Fibromyalgia is a chronic pain disorder that is characterized by diffuse musculoskeletal pain and sensitivity to mechanical stimulation. Naltrexone, in addition to antagonizing opioid receptors on neurons, also inhibits microglia activity in the central nervous system. At low doses (4.5mg) it may inhibit the activity of microglia and reverse central and peripheral inflammation.

A study conducted by Stanford University tested the effectiveness of low-dose naltrexone in treating the symptoms of fibromyalgia. The study consisted of ten women who met the criteria for fibromyalgia and were not taking opioid medication. Participants completed daily reports of symptom severity and visited the lab every 2 weeks for tests of mechanical, heat and cold pain sensitivity. The entire cohort experienced a reduction in fibromyalgia symptoms, with a greater than 30% reduction over placebo. In addition, lab visits showed that mechanical and heat pain thresholds were improved. Side effects were rare, and described as minor and transient, including insomnia and vivid dreams. the study concluded that low-dose naltrexone should be considered as an effective, highly tolerable, and inexpensive treatment for fibromyalgia.*

Understanding the role of the individual sex hormones in the production of pain perception and their various effects on nociceptors is imperative to managing potential underlying hormone disruptions in chronic pain syndromes. Some clinicians believe declining levels of progesterone may be related to the onset of fibromyalgia. Progesterone has inhibitory effects on nociceptors, therefore, deficiencies in progesterone can result in increased pain perception. The analgesic, antidepressant, and anxiolytic effects of progesterone along with the multitude of progestogenic effects on neurotransmitters and multiple pain receptors suggest a mechanism for the role of progesterone replacement therapy in chronic pain syndromes. Both high and low serum estradiol levels can increase pain perception, emphasizing the need for estrogen replacement therapy at correct physiologic levels in fibromyalgia patients. These patients also often have adrenal insufficiencies and low DHEA levels. Treatment of fibromyalgia should be customized to the patient's needs and adrenal, thyroid, and ovarian hormone support can lessen the painful burden of fibromyalgia through the modulation of various hormone-regulated pain production pathways. **

* www.nncbi/nlm.nih.gov/pubmed/19453963

** International Journal of Pharmaceutical Compounding May/June 2010