Fibromyalgia syndrome is a chronic pain illness which is characterized by widespread musculoskeletal aches, pains and stiffness, soft tissue tenderness, general fatigue and sleep disturbances. The most common sites of pain include the neck, back, shoulders, pelvic girdle and hands, but any body part can be involved.
“The pain of fibromyalgia is notoriously difficult to treat,” said Dr Patrick Wood, of the Louisiana State University Health Sciences Center in Shreveport, Louisiana. “The results from this trial are quite encouraging, and further study is warranted.”
The 8-week randomized, double-blind, placebo-controlled study examined two dosages of Xyrem (4.5g per day or 6g per day) taken in two equally divided doses, the first at bedtime and the second 2.5 to 4 hours later.
The primary outcome variable (POV) was a composite of changes from baseline in three co-primary, self-reported measures; pain visual analog scale (PVAS), fibromyalgia impact questionnaire total score (FIQ), and patient global impression of change (PGIC).
A statistically significant benefit in the POV was seen in both doses of Xyrem compared with placebo. Patient response rates in the POV were 34.5% [4.5g] and 27.3% [6g] compared to 12.5% in the placebo group. In the PVAS, both doses of Xyrem resulted in significantly greater improvement than placebo.
In this study, Xyrem was generally well tolerated and no treatment-related serious adverse events were reported.