Dose-Response and Pharmacokinetics of Gabapentin Enacarbil (GEn [XP13512 / GSK1838262]) in Restless Legs Syndrome (XP081)

This study has been completed.
Sponsor:
Information provided by (Responsible Party):
XenoPort, Inc.
ClinicalTrials.gov Identifier:
NCT01332305
First received: April 7, 2011
Last updated: July 15, 2013
Last verified: May 2011
Results First Received: April 28, 2011  
Study Type: Interventional
Study Design: Allocation: Randomized;   Endpoint Classification: Pharmacokinetics Study;   Intervention Model: Parallel Assignment;   Masking: Double Blind (Subject, Investigator);   Primary Purpose: Treatment
Condition: Restless Legs Syndrome
Interventions: Drug: GEn (XP13512/GSK1838262)
Drug: Placebo

  Participant Flow
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Recruitment Details
Key information relevant to the recruitment process for the overall study, such as dates of the recruitment period and locations
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Pre-Assignment Details
Significant events and approaches for the overall study following participant enrollment, but prior to group assignment
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Reporting Groups
  Description
GEn Placebo Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 6: two placebo tablets. Days 7 to 9: three placebo tablets. Days 10 to 84: four placebo tablets. On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: three placebo tablets. Days 87 to 88: two placebo tablets. Days 89 to 91: one placebo tablet.
GEn 600 mg Gabapentin enacarbil (GEn) (XP13512/GSK1838262) 600 milligrams (mg) taken orally once a day for 12 weeks. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 6: one ER tablet (600 mg GEn) and one placebo tablet. Days 8 to 10: one ER tablet (600 mg GEn) and two placebo tablets. Days 10 to 84: one ER tablet (600 mg GEn) and three placebo tablets. On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: three placebo tablets. Days 87 to 88: two placebo tablets. Days 89 to 91: one placebo tablet.
GEn 1200 mg Oral GEn 1200 mg taken once daily. Days 1 to 3: one ER tablet (600 mg GEn). Days 4 to 6: two ER tablets (1200 mg GEn). Days 8 to 10: two ER tablets (1200 mg GEn) and one placebo tablet. Days 10 to 84: two ER tablets (1200 mg GEn) and two placebo tablets. On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: one ER tablet (600 mg GEn) and two placebo tablets. Days 87 to 88: two placebo tablets. Days 89 to 91: one placebo tablet.
GEn 1800 mg Oral GEn 1800 mg taken once daily. Days 1 to 3: one ER tablet (600 mg GEn). Days 4 to 6: two ER tablets (1200 mg GEn). Days 8 to 10: three ER tablets (1800 mg GEn). Days 10 to 84: three ER tablets (1800 mg GEn) and one placebo tablet. On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: two ER tablets (1200 mg GEn) and one placebo tablet. Days 87 to 88: one ER tablet (600 mg) and one placebo tablet. Days 89 to 91: one placebo tablet.
GEn 2400 mg Oral GEn 1200 mg taken once daily. Days 1 to 3: one ER tablet (600 mg GEn). Days 4 to 6: two ER tablets (1200 mg GEn). Days 8 to 10: three ER tablets (1800 mg GEn). Days 10 to 84: four ER tablets (2400 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: three ER tablets (1800 mg GEn). Days 87 to 88: two ER tablets (1200 mg). Days 89 to 91: one ER (600 mg) tablet.

Participant Flow:   Overall Study
    GEn Placebo     GEn 600 mg     GEn 1200 mg     GEn 1800 mg     GEn 2400 mg  
STARTED     41     48     45     38     45  
COMPLETED     31     34     31     30     33  
NOT COMPLETED     10     14     14     8     12  
Adverse Event                 1                 4                 6                 3                 5  
Withdrawal by Subject                 6                 5                 4                 1                 0  
Lost to Follow-up                 0                 2                 3                 2                 3  
Protocol Violation                 1                 2                 1                 0                 3  
Withdrawal by Sponsor                 1                 0                 0                 1                 1  
Treatment Failure                 1                 1                 0                 0                 0  
Physician Decision                 0                 0                 0                 1                 0  



