A Study Of The Efficacy Of Gabapentin In Neuropathic Pain Patients As Measured By Quantitative Sensory Testing

Study Overview
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Brief Summary
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The purpose of this study is to assess the reproducibility and the effect of gabapentin on quantitative sensory testing assessments in neuropathic pain subjects.

Official Title
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A Randomized Double-Blind, Placebo-Controlled, Crossover Study To Assess The Reproducibility And The Effect Of Gabapentin On Quantitative Sensory Testing In Neuropathic Pain Patients

Conditions
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Neuralgia, Neuralgia, Postherpetic

Intervention / Treatment
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* Drug: 2-weeks placebo then gabapentin
* Drug: 1-week placebo then gabapentin


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Neuropathic pain of peripheral origin as a consequence of either post-herpetic neuralgia or post-traumatic neuropathic pain Well-defined skin area of mechanical allodynia to punctate (von Frey filament) stimuli Pain intensity score of ≥ 4/10 for von Frey filament-evoked allodynia at the skin area Exclusion Criteria: Patients who have undergone neurolytic or neurosurgical therapy, including skin excisions, for neuropathic pain Patients who have trigeminal neuralgia, central pain, chronic radiculopathy, or peripheral neuropathy of non-mechanical or unknown origin Patients with any other co-existing pain which cannot be differentiated from the neuropathic pain of peripheral origin

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Sequence 1<br> | Drug: 2-weeks placebo then gabapentin<br>* Placebo for 2 weeks followed by gabapentin 300 mg oral capsule once daily titrated over 1 week to gabapentin 600 mg three times daily for 1 week<br>|
| Experimental: Sequence 2<br> | Drug: 1-week placebo then gabapentin<br>* Placebo for 1 week followed by gabapentin 300 mg oral capsule once daily titrated over 1 week to gabapentin 600 mg three times daily for 2 weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Presence/intensity of punctate allodynia (von Frey filament), measured on the pain numeric rating scale (NRS) |  | Weeks 2 and 4 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Subject assessed quality of evoked pain for punctate allodynia |  | Weeks 2 and 4 | 
| Pain NRS score for temporal summation to dynamic brush allodynia (soft and coarse brush) |  | Weeks 2 and 4 | 
| Pressure pain tolerance threshold |  | Weeks 2 and 4 | 
| Pain NRS scores for pressure pain |  | Weeks 2 and 4 | 
| Subject assessed quality of evoked pain for temporal summation to dynamic brush allodynia (soft and coarse brush) |  | Weeks 2 and 4 | 
| Tactile threshold |  | Week 4 | 
| Pressure pain detection threshold |  | Weeks 2 and 4 | 
| Area of punctate and dynamic (soft and coarse brush) allodynia |  | Weeks 2 and 4 | 
| Pain NRS score for punctate allodynia |  | Weeks 2 and 4 | 
| Pain NRS scores for temporal summation to punctate stimuli |  | Weeks 2 and 4 | 
| Subject assessed quality of evoked pain for temporal summation to punctate stimuli |  | Weeks 2 and 4 | 
| Neuropathic pain scale |  | Week 4 | 
| Test-day global pain scale |  | Week 4 | 
| Pain diary card |  | Week 4 | 
| Pain NRS score for dynamic brush allodynia (soft brush) |  | Weeks 2 and 4 | 
| Subject assessed quality of evoked pain for dynamic brush allodynia (soft brush) |  | Weeks 2 and 4 | 
| Presence of metabonomic biomarkers |  | Weeks 1 and 4 | 
| Physical examination |  | 1 week after 4-week treatment period | 
| Adverse events |  | Throughout study duration | 
| Clinical laboratory tests |  | 1 week after 4-week treatment period | 
| Subject assessed quality of pressure pain |  | Weeks 2 and 4 |