Study protocol for Ketamine as an adjunctive therapy for major depression (2): a randomised controlled trial...

Depression is a common psychiatric disorder and a leading cause of disability worldwide. Conventional monoaminergic antidepressants have limited efficacy and take weeks to exert a therapeutic effect. Single infusions of subanaesthetic doses of ketamine exhibit rapid antidepressant action but effects are transient and relapse is common. One potential strategy for increasing ketamine's antidepressant efficacy and/or prolonging its therapeutic benefit may be serial infusions. There is limited evidence on the efficacy and safety of repeated ketamine infusions against an active comparator.

This protocol describes an ongoing pragmatic, randomised, controlled, parallel-group, patient- and rater-blind, superiority trial. Eligible adult inpatients with a confirmed DSM-5 diagnosis of a major depressive episode (unipolar or bipolar) are randomly allocated in a 1:1 ratio to a course of up to eight infusions of ketamine or midazolam twice-weekly over four weeks. The primary objective is to assess the efficacy of serial adjunctive ketamine infusions versus active comparator midazolam by measuring Montgomery-Åsberg Depression Rating Scale score difference between arms from before the first infusion to 24 h after the final infusion, supplemented by a 95% confidence interval. To facilitate generalisability of results, the trial takes place under "real world" conditions with both groups continuing to receive regular inpatient care including treatment-as-usual pharmacotherapy, nursing care, and psychological and other therapies during the randomised treatment phase and regular outpatient care thereafter. Participants are monitored for relapse during a 24-week follow-up after the end of the randomised phase. Secondary objectives of the trial are to assess: response and remission rates at the end of randomised phase; relapse status during the 24-week follow-up after the end of the randomised phase; the safety and tolerability of repeated ketamine infusions regarding psychotomimetic and other psychiatric side effects, cognitive side effects, as well as withdrawal symptoms, haemodynamic stability, neurological, urological, and other physical side effects; and quality of life and cost-effectiveness.

There is an unmet clinical need for rapidly-acting novel antidepressants. This trial will provide efficacy, safety and health economic data on serial ketamine infusions and thus help inform clinical practice on the potential role of this treatment in the management of depression.

EudraCT 2019-003109-92. Registered 2 October 2019.

gov NCT04939649. Registered 25 June 2021.