Sodium oxybate reduces pain, fatigue, and sleep disturbance and improves functionality in fibromyalgia: Results from a 14-week, randomized, double-blind, placebo-controlled study

This 14-week, phase 3, double-blind, randomized, controlled trial evaluated sodium oxybate (SXB) 4.5 and 6 g per night versus placebo in patients with fibromyalgia (FM). SXB is the sodium salt of gamma-hydroxybutyrate (GHB). GHB is an endogenous compound, synthesized from gamma-aminobutyric acid (GABA) and found broadly in the central nervous system and body. Among 548 randomized patients, a >= 30% reduction in pain was experienced by 54.2% and 58.5% of patients treated with SXB 4.5 and 6 g, respectively, versus 35.2% for placebo with a 100-mm Visual Analog Scale (VAS) (P < 0.001 for both comparisons). Relative to placebo, both SXB doses significantly reduced fatigue (with a 100-mm VAS; P < 0.001) and sleep disturbance (with the Jenkins Sleep Scale; P < 0.001), and resulted in significant improvements in function as measured by the FM Impact Questionnaire (P = 0.003 and P = 0.001 for 4.5 and 6 g per night, respectively). On the Short-Form 36 Health Survey, SXB-related improvement was significant on the Physical, but not the Mental, Component Scale. The proportion of patients who reported a global improvement of "much" or "very much" better on the Patient Global Impression of Change was significantly greater in both SXB groups versus placebo (P < 0.001). Headache, nausea, dizziness, vomiting, diarrhea, anxiety, and sinusitis were the most commonly reported adverse events, with an incidence at least twice that of placebo. These results expand the evidence from previous clinical trials suggesting that SXB is effective and safe in FM. (C) 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.