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Key inclusion & exclusion criteria
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Inclusion Criteria:
- 18 years or older
- Female subjects are eligible if of non-childbearing potential or not lactating, has a
negative pregnancy, and agrees to use one a specified highly effective method for
avoiding pregnancy
- Documented medical diagnosis of PHN of with pain present for at least three months
from the healing of a herpes zoster rash
- Baseline 24-hour average pain intensity score = 4.0 based on an 11-point PI-NRS
- Provides written informed consent in accordance with all applicable regulatory
requirements
Exclusion Criteria:
- Other chronic pain conditions not associated with PHN. However, the subject will not
be excluded if:
- The pain is located at a different region of the body; and
- The pain intensity is not greater than the pain intensity of the PHN; and
- The subject can assess PHN pain independently of other pain
- Is unable to discontinue prohibited medications or non-drug therapies or procedures
throughout the duration of the study
- Hepatic impairment defined as ALT or AST > 2x upper limit of normal (ULN), or alkaline
phosphatase or bilirubin > 1.5x ULN
- Chronic hepatitis B or C
- Impaired renal function defined as creatinine clearance <60 mL/min or requiring
hemodialysis
- Corrected QT (QTc) interval = 450 msec or QTc interval =480 msec for patients with
Bundle Branch Block
- Uncontrolled hypertension at screen (sitting systolic >160 mmHg and/or sitting
diastolic >90 mmHg)
- Current diagnosis of active epilepsy or any active seizure disorder requiring chronic
therapy with antiepileptic drugs
- Medical condition or disorder that would interfere with the action, absorption,
distribution, metabolism, or excretion of GEn, or, in the investigator's judgment
- Is considered to be clinically significant and may pose a safety concern, or,
- Could interfere with the accurate assessment of safety or efficacy, or,
- Could potentially affect a subject's safety or study outcome
- Meets criteria defined by the DSM-IV-TR for a major depressive episode or for active
significant psychiatric disorders within last year
- Depression in remission, with or without antidepressant treatment, may participate,
unless stable antidepressant regimen is a prohibited medication
- Antidepressant medication may not be changed or discontinued to meet entry criteria
and must be stable for at least three months prior to enrollment
- History of clinically significant drug or alcohol abuse (DSM-IV-TR) or is unable to
refrain from substance abuse throughout the study. Benzodiazepines or atypical
benzodiazepines as hypnotic sleep agents permitted.
- Currently participating in another clinical study in which the subject is, or will be
exposed to an investigational or non-investigational drug or device
- Has participated in a clinical study and was exposed to investigational or
non-investigational drug or device:
- Within preceding month for studies unrelated to PHN, or
- Within preceding six months for studies related to PHN
- Treated previously with GEn
- History of allergic or medically significant adverse reaction to investigational
products (including gabapentin) or their excipients, acetaminophen or related
compounds
Age minimum:
18 Years
Age maximum:
N/A
Gender:
All
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Secondary Outcome(s)
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Change From Baseline in Dynamic Allodynia at EOMT Using LOCF Data
[Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit)]
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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)]
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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)]
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Number of Participants Who Are Responders on the Clinician Global Impression of Change (CGIC) Questionnaire at EOMT Using LOCF Data
[Time Frame: EOMT (representing the earliest date of Week 13 visit/withdrawal visit)]
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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)]
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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)]
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Time to Onset of Sustained Improvement in the 24-hour Average Pain Intensity Score
[Time Frame: Anytime post-baseline until date of last dose of study medication (up to Week 13)]
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Change From Baseline in Severity of Pain and the Impact of Pain as Assessed by the Brief Pain Inventory (BPI) at EOMT Using LOCF Data
[Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit)]
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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)]
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Change From Baseline in Emotional Functioning as Assessed by the POMS-B at EOMT Using LOCF Data
[Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit)]
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Number of Participants Who Are Responders on the Patient Global Impression of Change (PGIC) Questionnaire at EOMT Using LOCF Data
[Time Frame: EOMT (representing the earliest date of Week 13 visit/withdrawal visit)]
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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)]
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Change From Baseline in the Mean Daily Dose in Milligrams of Rescue Medication at EOMT Using LOCF Data
[Time Frame: Baseline and EOMT (Week 13 or early withdrawal)]
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Number of Participants Achieving Various Levels of Percent Reduction From Baseline in the Mean 24-hour Average Pain Intensity Score at EOMT Using LOCF Data
[Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit)]
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Change From Baseline in Quality of Life as Assessed by the SF-36 at EOMT Using LOCF Data
[Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit)]
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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)]
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Change From Baseline in Pain Characteristics and Intensity as Assessed by the Short Form-McGill Pain Questionnaire (SF-MPQ) at EOMT Using LOCF Data
[Time Frame: Baseline and EOMT (representing the earliest date of Week 13 visit/withdrawal visit)]
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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)]
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