The drug esketamine, an intranasal formulation of the drug ketamine, has been found to be effective for people with treatment-resistant depression -- with some experiencing significant symptom improvement within 24 hours, researchers say. Photo by StockSnap/Pixabay

May 21 (UPI) -- New research suggests esketamine nasal spray, a new antidepressant, is safe and effective for patients who have failed to respond to other types of treatment.

More than a third of people with depression experience treatment resistance. For these patients, none of the antidepressants that work for others do much good. According to the latest study, published this week in the American Journal of Psychiatry, esketamine can help.


Esketamine is an intranasal formulation of the anesthetic ketamine, which also has a reputation as a party drug. Ketamine has been used off-label intravenously for treatment of refractory depression.

The intranasal version, however, has been approved by the U.S. Food and Drug Administration for use specifically with depression patients.

The latest study results are one of the main reasons the FDA approved the use of esketamine for depression earlier this year.

"This trial of esketamine was one of the pivotal trials in the FDA's review of this treatment for patients with treatment resistant depression. Not only was adjunctive esketamine therapy effective, the improvement was evident within the first 24 hours," Michael Thase, psychiatrist at the University of Pennsylvania School of Medicine, said in a news release.

For the study, researchers recruited participants with moderate to severe depression who had taken but failed to respond to at least two antidepressants. Study participants were randomly divided into two groups.

One group of patients was prescribed esketamine nasal spray combined with a new antidepressant. The second group of participants were given a placebo nasal spray and a new antidepressant.

After nearly a month, patients in the esketamine group described significant symptom improvements compared to the placebo group.

For some patients, the nasal spray caused side effects, including dissociation, nausea, vertigo, dizziness and the loss of taste. For most, the side effects appeared shortly after the first dosage and subsided within 1.5 hours. For seven percent of patients, the side effects caused participants to stop taking esketamine.

"The novel mechanism of action of esketamine, coupled with the rapidity of benefit, underpin just how important this development is for patients with difficult to treat depression," Thase said.

Though approved by the FDA, the drug is new and should be prescribed with caution and closely monitored by providers, according to a commentary accompanying the study's publication in the American Journal of Psychiatry.

"There are more questions than answers with intranasal esketamine, and care should be exercised in its application in clinical practice." said Alan Schatzberg, psychiatrist at the Stanford University School of Medicine.