Trial Outcomes & Findings for XP13512 vs. Placebo in Patients With Restless Legs Syndrome. (NCT NCT00365352)

NCT ID: NCT00365352

Last Updated: 2013-07-22

Results Overview

The International Restless Legs Syndrome (IRLS) Rating scale is a measure of RLS disease severity. The scale reflects the participant-reported assessment of primary sensory and motor features and associated sleep problems in RLS. Ten items (individually scored from 0 to 4) are included that assess the impact of symptoms on participants' mood, daily life, and activities. The total scale score is a sum of all of the individual item scores and ranges from 0-40 points, with 40 being the most severe. The scale assesses symptoms over the week prior to measurement.

• Recruitment status: COMPLETED
• Study phase: PHASE3
• Target enrollment: 325 participants
• Primary outcome timeframe: Baseline and Week 12
• Results posted on: 2013-07-22

Participant Flow

Participant milestones

Measure	Placebo Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 600 mg Gabapentin enacarbil (GEn) (XP13512/GSK1838262) 600 milligrams (mg) taken orally once a day for 12 weeks) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: one ER tablet (600 mg GEn) and one placebo tablet. On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Overall Study STARTED	97	115	113
Overall Study Safety Population	96	115	111
Overall Study Modified Intent-to-Treat Population	96	114	111
Overall Study COMPLETED	77	104	98
Overall Study NOT COMPLETED	20	11	15

Reasons for withdrawal

Measure	Placebo Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 600 mg Gabapentin enacarbil (GEn) (XP13512/GSK1838262) 600 milligrams (mg) taken orally once a day for 12 weeks) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: one ER tablet (600 mg GEn) and one placebo tablet. On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Overall Study Adverse Event	6	7	8
Overall Study Participant Withdrew Consent	8	3	4
Overall Study Lack of Efficacy	3	0	0
Overall Study Ineligible (Did Not Meet Entry Criteria)	0	0	2
Overall Study Non-Compliance (after Randomization)	1	0	1
Overall Study Lost to Follow-up	1	1	0
Overall Study Withdrawal of Participant by Sponsor	1	0	0

Baseline Characteristics

XP13512 vs. Placebo in Patients With Restless Legs Syndrome.

Baseline characteristics by cohort

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 600 mg n=114 Participants Gabapentin enacarbil (GEn) (XP13512/GSK1838262) 600 milligrams (mg) taken orally once a day for 12 weeks) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: one ER tablet (600 mg GEn) and one placebo tablet. On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	Total n=321 Participants Total of all reporting groups
Age Continuous	49.1 Years STANDARD_DEVIATION 12.19 • n=5 Participants	48.3 Years STANDARD_DEVIATION 12.88 • n=7 Participants	49.5 Years STANDARD_DEVIATION 12.67 • n=5 Participants	48.9 Years STANDARD_DEVIATION 12.58 • n=4 Participants
Sex: Female, Male Female	57 Participants n=5 Participants	66 Participants n=7 Participants	65 Participants n=5 Participants	188 Participants n=4 Participants
Sex: Female, Male Male	39 Participants n=5 Participants	48 Participants n=7 Participants	46 Participants n=5 Participants	133 Participants n=4 Participants
Race/Ethnicity, Customized American Indian or Alaskan Native	1 participants n=5 Participants	3 participants n=7 Participants	0 participants n=5 Participants	4 participants n=4 Participants
Race/Ethnicity, Customized Asian	2 participants n=5 Participants	0 participants n=7 Participants	1 participants n=5 Participants	3 participants n=4 Participants
Race/Ethnicity, Customized Black or African American	1 participants n=5 Participants	5 participants n=7 Participants	1 participants n=5 Participants	7 participants n=4 Participants
Race/Ethnicity, Customized Native Hawaiian or Other Pacific Islander	1 participants n=5 Participants	0 participants n=7 Participants	0 participants n=5 Participants	1 participants n=4 Participants
Race/Ethnicity, Customized White or Caucasian	92 participants n=5 Participants	106 participants n=7 Participants	107 participants n=5 Participants	305 participants n=4 Participants
Race/Ethnicity, Customized Unknown	0 participants n=5 Participants	2 participants n=7 Participants	2 participants n=5 Participants	4 participants n=4 Participants

