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Completed

NCT Number: NCT01332305

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

The objective of the study was to generate the data necessary to determine the gabapentin exposure produced by 4 dose levels of GEn (600 mg, 1200 mg, 1800 mg, and 2400 mg) or placebo, and the corresponding relief of symptoms in subjects with Restless Legs Syndrome (RLS).

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Key information

Conditions

Restless Legs Syndrome Dyssomnias Mental Disorders Nervous System Diseases Parasomnias Sleep Disorders, Intrinsic Sleep Wake Disorders

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

GSK Investigational Site

Dallas, Texas, 75213, United States

About this study

This was a multicenter, randomized, double blind, placebo controlled, parallel group study, comparing 4 doses of GEn (XP13512) with placebo given once daily to subjects with RLS. Eligible subjects were randomized in equal numbers into 1 of 5 treatment groups (GEn 600 mg, 1200 mg, 1800 mg, or 2400 mg or placebo) for 12 weeks of treatment. Data from this study will be utilized as part of a larger pharmacokinetic (PK) pharmacodynamic (PD) analysis of data from several studies (XP084/RXP111495) that are part of the GEn RLS clinical development program. Safety and tolerability were also assessed.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Men or women at least 18 years of age
  • RLS, based on the IRLSSG Diagnostic Criteria
  • History of RLS symptoms occurring at least 15 nights in the month prior to Screening or, if on RLS treatment, this frequency of symptoms must have been applicable prior to start of treatment
  • Documented RLS symptoms for at least 4 of the 7 consecutive evenings/nights
  • Total RLS severity score of 15 or greater on the IRLS Rating Scale
  • If taking dopamine agonists, gabapentin, or other treatments for RLS (e.g., opioids, benzodiazepines) medications must have been discontinued at least 2 weeks prior to Screening;
  • If taking any prescription medication, therapy must have been stabilized for at least 3 months prior to Screening with no anticipated changes for the duration of the study;
  • Body Mass Index (BMI) of 34 or below
  • estimated creatinine clearance of at least 60 mL/min

Exclusion criteria

  • a sleep disorder (e.g., sleep apnea) that may significantly affect the assessment of RLS
  • history of RLS symptom augmentation or end of dose rebound with previous dopamine agonist treatment
  • neurologic disease or movement disorder (e.g., diabetic neuropathy, Parkinson's disease, multiple sclerosis, dyskinesias, and dystonias);
  • other clinically significant or unstable medical condition or conditions which could affect RLS treatment efficacy assessments
  • serum ferritin level below 20 ng/mL
  • currently suffering from moderate or severe depression using the Diagnostic and Statistical Manual of Mental Disorders and Treatment IV (DSM IV TR)

Treatment and study plan

GEn (XP13512/GSK1838262)

Drug

Double-Blind Treatment Phase: 600 mg GEn (XP13512) orally, once daily for 3 days followed by 600 or 1200 mg on days 4-6, followed by 600 or 1200 or 1800 mg on days 7-9, followed by 600 or 1200 or 1800 or 2400 mg on days 10-84. Double-Blind Taper Phase: 600 or 1200 or 1800 mg GEn (XP13512) orally, once daily on days 85-86, followed by 600 mg or 1200 mg on days 87-88, followed by 600 mg on days 89-91

Other names: XP13512, GSK1838262

Placebo

Drug

Placebo orally once daily

Primary outcomes

  1. Mean Css, Max and Css, Min

    Time frame: 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.

  2. Mean Tmax and T1/2

    Time frame: 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.

  3. Mean AUCss

    Time frame: 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.

Sponsors and collaborators

Lead sponsor

XenoPort, Inc.

Industry

Registry information

Official study title

A Randomized, Double-Blind, Placebo-Controlled, Dose-Response Study to Assess the Efficacy, Safety, and Pharmacokinetics of XP13512 (GSK1838262) in Patients With Restless Legs Syndrome

Acronym: XP081

Important dates

Study start
2007
Primary completion
2008
Study completion
2008
First posted
Apr 11, 2011
Registry last updated
Jul 22, 2013

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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