Trial · NCT01332305

Dose-Response and Pharmacokinetics of Gabapentin Enacarbil (GEn [XP13512 / GSK1838262]) in Restless Legs Syndrome

NCT01332305, Phase 2, Completed, XenoPort, Inc.; results first posted 2011-05-26

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. Dose-Response and Pharmacokinetics of Gabapentin Enacarbil (GEn [XP13512 / GSK1838262]) in Restless Legs Syndrome. Trials, record NCT01332305. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT01332305

On this page

Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: Dose-Response and Pharmacokinetics of Gabapentin Enacarbil (GEn [XP13512 / GSK1838262]) in Restless Legs Syndrome
NCT number: NCT01332305
Status: Completed
Phases: Phase 2
Enrollment: 217 participants, actual
Lead sponsor: XenoPort, Inc.
Conditions: Restless Legs Syndrome
Interventions: GEn (XP13512/GSK1838262), Placebo
First posted: 2011-04-11
Last updated: 2013-07-22
Results first posted: 2011-05-26

Source ClinicalTrials.gov

Registered outcomes3

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	Mean Css, Max and Css, Min	Weeks 4 and 12	Css, max is defined as the maximum or "peak" concentration of a drug observed after multiple administration, at steady state. Css, max is one of the parameters of particular use in estimating the bioavailability of drugs, by measuring the total amount of drug absorbed. Css, min is defined as the minimum concentration of a drug observed after its administration, in steady state. ng, nanograms; PK, pharmacokinetic; W, week; BLQ, below limit of quantitation.
Primary	Mean Tmax and T1/2	Weeks 4 and 12	Tmax is defined as the time to the maximum or "peak" concentration of a drug observed after multiple administration. T1/2 is defined as the time to when half of the total amount of a particular substance is eliminated from the body.
Primary	Mean AUCss	Weeks 4 and 12	The area under the plot of plasma concentration of drug against time after drug administration is defined as the area under the curve (AUC). The AUCss is the area under the curve during the steady-state period. The AUCss is of particular use in estimating the bioavailability of drugs, by measuring the extent of absorption. AUCss used concentration data from 0 to 24 hours at steady-state for Weeks 4 and 12.

Source ClinicalTrials.gov

Outcomes3

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Population	Units	Measured as
PRIMARY	Mean Css, Max and Css, Min	Weeks 4 and 12	Safety Population: all participants (par.) who were randomized and received at least one (or any portion of a) dose of study drug. Population was analyzed as randomized. Placebo par. had no exposure to GEn and were not included in the PK assessments. Of par. who completed the study, some were not included at W12 (sample not taken or BLQ).	nanograms per milliliter (ng/ml)	MEAN
PRIMARY	Mean Tmax and T1/2	Weeks 4 and 12	Safety Population. Placebo participants (par.) were not included in the PK assessments, as they had no exposure to GEn. At W4, there were two par. excluded from the T1/2, as a result of no sample taken or a PK profile not possible. Of par. who completed the study, some were not included at W12 (sample not taken or below limit of quantitation).	hours	MEAN
PRIMARY	Mean AUCss	Weeks 4 and 12	Safety Population. Placebo participants were not included in the PK assessments, as they had no exposure to GEn. Of participants who completed the study, some were not included at Week 12 (sample not taken or below limit of quantitation).	ng*hour/ml	MEAN

