Effect of Gabapentin Enacarbil on Individual Items of the International Restless Legs Study Group Rating Scale and Post-sleep Questionnaire in Adults with Moderate-to-Severe Primary Restless Legs Syndrome: Pooled Analysis of 3 Randomized Trials.

PURPOSE: Few studies have investigated restless legs syndrome (RLS) treatment effects on individual International RLS Study Group Rating Scale (IRLS) items. We assessed the effects of gabapentin enacarbil (GEn) on individual IRLS items and their correlation with sleep disturbances in adults with moderate-to-severe primary RLS. METHODS: Data were pooled from the randomized, double-blind, placebo-controlled, 12-week studies of XP052, XP053, and XP081 for adults who received GEn (600 or 1200 mg) or placebo once daily. Adults had primary RLS, IRLS total score ≥15, and RLS symptoms >15 days during the month before screening and for ≥4 of the 7 consecutive evenings at baseline. End points included mean change from baseline to week 12 in individual IRLS and post-sleep questionnaire (PSQ) items. For IRLS items, least squares mean treatment differences were calculated from a mixed model for repeated measures. For PSQ items, Cochran-Mantel-Haenszel row mean scores tests with integer scoring were used. Correlations between IRLS and PSQ items were assessed by Spearman's rank coefficients. Safety profile outcomes included treatment-emergent adverse events (TEAEs) and serious TEAEs. FINDINGS: The modified intent-to-treat population included 671 patients (GEn 600 mg = 161; GEn 1200 mg = 266; placebo = 244). GEn significantly improved mean [SE] differences versus placebo for all IRLS items at week 12, including severity of sleep disturbance (GEn 600 mg, -0.4 [0.10]; GEn 1200 mg, -0.4 [0.09]), daytime tiredness (-0.4 [0.09]; -0.4 [0.08]), RLS severity (-0.4 [0.10]; -0.3 [0.08]), impact on daily affairs (-0.3 [0.07]; -0.3 [0.07]), and mood disturbance (-0.2 [0.07]; -0.3 [0.06]); all P<0.001). For PSQ items, significant (P<0.01) improvements occurred with both GEn doses versus placebo at week 12. The correlations between IRLS and PSQ items for change from baseline to week 12 were moderate to strong, and all correlations were significant (P<0.001). The most frequent TEAEs were somnolence (GEn 600 mg, 20%; GEn 1200 mg, 23%; placebo, 5%) and dizziness (GEn 600 mg, 14%; GEn 1200 mg, 22%; placebo, 5%). IMPLICATIONS: GEn significantly improved individual IRLS items and sleep disturbance versus placebo. Correlations between IRLS and PSQ items were moderate to strong. This was not a formal meta-analysis and was not powered to compare the GEn doses. Nevertheless, our study finds that the benefits of GEn extend to individual IRLS items and supports the importance of sleep quality in RLS treatment. ClinicalTrials.gov identifiers: NCT00298623, NCT00365352, and NCT01332305.

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

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.

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.

The Effect of Gabapentin Enacarbil on Pain Associated with Moderate-to-Severe Primary Restless Legs Syndrome in Adults: Pooled Analyses from Three Randomized Controlled Trials.

BACKGROUND: Adults with moderate-to-severe primary restless legs syndrome (RLS) often experience painful dysesthesias, which may lead to impaired quality of life. OBJECTIVES: The aim of this study was to assess the effects of gabapentin enacarbil (GEn) on pain associated with moderate-to-severe primary RLS in adults. METHODS: Data were pooled from three double-blind, randomized, placebo-controlled, 12-week trials (NCT00298623, NCT00365352, NCT01332305) for adults receiving GEn or placebo once daily. Change in average daily RLS pain score and a combined International Restless Legs Scale (IRLS)-pain response were examined. RESULTS: The modified intention-to-treat population included 671 adults (placebo, n = 244; GEn 600 mg, n = 161; GEn 1200 mg, n = 266). Both GEn doses significantly improved average daily RLS pain score at week 12 (p < 0.001 for GEn 600 mg vs. placebo and GEn 1200 mg vs. placebo). The combined IRLS-pain response subanalysis included 366 patients with a baseline IRLS total score ≥15 and pain score ≥4 (placebo, n = 133; GEn 600 mg, n = 86; GEn 1200 mg, n = 147). Most patients were both IRLS and pain responders (placebo, 40 %; GEn 600 mg, 70 %; GEn 1200 mg, 67 %). Spearman rank correlations between IRLS total and pain score (change from baseline to week 12) were moderate or strong. The most frequent treatment-emergent adverse events were somnolence (placebo, 5 %; GEn 600 mg, 20 %; GEn 1200 mg, 23 %) and dizziness (placebo, 4 %; GEn 600 mg, 13 %; GEn 1200 mg, 22 %). CONCLUSIONS: This post hoc pooled analysis suggests that GEn (600 and 1200 mg) once daily significantly improved pain associated with moderate-to-severe primary RLS in adults; however, the analysis was not powered to detect statistical differences between the two GEn doses. Numerically, more GEn-treated patients had a combined IRLS-pain response than placebo-treated patients.

Impact of Data Imputation Methodology on Pain Assessment over 24 Hours in a Randomized, Placebo-Controlled Study of Gabapentin Enacarbil in Patients with Neuropathic Pain Associated with Postherpetic Neuralgia.

