The objective of the current program of research will be to test whether intranasal ketamine treatment is more effective than placebo in reducing suicidal ideation in suicidal patients presenting for acute treatment in emergency department settings. Secondary objectives will test the effect of genotypic differences in the mu opioid receptor on efficacy of ketamine and the correlation of speech patterns and facial movement patterns with subjective reductions in suicidal ideation after ketamine treatment.

The objective of the current program of research will be to test whether intranasal ketamine treatment is more effective than placebo in reducing suicidal ideation in suicidal patients presenting for acute treatment in emergency department settings. Secondary objectives will test the effect of genotypic differences in the mu opioid receptor on efficacy of ketamine and the correlation of speech patterns and facial movement patterns with subjective reductions in suicidal ideation after ketamine treatment

Inclusion Criteria:

1. Males and females
2. Ages 18-65
3. All races and ethnicities
4. Willing and able to provide informed consent
5. A cutoff score of >3 on the Beck Scale for Suicidal Ideation
6. >2 on the Columbia Scale for Suicide Severity Rating

Exclusion Criteria:

1. Pregnancy or lactation; women of reproductive potential must have a negative urine pregnancy test

2. Post-partum state (within 2 months of delivery)

3. Homicide risk as determined by clinical interview

4. Any of the following Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) diagnoses:

   1. Any current primary psychotic disorder
   2. Acute intoxication or withdrawal from alcohol or any other substance of abuse, as determined by clinical interview and urine drug screen except opioids
   3. use of any hallucinogen (except cannabis), in the last month
   4. Any dissociative disorder
   5. Pervasive developmental disorder
   6. Cognitive disorder
   7. Cluster A personality disorder
   8. Anorexia nervosa.

5. Treatment with any medication known to affect the N-methyl-D-aspartate (NMDA) receptor system (e.g., lamotrigine, acamprosate, memantine, riluzole, or lithium)

6. Any known hypersensitivity or serious adverse effect with ketamine

7. Any clinically-significant medication or condition that would preclude the use of ketamine