Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Durability of Response in a 38-Week Open-Label Study of Sodium Oxybate in Patients with Fibromyalgia.

Spaeth5,  Michael, Russell7,  I. Jon, Perrot6,  Serge, Alvarez-Horine3,  Sarah, Guinta1,  Diane R., Wang2,  Y. Grace, Bennett4,  Robert M.

Jazz Pharmaceuticals Inc., Palo Alto, CA
Jazz Pharmaceuticals Inc.
Jazz Pharmaceuticals, Inc.
Oregon Health and Science Univ, Portland, OR
Rheumatologische Schwerpunktpraxis
Service de Medecine Interne et Centre de la Douleur, Hôtel-Dieu
University of Texas Health Science Center, San Antonio, TX

Background:

Two pivotal phase 3 clinical trials demonstrated the efficacy and tolerability of sodium oxybate (SXB) for the treatment of fibromyalgia (FM). Fibromyalgia is a chronic disorder characterized by widespread musculoskeletal pain, fatigue, sleep disturbances, and functional impairment. The current report describes the durability of response of SXB in a FM population.

Methods:

Patients with FM who completed a 14-week, placebo-controlled, phase 3 study of SXB were eligible to enroll in this international, open-label extension within 7 days after completing the previous study. Eligible subjects received open-label treatment for up to an additional 38 weeks. SXB was initiated at 4.5 g/night (administered in equally divided doses 2.5 to 4 hours apart), and increases were permitted in increments of 1.5 g/night, at intervals of at least 1 week, up to 9 g/night. Dose reductions were permitted in increments of 1.5 g/night to a minimum of 4.5 g/night; subjects unable to tolerate this dose were discontinued. Efficacy was evaluated based on reductions in pain and fatigue, recorded daily on a 100 mm Visual Analogue Scale (VAS), and improvement in function assessed using the Fibromyalgia Impact Questionnaire (FIQ) at each study visit. Study endpoint was defined as the last available data, whether obtained at study completion or early discontinuation.

Results:

Of 560 subjects who were treated (mean age, 46.9 years; 91.1% female), 366 subjects (65.4%) received study drug for at least 24 weeks and 269 subjects (48.0%) received study drug at least 38 weeks. Mean dose was 6.28 g/night at last dose for all subjects. Improvements seen on multiple measures in the previous trials were maintained. At study endpoint, the mean change from prior study baseline in pain VAS for all treated patients was –35.84 mm, with 68.8% and 53.0% achieving a >=30% and >=50% pain reduction, respectively. At study endpoint, the mean change from baseline in fatigue VAS was –37.15 mm. At endpoint, 69.7% of patients had achieved >=30% reduction from baseline in total FIQ score. The incidence of AEs was 88.9% overall. AEs were generally mild or moderate in severity. Twenty-three percent of subjects discontinued due to AEs. The most common AEs (>=5% in any treatment group) were nausea, headache, dizziness, nasopharyngitis, vomiting, sinusitis, diarrhea, anxiety, insomnia, influenza, somnolence, upper respiratory tract infection, muscle spasms, urinary tract infection, and viral gastroenteritis.

Conclusions:

This open-label study demonstrated the long-term durability of effect of SXB for the treatment of FM over a dose range of 4.5 to 9 g/night for 38 weeks. Treatment effects were substantial across multiple fibromyalgia symptoms, including pain, fatigue, and impairments in daily living and physical functioning. SXB was generally well-tolerated over the 38 weeks of treatment.

To cite this abstract, please use the following information:
Spaeth, Michael, Russell, I. Jon, Perrot, Serge, Alvarez-Horine, Sarah, Guinta, Diane R., Wang, Y. Grace, et al; Durability of Response in a 38-Week Open-Label Study of Sodium Oxybate in Patients with Fibromyalgia. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :97
DOI: 10.1002/art.27866

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