Medline ® Abstracts for References 3,38-42

A systematic literature review and meta-analyses (where appropriate) were performed to update the previous AASM practice parameters on the treatments, both dopaminergic and other, of RLS and PLMD. A considerable amount of literature has been published since these previous reviews were performed, necessitating an update of the corresponding practice parameters. Therapies with a STANDARD level of recommendation include pramipexole and ropinirole. Therapies with a GUIDELINE level of recommendation include levodopa with dopa decarboxylase inhibitor, opioids, gabapentin enacarbil, and cabergoline (which has additional caveats for use). Therapies with an OPTION level of recommendation include carbamazepine, gabapentin, pregabalin, clonidine, and for patients with low ferritin levels, iron supplementation. The committee recommends a STANDARD AGAINST the use of pergolide because of the risks of heart valve damage. Therapies for RLS secondary to ESRD, neuropathy, and superficial venous insufficiency are discussed. Lastly, therapies for PLMD are reviewed. However, it should be mentioned that because PLMD therapy typically mimics RLS therapy, the primary focus of this review is therapy for idiopathic RLS.

OBJECTIVE: To assess the efficacy and tolerability of the nondopaminergic agent XP13512/GSK1838262 in adults with moderate to severe primary restless legs syndrome (RLS).

METHODS: Patient Improvements in Vital Outcomes following Treatment in Restless Legs Syndrome I was a 12-week, multicenter, randomized, double-blind, placebo-controlled trial of XP13512 1,200 mg or placebo taken once daily at 5:00 pm with food. Coprimary endpoints were mean change from baseline International Restless Legs Scale (IRLS) total score and proportion of investigator-rated responders (very much improved or much improved on the Clinical Global Impression-Improvement scale) at week 12 (last observation carried forward). Tolerability was assessed using adverse events, vital signs, and clinical laboratory parameters.

RESULTS: A total of 222 patients were randomized (XP13512 = 114, placebo = 108) and 192 patients (XP13512 = 100, placebo = 92) completed the study. At week 12, the mean change from baseline IRLS total score was greater with XP13512 (-13.2) compared with placebo (-8.8). Analysis of covariance, adjusted for baseline score and pooled site, demonstrated a mean treatment difference of -4.0 (95% confidence interval [CI], -6.2 to -1.9; p = 0.0003). More patients treated with XP13512 (76.1%) were responders compared with placebo (38.9%; adjusted OR 5.1; 95% CI, 2.8 to 9.2; p<0.0001). Significant treatment effects for both coprimary measures were identified at week 1, the earliest time point measured. The most commonly reported adverse events were somnolence (XP13512 27%, placebo 7%) and dizziness (XP13512 20%, placebo 5%), which were mild to moderate in intensity and generally remitted.

CONCLUSIONS: XP13512 1,200 mg, taken once daily, significantly improved restless legs syndrome (RLS) symptoms compared with placebo and was generally well tolerated in adults with moderate to severe primary RLS.

STUDY OBJECTIVE: To evaluate the efficacy and tolerability of XP13512/ GSK1838262, an investigational nondopaminergic agent for the treatment of moderate-to-severe primary restless legs syndrome (RLS).

DESIGN: Randomized, double-blind, placebo-controlled, crossover trial.

SETTING: Nine US clinical sites.

PATIENTS: Thirty-eight treatment-naive subjects with RLS (mean +/- SD age 50.1 +/- 13.2 years).

INTERVENTIONS: XP13512 1800 mg/day followed by placebo or placebo followed by XP13512 1800 mg/day for 14 days, with a 7-day washout between treatment periods.

MEASUREMENTS AND RESULTS: The primary endpoint was mean change from baseline International RLS Study Group rating scale (IRLS) total score on Day 14, analyzed using analysis of variance with sequence, period, and treatment as fixed effects and subjects within sequence as a random effect. XP13512 significantly reduced IRLS total score on Day 14 compared with placebo (mean +/- SD: XP13512 -12.1 +/-6.5, placebo -1.9 +/- 6.3; P<0.0001). Polysomnographic data showed that XP13512 significantly improved sleep architecture on Day 14 compared with placebo (mean +/- SD change from baseline sleep time [minutes]: stage 1: XP13512 -9.8 +/- 23.9, placebo 0.4 +/-23.2; adjusted P<0.0054, nominal P<0.0001; stage 3/4 (slow-wave sleep): XP13512 22.8 +/- 40.8, placebo 1.4 +/- 34.3; adjusted P=0.0092, nominal P=0.0002). The most frequently reported adverse events were somnolence (XP13512 30.6%, placebo 2.8%) and dizziness (XP13512 27.8%, placebo 5.6%).

