This study aims to examine the antidepressant efficacy of riluzole, employing a randomized, double-blind, placebo-controlled, 8 week trial of adjunctive trial in treatment-resistant major depressive disorder (TRD). Preclinical studies have shown riluzole to modulate Glu release and clearance, and to have potent neuroprotective properties, promoting neuro-resiliency. Other preclinical data now also show the drug to have antidepressant-like effects in rodent models used to screen for antidepressant activity. In addition, several small open-label clinical studies further suggest riluzole has antidepressant and anxiolytic properties, even in patients who do not respond to standard monoaminergic antidepressant and anxiolytic medications.