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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Masking
DOUBLE
Enrollment
33
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.
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.
Washington University School of Medicine
St Louis, Missouri, United States
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.
Time frame: During approximately 7 hours of consecutive assessments
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.
Time frame: 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.
Time frame: 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.
Time frame: 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)
Time frame: 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
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Time frame: During approximately 6 hours of consecutive assessments