Nitrous Oxide in the Treatment of Acute Suicidal Ideation
ID: NCT06636357
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The primary aim of the NITOS study is to investigate the potential rapid antisuicidal effects of N2O in the transdiagnostic treatment of suicidal ideation. On day 1, patients will receive either nitrous oxide (50% N2O balanced with oxygen) or placebo (50% oxygen balanced with air). Seven days after the first inhalation, a second inhalation will be performed. All patients will receive N2O at least once during this trial. While the first inhalation will be double-blind, only the patients but not the raters will be blinded to the second inhalation (day 8). For mechanism of action and prediction, a nested biomarker substudy will employ multimodal techniques including analysis of hair and blood samples, and EEG.
Inhalation of 50% N2O plus 50% O2 for 45 min
50% O2 plus 50% air for 45 min
Treatment Arms Description
Patients will be treated with N20 (50% N2O combined with 50% oxygen) for 45 minutes. Both the study subject and the rater will be blinded to the treatment assignment.
Here, patients will be treated with 50% oxygen plus air for 45 minutes. Both the study subject and the rater will be blinded to the treatment assignment.
- Ability to give written informed consent
- Moderate to severe suicidal ideation defined as a score ≥3 on the Montgomery-Asberg Depression Rating Scale (MADRS; Schmidtke et al., 1985) suicide item (item #10) as well as a self-report Beck Scale for Suicide Ideation (BSS; Kliem et al., 2017) items #4 plus #5 score ≥ 2
- Plasma homocysteine level ≤ 14 µmol/l
- Organic, including symptomatic, mental disorders (F00-F09; lifetime diagnosis)
- Schizophrenia, schizotypal and delusional disorders (F20-F29; lifetime diagnosis)
- Mental and behavioral disorders due to psychoactive substance use. Nicotine and cannabis will be ignored (F10-F19)
- Non-medical (i.e., recreational) use of inhalational N2O during the last 12 months
- Past intolerance or hypersensitivity to N2O
- Critical illness
- Severe cardiac disease
- Pregnancy or breastfeeding
- Pulmonary hypertension
- Chronic cobalamin or folate deficiency unless treated with folic acid and/or vitamin B12
- History or evidence of any other medical or neurological condition that would expose the subject to an undue risk of a significant adverse event as determined by the clinical judgment of the investigator
- Treatment with ketamine/esketamine during the last 4 weeks
- Treatment with opioid medications during the last 3 months
- Treatment with vagus nerve stimulation (VNS) or electroconvulsive therapy (ECT) within the last 3 months
- Recent (within the last 4 weeks) or current use of benzodiazepines in excess of 5 mg lorazepam or equivalent per day
- Finally, any other factors that, in the investigator's judgment, would unduly impact patient safety or compliance during the study.
Primary Outcome Measures
- Beck Scale for Suicidal Ideation (BSS) — Time Frame: Day 0 to Day 2
Change of BSS score between Day 0 and Day 2. Double-blind treatment with either N2O or placebo inhalation on Day 1.
View Secondary Outcome Measures (4)
- Montgomery-Åsberg Depression Rating Scale (MADRS ) — Time Frame: Day 0 to Day 2
- EEG changes associated with N2O / placebo inhalation — Time Frame: Day 1
EEG will be performed before, during, and after inhalation
- Suicide Visual Analog Scale (S-VAS) — Time Frame: Day 1
Briefly, the S-VAS uses the phrase "urge to kill myself". Next to the phrase, the patient sees a line that is anchored on the left with the word "none" and on the right with the word "extreme" . Score ranges from 0 to 100.
- Perceived Burdensomeness Visual Analog Scale (PB-VAS) — Time Frame: Day 1
The PB-VAS uses the phrase "like a burden". Next to the phrase, the patient sees a line that is anchored on the left with the word "none" and on the right with the word "extreme" . Score ranges from 0 to 100.
This trial is recruiting at 1 study facilities worldwide. Click below to see if there is a clinic or hospital in your area:
Show All 1 Facilities & Contact Sites
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- Kronenberg G, Bankwitz A, Provaznikova B, Muller M, Quednow BB, Seifritz E, Olbrich S. Inhalational nitrous oxide as a transdiagnostic approach for the treatment of suicidal ideation and suicidality in psychiatric inpatients: protocol for a double-blind randomised, controlled clinical single-centre trial. BMJ Open. 2025 Jul 16;15(7):e096825. doi: 10.1136/bmjopen-2024-096825.PubMed ↗
View Official Medical/Scientific Title
Nitrous Oxide in the Treatment of Acute Suicidal Ideation