PRIMARY outcome

Timeframe: Baseline and Week 12

Population: Modified Intent-to-Treat (MITT) Population: all participants in the Safety Population who also satisfied all of the following conditions: (1) completed the IRLS Rating Scale at Baseline; and (2) completed at least one on-treatment IRLS Rating Scale score during the treatment period

The International Restless Legs Syndrome (IRLS) Rating scale is a measure of RLS disease severity. The scale reflects the participant-reported assessment of primary sensory and motor features and associated sleep problems in RLS. Ten items (individually scored from 0 to 4) are included that assess the impact of symptoms on participants' mood, daily life, and activities. The total scale score is a sum of all of the individual item scores and ranges from 0-40 points, with 40 being the most severe. The scale assesses symptoms over the week prior to measurement.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in IRLS Rating Scale Total Score at Week 12 Using Last Observation Carried Forward (LOCF)	-9.8 scores on a scale Standard Deviation 7.69	-13.0 scores on a scale Standard Deviation 9.12	—

PRIMARY outcome

Timeframe: Week 12

Population: MITT Population

The investigator -rated Clinical Global Impression of Improvement (CGI-I) scale is an assessment designed to allow investigators to rate the change of a participant's disease severity over time based on a seven-point scale, with a score of 1 being "very much improved," a score of 2 being "much improved," a score of 3 being "minimally improved," a score of 4 being "no change," a score of 5 being "minimally improved,"a score of 6 being "much worse," and a score of 7 being "very much worse." Participants with a response of "much improved" or "very much improved" were classified as responders.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Participants With a Score of "Much Improved" or "Very Much Improved" on the Investigator-rated CGI-I Scale (Response) at (Week 12) Using LOCF	43 participants	86 participants	—

SECONDARY outcome

Timeframe: Baseline (Day 1) and End of Treatment (Week 12)

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The IRLS Rating scale is a measure of RLS disease severity. The scale reflects the participant-reported assessment of primary sensory and motor features and associated sleep problems in RLS. Items (individually scored from 0 to 4) are included that assess the impact of symptoms on participants' mood, daily life, and activities. The total scale score is a sum of all of the individual item scores and ranges from 0-40 points, with 40 being the most severe. The scale assesses symptoms over the week prior to measurement.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline to the End of Treatment (Week 12) in the IRLS Rating Scale Total Score Using LOCF	-9.8 scores on a scale Standard Deviation 7.69	-13.8 scores on a scale Standard Deviation 8.09	—

SECONDARY outcome

Timeframe: Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The CGI-I scale is a standardized tool that is widely used in psychopharmacologic trials. For the CGI-I, the investigator was asked to rate the participant's overall change in RLS symptoms from Baseline. Scores ranged from 1 (very much improved) to 7 (very much worse). Participants who were much improved (score of 2) or very much improved on the CGI-I scale at the end of treatment (Week 12) are classified as "Responders."

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Participants Classsified as Responders on the Investigator-rated CGI-I Scale at Week 12 Using LOCF	43 participants	83 participants	—

SECONDARY outcome

Timeframe: End of Week 1

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The IRLS Rating scale is a measure of RLS disease severity. Items (individually scored from 0 to 4) are included that assess the impact of symptoms on participants' mood, daily life, and activities. The total scale score is a sum of all of the individual item scores and ranges from 0-40 points, with 40 being the most severe. Response was defined by an IRLS Rating Scale total score at the end of Week 1 < 15 and at least a 6-point reduction from the participant's Baseline score and an investigator-rated CGI-I response of "much improved" or "very much improved."

