The Effect of Gabapentin Enacarbil (GEn) on Pain Outcomes in Adults with Moderate-to-Severe and Severe Primary Restless Legs Syndrome (RLS): Pooled Analyses from 3 Randomized Controlled Trials (P7.294)

OBJECTIVE: To determine the effect of treatment with GEn on pain in adult patients with moderate-to-severe and severe primary RLS. BACKGROUND: GEn significantly improved RLS symptoms vs placebo in adults with moderate-to-severe primary RLS in the XP052, XP053, and XP081 trials. DESIGN/METHODS: Trial data were pooled. Adult patients with moderate-to-severe primary RLS received once-daily GEn (600 mg or 1200 mg) or placebo. Daily pain scores were assessed with a Visual Analog Scale (VAS) for pain (scale 0-10), averaged over the 7 days before baseline and study visits. Changes from baseline were evaluated among the modified intent-to-treat population of patients with moderate-to-severe and severe primary RLS (IRLS Rating Scale 蠅15 and 蠅24, respectively). Treatment effects were analyzed using a mixed model for the change from baseline. RESULTS: Patients were randomized to placebo (n=244), GEn 600 mg (n=161), GEn 1200 mg (n=266); 307 patients had severe primary RLS (placebo, n=110; GEn 600 mg, n=80; GEn 1200 mg, n=119). In the moderate-to-severe primary RLS population, least squares (LS)mean (standard error) changes in VAS from baseline to week 12 were: placebo, −1.6 (0.13); GEn 600 mg, −2.4 (0.16); GEn 1200, mg −2.5 (0.12). Differences between both GEn doses and placebo were statistically significant ( P P <0.01) at all time points (weeks 2, 4, 8, and 12). CONCLUSIONS: In this pooled analysis of adult patients with moderate-to-severe and severe primary RLS, GEn treatment significantly improved pain outcomes. Within each of the studies, the most common treatment-emergent adverse events were somnolence and dizziness. Disclosure: Dr. Hermanowicz has received research support from Acadia, Allergan Inc., Boehringer Ingelheim Pharmaceuticals Inc., GalxoSmithKline Inc., Kyowa, Merz Pharma, Novartis, and Parkinson9s Study Group. Dr. Buchfuhrer has nothing to disclose. Dr. Wynn Acorda Therapeutics, Avanir Pharmaceuticals, EMD Serono, Genzyme Corporation, GlaxoSmithKline, Sanofi-Aventis Pharmaceuticals, Inc., Teva Neuroscience, and XenoPort as a speaker and/or consultant. Dr. Jaros has received personal compensation for activities with XenoPort, Inc. as an employee. Dr. Kim has received personal compensation for activities with XenoPort, Inc. as an employee. Dr. Shang has received personal compensation for activities with XenoPort, Inc. as an employee.