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Fatigue, Sleep Disturbance, and Patient Global Impressions of Change Improve With Sodium Oxybate: Presented at ACR/ARHP

By Liz Meszaros

PHILADELPHIA -- October 21, 2009 -- Treatment with sodium oxybate in patients with fibromyalgia incurred clinically meaningful improvements in pain, fatigue, and global improvements, as well as a decrease in sleep disturbance, according to a study presented here at the 2009 Annual Scientific Meeting of the American College of Rheumatology/Association of Rheumatology Health Professionals (ACR/ARHP).

Treatment of fibromyalgia with sodium oxybate (SXB), a sodium salt of gamma-hydroxybutyrate, is a very different approach to treatment of this disease, according to presenter Andrew J. Holman, MD, Pacific Rheumatology Associates, Inc., in Renton, Washington.

"This is the first attempt to treat fibromyalgia in a completely new way," he said on October 20. "Sodium oxybate is not an antidepressant or an antiepileptic. It is a naturally occurring molecule that appears to improve sleep stage architecture. Sodium oxybate is not a new medication, and by giving it to patients with fibromyalgia who have known sleep deficits as well as autonomic problems, in addition to pain and fatigue, it demonstrated a response rate that is actually superior to other clinical trials that have been done."

The 14-week, phase 3, controlled trial included 548 patients who met ACR criteria for fibromyalgia. Patients were randomised in a 1:1:1 ratio to parallel therapy with sodium oxybate 4.5 mg/night (SXB4.5), SXB 6 g/night (SXB6), or placebo. Treatment was administered as 2 equal, divided doses at bedtime, and then 2.5 to 4 hours later.

The primary outcome measure was the percentage of subjects who reported a clinically relevant, >=30% reduction in the Pain visual analogue scale (VAS) from baseline to week 14.

At week 14, significant reductions were seen in mean fatigue VAS scores in the SXB4.5 and SXB6 groups, compared with placebo (-27.94 and -30.02, respectively, vs -17.57; both P < .001). These reductions were also seen at all weekly time points as early as week 1 (P < .01 for all).

Reductions of >= 30% in pain VAS at week 14 were similar for the SXB4.5 and SXB6 groups compared with placebo (P < .001). Significantly greater reductions were also seen in both active treatment groups in mean Jenkins Sleep Scale (JSS) scores at week 14 compared with placebo (-6.1 and -6.2, respectively, vs -2.9; both P < .001), and beginning at week 4 for all other measures (P < .001).

Clinically meaningful improvements in global status -- with patient global impression of change scores of "much better" or "very much better" -- were also reported by a greater percentage of patients in both of the active treatment groups compared with placebo (48.3% and 45.4%, respectively, vs 27.2%; both P < .001).

Strong Pearson correlations for changes in pain were seen with fatigue VAS and JSS scores (0.89 and 0.51, respectively; P < .001).

The most common adverse event was headache, with the highest incidence reported in the group treated with 6 mg SXB (23.1%), compared with 15% in the SXB4.5 group, and 11% in placebo.

Funding for this study was provided by Jazz Pharmaceuticals, Inc.

[Presentation title: Sodium Oxybate Improves Fatigue, Sleep Disturbance, and PGIc in Fibromyalgia: Results From a Phase 3, 14-Week, Controlled Trial. Abstract 1412]

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