Inhaled Nitrous Oxide for Treatment-Resistant Depression: Optimizing Dosing Strategies

Phase 2

Completed

• Conditions: Depressive Disorder, Treatment-Resistant; Depressive Disorder, Major
• Interventions: Drug: Nitrous Oxide 25%; Drug: Nitrous Oxide 50%; Drug: Placebo Gas

• Registration Number: NCT03283670
• Lead Sponsor: Washington University School of Medicine

Brief Summary

The purpose of the study aims to determine whether different concentrations of nitrous oxide (N2O) have different antidepressant effects for adults with treatment-resistant major depression.

Detailed Description

Most clinical major depression responds to standard treatments (medication and psychotherapy); however, a significant subset of depressed patients (15-20%) do not respond to these treatments and are referred to as treatment-resistant major depression (TRMD). New treatments for TRMD are needed, and one promising line of research are drugs known as N-methyl-D-aspartate (NMDA) glutamate receptor antagonists. In a recent pilot study, our group demonstrated that the NMDA antagonist nitrous oxide is effective in TRMD.

All patients will receive 3 randomized, one hour nitrous oxide inhalations to placebo (0% N2O), low dose (25% N2O), and high dose (50% N2O). Inhalation sessions will be at least 4 weeks apart. Mood will be assessed at baseline, 2 and 24 hours, and 1, 2, and 4 weeks post-inhalation for each dose.

Study Timeline

• Study First Submitted: 2016-11-09
• Study Start: 2016-11-22
• Study First Submitted QC: 2017-09-13
• Study First Posted: 2017-09-14
• Primary Completion: 2020-02-18
• Study Completion: 2020-02-18
• Results First Submitted: 2021-02-09
• Status Verified: 2022-03
• Results First Submitted QC: 2022-03-28
• Last Update Submitted: 2022-03-28
• Results First Posted: 2022-04-04
• Last Update Posted: 2022-04-04

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 24

Inclusion Criteria

Not provided

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Exclusion Criteria

Not provided

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
1. 25% nitrous oxide, 25% nitrogen, 25% oxygen	Nitrous Oxide 25%	Participants will be studied for 14 visits over approximately 18 weeks. The participants will receive 1 hour-long gas inhalation mixtures at 3 different times, which are randomly assigned.
2. 50% nitrous oxide, 50% oxygen	Nitrous Oxide 50%	Participants will be studied for 14 visits over approximately 18 weeks. The participants will receive 1 hour-long gas inhalation mixtures at 3 different times, which are randomly assigned.
3. Placebo gas: 50% nitrogen(inert), 50% oxygen	Placebo Gas	Participants will be studied for 14 visits over approximately 18 weeks. The participants will receive 1 hour-long gas inhalation mixtures at 3 different times, which are randomly assigned.

Primary Outcome Measures

Name	Time	Method
Change in Depression Symptoms Measured by the Hamilton Depression Rating Scale- 21 Items	2 and 24 hours after inhalation	Change in depression symptoms measured by the Hamilton Depression Rating Scale- 21 items. The HAMD-21 is designed to rate the severity of depression in patients. Although it contains 21 areas, calculate the patient's score as the total score on the first 17 answers. Scale: 0=absent, 4=worst level possible) the scores on the individual items are summed. Changes will be based on measurements obtained at baseline, approximately 2 hours after inhalation, and approximately 24 hours after inhalation. Changes are based on subtracti on of baseline score.

Trial Locations

Locations (1)

Washington University School of Medicine; 🇺🇸 Saint Louis, Missouri, United States