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

Conditions:Depression, Depression, Major Depression Disorder (MDD)
Therapuetic Areas:Psychiatry / Psychology, Pulmonary / Respiratory Diseases
Age Range:18 - 75
Start Date:November 22, 2016
End Date:December 2020
Contact:Britt Gott, MS

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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.

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

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.

Inclusion Criteria

1. Adults 18-75 years of age;

2. Current diagnosis of unipolar major depressive disorder (MDD) without psychosis as
confirmed by structured clinical interview for DSM-IV disorders;

3. A score of >= 9 on the Montgomery-Åsberg Depression Rating Scale (MADRS);

4. Documented (i.e., chart review) lifetime failure to respond to >=3 adequate
dose/duration antidepressant treatment trials, ≥1 medication failure in the current
depressive episode;

5. Good command of the English language.

Exclusion Criteria

1. Meets criteria for any DSM-IV diagnosis for schizophrenia, bipolar, schizoaffective,
obsessive-compulsive, personality, or panic disorders;

2. Any recent (within past 12 months) history of substance dependence or abuse (except
tobacco), determined by reported history or urine drug screen;

3. Ability to become pregnant and not using effective contraception;

4. Contraindication against the use of nitrous oxide:

1. Pneumothorax

2. Bowel obstruction

3. Middle ear occlusion

4. Elevated intracranial pressure

5. Chronic cobalamin and/or folate deficiency treated with folic acid or vitamin B12

6. Pregnant patients

7. Breastfeeding women

5. Inability to provide informed consent;

6. Any other factor that in the investigators' judgment may affect patient safety or
We found this trial at
660 S Euclid Ave
Saint Louis, Missouri 63110
(314) 362-5000
Principal Investigator: Peter Nagele, MD
Phone: 314-362-2463
Washington University School of Medicine Washington University Physicians is the clinical practice of the School...
Saint Louis, MO
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