The US Food and Drug Administration (FDA) has approved Spravato (esketamine), a new nasal spray medication for treatment-resistant depression.

The approval is in conjunction with an oral antidepressant, for the treatment of depression in adults who have tried other antidepressant medicines but have not benefited from them.

Earlier this year, an FDA advisory body voted 14-2 in favour of the Johnson & Johnson drug, based on three short-term clinical trials and one longer-term maintenance-of-effect trial.

In the short-term study, the spray demonstrated statistically significant effect compared to placebo on the severity of depression, and some effect was seen within two days.

In the longer-term maintenance-of-effect trial, patients who continued the use of Spravato experienced a statistically significantly longer time to relapse of depressive symptoms than patients on placebo nasal spray and oral antidepressant.

The treatment is only available through a restricted distribution system, under a Risk Evaluation and Mitigation Strategy (REMS), because of the risk of adverse outcomes resulting from sedation and dissociation. This is due to strong potential for abuse and misuse of the drug, as it contains a compound similar to street-drug ketamine.

"There has been a long-standing need for additional effective treatments for treatment-resistant depression, a serious and life-threatening condition," said Tiffany Farchione, acting director of the Division of Psychiatry Products in the FDA's Centre for Drug Evaluation and Research.

"Controlled clinical trials that studied the safety and efficacy of this drug, along with careful review through the FDA’s drug approval process including a robust discussion with our external advisory committees, were important to our decision to approve this treatment. Because of safety concerns, the drug will only be available through a restricted distribution system and it must be administered in a certified medical office where the health care provider can monitor the patient.”

Esketamine is the s-enantiomer of ketamine. Ketamine is a mixture of two enantiomers (mirror image molecules), and this is the first FDA approval of esketamine for any use.