Subcutaneous ketamine reduces suicide risk and improves functioning in depression: A proof-of-concept study

•Subcutaneous Ketamine lowers suicide risk, depressive symptoms, improves functionality.•Subcutaneous Ketamine: effective, well-tolerated, cost-effective for depression.•Subcutaneous Ketamine response became significant after an average of 8 sessions.•Subcutaneous Ketamine remained during the 6-month follow-up period. This investigation explores the efficacy of subcutaneous ketamine for mitigating depressive symptoms and suicidal ideation, addressing a crucial need for rapid-onset treatments in severe depression cases. It introduces an innovative approach to administering an NMDA receptor antagonist, significantly advancing psychopharmacological methods for treating suicidal behaviors as distinct entities, even within depressive episodes. The study's objective is to assess the impact of subcutaneous ketamine on diminishing suicidal thoughts and mood symptoms during depressive episodes through a naturalistic, prospective observational design. Conducted at Hospital de Clínicas de Porto Alegre, Brazil, between 2021 and 2023, the study involved 26 patients undergoing a current depressive episode. Of these, 23 completed the acute phase of treatment, and 18 were followed up for 6 months. The treatment regimen commenced with a ketamine dose of 0.5 mg/kg, which was adjusted according to individual responses under psychiatric supervision. The findings revealed substantial decreases in Columbia Suicide Severity Rating Scale scores following multiple ketamine sessions, with most patients achieving remission after approximately eight sessions. A notable reduction in depressive symptoms was also observed. A clear dose-response relationship was established, indicating that higher doses of ketamine were associated with more significant improvements in depressive symptoms, suicidal ideation, and overall functionality. Follow-up assessments suggested that these improvements were sustained over time. The subcutaneous administration of ketamine was generally well-tolerated, with minor and short-lived side effects. The study posits that subcutaneous ketamine may present a promising solution for treating severe depression accompanied by suicidal tendencies, particularly considering its positive influence on patient functionality and well-being. This method could offer a cost-effective and accessible treatment alternative, especially relevant in settings with limited resources. Given its potential in reducing long-term disability and economic viability, the study advocates for