  Baseline Characteristics
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Population Description
Explanation of how the number of participants for analysis was determined. Includes whether analysis was per protocol, intention to treat, or another method. Also provides relevant details such as imputation technique, as appropriate.
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Reporting Groups
  Description
GEn Placebo Oral placebo tablet taken once daily. Days 1 to 3: one placebo tablet. Days 4 to 6: two placebo tablets. Days 7 to 9: three placebo tablets. Days 10 to 84: four placebo tablets. On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: three placebo tablets. Days 87 to 88: two placebo tablets. Days 89 to 91: one placebo tablet.
GEn 600 mg Gabapentin enacarbil (GEn) (XP13512/GSK1838262) 600 milligrams (mg) taken orally once a day for 12 weeks. Days 1 to 3: one extended release (ER) tablet (600 mg GEn). Days 4 to 6: one ER tablet (600 mg GEn) and one placebo tablet. Days 8 to 10: one ER tablet (600 mg GEn) and two placebo tablets. Days 10 to 84: one ER tablet (600 mg GEn) and three placebo tablets. On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: three placebo tablets. Days 87 to 88: two placebo tablets. Days 89 to 91: one placebo tablet.
GEn 1200 mg Oral GEn 1200 mg taken once daily. Days 1 to 3: one ER tablet (600 mg GEn). Days 4 to 6: two ER tablets (1200 mg GEn). Days 8 to 10: two ER tablets (1200 mg GEn) and one placebo tablet. Days 10 to 84: two ER tablets (1200 mg GEn) and two placebo tablets. On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: one ER tablet (600 mg GEn) and two placebo tablets. Days 87 to 88: two placebo tablets. Days 89 to 91: one placebo tablet.
GEn 1800 mg Oral GEn 1800 mg taken once daily. Days 1 to 3: one ER tablet (600 mg GEn). Days 4 to 6: two ER tablets (1200 mg GEn). Days 8 to 10: three ER tablets (1800 mg GEn). Days 10 to 84: three ER tablets (1800 mg GEn) and one placebo tablet. On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: two ER tablets (1200 mg GEn) and one placebo tablet. Days 87 to 88: one ER tablet (600 mg) and one placebo tablet. Days 89 to 91: one placebo tablet.
GEn 2400 mg Oral GEn 1200 mg taken once daily. Days 1 to 3: one ER tablet (600 mg GEn). Days 4 to 6: two ER tablets (1200 mg GEn). Days 8 to 10: three ER tablets (1800 mg GEn). Days 10 to 84: four ER tablets (2400 mg GEn). On Day 85, participants entered a 7-day Taper Period. Days 85 to 86: three ER tablets (1800 mg GEn). Days 87 to 88: two ER tablets (1200 mg). Days 89 to 91: one ER (600 mg) tablet.
Total Total of all reporting groups

Baseline Measures
    GEn Placebo     GEn 600 mg     GEn 1200 mg     GEn 1800 mg     GEn 2400 mg     Total  
Number of Participants  
[units: participants]
  41     48     45     38     45     217  
Age  
[units: Years]
Mean ± Standard Deviation
  47.1  ± 11.16     47.3  ± 12.78     49.8  ± 11.51     50.2  ± 13.79     45.9  ± 13.93     48.0  ± 12.67  
Gender  
[units: Participants]
           
Female     29     31     23     27     29     139  
Male     12     17     22     11     16     78  
Race/Ethnicity, Customized [1]
[units: participants]
           
White or Caucasian     39     48     44     35     42     208  
Black or African American     1     0     1     2     2     6  
American Indian or Alaska Native     1     0     0     0     1     2  
Asian     0     0     0     1     1     2  
[1] There was one participant in the GEn 2400 mg arm who was categorized in more than one race.



  Outcome Measures
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1.  Primary:   Mean Css, Max and Css, Min   [ Time Frame: Weeks 4 and 12 ]

2.  Primary:   Mean Tmax and T1/2   [ Time Frame: Weeks 4 and 12 ]

3.  Primary:   Mean AUCss   [ Time Frame: Weeks 4 and 12 ]


  Serious Adverse Events


  Other Adverse Events


  Limitations and Caveats
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Limitations of the study, such as early termination leading to small numbers of participants analyzed and technical problems with measurement leading to unreliable or uninterpretable data
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  More Information
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Certain Agreements:  
Principal Investigators are NOT employed by the organization sponsoring the study.
There IS an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.
The agreement is:
unchecked The only disclosure restriction on the PI is that the sponsor can review results communications prior to public release and can embargo communications regarding trial results for a period that is less than or equal to 60 days. The sponsor cannot require changes to the communication and cannot extend the embargo.
unchecked The only disclosure restriction on the PI is that the sponsor can review results communications prior to public release and can embargo communications regarding trial results for a period that is more than 60 days but less than or equal to 180 days. The sponsor cannot require changes to the communication and cannot extend the embargo.


Results Point of Contact:  
Name/Title: XenoPort Call Center
Organization: XenoPort, Inc.
phone: 877-936-6778


No publications provided by XenoPort, Inc.

Publications automatically indexed to this study:

Responsible Party: XenoPort, Inc.
ClinicalTrials.gov Identifier: NCT01332305     History of Changes
Other Study ID Numbers: 111462
Study First Received: April 7, 2011
Results First Received: April 28, 2011
Last Updated: July 15, 2013
Health Authority: United States: Food and Drug Administration