SPL026 (DMT Fumarate) in Healthy Subjects and MDD Patients

2-part study. Part A in psychedelic-naïve healthy volunteers. Part B in patients with MDD who score moderate-severe on Ham-D. Healthy volunteers will receive a single dose of SPL026 in a dose-escalation parallel group study. Patients will receive up to 2 single doses of SPL026, 2 weeks apart. Dose 1 will be randomised double-blind with placebo. Dose 2 will be open label, active SPL026. SPL026 will be administered by IV injection. Safety and tolerability, PK, PD and efficacy will be measured.