Safety and Efficacy of Ketamine Intravenous Infusions in the Treatment of Fibromyalgia

Previous studies of intravenous ketamine, which is a non-competitive N-methyl-D aspartate receptor antagonist, for fibromyalgia pain relief are limited to three studies. Two studies have focused on short-term pain relief of intravenous ketamine by measuring the patients' pain levels immediately before and after the infusion. Currently, existing studies used short-term infusions (30-40 minutes) of sub-anesthetic doses of ketamine for pain relief in fibromyalgia patients, whereas the Consensus Guidelines on the Use of Intravenous Ketamine Infusions for Chronic Pain from the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, and the American Society of Anesthesiologists recommend infusing IV ketamine for at least two hours and a minimal total dose of 80 mg.

The rationale of this study is to expand on the existing data of safety and efficacy of intravenous ketamine to relieve fibromyalgia pain. Specifically, this investigation will add data to fill the existing gap regarding the short- and long-term pain relief in the treatment of fibromyalgia with intravenous ketamine infusions. The study will also attempt to determine safety and tolerability. In addition, the characteristics of treatment responders versus non-responders will be assessed in an effort to determine whether specific characteristics can be used to predict treatment response in this group of patients.

This study consists of two parts. The first part is a single-centre, retrospective chart review to analyze and summarize the investigators' experience with intravenous ketamine infusions in the treatment of patients with fibromyalgia who received at least four infusions for pain management. For the second part, patients who already received at least three intravenous ketamine infusions (for optimal dose determination) will be enrolled in an open single-group prospective study to receive one intravenous ketamine treatment. In this prospective study, the investigators will evaluate infusion effectiveness, safety, and tolerability as well as the influence of patients' demographic and medical characteristics, including depression status and ketamine dissociation symptoms, on the treatment outcome.

This two-part study aims to evaluate whether intravenous ketamine is effective in reducing pain in patients diagnosed with fibromyalgia. To achieve this goal, the study will assess the effect of intravenous ketamine infusions on short- and long-term pain relief. The study will also evaluate the safety and tolerability of ketamine infusions in fibromyalgia patients and factors that may have an impact on the treatment outcome.

Eligibility Criteria:
Inclusion criteria:

To be included in Part 1 of the study, patients must fulfil the following criteria:

* Given written consent to permit Wilderman Medical Clinic investigators to use their medical and demographic information in research studies.
* Male or female \>18 years of age
* Having been diagnosed with fibromyalgia
* Received at least 4 IV ketamine infusion(s)
* Made at least one rating of pain (NRS) immediately before the intervention and one after the intervention
* Had follow-up data recorded on the follow-up visit: percentage and duration of pain relief

To be included in Part 2 of the study, patients must fulfil the following criteria:

* Male or female \>18 years of age
* Given the written Informed Consent Form to participate in the study
* Having been diagnosed with fibromyalgia
* Having been prescribed IV ketamine infusions treatment
* Passed safety screening for ketamine infusions
* Had at least 3 IV ketamine infusions for dose optimization
* Willingness and ability to comply with the study procedure and the ability to follow verbal and written instructions

Exclusion Criteria:

Patients will be excluded from Part 1 of the study if they meet any of the following criteria:

* Age less than 18 years old
* Absence of signed Informed Consent Form
* Patients who received less than 4 IV ketamine infusion(s)
* Insufficient information to conduct analysis (e.g. absence of pain ratings or follow up measurements)

Patients will be excluded from the Part II of the study if they meet any of the following criteria:

* Age less than 18 years old
* Absence of signed Informed Consent Form
* Received less than 3 IV ketamine infusions
* Have any contradictions to the administration of intravenous ketamine (known allergy to ketamine or fail to pass Ketamine treatment screening)
* Diagnosis of dementia or other cognitive impairments
* Any clinically significant acute or chronic medical condition that in the judgment of Investigator may preclude the use of intravenous ketamine or compromise patient safety, limit patient's ability to complete the study, and/or compromise the objectives of the study.
* Participation in any other clinical study within 3 months prior to screening and during the study period.