OBJECTIVE: To assess the impact of gabapentin enacarbil on primary and secondary pain endpoints using three data imputation methodologies in a randomized phase II study of adult patients with postherpetic neuralgia. METHODS: The primary endpoint was change from baseline to end of maintenance treatment in mean 24-hour average pain intensity score. Secondary endpoints (daytime/nighttime average pain intensity score, daytime/nighttime current pain intensity score, and daytime/nighttime worst pain intensity score) were based on daily electronic diary assessments. Comparisons of each gabapentin enacarbil dose with placebo were performed using three different statistical methodologies: last observation carried forward, baseline observation carried forward, and mixed-effect model for repeated measures. RESULTS: Of the 376 randomized patients, 371 were in the intent-to-treat population (gabapentin enacarbil 1,200 mg, 107; 2,400 mg, 82; 3,600 mg, 87; placebo, 95). For mean 24-hour average pain intensity score, there were statistically significant improvements from baseline to end of maintenance treatment for all gabapentin enacarbil groups vs placebo using the three analysis methods. Significant improvements were also observed for all secondary endpoints with gabapentin enacarbil 1,200 mg using the three analysis methods. Most secondary endpoints also showed improvements following treatment with gabapentin enacarbil 2,400 mg or 3,600 mg compared with placebo. CONCLUSIONS: Gabapentin enacarbil (1,200 mg, 2,400 mg, and 3,600 mg) was effective and well tolerated in patients with postherpetic neuralgia compared with placebo, as confirmed by three different and robust statistical methodologies.

Treatment response to sleep, pain, and mood disturbance and their correlation with sleep disturbance in adult patients with moderate-to-severe primary restless legs syndrome: Pooled analyses from 3 trials of gabapentin enacarbil.

INTRODUCTION: This pooled analysis investigated the effects of gabapentin enacarbil (GEn) on clinical correlates of sleep disturbance in adults with moderate-to-severe primary restless legs syndrome (RLS) and no-to-moderate or severe-to-very severe baseline sleep disturbance. METHODS: Co-primary end-points were mean change from baseline to week 12 in International Restless Legs Scale (IRLS) total score and proportion of responders ('much'/'very much' improved) on the investigator-rated Clinical Global Impression-Improvement (CGI-I) scale (week 12). Pain, mood, individual IRLS items, and safety were assessed. RESULTS: The modified intent-to-treat population was 671 adults randomized to GEn 600 mg (n = 161), GEn 1200 mg (n = 266), or placebo (n = 244). GEn significantly improved least squares mean change in IRLS total score from baseline versus placebo for no-to-moderate (GEn 600 mg,- 12.3; 1200 mg, - 11.3; placebo, - 7.7) and severe-to-very severe (- 16.6; - 17.0; - 12.7) groups (all P < 0.01). Significantly more GEn-treated patients (both doses) were CGI-I responders (week 12) versus placebo in both sleep subgroups (all P < 0.01). GEn substantially improved mood and pain scores for both sleep subgroups versus placebo. The most frequent treatment-emergent adverse events were somnolence and dizziness. CONCLUSION: GEn (600 mg and 1200 mg) was effective and well tolerated in adults with moderate-to-severe primary RLS regardless of baseline sleep disturbance level.

Effect of prior exposure to dopamine agonists on treatment with gabapentin enacarbil in adults with moderate-to-severe primary restless legs syndrome: pooled analyses from 3 randomized trials.

BACKGROUND: Dopamine agonists (DAs) are a first-line therapy for moderate-to-severe restless legs syndrome (RLS), but these treatments may lead to complications, such as augmentation and impulse control disorders, requiring switching to another therapeutic class. Here we assess efficacy and tolerability of gabapentin enacarbil (GEn) in adults with moderate-to-severe primary RLS, with or without prior DA exposure. METHODS: Data from 3 trials were pooled. Patients were identified as DA-naive or DA-exposed, based on prior treatment with ropinirole, pramipexole, rotigotine, or pergolide mesylate, and the dopamine precursor levodopa. Details on prior treatment duration and dose were unavailable. Patients with a history of augmentation were excluded. Within DA-naive/DA-exposed patients we investigated the co-primary end points from the pivotal trials: mean change from baseline to week 12 in International RLS (IRLS) Rating Scale total score and proportion of responders ("much"/"very much" improved) on the investigator-rated Clinical Global Impression-Improvement (CGI-I) scale. Safety was also assessed. RESULTS: 671 patients were randomized (DA-naive: placebo, n = 194; GEn 600 mg, n = 131; GEn 1200 mg, n = 214; DA-exposed: placebo, n = 50; GEn 600 mg, n = 30; GEn 1200 mg, n = 52). Across treatment arms, no significant differences between DA-naive and DA-exposed subgroups in IRLS Rating Scale total score change from baseline at any visit were seen, except week 1 in the placebo group (-6.1 DA-naive vs -3.4 DA-exposed, P = .020). No significant differences in the odds of CGI-I response at week 12 between DA-naive vs DA-exposed patients in any treatment group were seen; however, with placebo there was a nonsignificant trend toward fewer responders among DA-exposed (34.0%) vs DA-naive (44.3%) patients. Both GEn doses significantly improved the IRLS Rating Scale total score change from baseline and CGI-I response vs placebo, regardless of prior DA exposure. The most common treatment-emergent adverse events were dizziness and somnolence. CONCLUSIONS: Prior DA exposure had no significant effect on efficacy or tolerability of GEn (600 or 1200 mg) in this pooled analysis of adults with moderate-to-severe primary RLS. These data support the use of GEn in DA-exposed and DA-naive patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT00298623, NCT00365352, and NCT01332305.