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Participants Who Had an Onset of Response to Treatment at the End of Week 1 Based Upon the IRLS Rating Scale Total Score and the Investigator-rated CGI-I Using LOCF	13 participants	36 participants	40 participants

SECONDARY outcome

Timeframe: Baseline (Day 1) to End of Treatment (Week 12)

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The Response was defined by an IRLS Rating Scale total score at the end of Week 1 < 15 and at least a 6-point reduction from the participant's Baseline score and an investigator-rated CGI-I response of much improved or very much improved. The median time to onset is estimated using the product-limit estimation method.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
The Time to Onset of the First Response to Treatment on the IRLS Rating Scale Total Score and the Investigator-rated CGI-I	NA weeks The median value was not estimable because fewer than 50% of the participants experienced the event.	4.1 weeks Interval 2.1 to 8.1	2.1 weeks Interval 2.1 to 4.0

SECONDARY outcome

Timeframe: Baseline (Day 1) and Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The IRLS Rating scale is a measure of RLS disease severity. The scale reflects the participant-reported assessment of primary sensory and motor features and associated sleep problems in RLS. Ten items (individually scored from 0 to 4) are included that assess the impact of symptoms on participants' mood, daily life, and activities. The total scale score is a sum of all of the individual item scores and ranges from 0-40 points, with 40 being the most severe. The scale assesses symptoms over the week prior to measurement.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Mean Change in the IRLS Rating Scale Total Score From Baseline at Week 12 by RLS Treatment History Using LOCF No RLS Treatment History	-8.8 scores on a scale Standard Deviation 7.08	-13.7 scores on a scale Standard Deviation 8.23	-12.5 scores on a scale Standard Deviation 8.78
Mean Change in the IRLS Rating Scale Total Score From Baseline at Week 12 by RLS Treatment History Using LOCF Treatment terminated	-13.3 scores on a scale Standard Deviation 9.09	-12.4 scores on a scale Standard Deviation 7.26	-17.1 scores on a scale Standard Deviation 7.94
Mean Change in the IRLS Rating Scale Total Score From Baseline at Week 12 by RLS Treatment History Using LOCF Treatment within 1 month of study start	-10.7 scores on a scale Standard Deviation 8.11	-14.6 scores on a scale Standard Deviation 8.39	-12.1 scores on a scale Standard Deviation 10.43

SECONDARY outcome

Timeframe: Baseline (Day 1) and Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The IRLS Rating scale is a measure of RLS disease severity. The scale reflects the participant-reported assessment of primary sensory and motor features and associated sleep problems in RLS. Ten items (individually scored from 0 to 4) are included that assess the impact of symptoms on participants' mood, daily life, and activities. The total scale score is a sum of all of the individual item scores and ranges from 0-40 points, with 40 being the most severe. The scale assesses symptoms over the week prior to measurement.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in the IRLS Rating Scale Total Score at Week 12 by Baseline RLS Rating Scale Total Score Category (Baseline RLS Severity) Using LOCF IRLS Total Score < 17.5	-6.3 scores on a scale Standard Deviation 4.98	-8.9 scores on a scale Standard Deviation 6.02	-7.9 scores on a scale Standard Deviation 6.81
Change From Baseline in the IRLS Rating Scale Total Score at Week 12 by Baseline RLS Rating Scale Total Score Category (Baseline RLS Severity) Using LOCF IRLS Total Score 17.5 to < 22.5	-8.5 scores on a scale Standard Deviation 7.11	-11.9 scores on a scale Standard Deviation 6.34	-8.8 scores on a scale Standard Deviation 7.77
Change From Baseline in the IRLS Rating Scale Total Score at Week 12 by Baseline RLS Rating Scale Total Score Category (Baseline RLS Severity) Using LOCF IRLS Total Score 22.5 to < 27.5	-9.6 scores on a scale Standard Deviation 8.21	-15.1 scores on a scale Standard Deviation 6.65	-15.5 scores on a scale Standard Deviation 8.12
Change From Baseline in the IRLS Rating Scale Total Score at Week 12 by Baseline RLS Rating Scale Total Score Category (Baseline RLS Severity) Using LOCF IRLS Total Score >= 27.5	-13.3 scores on a scale Standard Deviation 7.74	-18.2 scores on a scale Standard Deviation 11.28	-19.6 scores on a scale Standard Deviation 8.80