CONCLUSIONS: XP13512 1800 mg/day significantly reduced RLS symptoms, improved sleep, and was generally well tolerated in subjects with moderate-to-severe primary RLS across 14 days of treatment.

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.

STUDY OBJECTIVE: To evaluate the efficacy and tolerability of gabapentin enacarbil (GEn) 1200 mg or 600 mg compared with placebo in subjects with moderate-to-severe primary restless legs syndrome (RLS).

METHODS: This 12-week, multicenter, double-blind, placebo-controlled study randomized subjects (1:1:1) to GEn 1200 mg, 600 mg, or placebo. Co-primary endpoints: mean change from baseline in International Restless Legs Scale (IRLS) total score and proportion of responders (rated as "very much" or "much" improved) on the investigator-rated Clinical Global Impression-Improvement scale (CGI-I) at Week 12 LOCF for GEn 1200 mg compared with placebo. Secondary endpoints included GEn 600 mg compared with placebo on the IRLS and CGI-I at Week 12 LOCF and subjective measures for sleep. Safety and tolerability assessments included adverse events.

RESULTS: 325 subjects were randomized (GEn 1200 mg = 113; 600 mg = 115; placebo = 97). GEn 1200 mg significantly improved mean [SD]IRLS total score at Week 12 LOCF (baseline: 23.2 [5.32];Week 12: 10.2 [8.03]) compared with placebo (baseline: 23.8 [4.58]; Week 12: 14.0 [7.87]; adjusted mean treatment difference [AMTD]: -3.5; p = 0.0015), and significantly more GEn 1200 mg-treated (77.5%) than placebo-treated (44.8%) subjects were CGI-I responders (p<0.0001). Similar significant results were observed with GEn 600 mg for IRLS (AMTD: -4.3; p<0.0001) and CGI-I (72.8% compared with 44.8%; p<0.0001). GEn also significantly improved sleep outcomes (Post-Sleep Questionnaire, Pittsburgh Sleep Diary and Medical Outcomes Sleep Scale) compared with placebo. The most commonly reported adverse events were somnolence (GEn 1200 mg = 18.0%; 600 mg = 21.7%; placebo = 2.1%) and dizziness (GEn 1200 mg = 24.3%; 600 mg = 10.4%; placebo = 5.2%). Dizziness increased with increased dose and led to discontinuation in 2 subjects (GEn 1200 mg, n = 1; GEn 600 mg, n = 1). Somnolence led to discontinuation in 3 subjects (GEn 600 mg).

CONCLUSIONS: GEn 1200 mg and 600 mg significantly improve RLS symptoms and sleep disturbance compared with placebo and are generally well tolerated.

We assessed the efficacy and tolerability of gabapentin enacarbil in the treatment of moderate to severe primary restless legs syndrome and associated sleep disturbance. This was a multicenter, randomized, double-blind, placebo-controlled, 2-period crossover polysomnography study of gabapentin enacarbil 1200 mg or placebo taken once daily. Subjects were randomized 1:1 to a sequence of gabapentin enacarbil:placebo or placebo:gabapentin enacarbil, receiving each treatment for 4 weeks. The primary end point was the mean change from baseline at weeks 4 and 10 (4/10) last observation carried forward in wake time during sleep. The key secondary end point was the mean change from baseline at weeks 4/10 last observation carried forward in periodic limb movements associated with arousal per hour of sleep. Tolerability assessments included adverse events. One hundred thirty-six subjects were randomized (gabapentin enacarbil:placebo, 67; placebo:gabapentin enacarbil, 69), and 114 (gabapentin enacarbil:placebo, 53; placebo:gabapentin enacarbil, 61) completed the study. Gabapentin enacarbil 1200 mg significantly reduced wake time during sleep (mean change from baseline [adjusted mean treatment difference]: -26.0 minutes; P<.0001) and periodic limb movements associated with arousal per hour of sleep (adjusted mean treatment difference: -3.1 periodic limb movements with arousal/hour; P = .002) compared with placebo at weeks 4/10 last observation carried forward. The most commonly reported adverse events were dizziness (gabapentin enacarbil 20%, placebo 2%) and somnolence (gabapentin enacarbil 13%, placebo 2%). Gabapentin enacarbil 1200 mg once daily significantly reduces restless legs syndrome-associated sleep disturbance and periodic limb movements associated with arousal per hour of sleep and is generally well tolerated in adults with moderate to severe primary restless legs syndrome.