WithdrawnPhase 2
Antidepressant Effects of Nitrous Oxide
Key facts
- Who runs it
- University of Chicago
- Where
- Chicago, United StatesSee the siteAlso in 1 other country, 1 site
- Trial code
- Status
- Withdrawn
- Phase
- Phase 2
- Started
- 30 Jun 2021
- Ended
- 27 Feb 2026
- Type of study
- Interventional, 2 groupsOne group gets an existing treatment, for comparison.
- Treatments tested
- Nitrous oxide gas for inhalation
- Placebo
- Record updated
- 14 May 2026
- Why it stopped
- PI has left the university
Who can take part
- Age
- 18 years and older
- Sex
- Women and men
- Healthy volunteers
- Can take part
The registry criteria, word for word
Show all 11 criteriaShow less
Who can take part
- Adult (≥18 years, both sexes)
- DSM-5 criteria for MDD without psychosis, as determined using a structured clinical interview [Mini International Neuropsychiatric Interview], MDD, defined by a pre-treatment score >16 on the HDRS-21 scale and meeting DSM-5 for MDD
Who cannot take part
- Administration of NMDA-antagonists (e.g., ketamine) in previous 3 months
- Ongoing treatment with ECT
- Any contraindications to the use of nitrous oxide (e.g., pneumothorax, middle ear occlusion, elevated intracranial pressure, chronic cobalamin or folate deficiency unless treated with folic acid or vitamin B12)
- A current or past history of bipolar disorder, schizophrenia, or schizoaffective disorder
- Current obsessive-compulsive disorder, panic disorder, or documented Axis II diagnoses
- Active or recent (<12 months) substance use disorder; excluding nicotine
- Presence of acute medical illness that could interfere with study participation, including significant pulmonary disease
- Active suicidal intention, as determined by clinical interview assessment tool (Sheehan-STS) and clinical examination
- Pregnancy or breastfeeding
Where in United States
Also in 1 other country, 1 site
- University of Chicago MedicineChicago, United StatesNo longer taking part
About the trial
What the trial wants to find out
To evaluate the acute and sustained antidepressant effects of nitrous oxide in people with major depressive disorder; and further evaluate these effects by identifying the optimal dose and regimen to guide current practice, and to plan a future large pragmatic trial.
The 2 groups in the trial
- Treatment; Nitrous Oxide 50% or 25%, groupExisting treatment, for comparison
Four-weekly, 60-minute inhalation sessions of 25% or 50% nitrous oxide, randomly assigned.
Treatment: Nitrous oxide gas for inhalation
- Control; Oxygen-air mixture, groupPlacebo, for comparison
Four-weekly, 60-minute inhalation sessions of an oxygen and air mixture.
Treatment: Placebo
Data and sources
- Registry record
- Listed on ClinicalTrials.gov.
- Official title
- Evaluation of the Antidepressant Effects of Nitrous Oxide in People With Major Depressive Disorder
- Record updated
- 14 May 2026