Intranasal Ketamine for Suicidal Ideation in Veterans

Inclusion Criteria: 1. Male or female patients, 21-70 years of age 2. Female individuals who are not of childbearing potential (i.e., surgically sterile, postmenopausal for at least one year) or using a medically accepted reliable means of contraception. Women using oral contraceptive medication for birth control must also be using a barrier contraceptive. Women of childbearing potential must also have a negative pregnancy test at screening and at pre-administration 3. Any non-psychotic disorder diagnosis 4. Score \>4 on the suicide item of the Montgomery-Asberg Depression Rating Scale (MADRS-SI; range 0-6)for clinically significant suicidal ideation or past suicide attempts 5. Each participant must have a level of understanding sufficient to agree to all tests and examinations required by the protocol and must sign an informed consent document 6. Each participant must agree to avoid future enrollment in ketamine trials. Exclusion Criteria: 1. current psychotic symptoms or lifetime history of primary psychotic disorder 2. active substance use in the preceding two weeks or needing medical attention for withdrawal 3. neurodevelopmental disorder (e.g., ASD) 4. major neurocognitive disorder (e.g., Alzheimer's type dementia) 5. serious cardiac disease 6. suicide attempt precipitating current admission requiring medical stabilization 7. Lifetime histories of autism, mental retardation, pervasive developmental disorders, or Tourette's syndrome 8. Women who are either pregnant or nursing 9. Hypertension (systolic BP \>160 mm Hg or diastolic BP \>90 mm Hg) at screening or immediately prior to treatment with study drug 10. Previously received ketamine for refractory depression.