Neurocognitive aspects of ketamine and esketamine on subjects with treatment-resistant depression: A comparative, randomized and double-blind study.

The objective of this study is to evaluate cognition in patients using either ketamine or esketamine to treat TRD. We also evaluate if both ketamine and esketamine as one group influence cognition in patients with TRD. Fifty-four patients with TRD were infused with either ketamine or esketamine and were assessed at three time points: baseline, 24 h, and 7 days after infusion. We applied neuropsychological tests to evaluate executive functions, processing speed, short term memory, and auditory-verbal episodic memory. There is no cognitive difference between ketamine and esketamine, with the exception of one variable. When considered as one group, ketamine and esketamine do not impair cognition; on the contrary, they improve some neuropsychological functions such as visuospatial short-term memory, executive functions, processing speed, and several measures related to episodic verbal memory. Ketamine and esketamine do not present differing cognitive effects when used in antidepressant doses to treat TRD. Furthermore, they rapidly improve many cognitive aspects of patients with TRD at 24 h after the infusion and maintain these effects for at least 7 days.

Comparative study of esketamine and racemic ketamine in treatment-resistant depression: Protocol for a non-inferiority clinical trial.

INTRODUCTION: The use of ketamine as an option in the treatment of depressive disorder is growing rapidly, supported by numerous clinical trials attesting its efficacy and safety. Esketamine, the S (+) enantiomer of ketamine, is the most widely used form in the anesthetic environment in some countries, and new studies have shown that it may also be effective in depression and with better tolerability. However, no study so far has directly compared esketamine with racemic ketamine. Here we propose a protocol of a clinical trial to evaluate esketamine as a noninferior medication when compared to ketamine in the treatment of patients with treatment-resistant depression. METHODS/DESIGN: This study protocol is for a randomized, controlled, double-blind noninferiority clinical trial. Subjects will be 18 years or older, with major depression characterized as treatment-resistant. Participants will receive a single infusion of either esketamine (0.25 mg/kg) or ketamine (0.5 mg/kg) over 40 minutes. The primary outcome will be the difference in remission rates between the 2 treatment arms at 24 and 72 hours after drug infusion. Secondary outcomes will include other timepoints, measurements of cognition, dissociation, and blood biomarkers. DISCUSSION: A head-to-head study is the best way to evaluate whether the esketamine is in fact comparable to the racemic ketamine in terms of both efficacy and safety, and, if positive, it would be an initial step to increase the access to that type of treatment worldwide. ETHICS AND DISSEMINATION: The study was approved by the local Institutional Review Board (University Hospital Professor Edgard Santos-Federal University of Bahia-Number: 46657415.0.0000.0049). Subjects will only participate after voluntarily agreeing and signing the Informed Consent Form. The study findings will be published in peer-reviewed journals and presented at national and international conferences. TRIAL REGISTRATION: This trial has been registered in the Japan Primary Registries Network (JPRN): UMIN000032355, which is affiliated with the World Health Organization.