NEW YORK (Reuters Health) Jan 21 – Sodium oxybate relieves pain and improves function, with few adverse events, in patients with fibromyalgia syndrome, researchers report in the January issue of Arthritis and Rheumatism.
“Sodium oxybate therapy was well tolerated and significantly improved the primary outcome variables,” lead investigator Dr. I. Jon Russell told Reuters Health. “In addition, significant improvement was seen with many of the secondary outcome variables which addressed a wide variety of the fibromyalgia syndrome symptoms.”
Dr. Russell of University of Texas Health Science Center at San Antonio and colleagues came to this conclusion following a study involving 188 patients. After discontinuing their prestudy medications, the patients were randomized to 4.5 gm or 6 gm of sodium oxybate or matching placebo once nightly for 8 weeks.
“Sodium oxybate is the sodium salt of gamma-hydroxybutyrate, a metabolite of gamma-aminobutyrate acid,” the investigators explain. The drug is currently approved by the U.S. Food and Drug Administration to treat cataplexy and symptoms of daytime sleepiness in narcolepsy patients.
One hundred forty-seven patients (78%) completed the trial. Intention-to-treat analysis showed significant benefit with both doses of the agent, based on patient self-reports of pain, sleep outcomes and quality of life. Improvements in their visual analogue pain score were significantly correlated with sleep outcomes.
Less than 28% of patients reported dose-related nausea and less than 18% reported dose-related dizziness. Most episodes tended to resolve and caused few patients to withdraw from the study.
The investigators conclude that “this proof-of-concept study suggests that sodium oxybate is effective and safe for the management of fibromyalgia syndrome symptoms,” and that further investigation is warranted.
Arthritis Rheum 2009;60:299-309.