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CompletedNCT00636636Updated Feb 22, 2012Results posted

Safety and Efficacy of Gabapentin in Postherpetic Neuralgia

A Phase 3 interventional study of Gabapentin Extended Release tablets and Placebo in Neuralgia,Postherpetic, sponsored by Depomed. Completed at 39 sites in 3 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2012-02-22.

Sponsored by Depomed · Phase 3, Interventional, and Treatment

Phase
Phase 3
Study type
Interventional
Enrollment
452
Allocation
Randomized
Ages
18 Years and older
Sex
All
01

Study summary

Gabapentin and pregabalin are treatments for some types of neuropathic pain, including postherpetic neuralgia (PHN). However, these treatments usually need to be taken 3 times a day for effective pain control. The purpose of this study is to determine whether a new gabapentin tablet, which only needs to be taken once a day, is safe and effective for the treatment of postherpetic neuralgia.

Read the detailed description

The primary study objective is to assess the relative efficacy of G-ER dosed once daily (1800 mg following the evening meal), versus placebo in reducing the mean daily pain score from the baseline week to the end of the efficacy treatment period (Treatment Week 10) in patients with PHN.

Secondary efficacy measures will include changes from baseline in mean weekly sleep interference scores, Short-Form McGill Pain Questionnaire (SF-MPQ), the Neuropathic Pain Scale (NPS), Brief Pain Inventory (BPI), Patient Global Impression of Change (PGIC), and Investigator-Rated Clinical Global Impression of Change (CGIC).

02

Conditions studied

  • Neuralgia,Postherpetic

Keywords

  • Postherpetic Neuralgia (PHN), shingles
03

In context

Neuralgia

1,287 studies on the registry are indexed under Neuralgia; 256 are open to participants now.

This study's enrollment of 452 is above the median of 52 across 973 interventional studies indexed under Neuralgia.

Browse Neuralgia studies →

Lead sponsor

Depomed is the lead sponsor of 14 studies on the registry; none are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Inclusion criteria

  1. Men or women 18 years or older who have experienced pain for at least 6 months, but not more than 5 years after the healing of a herpes zoster skin rash(typically about 4 months after the rash first appears).
  2. Patient has a pain intensity score of at least 4 on the 11-point Numerical Rating Scale (NRS). Patients should never be informed of the pain intensity criterion prior to screening or randomization.
  3. Patients of child-bearing potential must have a negative serum pregnancy test at screening and a negative follow-up urine pregnancy test at randomization.
  4. Patient has a mean baseline week pain intensity score of at least 4 on the 11-point NRS scale at the end of a 1-week baseline period and has completed at least 4 days of daily pain diary entries during the baseline week.
  5. Patients must have a minimum washout period of greater than 5 times the half-life of the drug of several medications.
  6. Patients currently treated with gabapentin pr pregabalin at screening may be eligible for the study, but must have a tapering period wherein the dose of gabapentin or pregabalin is reduced gradually over a period of 5 days followed by a two day washout prior to the Baseline Week.

Exclusion criteria

Exclusion Criteria:

  1. Patients who have previously not responded to treatment for PHN with gabapentin or pregabalin.
  2. Patients who previously experienced dose-limiting adverse effects that prevented titration of gabapentin to an effective dose.
  3. Patient is a nursing mother.
  4. Patient has hypersensitivity to gabapentin.
  5. Patient has had neurolytic or neurosurgical treatment for PHN.
  6. Patient has severe pain from causes other than PHN.
  7. Patient has used injected anesthetics or steroids within 30 days of baseline.
  8. Patient has skin conditions in the area affected by the neuropathy that could alter sensation.
  9. Patient is in an immunocompromised state.
  10. Patient has an estimated creatinine clearance less than 50 ml/min.
  11. Patient has had malignancy within past 2 years other than basal cell carcinoma.
  12. Patient has had gastric reduction surgery.
  13. Patient has severe chronic diarrhea, chronic constipation [unless attributed to drugs that will be washed out], uncontrolled irritable bowel syndrome (IBS) or unexplained weight loss.
  14. Patient has any abnormal chemistry or hematology results that are deemed by the investigator to be clinically significant.
  15. Patient has a history of substance abuse within the past year.
  16. Patient has a history of seizure (except for infantile febrile seizure) or is at risk of seizure due to head trauma.
  17. Patient has a history of chronic hepatitis B or C, hepatitis within the past 3 months, or HIV infection.
  18. Patient has any other clinically significant medical or psychological condition that, in the opinion of the Investigator would jeopardize the safety of the patient or affect the validity of the study results.
  19. Continuing use of any concomitant medication excluded by Inclusion Criterion 5.
  20. Patient has participated in a clinical trial of an investigational drug or device within 30 days of the screening visit.
05

