility as well, and as physicians, we are responsible for preventing new drug epidemics."
For his part, Lorber thinks that if longer, larger studies pan out, esketamine might have a role to play in resolving short-term suicidal crises.
"Traditional antidepressants typically take four to six weeks before there is an improvement in depression, and they have not been shown to decrease the incidence of suicide, so the quick response combined with the improvement in suicidality sets ketamine apart from traditional medications alone," he said.
Dr. Robert Dicker helps direct child and adolescent psychiatry at Northwell Health in New Hyde Park, N.Y. He agreed that new and better depression medications are needed.
"One must keep in mind that the prevalence of depression in our adult population is high -- 1 in 15," Dicker said. "That depression is the most common diagnosis related to suicide [and] 1 million American adults attempt suicide [each year].
"A large number of adults being treated for depression are resistant to our current treatments, so the need to develop new treatment approaches are tremendous," he added. "The possible utility of ketamine in treating this population is an important avenue of study."