Antidepressant Effects of Nitrous Oxide

Phase 2

Recruiting

• Conditions: Treatment Resistant Depression; Major Depressive Disorder
• Interventions: Drug: Nitrous oxide gas for inhalation; Drug: Placebo

• Registration Number: NCT05357040
• Lead Sponsor: University of Chicago

Brief Summary

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.

Detailed Description

The investigators are conducting a randomized controlled trial to evaluate the antidepressant effects of nitrous oxide in people with Major Depressive Disorder (MDD). MDD is a global medical condition that causes significant health and economic burden. Recent studies have shown that a single dose of ketamine, an NMDA-antagonist, has fast and long lasting anti-depressant effect. Nitrous oxide, another NMDA-antagonist, is widely used for anesthesia and analgesia, safer to administer and has fewer side effects than ketamine.

A randomized controlled crossover feasibility study showed significant reduction in depressive symptoms at 2 and 24 hours after a single 1-hour treatment session of inhaled nitrous oxide compared with placebo. Nitrous oxide is inexpensive and can be safely administered by any trained clinician. If found to be efficacious, it could be used to provide rapid anti-depressant effect whilst the benefit of traditional anti-depressants has its delayed effect. Another potential application could be in acutely suicidal patients.

This trial will enable confirmation and extension of the findings from the feasibility study, and identify the optimal dose and regimen in a broader population of those with MDD. Participants will be randomized to receive a weekly 1-hour inhalational session of either nitrous oxide or placebo (oxygen-air mixture) for 4 weeks, and the nitrous group will be further randomly assigned to a dose of 50% or 25% nitrous oxide. Depression severity and outcomes related to treatment responses will be continuously assessed by a 'blinded-to-randomization' psychiatry (MD) rater at weekly intervals during study patient participation, using validated psychiatric diagnostics (Hamilton Depression Rating Scale-21 \[HDRS-21 or HAM-D\]; Profile of Mood States \[POMS\]; Computerized Adaptive Test-Mental Health \[CAT-MH\]; Sheehan-STS \[S-STS\]; Visual Analog Scale \[VAS\]).

Study Timeline

• Study Start: 2021-06-30
• Study First Submitted: 2021-11-09
• Study First Submitted QC: 2022-04-26
• Study First Posted: 2022-05-02
• Status Verified: 2024-05
• Last Update Submitted: 2024-12-03
• Last Update Posted: 2024-12-04
• Primary Completion: 2025-10-01
• Study Completion: 2025-12-01

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 172

Inclusion Criteria

1. Adult (≥18 years, both sexes)
2. 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

Exclusion Criteria

1. A current or past history of bipolar disorder, schizophrenia, or schizoaffective disorder.
2. Current obsessive-compulsive disorder, panic disorder, or documented Axis II diagnoses
3. Active suicidal intention, as determined by clinical interview assessment tool (Sheehan-STS) and clinical examination
4. Active or recent (<12 months) substance use disorder; excluding nicotine
5. Administration of NMDA-antagonists (e.g., ketamine) in previous 3 months
6. Ongoing treatment with ECT
7. Presence of acute medical illness that could interfere with study participation, including significant pulmonary disease
8. Pregnancy or breastfeeding
9. 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).

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Treatment; Nitrous Oxide 50% or 25%, group	Nitrous oxide gas for inhalation	Four-weekly, 60-minute inhalation sessions of 25% or 50% nitrous oxide, randomly assigned.
Control; Oxygen-air mixture, group	Placebo	Four-weekly, 60-minute inhalation sessions of an oxygen and air mixture.

Primary Outcome Measures

Name	Time	Method
Change in HDRS-21 score	Over 4-weeks from baseline	Monitor changes in Hamilton Depression Rating Scale-21 (HDRS-21) scores to determine whether a series of four, 60-minute sessions of inhaled nitrous oxide vs placebo (once-per-week) has significant antidepressant activity.; The HDRS-21 is an interview-based psychiatric diagnostic used to evaluate depression severity. Scores are calculated by using the first 17 responses of this 21 item questionnaire.; Higher scores are associated with more severe depression: 0 - 7 = Normal 8 - 13 = Mild Depression 14-18 = Moderate Depression 19 - 22 = Severe Depression \> 23 = Very Severe Depression Max score = 52

