A leading US psychiatrist has urged caution on the use of intranasal esketamine, which was recently approved as a treatment for refractory depression by the country’s Food and Drug Administration.

Professor Alan Schatzberg, a former president of the American Psychiatric Association, lists “worrisome findings” and calls for a “concise framework for assessing the risk-benefit balance for using this formulation of ketamine”, in an editorial in the American Journal of Psychiatry.

The article by the Stanford University professor accompanies the publication of the pivotal phase 3 trial of the nasal spray, which led to its approval by the FDA earlier this year.

In the trial, conducted across 39 US outpatient centres, 227 adults with moderate-to-severe depression were randomised to either esketamine nasal spray (54-84mg) twice weekly, or to a saline placebo spray, with a bitter-tasting chemical added.