Study design

Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Double (Participant, Investigator)
Enrollment
452 participants (actual)

Study arms

  • Experimental
    G-ER

    Gabapentin - Extended Release

    Drug: Gabapentin Extended Release tablets

  • Placebo comparator
    Placebo

    Sugar pill

    Drug: Placebo

Interventions

  • DrugGabapentin Extended Release tablets

    Once-Daily; 300 mg and 600 mg tablets

  • DrugPlacebo

    Once daily; 300 mg and 600 mg tablets

06

What researchers measure

Primary outcomes

  1. Mean Change in Baseline Observation Carried Forward (BOCF) Average Daily Pain Score

    Average daily pain scored on 11-point numerical rating scale (where 0 = no pain, 10 = worst possible pain). Results presented as least squares (LS) mean change in baseline observation carried forward (BOCF) average daily pain score from baseline to the final week of efficacy treatment period (Week 10).

    Time frame: 10 weeks

Secondary outcomes

  1. Patient Global Impression of Change (PGIC)

    Patient self-assessment of how much pain had changed at end of treatment period (Week 10) compared to pain at baseline; scored on 7-point numerical rating scale (where 1 = very much improved, 7 = very much worse). Results presented as number of participants categorized at end of treatment (Week 10) as "very much improved" (score = 1) or "much improved" (score = 2).

    Time frame: 10 weeks

  2. Clinical Global Impression of Change (CGIC)

    Investigator assessment of patient's overall PHN symptoms at end of treatment period (Week 10) compared to overall PHN symptoms at baseline; scored on 7-point numerical rating scale (where 1 = very much improved, 7 = very much worse). Results presented as number of participants categorized at end of treatment (Week 10) as "very much improved" (score = 1) or "much improved" (score = 2).

    Time frame: 10 weeks

  3. Average Daily Sleep Interference Score

    Assessed on 11-point numeric rating scale (where 0 = pain does not interfere with sleep, 10 = pain completely interferes with sleep); evaluated from daily sleep entry in electronic diary. Results presented as least squares (LS) mean change in baseline observation carried forward (BOCF) average daily sleep interference score from baseline to final week of treatment period (Week 10).

    Time frame: 10 weeks

Other outcomes

  1. Mean Change in Last Observation Carried Forward (LOCF) Average Daily Pain Score

    Average daily pain scored on 11-point numerical rating scale (where 0 = no pain, 10 = worst possible pain). Results presented as least squares (LS) mean change in last observation carried forward (LOCF) average daily pain score from baseline to final week of efficacy treatment period (Week 10).

    Time frame: 10 weeks

07

Results

Posted Jan 13, 2012

Participant flow

Recruitment period was from March 2008 through May 2009.

Participant flow — Overall Study
MilestoneG-ERPlacebo
Started221231
Safety & efficacy of gabapentin er186194
379186194
Completed185192
Not completed3639
Withdrew: Other reason46
Withdrew: Adverse event198
Withdrew: Lack of efficacy712
Withdrew: Protocol violation22
Withdrew: Lost to follow-up01
Withdrew: Death01
Withdrew: Withdrawal by subject49

Outcome measures

PrimaryMean Change in Baseline Observation Carried Forward (BOCF) Average Daily Pain Score

Average daily pain scored on 11-point numerical rating scale (where 0 = no pain, 10 = worst possible pain). Results presented as least squares (LS) mean change in baseline observation carried forward (BOCF) average daily pain score from baseline to the final week of efficacy treatment period (Week 10).

