Weekly Ketamine Infusions Show Initial, Repeated Depression Benefits

Jennifer L. Phillips, PhD

A new study shows that weekly ketamine infusions are associated with continued and maintained reductions in depressive symptoms among patients with treatment-resistant depression.

The findings, which are considered novel among studies assessing ketamine administration for patients with treatment-resistant depression, evidence the promising role the controversial drug could play in psychiatric care.

A team of investigators, led by Jennifer L. Phillips, PhD, an associate scientist in the Mood Disorders Research Unit at The Royal’s Institute of Mental Health Research, conducted a randomized, double-blind crossover comparison of single ketamine infusion versus active placebo control midazolam. The assessment, held with 41 participants with treatment-resistant depression at single treatment center, observed patients receive 6 open-label ketamine infusions 3 times per week over 2 once patients had a relapse of depressive symptoms.

Patients who reported a decrease of at least 50% in the Montgomery-Åsberg Depression Rating Scale (MADRS) received another 4 additional infusions once weekly in a maintenance phase.

Those administered a single ketamine infusion reported significantly reduced depressive symptoms at the primary efficacy endpoint of 24 hours post-care versus those treated with midazolam. The therapy showed cumulative antidepressant effects over repeated infusions, as well a doubling of antidepressant response rate in patients, according to linear mixed models.

Investigators found that 59% of patients met the response criteria following repeated infusions, with 3 infusions serving as the median dosage required to reach achieved response. In patients receiving weekly maintenance infusions, no further improvement in MADRS scores were reported.

The first-of-its-kind findings come just 1 month following the US Food and Drug Administration (FDA) approval of esketamine nasal spray (Spravato) for the treatment of patients with treatment-resistant depression. At the time, the therapy made history as the first novel treatment indicated for depression in 30 years—and headlines as one of the first hallucinogenic drugs to reach indication for a common condition.

Dennis Charney, MD, Dean of Icahn School of Medicine at Mount Sinai and a member of the Yale University team that led pioneering antidepressant ketamine trials in the 1990s, told MD Magazine® that microdosing or implementing controversial therapies for psychiatric care require what any other trial requires: control, safety, and a carefully-assessed standard for efficacy.

“No matter what treatment is being assessed, you have to follow those scientific approaches,” Charney said. “For conditions that don’t have effective treatments available, there should be an open mind.”

Adversely, Dan Iosifescu, MD, associate professor of Psychiatry at NYU School of Medicine, director of Clinical Research at Nathan S. Kline Institute for Psychiatric Research, and prominent ketamine investigator, told MD Mag that—among other reasons—ketamine will never reach at-home therapy use due to its prominent abuse as street drug Special-K. He anticipated the marketed therapy will be costly, and prescribed as long-term therapy for only a small depression patient population.

“For the majority of individuals that benefit from it, it will be essentially buying them time for other treatments—be them pharmacotherapies or device-based treatment, or psychotherapies, because those are beginning to work much more slower than ketamine does,” he said.

Whatever its marketed use entails, Phillips and colleagues concluded positively that ketamine showed both initial and repeated benefits for antidepressant effects as a once-weekly infusion.

“These findings provide novel data on efficacious administration strategies for ketamine in patients with treatment-resistant depression,” they wrote. “Future studies should further expand on optimizing administration to better translate the use of ketamine into clinical settings.”

The study, "Single, Repeated, and Maintenance Ketamine Infusions for Treatment-Resistant Depression: A Randomized Controlled Trial," was published online in The American Journal of Psychiatry.