Secondary Outcome Measures

Name	Time	Method
Treatment response	At 24-hours (following treatment-1)	Treatment response (≥50% reduction on HDRS-21) to nitrous oxide vs placebo will be measured.
Changes in 'Profile of Mood States' scores	Up to 1-week (following treatment-1)	Monitoring daily mood changes using the Profile of Mood States (POMS) a validated 'self-report' psychological diagnostic containing 65 emotions or 'mood states' to determine the pattern of treatment response; Patients rank their current mood states using a scale of 'not-at-all', 'a-little', 'moderately', 'quite-a-lot', 'extremely'. Responses are scored to calculated the Total Mood Disturbance (TMD): TMD = (tension + depression + anger + fatigue + confusion) - Vigor
Sustainability of treatment response	Over 7-weeks (length of study participation).	Determine sustained response and remission following study treatments (nitrous vs placebo) using Hamilton Depression Rating Scale-21 (HDRS-21) score.; The HDRS-21 is an interview-based psychiatric diagnostic used to evaluate depression severity. Scores are calculated by using the first 17 responses of this 21 item questionnaire.; Higher scores are associated with more severe depression: 0 - 7 = Normal 8 - 13 = Mild Depression 14-18 = Moderate Depression 19 - 22 = Severe Depression \> 23 = Very Severe Depression Max score = 52
Treatment dose response comparison	Over 7-weeks (length of study participation)	Compare dose response of 25% vs 50% nitrous oxide to establish whether the concentration is related to outcome.; Determined with treatment-by-dose (group) interaction term in a logistic regression model to assess for statistical significance.
Changes in Computerize Adaptive Testing - Mental Health (CAT-MH) 'depression' scores	Over 7-weeks (length of study participation) from Baseline	This CAT-MH is a validated self-reporting diagnostic that adaptively selects a small optimal set of items from a large bank of approximately 1,500 items, targeted to individuals current or historical level of severity and likelihood of 'depression'.; Generated scores include severity and liklihood percentile: - depression = (%) normal, mild, moderate, severe
Changes in Computerize Adaptive Testing - Mental Health (CAT-MH) 'anxiety' scores	Over 7-weeks (length of study participation) from Baseline	This CAT-MH is a validated self-reporting diagnostic that adaptively selects a small optimal set of items from a large bank of approximately 1,500 items, targeted to individuals current or historical level of severity and likelihood of 'anxiety'.; Generated scores include severity and liklihood percentile: - anxiety = (%) normal, mild, moderate, severe
Treatment cycle compliance	Over 4-weeks (weekly treatment sessions)	Evaluate compliance to complete 4-cycle inhalation treatments of nitrous oxide vs placebo.; Determined by ability, inability, or refusal to receive all 4-treatments of randomized inhalation sessions (nitrous oxide vs placebo).
Changes in Computerize Adaptive Testing - Mental Health (CAT-MH) 'suicide' scores	Over 7-weeks (length of study participation) from Baseline	This CAT-MH is a validated self-reporting diagnostic that adaptively selects a small optimal set of items from a large bank of approximately 1,500 items, targeted to individuals current or historical level of severity and likelihood of 'suicide'.; Generated scores include severity and liklihood percentile: - suicide = (%) low, intermediate, high
Suicidal ideation tracking	Over 7-weeks (length of study participation) from Baseline	Suicidal ideation will be be tracked using the Sheehan Suicidality Tracking Scale (S-STS), a validated self-report diagnostic tool designed to assess and monitor suicidality.; The standard S-STS consists of 14 core questions related to suicidality phenomena and is designed for use in clinical research studies and in clinical settings.; Scores are summed based on individual responses 'not-at-all = 0', 'a little = 1', 'moderately = 2', 'very = 3', 'extremely = 4', to generate a summated score (total score), individual factor scores for suicidal ideation, suicidal intent, suicidal planning, suicidal behavior, and non-suicidal self-injury.; All results are monitored in real time by a trained psychiatry (MD) rater.
Treatment remission	At 24-hours (following treatment-1)	Treatment remission (HDRS-21 ≤7 points) to nitrous oxide vs. placebo will be measured.
Visual Analog Scale (VAS)	At Baseline (Prior to treatment-1)	The VAS is a unidimensional measure of pain intensity and use in the field of psychology to measure 'well-being'.; Patients mark on a line the point that they feel represents their perception of their current state, with the score determined by measuring in millimetres from the left hand end of the line to the point that the patient marks.; The range of score from 0-100 mm and represent: no pain (0-4 mm), mild pain(5-44 mm), moderate pain (45-74 mm), and severe pain (75-100 mm).

Trial Locations

Locations (2)

University of Chicago Medicine; 🇺🇸 Chicago, Illinois, United States

The Alfred Hospital; 🇦🇺 Melbourne, Victoria, Australia