Clinical Trial: A Study In Patients With Neuropathic Pain From Post-Herpetic Neuralgia (PHN)

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Study PXN110748: An Efficacy and Safety Study of XP13512 Compared With a Concurrent Placebo Control in Subjects With Neuropathic Pain Associated With Post-herpetic Neuralgia

Brief Summary: The purpose of this study is to determine whether gabapentin enacarbil (XP13512/GSK1838262), hereafter referred to as GEn is effective in the treatment of neuropathic pain associated with post-herpetic neuralgia (PHN).

Detailed Summary: The primary purpose of study PXN110748 was to evaluate efficacy and safety of 3 fixed doses of GEn in the treatment of PHN.
Sponsor: XenoPort, Inc.

Current Primary Outcome: Change From Baseline in the Mean 24-hour Average Pain Intensity (API) Score at the End of Maintenance Treatment (EOMT) Using Last Observation Carried Forward (LOCF) Data [ Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit) ]

Baseline and EOMT values are the calculated means of the daily 24-hour API scores for each participant during the last 7 days prior to randomization (Baseline) and the earliest date of Week 13 visit/Withdrawal visit/last dose of study drug (EOMT). Participants used a hand-held diary to rate their average pain intensity over the preceding 24 hours, using an 11-point PI-Numerical Rating Scale (0=no pain, 10=pain as bad as you can imagine). LOCF was used if less than 4 days of diary data were provided. Change from baseline was calculated as EOMT score minus Baseline score.


Original Primary Outcome: The change from baseline to end of treatment with respect to the mean 24-hour average pain intensity score based on an 11-point PI-NRS (0 = "no pain" and 10 = "pain as bad as you can imagine").

Current Secondary Outcome:

  • Change From Baseline in the Mean Night-time Average Pain Intensity (API) Score at EOMT Using LOCF Data [ Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit) ]
    Night-time is defined as the time between going to bed at night and rising in the morning. Participants recorded night-time API on a daily basis in the morning upon awakening using an 11-point PI-NRS (0=no pain, 10=pain as bad as you can imagine). Baseline and EOMT are as defined for the primary endpoint. Change from baseline wss calculated as the EOMT score minus the baseline score. An ANCOVA model with baseline value, BMI, grouped center as covariates was used.
  • Change From Baseline in the Mean Current Morning Pain Intensity Score at EOMT Using LOCF Data [ Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit) ]
    Current pain is defined as the participant's assessment of pain intensity "right now." Participants recorded their current morning pain intensity in the morning upon wakening using an 11-point PI-NRS (0=no pain, 10=pain as bad as you can imagine). Baseline and EOMT are as defined for the primary endpoint. Change from baseline was calculated as the EOMT score minus the baseline score. An ANCOVA model with baseline value, BMI, grouped center as covariates was used.
  • Change From Baseline in the Mean Night-time Worst Pain Intensity Score at EOMT Using LOCF Data [ Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit) ]
    Night-time worst pain is defined as the participant's assessment of their worst pain between going to bed at night and rising in the morning. Participants recorded night-time worst pain in the morning upon awakening using an 11-point PI-NRS (0=no pain, 10=pain as bad as you can imagine). Baseline and EOMT are as defined for the primary endpoint. Change from baseline was calculated as the EOMT score minus the baseline score. An ANCOVA model with baseline value, BMI, grouped center as covariates was used.
  • Change From Baseline in the Mean Sleep Interference Score at EOMT Using LOCF Data [ Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit) ]
    Participants assessed sleep interference due to pain on a daily basis using the 11-point NRS (0=pain does not interfere with sleep, 10=pain completely interferes with sleep). Baseline and EOMT are as defined for the primary endpoint. Change from baseline was calculated as the EOMT score minus the baseline score. An ANCOVA model with baseline value, BMI, grouped center as covariates was used.
  • Change From Baseline in the Mean Day-time Average Pain Intensity(API) Score at EOMT Using LOCF Data [ Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit) ]
    Day-time is defined as the time between rising in the morning and going to bed at night. Participants recorded day-time API on a daily basis in the evening before bedtime using an 11-point PI-NRS (0=no pain, 10=pain as bad as you can imagine). Baseline and EOMT are as defined for the primary endpoint. Change from baseline was calculated as the EOMT score minus the baseline score. An ANCOVA model with baseline value, BMI, grouped center as covariates was used.
  • Change From Baseline in the Mean Current Evening Pain Intensity Score at EOMT Using LOCF Data [ Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit) ]
    Current pain is defined as the participant's assessment of pain intensity "right now." Participants recorded their current evening pain intensity in the evening before bedtime using an 11-point PI-NRS (0=no pain, 10=pain as bad as you can imagine). Baseline and EOMT are as defined for the primary endpoint. Change from baseline was calculated as the EOMT score minus the baseline score. An ANCOVA model with baseline value, BMI, grouped center as covariates was used.
  • Change From Baseline in the Mean Day-time Worst Pain Intensity Score at EOMT Using LOCF Data [ Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit) ]
    Day-time worst pain is defined as the participant's assessment of their worst pain between rising in the morning and going to bed at night. Participants recorded day-time worst pain in the evening before bedtime using an 11-point PI-NRS (0=no pain, 10=pain as bad as you can imagine). Baseline and EOMT are as defined for the primary endpoint. Change from baseline was calculated as the EOMT score minus the baseline score. An ANCOVA model with baseline value, BMI, grouped center as covariates was used.
  • Change From Baseline in Pain Quality as Assessed by the Neuropathic Pain Scale (NPS) Summary Scores at EOMT Using LOCF Data [ Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit) ]
    The NPS assesses pain qualities and consists of 11-items, 10 assessed on an 11-point NRS (0=no impact to 10=greatest impact); and 1 open-ended question not used in score calculation. 4 summary scores are calculated: NPS 10

    Original Secondary Outcome: 24-hour, Day-time, Night time average pain intensity score; Current pain intensity score; Day-time and Night time worst pain intensity score; Sleep interference score; and Amount of rescue analgesic consumed.

    Information By: XenoPort, Inc.

    Dates:
    Date Received: February 7, 2008
    Date Started: February 2008
    Date Completion:
    Last Updated: July 15, 2013
    Last Verified: January 2013