Time frame:
10 weeks
Reported as:
Least squares mean · Scores on a scale
Mean Change in Baseline Observation Carried Forward (BOCF) Average Daily Pain Score
Scores on a scaleG-ERPlacebo
Mean Change in Baseline Observation Carried Forward (BOCF) Average Daily Pain Score-2.12 ± 0.17-1.63 ± 0.16
Statistical analysis
  • G-ER vs Placebo · ANCOVA · p = 0.0125 · Least squares mean difference: -0.49 · 95% CI -0.88 to -0.11
SecondaryPatient Global Impression of Change (PGIC)

Patient self-assessment of how much pain had changed at end of treatment period (Week 10) compared to pain at baseline; scored on 7-point numerical rating scale (where 1 = very much improved, 7 = very much worse). Results presented as number of participants categorized at end of treatment (Week 10) as "very much improved" (score = 1) or "much improved" (score = 2).

Time frame:
10 weeks
Reported as:
Number · Participants
Patient Global Impression of Change (PGIC)
ParticipantsG-ERPlacebo
Patient Global Impression of Change (PGIC)9477
Statistical analysis
  • G-ER vs Placebo · Z test · p = 0.0434 · Difference in proportion: 0.092 · 95% CI -0.00 to 0.18
SecondaryClinical Global Impression of Change (CGIC)

Investigator assessment of patient's overall PHN symptoms at end of treatment period (Week 10) compared to overall PHN symptoms at baseline; scored on 7-point numerical rating scale (where 1 = very much improved, 7 = very much worse). Results presented as number of participants categorized at end of treatment (Week 10) as "very much improved" (score = 1) or "much improved" (score = 2).

Time frame:
10 weeks
Reported as:
Number · Participants
Clinical Global Impression of Change (CGIC)
ParticipantsG-ERPlacebo
Clinical Global Impression of Change (CGIC)9778
Statistical analysis
  • G-ER vs Placebo · Z test · p = 0.0268 · Difference in proportion: 0.102 · 95% CI 0.01 to 0.19
SecondaryAverage Daily Sleep Interference Score

Assessed on 11-point numeric rating scale (where 0 = pain does not interfere with sleep, 10 = pain completely interferes with sleep); evaluated from daily sleep entry in electronic diary. Results presented as least squares (LS) mean change in baseline observation carried forward (BOCF) average daily sleep interference score from baseline to final week of treatment period (Week 10).

Time frame:
10 weeks
Reported as:
Least squares mean · Scores on a scale
Average Daily Sleep Interference Score
Scores on a scaleG-ERPlacebo
Average Daily Sleep Interference Score-2.30 ± 0.16-1.59 ± 0.15
Statistical analysis
  • G-ER vs Placebo · ANCOVA · p = 0.0001 · Least square mean difference: -0.71 · 95% CI -1.07 to -0.35P-value versus Placebo for pairwise test of difference of LS mean change from baseline between G-ER and Placebo groups is based on t-test of Type III analysis.
Other pre-specifiedMean Change in Last Observation Carried Forward (LOCF) Average Daily Pain Score

Average daily pain scored on 11-point numerical rating scale (where 0 = no pain, 10 = worst possible pain). Results presented as least squares (LS) mean change in last observation carried forward (LOCF) average daily pain score from baseline to final week of efficacy treatment period (Week 10).

Time frame:
10 weeks
Reported as:
Least squares mean · Scores on a scale
Mean Change in Last Observation Carried Forward (LOCF) Average Daily Pain Score
Scores on a scaleG-ERPlacebo
Mean Change in Last Observation Carried Forward (LOCF) Average Daily Pain Score-2.40 ± 0.17-1.85 ± 0.17
Statistical analysis
  • G-ER vs Placebo · ANCOVA · p = 0.007 · Least square mean difference: -0.55 · 95% CI -0.96 to -0.15

