Fenobam on Heat/Capsaicin Induced Hyperalgesia in Healthy Volunteers

Study Overview
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Brief Summary
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Our goal is to demonstrate that healthy volunteers treated with fenobam will develop a significantly reduced area of cutaneous hyperalgesia compared to volunteers treated with placebo, after exposure to the heat/capsaicin model of cutaneous sensitization. Additionally we are going to assess changes in mood/affect and cognitive function of subjects following administration of fenobam and after cutaneous sensitization compared to baseline.

Detailed Description
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All subjects will receive a topical dose of capsaicin cream 0.1%(Capzasin-HP) to the forearm at the start of the study visit. The order of the 2 treatment regimens indicated below will be randomized and blinded to subjects and researchers. Treatment Regimen 1: Fenobam [1-(3-chlorophenyl)-3-(1-methyl-4-oxo-2-imidazolidinylidine) urea hydrate]: administration of one 150 mg gelatin capsule. Treatment Regimen 2: Placebo (lactose monohydrate): administration of one 150 mg gelatin capsule.

Official Title
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A Double Blind, Randomized, Placebo Controlled, Crossover Study to Investigate the Anti-hyperalgesic Efficacy of a Single Dose of Fenobam on Heat/Capsaicin Induced Cutaneous Hyperalgesia in Adult Healthy Volunteers.

Conditions
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Hyperalgesia, Allodynia

Intervention / Treatment
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* Drug: Fenobam
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-50 year old Good general health with no remarkable medical conditions (e.g. liver, kidney, heart, or lung failure) BMI between 20-33 Willing to comply with study guidelines as outlined in protocol [including: women of childbearing age must be willing to use a double-barrier method (e.g. oral contraception and condom) for contraception during participation in the study] Willing to provide informed consent Exclusion Criteria: Anatomical malformation of upper extremities Status post recent trauma or chronic lesions on either forearm Medication use (includes vitamin, herbal, dietary and mineral supplements and grapefruit products during or within 14 days prior to study participation; excludes contraceptives) History of allergy or intolerance to capsaicin History of multiple drug allergies History of addiction to drugs or alcohol (prior or present addiction or treatment for addiction) History of chronic pain syndromes Pregnant and nursing females Smokers

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Treatment regimn 1<br>150 mg Fenobam Orally - once | Drug: Fenobam<br>* Fenobam 150 mg will be administered and subjects will be monitored for up to 8 hours. During the study day questionnaires will be administered, blood will be drawn a testing site will be marked and pain testing and heat/capsaicin sensitization will be measured.<br>* Other names: [1-(3-chlorophenyl)-3-(1-methyl-4-oxo-2-imidazolidinylidine) urea hydrate];|
| Placebo Comparator: Treatment Regimen 2<br>Placebo orally - once | Drug: Placebo<br>* A placebo will be administered and subjects will be monitored for up to 8 hours. During the study day questionnaires will be administered, blood will be drawn a testing site will be marked and pain testing and heat/capsaicin sensitization will be measured.<br>* Other names: Lactose monohydrate;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Suppression of the development of cutaneous hyperalgesia and allodynia around the area treated with heat/capsaicin. | size of the area of hyperalgesia and allodynia around the area sensitized by heat/capsaicin as quantified by cutaneous stimulation with foam brush strokes and a von Frey filament requiring 26 g of bending force. | During approximately 7 hours of consecutive assessments | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Evaluation of nociception after drug administration as evaluated by prolonged (1 min) thermal stimulation on normal (untreated) skin. | Visual Analog Scale (VAS) rating of pain perception at 1 min 45°C heat stimulation on normal skin. | During approximately 7 hours of consecutive assessments | 
| Assessment of Heat Pain Detection Thresholds (HPDT) in normal and sensitized skin pre and post treatment with fenobam. | lowest temperature perceived as painful with stimulation starting at 32°C and with a safety cut-off at 52°C. | During approximately 7 hours of consecutive assessments | 
| Absence of significant side effects | Determined by subjects' monitoring during treatment sessions and follow up at 1 day and 1 week after treatment with drug. | 7 days | 
| Assessment of significant change in mood/affect | As determined by evaluation of the subjects by combined brief Positive And Negative Affect Scale/Brief State Anxiety Measure (PANAS/BSAM) | During approximately 6 hours of consecutive assessments | 
| Assessment of significant change in cognitive function | As determined by evaluation of the Letter and Number Sequencing (LNS) assessment | During approximately 6 hours of consecutive assessments | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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fenobam, heat, capsaicin, hyperalgesia, allodynia, mood, cognitive function