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.
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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
24
Nitrous oxide, an odorless, colorless gas typically used as an induction agent for general anesthesia or for dental sedation, is a known N-methyl-D-aspartate (NMDA) antagonist. It will be given at a concentration of 25% nitrous oxide/50% oxygen/25% nitrogen.
Nitrous oxide, an odorless, colorless gas typically used as an induction agent for general anesthesia or for dental sedation, is a known N-methyl-D-aspartate (NMDA) antagonist. It will be given at a concentration of 50% nitrous oxide/50% oxygen.
Placebo gas given at 50% nitrogen \[inert\]/50% oxygen.
Washington University School of Medicine
St Louis, Missouri, United States
Change in Depression Symptoms Measured by the Hamilton Depression Rating Scale- 21 Items
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.
Time frame: 2 and 24 hours after inhalation
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