SECONDARY outcome

Timeframe: Baseline and the End of Week 1

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The IRLS Rating scale is a measure of RLS disease severity. The scale reflects the participant-reported assessment of primary sensory and motor features and associated sleep problems in RLS. Items (individually scored from 0 to 4) are included that assess the impact of symptoms on participants' mood, daily life, and activities. The total scale score is a sum of all of the individual item scores and ranges from 0-40 points, with 40 being the most severe. The scale assesses symptoms over the week prior to measurement.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline to the End of Week 1 in the IRLS Rating Scale Total Score Using LOCF	-6.0 scores on a scale Standard Deviation 5.59	-9.8 scores on a scale Standard Deviation 7.76	-8.7 scores on a scale Standard Deviation 8.09

SECONDARY outcome

Timeframe: Basline and Week 12

Population: Participants included in the MITT Population with a known RLS treatment history

The CGI-I scale is a standardized tool that is widely used in psychopharmacologic trials. For the CGI-I, the investigator was asked to rate the participant's overall change in RLS symptoms from Baseline. Scores ranged from 1 (very much improved) to 7 (very much worse). Participants who were much improved (score of 2) or very much improved on the CGI-I scale at the end of treatment (Week 12) are classified as "Responders."

Outcome measures

Measure	Placebo n=94 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=112 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=110 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Participants Classified as Investigator-rated CGI-I Scale Responders at Week 12 by RLS Treatment History Using LOCF No RLS Treatment History	26 participants	54 participants	57 participants
Number of Participants Classified as Investigator-rated CGI-I Scale Responders at Week 12 by RLS Treatment History Using LOCF Treatment terminated	5 participants	9 participants	13 participants
Number of Participants Classified as Investigator-rated CGI-I Scale Responders at Week 12 by RLS Treatment History Using LOCF Treatment within 1 month of study start	11 participants	18 participants	15 participants

SECONDARY outcome

Timeframe: End of Week 1

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The CGI-I scale is a standardized tool that is widely used in psychopharmacologic trials. For the CGI-I, the investigator was asked to rate the participant's overall change in RLS symptoms from Baseline. Scores ranged from 1 (very much improved) to 7 (very much worse). Participants who were much improved (score of 2) or very much improved on the CGI-I scale at the end of treatment (Week 12) are classified as "Responders."

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Total Responders to Treatment Based on the Investigator-Rated CGI of Improvement at the End of One Week of Treatment	26 responders	54 responders	59 responders

SECONDARY outcome

Timeframe: Baseline to End of Treatment (Week 12)

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

Average daily total sleep time was derived from the Pittsburgh Sleep Diary (PghSD; an instrument with separate components to be completed [self-reported] at bedtime and waketime) as the mean of non-missing total sleep time over the 7 days before each visit, where total sleep time = [(wake up time - lights out time) - time to fall asleep - time awake during the night] in hours. The change was calculated as the end of treatment (Week 12) value minus the Baseline value.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=113 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline to the End of Treatment in Average Daily Total Sleep Time (Hours) Using LOCF	0.6 hours Standard Deviation 1.36	0.7 hours Standard Deviation 1.25	1.0 hours Standard Deviation 1.32

SECONDARY outcome

Timeframe: Baseline to End of Treatment (Week 12)

Population: MITT Popultion. The number of participants assessed varies due to incomplete/missing data.

Average daily wake time after sleep onset was derived from the Pittsburgh Sleep Diary (PghSD) as the mean of non-missing total hours awake during the night after falling asleep over the 7 days before each visit. The change was calculated as the end of treatment (Week 12) value minus the Baseline value.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=113 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline to the End of Treatment in Average Daily Wake Time (Minutes) After Sleep Onset Using LOCF	-12.5 minutes Standard Deviation 31.01	-16.4 minutes Standard Deviation 22.33	-18.5 minutes Standard Deviation 28.67

SECONDARY outcome

Timeframe: Baseline and End of Treatment (Week 12)

