WASHINGTON – Gabapentin brought greater relief of symptoms to patients with primary fibromyalgia than placebo in a randomized, double-blind trial, Dr. Lesley M. Arnold reported at the annual meeting of the American College of Rheumatology.
Gabapentin is known to be effective for neuropathic pain conditions, and growing evidence suggests fibromyalgia might share some of the same pathogenic mechanisms, said Dr. Arnold of the department of psychiatry at the University of Cincinnati.
The trial of 150 patients involved a 60-day phase when other psychotropic, sleep, and pain medications (besides over-the-counter NSAIDs and acetaminophen) were not allowed, a 6-week acute therapy phase when the dosage was titrated to 1,200–2,400 mg/day, and a 6-week stable dosage phase.
At week 12, the 75 gabapentin-treated patients had a significantly greater mean improvement on the Brief Pain Inventory (BPI) 24-hour average pain severity score than did the 75 placebo patients; this was the primary outcome of the study. Gabapentin-treated patients scored an average of 0.92 less on that inventory than did placebo patients. The BPI 24-hour average pain severity score is measured on a range from 0 (no pain) to 10 (worst pain imaginable).
A significantly higher percentage of gabapentin patients responded to treatment than did placebo patients (51% vs. 31%).
Gabapentin also significantly improved measures of the interference and impact of symptoms on daily life and functioning, clinical impressions, and sleep. But the drug provided no significant changes in tender point threshold or relief of depressive symptoms, said Dr. Arnold, who disclosed that she has received research grants and consulting fees or other payments from Pfizer Inc., and has served on its speakers' bureau.
The trial was supported by the National Institutes of Health.