Adverse events

Collected over 11 weeks (plus 30 days for SAEs). Non-serious events are listed at a 1% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
G-ER—4/221 (1.8%)92/221 (41.6%)
Placebo—6/231 (2.6%)63/231 (27.3%)
Most frequent serious events
Most frequent serious events
EventG-ERPlacebo
Left arm fractureMusculoskeletal and connective tissue disorders1/2211/231
OsteochondrosisMusculoskeletal and connective tissue disorders1/2210/231
Pancoast tumorRespiratory, thoracic and mediastinal disorders1/2210/231
Pancreatitis chronicGastrointestinal disorders1/2210/231
Cardiac failure congestionCardiac disorders0/2211/231
CellulitisSkin and subcutaneous tissue disorders0/2211/231
HematuriaRenal and urinary disorders0/2211/231
Myocardial infarctionCardiac disorders0/2211/231
ThrombophlebitisVascular disorders0/2211/231
Most frequent other events
Showing 10 of 17
Most frequent other events
EventG-ERPlacebo
DizzinessNervous system disorders25/2214/231
SomnolenceNervous system disorders12/2217/231
HeadacheNervous system disorders10/2219/231
NauseaGastrointestinal disorders10/2217/231
Peripheral edemaGeneral disorders7/2211/231
DiarrheaGastrointestinal disorders6/2215/231
Abdominal pain upperGastrointestinal disorders3/2216/231
NasopharyngitisInfections and infestations5/2216/231
Dry mouthGastrointestinal disorders4/2212/231
DyspepsiaGastrointestinal disorders4/2211/231

Baseline characteristics

Age Continuous
Age Continuous(years)G-ERPlaceboTotal
Mean65.3 ± 13.365.9 ± 11.165.6 ± 12.2
Age, Customized
Age, Customized(participants)G-ERPlaceboTotal
<65 years8189170
65 to 74 years8286168
>=75 years5755112
Sex: Female, Male
Sex: Female, Male(Participants)G-ERPlaceboTotal
Female134147281
Male8683169
Race/Ethnicity, Customized
Race/Ethnicity, Customized(Participants)G-ERPlaceboTotal
Caucasian196204400
Black10616
Asian123
Other131831
08

Study locations

39 sites
  • Birmingham, Alabama, United States
  • Tuscaloosa, Alabama, United States
  • Phoenix, Arizona, United States
  • Little Rock, Arkansas, United States
  • Lancaster, California, United States
  • Los Angeles, California, United States
  • Pismo Beach, California, United States
  • Colorado Springs, Colorado, United States
  • Pueblo, Colorado, United States
  • Daytona Beach, Florida, United States
  • Naples, Florida, United States
  • New Port Richey, Florida, United States
  • Orlando, Florida, United States
  • Tampa, Florida, United States
  • Marietta, Georgia, United States
  • Honolulu, Hawaii, United States
  • Elk Grove Village, Illinois, United States
  • Shreveport, Louisiana, United States
  • West Yarmouth, Massachusetts, United States
  • Ann Arbor, Michigan, United States
  • Florissant, Missouri, United States
  • Jefferson City, Missouri, United States
  • Albuquerque, New Mexico, United States
  • High Point, North Carolina, United States
  • Bismarck, North Dakota, United States
  • Fargo, North Dakota, United States
  • Canton, Ohio, United States
  • Cincinnati, Ohio, United States
  • Kettering, Ohio, United States
  • Warwick, Rhode Island, United States
  • Murrells Inlet, South Carolina, United States
  • Pelzer, South Carolina, United States
  • Tullahoma, Tennessee, United States
  • Austin, Texas, United States
  • Longview, Texas, United States
  • Spokane, Washington, United States
  • Buenos Aires, Argentina
  • All over Russia, Russian Federation
  • St. Petersburg, Russian Federation
09

References and documents

Publications

  • Mehta N, Bucior I, Bujanover S, Shah R, Gulati A. Relationship between pain relief, reduction in pain-associated sleep interference, and overall impression of improvement in patients with postherpetic neuralgia treated with extended-release gabapentin. Health Qual Life Outcomes. 2016 Apr 1;14:54. doi: 10.1186/s12955-016-0456-0. PubMed 27037091 ↗
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Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Feb 22, 2012, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
11

Registry details

Key details

Study ID
NCT00636636
Lead sponsor
Depomed
Responsible party
Sponsor
First posted
Mar 14, 2008
Start date
Mar 2008
Primary completion
Aug 2009
Completion
Sep 2009
Results posted
Jan 13, 2012
Last update
Feb 22, 2012

Oversight

Data monitoring committee
No
View the source record on ClinicalTrials.gov ↗

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