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The Daily RLS pain score was assessed by participants reporting whether they experienced any pain associated with RLS in the last 24 hours and rating their pain levels on an 11-point numerical rating scale, with 0 being no pain and 10 the most intense pain imaginable. The assessment was performed for 7 days prior to Baseline and pre-defined study visits. The change from baseline was calculated as the End of Treatment (Week 12) value minus the Baseline (Day 1) value.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in the Average Daily RLS Pain Score at the End of Treatment (Week 12) for Participants With Pain at Baseline or the End of Week 12 Using LOCF	-1.7 scores on a scale Standard Deviation 2.28	-2.5 scores on a scale Standard Deviation 2.20	-2.6 scores on a scale Standard Deviation 2.43

SECONDARY outcome

Timeframe: Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The Mean Daily RLS pain was assessed by participants reporting whether they experienced any pain associated with RLS in the last 24 hours and rating their pain levels on an 11-point numerical rating scale, with 0 being no pain and 10 the most intense pain imaginable. The assessment was performed for 7 days prior to Baseline and pre-defined visits A "Responder" is a participant with a score of "much improved" or "very much improved" on the investigator rated CGI I Scale at the end of treatment (Week 12 using LOCF).

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Participants Classified as Responders With at Least 30% and 50% Improvement in the Average Daily RLS Pain Score Using LOCF > or equal to 30% response	48 participants	75 participants	76 participants
Number of Participants Classified as Responders With at Least 30% and 50% Improvement in the Average Daily RLS Pain Score Using LOCF > or equal to 50% response	41 participants	62 participants	66 participants

SECONDARY outcome

Timeframe: Baseline and Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The Average Daily RLS pain was assessed by participants reporting whether they experienced any pain associated with RLS in the last 24 hours and rating their pain levels on an 11-point numerical rating scale, with 0 being no pain and 10 the most intense pain imaginable. The assessment was performed for 7 days prior to Baseline and pre-defined visits. The change from baseline was calculated as the End of Treatment (Week 12) value minus the Baseline (Day 1) value.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in the Average Daily RLS Pain Score to Week 12 for Participants With a Baseline Pain Score of at Least 4 Using LOCF	-2.3 scores on a scale Standard Deviation 2.34	-3.5 scores on a scale Standard Deviation 2.19	-3.5 scores on a scale Standard Deviation 2.51

SECONDARY outcome

Timeframe: Week 1 and Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The CGI-I scale is a standardized tool that is widely used in psychopharmacologic trials. For the CGI-I, the investigator was asked to rate the participant's overall change in RLS symptoms from Baseline. Scores ranged from 1 (very much improved) to 7 (very much worse). Participants who were much improved (score of 2) or very much improved on the CGI-I scale at the end of treatment (Week 12) are classified as "Responders."

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Participants Classified as Responders to Treatment Based on the Participant-Rated CGI of Improvement at Week 1 and Week 12 (End of Treatment) Responders at the End of Treatment (Week 12)	46 participants	90 participants	83 participants
Number of Participants Classified as Responders to Treatment Based on the Participant-Rated CGI of Improvement at Week 1 and Week 12 (End of Treatment) Responders at the End of One Week	20 participants	55 participants	52 participants

SECONDARY outcome

Timeframe: End of Treatment (Week 12)

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The Post-Sleep Questionnaire (PSQ) was designed to evaluate overall sleep quality, ability to function, and RLS symptoms' interference with sleep over the past week. Participants were asked to rate overall sleep quality (as either "Excellent," "Reasonable," or "Poor"), ability to function, number of nights with RLS symptoms, number of nights awakened by RLS symptoms, and the number of hours spent awake due to RLS symptoms over the past week.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Participants With a Rating of Excellent for the Overall Quality of Sleep in Past Week Measured by the Post-Sleep Questionnaire (PSQ) at the End of Treatment (Week 12) Using LOCF	14 participants	24 participants	30 participants

SECONDARY outcome

Timeframe: Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The Mood Assessment is a non-disease-specific question surveying global change in a participant's overall mood. Participants were asked to rate their overall change in mood since the start of the study by choosing a score in a range from 1 (Very Much Improved) to 7 (Very Much Worse). The assessment was completed at Day 1 and the ends of Weeks 4, 8, and 12 or (Early Termination).

