(HealthDay News) – Low-dose naltrexone treatment is associated with significant reductions in pain in patients with fibromyalgia, according to a study published in the February issue of Arthritis & Rheumatism.

Jarred Younger, PhD, from the Stanford University School of Medicine in Palo Alto, CA, and colleagues conducted a crossover study involving 31 women with fibromyalgia who were randomly assigned to a four-week placebo stage and a 12-week active phase comprising 4.5mg/day of naltrexone. Daily levels of pain were assessed.

The researchers found that baseline pain was significantly reduced in patients taking low-dose naltrexone vs. placebo (reduction of 28.8% vs. 18%). There was also significant improvement in general satisfaction with life and mood in patients taking naltrexone, although there was no improvement in fatigue or sleep. The response rate, as assessed by significant reductions in pain plus a significant reduction either fatigue or sleep problems, was significantly higher for low-dose naltrexone than placebo (32% vs. 11%). Naltrexone was as well tolerated as placebo and there were no serious side effects.

“Our replicated observation that low-dose naltrexone affects levels of pain, together with the low cost and tolerable nature of low-dose naltrexone, makes it a promising target for future investigation,” Younger and colleagues conclude.

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