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A potential anti-inflammatory effect of low-dose naltrexone in fibromyalgia (Abstract)
A potential anti-inflammatory effect of low-dose naltrexone in fibromyalgia
01 April 2015
Fibromyalgia (FM) is a chronic pain disorder of an uncertain pathophysiology, that predominantly affects females. FM is mainly characterized by widespread pain, increased sensitivity to normal physical stimuli, and fatigue. Changes in neuroimmune function, such as a shift in the microglia towards a pro-inflammatory phenotype, could be involved in the generation and maintenance of FM symptoms. The drug naltrexone has previously been shown to suppress glial activation in animal models. At low doses, naltrexone (LDN) has also been shown to be effective in reducing symptoms of FM in women. The mechanism of this clinical effect, however, is not known. In this pilot study, we tested the hypothesis that LDN has an anti-inflammatory effect in women with FM. Specifically, we predicted that serum secreted pro-inflammatory cytokine concentrations would be reduced after 8 weeks of LDN treatment. We recruited female participants with FM who had no known inflammatory or autoimmune disorders, as confirmed by medical history and laboratory tests. Participants self-reported their FM pain severity daily using a handheld computer. Participants also provided venous blood samples twice weekly. Cytokine concentrations were assayed using a Luminex 63-plex inflammatory panel. A baseline period of 2 weeks was followed by 8 weeks of oral LDN, administered at 4.5mg/day. Five participants had an overall reduction in pain during the study period (range: 12.2–52.3%). In exploratory analyses, five of the analytes showed a significant decrease over time in the entire group: TGF-α (p=0.031), IL-6 (p=0.005), IL-17A (p=0.026), BDNF (p=0.040), and MCP-3 (p=0.008). One analyte, resistin, showed a significant increase over time (p=0.006). These findings suggest that LDN administration may have a specific anti-inflammatory effect on immune function. The exploratory nature of this study, however, requires that additional studies be conducted to confirm the findings and their clinical relevance. Supported, in part, by an IASP Scan|Design trainee fellowship.