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Participants Who Indicated on the Mood Assessment That Their Mood Was Much Improved or Very Much Improved at Week 12 (End of Treatment) Using LOCF	19 participants	35 participants	39 participants

SECONDARY outcome

Timeframe: Baseline to End of Treatment (Week 12)

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The Profile of Mood States (POMS) Brief Form contains 30 adjectives; each participant is asked to rate the degree to which each adjective describes themselves based on how they felt during the past week including the date on which the adjective was rated. The possible ratings range from "0" (Not all all) to "4" (Extremely). The Total Mood Disturbance Score (range of 0 to 120) is obtained by summing the values of six domains. Higher scores indicate a more negative mood disturbance. The POMS was completed at Baseline (Day 1), and at the end of Weeks 4, 8, and 12 (or Early Termination).

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in the Profile of Mood State (POMS) Scale at Week 12 Using LOCF	-7.3 scores on a scale Standard Deviation 14.89	-10.9 scores on a scale Standard Deviation 17.97	-11.5 scores on a scale Standard Deviation 16.87

SECONDARY outcome

Timeframe: Baseline and Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The MOS Sleep Scale measures most constructs of sleep. The scale has a battery of questions to measure specific aspects of sleep in participants with co-morbidities. The four domains scored from the MOS Sleep Scale were "sleep disturbance,"' "sleep quantity,"' "sleep adequacy," and "daytime somnolence." The scores of the daytime somnolence domain ranged from 1 to 100, with a high score indicating greater daytime somnolence. The assessment was completed at Baseline (Day 1) and end of Weeks, 4, 8, and 12 (or end of Treatment).

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=112 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=110 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in the Daytime Somnolence Score, an Item on the Medical Outcomes Study (MOS) Sleep Scale, at Week 12 Using LOCF	-9.7 scores on a scale Standard Deviation 20.39	-9.8 scores on a scale Standard Deviation 20.35	-16.1 scores on a scale Standard Deviation 19.58

SECONDARY outcome

Timeframe: Baseline and Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The MOS Sleep Scale measures most constructs of sleep. The scale has a battery of questions to measure specific aspects of sleep in participants with co-morbidities. The four domains scored from the MOS Sleep Scale were "sleep disturbance,"' "sleep quantity,"' "sleep adequacy," and "daytime somnolence." The scores of the sleep disturbance domain ranged from 1 to 100, with a high score indicating greater impairment of sleep. The assessment was completed at Baseline (Day 1) and end of Weeks, 4, 8, and 12 (or end of Treatment).

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=112 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=110 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in the Sleep Disturbance Score, an Item on the MOS Sleep Scale, at Week 12 Using LOCF	-17.0 scores on a scale Standard Deviation 20.40	-29.5 scores on a scale Standard Deviation 23.27	-30.7 scores on a scale Standard Deviation 25.45

SECONDARY outcome

Timeframe: Basline and Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The MOS Sleep Scale measures most constructs of sleep. The scale has a battery of questions to measure specific aspects of sleep in participants with co-morbidities. The four domains scored from the MOS Sleep Scale were "sleep disturbance,"' "sleep quantity,"' "sleep adequacy," and "daytime somnolence." The scores of the sleep adequacy domain ranged from 1 to 100, with a high score indicating greater adequacy. The assessment was completed at Baseline (Day 1) and end of Weeks, 4, 8, and 12 (or end of Treatment).

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=112 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=110 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in Sleep Adequacy, an Item on the MOS Sleep Scale, at Week 12 Using LOCF	13.6 scores on a scale Standard Deviation 24.59	29.1 scores on a scale Standard Deviation 29.91	27.7 scores on a scale Standard Deviation 29.91

SECONDARY outcome

Timeframe: Baseline and Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The MOS Sleep Scale measures most constructs of sleep. The scale has a battery of questions to measure specific aspects of sleep in participants with co-morbidities. The four domains scored from the MOS Sleep Scale were "sleep disturbance,"' "sleep quantity,"' "sleep adequacy," and "daytime somnolence." The scores of the sleep quantity domain were measured in time (number of hours of sleep each night). The assessment was completed at Baseline (Day 1) and end of Weeks, 4, 8, and 12 (or end of Treatment).

