A longitudinal open-label, dose-ranging clinical trial to evaluate the effectiveness of oral ketamine, an NMDA (N-methyl-D-aspartate) receptor antagonist, in patients who are experiencing chronic suicidal ideation

This open-label extension invites participants from the original OKTOS pilot to receive individually titrated sub-anaesthetic oral ketamine across two phases: OKTOS-E (up to 12 weeks; 4–11 doses) and OKTOS-M (up to 26 weeks; 7–26 doses).

Primary outcome is change in suicidality measured by the Beck Scale for Suicide Ideation (BSS) and SIDAS. Exploratory outcomes include MRI/EEG measures of resting-state and glutamatergic markers collected within +1–10 days after final treatment, and safety/tolerability monitoring.