Condition: Treatment Resistant Depression

The main purpose of this study is to assess the efficacy and safety of daily and intermittent dosing of MK-1942 compared to placebo among participants with Treatment-Resistant Depression (TRD) on a stable course of antidepressant therapy. The dual primary hypotheses of the study are that the daily MK-1942 treatment and/or intermittent MK-1942 treatment are superior to placebo in reducing Montgomery-Asberg Depression Rating Scale (MADRS) score.