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=110 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in Sleep Quantity, an Item on the MOS Sleep Scale, at Week 12 Using LOCF	0.3 hours Standard Deviation 1.19	0.6 hours Standard Deviation 1.25	0.8 hours Standard Deviation 1.66

SECONDARY outcome

Timeframe: Baseline and Week 12

Population: MITT Population: The number of participants assessed varies due to incomplete/missing data.

The Restless Legs Syndrome Quality of Life (RLS-QoL) questionnaire is a disease-specific, participant-rated questionnaire that assesses the impact of RLS on daily life, emotional well-being, social life, and work life of the participants. The RLS-QoL Questionnaire is presented on a 0 (lowest possible score) to 100 (highest possible score) scale. It was completed at Day 1 and at the end of Weeks 4, 8, and 12 (or Early Termination).

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Change From Baseline in the Overall Life-Impact Score of the RLS Quality of Life (QoL) Questionnaire at Week 12 Using LOCF	14.5 scores on a scale Standard Deviation 15.74	19.3 scores on a scale Standard Deviation 15.57	20.4 scores on a scale Standard Deviation 17.14

SECONDARY outcome

Timeframe: Week 12

Population: MITT Population. The number analyzed represents participants within the MITT Population who reported no RLS symptoms at the end of Week 12.

RLS severity ratings were summarized in 6 non-overlapping 4-hour periods beginning at 8 AM. A 4-hour period from 6 PM to 10 PM was also prospectively included to reflect the time frame when the most participants would experience their first symptoms of the day.

Outcome measures

Measure	Placebo n=74 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=99 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=92 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Number of Participants Experiencing No RLS Symptoms in Each of the Seven 4-hour Periods From the 24-hour RLS Record at Week 12 (End of Treatment) 8 AM to 12 PM	52 participants	85 participants	74 participants
Number of Participants Experiencing No RLS Symptoms in Each of the Seven 4-hour Periods From the 24-hour RLS Record at Week 12 (End of Treatment) 12 PM to 4 PM	51 participants	74 participants	69 participants
Number of Participants Experiencing No RLS Symptoms in Each of the Seven 4-hour Periods From the 24-hour RLS Record at Week 12 (End of Treatment) 4 PM to 8 PM	45 participants	68 participants	61 participants
Number of Participants Experiencing No RLS Symptoms in Each of the Seven 4-hour Periods From the 24-hour RLS Record at Week 12 (End of Treatment) 6 PM to 10 PM	39 participants	55 participants	55 participants
Number of Participants Experiencing No RLS Symptoms in Each of the Seven 4-hour Periods From the 24-hour RLS Record at Week 12 (End of Treatment) 8 PM to 12 AM	27 participants	49 participants	48 participants
Number of Participants Experiencing No RLS Symptoms in Each of the Seven 4-hour Periods From the 24-hour RLS Record at Week 12 (End of Treatment) 12 AM to 4 AM	38 participants	74 participants	67 participants
Number of Participants Experiencing No RLS Symptoms in Each of the Seven 4-hour Periods From the 24-hour RLS Record at Week 12 (End of Treatment) 4 AM to 8 AM	56 participants	79 participants	72 participants

SECONDARY outcome

Timeframe: Week 12

Population: MITT Population. The number of participants assessed varies due to incomplete/missing data.

The time to onset of the first RLS symptoms from the 24-hour RLS Record is defined as the length of time from the start of the 24-hour assessment period (8:00 AM) to the time when 50% of participants experienced their first symptom.

