Effects of naltrexone on pain sensitivity and mood in fibromyalgia: no evidence for endogenous opioid pathophysiology.
The pathophysiological mechanisms underlying fibromyalgia are still unknown, although some evidence points to endogenous opioid dysfunction. We examined how endogenous opioid antagonism affects pain and mood for women with and without fibromyalgia. Ten women with fibromyalgia and ten age- and gender-matched, healthy controls each attended two laboratory sessions. Each participant received naltrexone (50mg) at one session, and placebo at the other session, in a randomized and double-blind fashion. Participants were tested for changes in sensitivity to heat, cold, and mechanical pain. Additionally, we collected measures of mood and opioid withdrawal symptoms during the laboratory sessions and at home the night following each session. At baseline, the fibromyalgia group exhibited more somatic complaints, greater sensory sensitivity, more opioid withdrawal somatic symptoms, and lower mechanical and cold pain-tolerance than did the healthy control group. Neither group experienced changes in pain sensitivity due to naltrexone administration. Naltrexone did not differentially affect self-reported withdrawal symptoms, or mood, in the fibromyalgia and control groups. Consistent with prior research, there was no evidence found for abnormal endogenous opioid activity in women with fibromyalgia.
Department of Anesthesia, Stanford University School of Medicine, Palo Alto, California, United States of America. Jarred.Younger@stanford.edu
Jarred W
JW
Younger
Alex J
AJ
Zautra
Eric T
ET
Cummins
D004311:Double-Blind Method; D005260:Female; D005356:Fibromyalgia / Q000188:drug therapy / Q000503:physiopathology; D006801:Humans; D008875:Middle Aged; D009271:Naltrexone / Q000494:pharmacology / Q000627:therapeutic use; D009292:Narcotic Antagonists / Q000494:pharmacology / Q000627:therapeutic use; D018847:Opioid Peptides / Q000378:metabolism*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects*; D010919:Placebos / Q000494:pharmacology; D013375:Substance Withdrawal Syndrome; D016896:Treatment Outcome
D009292:Narcotic Antagonists; D018847:Opioid Peptides; D010919:Placebos; D009271:Naltrexone