Polysomnography Study of GSK1838262 Extended Release Tablets Versus Placebo in RLS and Associated Sleep Disturbance

Study RXP110908, a Polysomnography Study of GSK1838262 (XP13512) Extended Release Tablets Versus Placebo in the Treatment of Restless Legs Syndrome (RLS) and Associated Sleep Disturbance

The purpose of this study is to assess the efficacy and safety of GSK1838262 extended release tablets in the treatment of patients with Restless Legs Syndrome and associated sleep disturbance.

Double-blind, multi-center, placebo-controlled, 2-period crossover study which assessed the efficacy and safety of gabapentin enacarbil (GEn; GSK1838262; XP13512) extended release tablets in adults with Restless Legs Syndrome (RLS)-associated sleep disturbance. One hundred thirty-six (136) adult subjects with RLS-associated sleep disturbance and periodic limb movements (PLM) were randomized from 23 centers in the United States. Subjects who met all eligibility criteria were randomized to receive a treatment sequence of GEn:placebo or placebo:GEn. Investigational product was taken with food at approximately 5pm. Investigational product was dosed as 600mg/day x3 days followed by 1200mg/day x25 days for each 4-week treatment period. There was a 1-week taper at 600mg after each treatment period followed by a 1-week washout between treatments. Polysomnography (PSG) was used to objectively evaluate changes in sleep and PLMs.

Inclusion criteria:

• Provided written informed consent.
• Diagnosed with primary RLS using the International RLS Study Group Diagnostic Criteria with a total score of 15 or greater on the International RLS (IRLS) Rating Scale and significant sleep disturbance indicated on Item 4 of the IRLS rating scale.
• Have history of RLS symptoms at least 15 nights/month.
• Minimum average of 15 Periodic Limb Movements during Sleep per hour (measured using actigraphy).

Exclusion criteria:

• Secondary RLS
• Primary sleep disorder
• Sleep apnea
• Have any medical conditions that may impact efficacy assessments or that may present a safety concern.
• Pregnant or lactating or women of child-bearing potential who are not practicing an acceptable method of birth control.
• Use of any prohibited medication.