Outcome measures

Measure	Placebo n=96 Participants Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=114 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).	GEn (XP13512/GSK1838262) 1200 mg n=111 Participants Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Time to Onset of the First RLS Symptom From the 24-hour RLS Record Obtained at the End of Treatment (Week 12)	12.8 hours Interval 9.5 to 15.0	13.5 hours Interval 12.5 to 16.5	13.8 hours Interval 11.5 to 17.0

Adverse Events

Placebo

Serious events: 1 serious events

Other events: 36 other events

Deaths: 0 deaths

GEn (XP13512/GSK1838262) 600 mg

Serious events: 2 serious events

Other events: 68 other events

Deaths: 0 deaths

GEn (XP13512/GSK1838262) 1200 mg

Serious events: 0 serious events

Other events: 64 other events

Deaths: 0 deaths

Serious adverse events

Measure	Placebo n=96 participants at risk Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 600 mg n=115 participants at risk Gabapentin enacarbil (GEn) (XP13512/GSK1838262) 600 milligrams (mg) taken orally once a day for 12 weeks) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: one ER tablet (600 mg GEn) and one placebo tablet. On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=111 participants at risk Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Hepatobiliary disorders Cholelithiasis	1.0% 1/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	0.00% 0/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	0.00% 0/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Infections and infestations Cellulitis	0.00% 0/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	0.87% 1/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	0.00% 0/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Musculoskeletal and connective tissue disorders Herniated Disc L5	0.00% 0/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	0.87% 1/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	0.00% 0/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.

Other adverse events

Measure	Placebo n=96 participants at risk Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 84: two placebo tablets. On Days 85 participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 600 mg n=115 participants at risk Gabapentin enacarbil (GEn) (XP13512/GSK1838262) 600 milligrams (mg) taken orally once a day for 12 weeks) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: one ER tablet (600 mg GEn) and one placebo tablet. On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one placebo tablet.	GEn (XP13512/GSK1838262) 1200 mg n=111 participants at risk Oral GEn (gabapentin enacarbil) 1200 milligrams (mg) taken once daily. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 84: two ER tablets (1200 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 91: one ER tablet (600 mg GEn).
Nervous system disorders Somnolence	2.1% 2/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	21.7% 25/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	18.0% 20/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Nervous system disorders Dizziness	5.2% 5/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	10.4% 12/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	24.3% 27/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Nervous system disorders Headache	8.3% 8/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	14.8% 17/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	13.5% 15/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Infections and infestations Nasopharyngitis	7.3% 7/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	11.3% 13/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	9.9% 11/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Gastrointestinal disorders Dry Mouth	2.1% 2/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	4.3% 5/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	8.1% 9/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Gastrointestinal disorders Nausea	4.2% 4/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	5.2% 6/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	5.4% 6/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
General disorders Fatigue	5.2% 5/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	5.2% 6/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	2.7% 3/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Infections and infestations Upper Respiratory Tract Infection	2.1% 2/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	7.8% 9/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	1.8% 2/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Musculoskeletal and connective tissue disorders Back Pain	3.1% 3/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	5.2% 6/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	2.7% 3/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Nervous system disorders Sedation	2.1% 2/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	0.87% 1/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	5.4% 6/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.
Respiratory, thoracic and mediastinal disorders Sinus	5.2% 5/96 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	0.87% 1/115 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.	1.8% 2/111 • Adverse event (AE) and serious adverse event (SAE) collection started immediately following informed consent and continued throughout the study (up to Week 17). At the end of the follow-up period (30 days after the last day of taper \[Day 119\]), the study coordinator called participants (+/- 3 day window) who did not enroll in the open-label extension protocol to determine if any SAEs occurred, and the resolution date for any AEs that were ongoing at the end of the study.

Additional Information

XenoPort Call Center

XenoPort, Inc.

Phone: 877-936-6778

Results disclosure agreements

• Principal investigator is a sponsor employee GSK agreements may vary with individual investigators, but will not prohibit any investigator from publishing. GSK supports the publication of results from all centers of a multi-center trial but requests that reports based on single-site data not precede the primary publication of the entire clinical trial.
• Publication restrictions are in place

Restriction type: OTHER