Repeated subcutaneous esketamine on treatment-resistant depression: An open-label dose titration study

Background: Ketamine has gained prominence as one of the most effective therapeutic options in unipolar treatment-resistant depression (TRD). However, most studies related to the antidepressant action of ketamine used intravenous (IV) or intranasal (IN) administration. The subcutaneous (SC) route of administration is a promising alternative, as it results in plasma levels comparable to IV, causes fewer side effects, and is easier and cheaper to administer than both IV and/or IN routes. Methods: In this context, we conducted an open-label clinical trial for investigating the efficacy and safety of 8 weekly sessions of SC esketamine in TRD patients (n n = 30). Results: At the end of the treatment, a partial response rate of 26.09 %, a response rate of 52.17 % and remission rate of 34.78 % were observed, assessed by Montgomery-& Aring;sberg Depression Rating Scale. Moreover, the self- reported depressive symptoms, as measured by the Beck Depression Inventory II (BDI-II), significantly decreased from the baseline to the final session, and the improvements were sustained throughout the week. Follow-up evaluations (BDI-II) up to the sixth month consistently showed scores lower than the baseline. Limitations: The small sample size and the drop-out during the follow-up phase may limit the generalizability of the findings. Additionally, the absence of a control group necessitates cautious interpretation of causality. Conclusions: This groundbreaking study, which addresses SC esketamine treatment for TRD, reported promising response and remission rates, as well as sustained antidepressant effects. It highlights the need for further research to improve and expand our knowledge of this innovative, more accessible, and cost-effective therapeutic approach.