Antidepressant Effects of Nitrous Oxide

University of Chicago

Overview

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 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 Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Conditions

Major Depressive Disorder Treatment Resistant Depression

Interventions

Nitrous oxide gas for inhalationDRUG

60-minute sessions of inhaled 50% nitrous oxide in oxygen (FiO2 0.5) or 25% nitrous oxide in oxygen (FiO2 0.75), administered weekly for 4-weeks. Administration will be under the direct supervision of a licensed practitioner who is experienced in the use and administration of the study drug, and is familiar with the indications, effects, dosages, methods, and frequency and duration of administration, and with the hazards, contraindications, and side effects and the precautions to be taken (MD, or CRNA); with study patient monitoring of pulse oximetry, heart rate, respiratory, non-invasive blood pressure, and end-tidal carbon dioxide.

PlaceboDRUG

60-minute sessions of inhaled oxygen-air mixture (FiO2 ≈0.3) to be administered weekly for 4-weeks. Administration will be under the direct supervision of a licensed practitioner who is experienced in the use and administration of the study drug, and is familiar with the indications, effects, dosages, methods, and frequency and duration of administration, and with the hazards, contraindications, and side effects and the precautions to be taken (MD, or CRNA); with study patient monitoring of pulse oximetry, heart rate, respiratory, non-invasive blood pressure, and end-tidal carbon dioxide.

Eligibility

Sex: ALLMin age: 18 YearsHealthy volunteers:

Medical Language ↔ Plain English

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).

Locations (2)

University of Chicago Medicine

Chicago, Illinois, United States

The Alfred Hospital

Melbourne, Victoria, Australia

Outcomes

Primary Outcomes

Change in HDRS-21 score

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

Time frame: Over 4-weeks from baseline

Secondary Outcomes

Treatment response

Treatment response (≥50% reduction on HDRS-21) to nitrous oxide vs placebo will be measured.

Time frame: At 24-hours (following treatment-1)

Changes in 'Profile of Mood States' scores

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

Time frame: Up to 1-week (following treatment-1)

Sustainability of treatment response

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

Data from ClinicalTrials.gov

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