Source ClinicalTrials.gov

Results by group40

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Category	Value	Spread	Units
Mean Css, Max and Css, Min	GEn 600 mg	Css, max; Week 4, n=0, 39, 33, 33, 36	3.86	Standard Deviation 1.25	nanograms per milliliter (ng/ml)
Mean Css, Max and Css, Min	GEn 1200 mg	Css, max; Week 4, n=0, 39, 33, 33, 36	7.14	Standard Deviation 2.62	nanograms per milliliter (ng/ml)
Mean Css, Max and Css, Min	GEn 1800 mg	Css, max; Week 4, n=0, 39, 33, 33, 36	11.4	Standard Deviation 3.54	nanograms per milliliter (ng/ml)
Mean Css, Max and Css, Min	GEn 2400 mg	Css, max; Week 4, n=0, 39, 33, 33, 36	14.0	Standard Deviation 4.23	nanograms per milliliter (ng/ml)
Mean Css, Max and Css, Min	GEn 600 mg	Css, max; Week 12, n=0, 32, 30, 30, 31	4.14	Standard Deviation 1.19	nanograms per milliliter (ng/ml)
Mean Css, Max and Css, Min	GEn 1200 mg	Css, max; Week 12, n=0, 32, 30, 30, 31	7.15	Standard Deviation 2.76	nanograms per milliliter (ng/ml)
Mean Css, Max and Css, Min	GEn 1800 mg	Css, max; Week 12, n=0, 32, 30, 30, 31	12.0	Standard Deviation 3.83	nanograms per milliliter (ng/ml)
Mean Css, Max and Css, Min	GEn 2400 mg	Css, max; Week 12, n=0, 32, 30, 30, 31	13.3	Standard Deviation 3.83	nanograms per milliliter (ng/ml)
Mean Css, Max and Css, Min	GEn 600 mg	Css, min; Week 4, n=0, 39, 33, 33, 36	0.690	Standard Deviation 0.359	nanograms per milliliter (ng/ml)
Mean Css, Max and Css, Min	GEn 1200 mg	Css, min; Week 4, n=0, 39, 33, 33, 36	1.37	Standard Deviation 0.894	nanograms per milliliter (ng/ml)

1 to 10 of 40Source ClinicalTrials.gov

See all 40 results by group

Participant flow15

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Overall Study	STARTED	GEn Placebo	41
Overall Study	STARTED	GEn 600 mg	48
Overall Study	STARTED	GEn 1200 mg	45
Overall Study	STARTED	GEn 1800 mg	38
Overall Study	STARTED	GEn 2400 mg	45
Overall Study	COMPLETED	GEn Placebo	31
Overall Study	COMPLETED	GEn 600 mg	34
Overall Study	COMPLETED	GEn 1200 mg	31
Overall Study	COMPLETED	GEn 1800 mg	30
Overall Study	COMPLETED	GEn 2400 mg	33

1 to 10 of 15Source ClinicalTrials.gov

See all 15 participant flow

Adverse events145

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk
other	Somnolence	Nervous system disorders	GEn Placebo	2	41
other	Somnolence	Nervous system disorders	GEn 600 mg	7	48
other	Somnolence	Nervous system disorders	GEn 1200 mg	11	45
other	Somnolence	Nervous system disorders	GEn 1800 mg	10	38
other	Somnolence	Nervous system disorders	GEn 2400 mg	23	45
other	Dizziness	Nervous system disorders	GEn Placebo	1	41
other	Dizziness	Nervous system disorders	GEn 600 mg	10	48
other	Dizziness	Nervous system disorders	GEn 1200 mg	10	45
other	Dizziness	Nervous system disorders	GEn 1800 mg	10	38
other	Dizziness	Nervous system disorders	GEn 2400 mg	18	45

1 to 10 of 145Source ClinicalTrials.gov

See all 145 adverse events

Adverse event totals15

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	GEn Placebo
Total, all-cause mortality	GEn 600 mg
Total, all-cause mortality	GEn 1200 mg
Total, all-cause mortality	GEn 1800 mg
Total, all-cause mortality	GEn 2400 mg
Total, other adverse events	GEn Placebo	21	41
Total, other adverse events	GEn 600 mg	24	48
Total, other adverse events	GEn 1200 mg	33	45
Total, other adverse events	GEn 1800 mg	25	38
Total, other adverse events	GEn 2400 mg	42	45

1 to 10 of 15Source ClinicalTrials.gov

See all 15 adverse event totals

Papers4

The papers the trial lists on ClinicalTrials.gov.

PMID	Listed as	Source
22664749	DERIVED	PubMed
26788345	DERIVED	PubMed
27067343	DERIVED	PubMed
27288210	DERIVED	PubMed

Grants0

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

None in this release.

Trial comparisons0

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

None in this release.

Tests0

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

None in this release.

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

For software

Read this trial from software.

The record and each of its lists are JSON, twenty rows a page. No key.

GET https://conductscience.org/api/trials/v1/NCT01332305

GET https://conductscience.org/api/trials/v1/NCT01332305/results?page=2

API reference For AI assistants