Nitrous Oxide as Treatment for Fibromyalgia

Inclusion Criteria:

* 2016 American College of Rheumatology Revised criteria for fibromyalgia (2016-ACR)
* Subjects 18 -75 years of age.
* Self-reported pain of at least 4 on the Numeric Pain Rating Scale (NPRS) at screening and baseline.
* Subject receives and agrees to remain on their stable fibromyalgia treatment plan established at least 4 weeks prior to dosing. Stable means no change in dose or any pain medication.
* Ability to understand the requirements of the study, provide written informed consent, abide by the study restrictions, and agree to return for the required assessments
* If currently on psychotherapy, it must have been maintained at the same frequency for 4 weeks prior to treatment.

Exclusion Criteria:

* Unstable doses of allowed antidepressants or muscle relaxants or dosages for any other medical condition.
* Pain due to concurrent autoimmune or inflammatory disease such as rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, or other chronic widespread pain condition(s) that may confound fibromyalgia pain.
* Psychiatric or cognitive disorder (e.g., current schizophrenia, severe depression, suicidal ideation, dementia, etc.) that the investigator or sponsor considers significant for this study.
* Clinically significant alcohol or other substance abuse within the last 2 years, in the opinion of the investigator.
* Current or recent history of medically inappropriate or illegal use of drugs of abuse including benzodiazepines, opiates, cocaine, cannabinoids, and amphetamines.
* Current treatment with N-methyl-D-aspartate receptor (NMDAR) ligands including ketamine, amantadine, dextromethorphan, memantine, methadone, or dextropropoxyphene.
* Subjects who are pregnant, breast feeding, or planning to become pregnant during the course of the study and for 28 days after the final administration of investigational product.
* Any other serious medical condition affecting heart, lung or any other organ system.
* Any impairment, activity or situation that in the judgment of the investigator would prevent satisfactory completion of the study protocol.