Safety and Efficacy of 50 mg NYX-783 QD vs. Placebo in PTSD

Inclusion Criteria: * PTSD (DSM-5 criteria) * Stable allowed medications with no planned changes from 30 days prior to screening through study participation * Willing to use highly effective birth control * Willing to comply with protocol visits and procedures Exclusion Criteria: * Moderate to severe traumatic brain injury * Other psychiatric disorders (based on SCID-5-CT) or neurodegenerative disorders * Substance use disorder or alcohol use disorder within 6 months prior to screening * Psychotherapy or cognitive based therapy within 30 days prior to screening * Use of investigational drug within 30 days prior to screening * Prior participation in study of NYX-783, NYX-2925 or NYX-458.