Low-dose naltrexone and fibromyalgia

Low-dose naltrexone and fibromyalgia

Perform a Google search of "low-dose naltrexone" and you will find a myriad of anecdotal testimonies to the benefits of the drug in a wide range of diseases including fibromyalgia. Now a small study suggests that naltrexone may be of some benefit in this difficult condition. Naltrexone (not to be confused with naloxone) is an opioid receptor antagonist used primarily for treatment of alcohol dependence and opioid dependence. Because of multiple internet reports of benefit in patients with fibromyalgia, researchers from Stanford performed a single-blind, placebo-controlled crossover study of 10 patients with moderately severe fibromyalgia who were not on opioids. The dose of naltrexone used was 4.5 mg per day, which is less than 10 times lower than the dose used for addiction (50 mg per day). Patients on active treatment reported a 32.5% reduction in fibromyalgia symptoms compared to baseline vs a 2.3% reduction for placebo (P = 0.003 vs placebo). Side effects, which included insomnia and vivid dreams, were rare. Interestingly, patients with higher sedimentation rates had the greatest reduction in symptoms and best response to low-dose naltrexone. The authors hypothesize that low-dose naltrexone may inhibit the activity of microglia and reverse central or peripheral inflammation, thus reducing symptoms of fibromyalgia, although more studies are needed. They also suggest that naltrexone can be used in addition to other medications commonly used for fibromyalgia (Pain Med 2009 April 22; epub ahead of print).