Efficacy of gabapentin enacarbil in adult patients with severe primary restless legs syndrome

Abstract Aim Assess efficacy and tolerability of gabapentin enacarbil (GEn) in adults with severe primary restless legs syndrome (RLS). Methods We pooled data from three 12-week, double-blind, placebo-controlled, randomized trials (NCT00298623, NCT00365352, NCT01332305) across GEn 600-mg, GEn 1200-mg, and placebo treatment groups for severe primary RLS (baseline International Restless Legs Scale (IRLS) total score ≥24). Co-primary end points at week 12 were mean change from baseline in IRLS total score and proportion of responders ("much"/very much" improved) on the investigator-rated Clinical Global Impression – Improvement (CGI-I) Scale. Outcomes for individual IRLS items (eg, sleep, mood, quality of life, pain, safety) were assessed. Results A total of 309 patients had severe primary RLS (placebo, n  = 110; GEn 600 mg, n  = 80; GEn 1200 mg, n  = 119). GEn 600 mg and 1200 mg significantly improved least-squares mean IRLS total scores versus placebo at week 12 (placebo, −12.3; GEn 600 mg, −16.3; GEn 1200 mg, −18.0; treatment difference vs. placebo, both p  0.01). Significantly more patients with severe primary RLS treated with GEn 600 mg (64%) and 1200 mg (74%) were CGI-I responders at week 12 versus placebo (42%; p  0.01 for both GEn doses). Both GEn doses led to significant improvements in the other outcomes explored versus placebo at week 12. The most frequent treatment-emergent adverse events (TEAEs) were somnolence (GEn, 21–24%; placebo, 3%) and dizziness (GEn, 14–19%; placebo, 3%). Conclusions GEn (600 mg or 1200 mg) once daily significantly improved RLS symptoms and consequences of these symptoms in severe primary RLS. The most frequent TEAEs were somnolence and dizziness.