The Effect of Gabapentin Enacarbil on Quality of Life and Mood Outcomes in a Pooled Population of Adult Patients with Moderate-to-Severe Primary Restless Legs Syndrome.

OBJECTIVE

The aim was to assess gabapentin enacarbil (GEn) treatment effects on quality of life (QOL) and mood in adults with moderate-to-severe primary restless legs syndrome (RLS).

METHODS

Data were pooled from three placebo-controlled, randomized, double-blind, 12-week trials for adults receiving GEn (600 mg or 1200 mg) or placebo once daily. QOL was assessed with the RLS QOL questionnaire in two studies. Mood was examined with the Profile of Mood States Brief Form (POMS-B), and as an exploratory analysis with International Restless Legs Scale (IRLS) item 9 (daily affairs) and item 10 (mood disturbance) across all three studies. Mood and QOL were secondary endpoints in the individual clinical trials. No adjustments for multiplicity were applied.

RESULTS

The QOL analysis modified intent-to-treat (MITT) population included 541 adults (placebo, n = 204; GEn 600 mg, n = 114; GEn 1200 mg, n = 223). Both GEn doses significantly improved QOL versus placebo (week 12; p < 0.01). The mood analysis MITT population included 671 adults (placebo, n = 244; GEn 600 mg, n = 161; GEn 1200 mg, n = 266). GEn 600 mg significantly improved POMS vigor-activity versus placebo (week 12; p < 0.05); other POMS criteria were not significantly affected. GEn 1200 mg significantly improved POMS scores for total mood disturbance, depression-dejection, fatigue-inertia, vigor-activity, and confusion-bewilderment versus placebo at week 12 (p < 0.05); tension-anxiety and anger-hostility were not significantly affected. Both GEn doses significantly improved IRLS item 9 and item 10 versus placebo at week 12 (p < 0.05). The most frequent treatment-emergent adverse events with GEn were somnolence and dizziness.

CONCLUSIONS

GEn (600 mg and 1200 mg) once daily significantly improved QOL in adults with moderate-to-severe primary RLS at all time points examined. While the only POMS item significantly improved by GEn 600 mg versus placebo at week 12 was vigor-activity, GEn 1200 mg significantly improved total mood disturbance and several other POMS items versus placebo at week 12. Both QOL and mood improvements were numerically greater with GEn 1200 mg versus 600 mg.

TRIAL REGISTRATIONS: Clinicaltrials.gov identifiers NCT00298623, NCT00365352, NCT01332305.