Patients with fibromyalgia got no more pain relief from low-dose naltrexone than from placebo in a randomized trial, researchers said, dashing hopes that the opioid receptor antagonist might succeed where others have failed.
In the 99-patient trial, those assigned to naltrexone reported a mean 1.3-point decline in pain intensity after 12 weeks, compared with a decrease of 0.9 points in a placebo group (P=0.27), according to Karin Due Bruun, MD, PhD, of Odense University Hospital in Denmark, and colleagues. Given that pain was rated on an 11-point scale, the difference of 0.4 points would not have been clinically important even if it had achieved statistical significance.