Itch Relieving Effect of Botox: a Study in Healthy Subjects

Study Overview
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Brief Summary
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The purpose of this study is to determine if Botox is effective in the treatment of an experimentally induced itch that mimics chronic itch in healthy volunteers.

Detailed Description
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Several studies have shown that botulinum toxin type A (BoNT/A) has an antipruritic effect due to the inhibition of acetylcholine and other pruritic factors, such as substance P and glutamate. For instance, subcutaneous BoNT/A improves itch accompanied to hand eczema, dermatitis, lichen simplex, and rhinitis. Furthermore, a double-blind, placebo-controlled study showed that BoNT/A reduced histamine itch intensity in healthy men. Since acetylcholine has been shown to mediate itch in atopic dermatitis, this study aims to test the itch relieving effect of BoNT/A on a non-histaminergic model for chronic itch. This non-histaminergic model using the plant cowhage induces itch by activating protease activated receptor 2 (PAR2) receptors, which play a role in the itch of atopic dermatitis, also making this model better suited to test the efficacy of BoNT/A to relive chronic itch.

Official Title
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Itch Relieving Effect of Botox: a Study in Healthy Subjects

Conditions
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Pruritus

Intervention / Treatment
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* Drug: Botox
* Drug: Saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy volunteers between 18 and 50 years of age. Must be in general good health with no disease or physical conditions that would impair evaluation of itch and pain perception. No history of chronic itch or pain. Must abstain from the use of any systemic or topical anti-histamine, steroid, or pain relief medications from the week prior to the study till the completion of the study. Must abstain from the use of moisturizers on the arm. Exclusion Criteria: Individuals under 18 or over 50 years of age. Inability to complete the required measures. The presence of an itchy skin disease. Diagnosis of diseased that would affect itch or pain perception (e.g. neuropathies). Currently enrolled in any investigational study in which the subject is receiving any type of drug, biological, or non-drug therapy. Use of oral, topical analgesics, or other medications known to interfere with itch or pain perception in the week prior to the study and throughout the study (e.g. antihistamines, anesthetics, opioids, neuroleptics, etc.). Use of emollients on the arms a week prior to the study and throughout the study. Use of anti-depressants, anti-psychotics, and illicit drugs. Known history of neuropathy, uremia, uncontrolled thyroid disease, and diabetes mellitus. Use of Botulinum toxin in the last year. Known allergies to Botox. Pregnant women. (Women of child bearing potential will undergo an human chorionic gonadotrophin (hCG) pregnancy test before Botox application). Hypersensitivity to any botulinum toxin preparation or to any of the components in the formulation. Infection at the injection site. Cardiovascular disease. Neuromuscular disorder (e.g., amyotrophic lateral sclerosis, myasthenia gravis, or Lambert-Eaton syndrome). Compromised respiratory function. Dysphagia. History of urinary tract infection. History of urinary retention.

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

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Botox<br>10 units of Botox intradermally injected into one forearm. The subject is blinded to which forearm receives the Botox and which forearm receives the saline vehicle. | Drug: Botox<br>* 10 units of Botox will be intradermally injected into one 4x4cm area on the volar forearm on 1st study visit.<br>|
| Placebo Comparator: Saline<br>Saline vehicle intradermally injected into the other forearm. The subject is blinded to which forearm receives the Botox and which forearm receives the saline vehicle. | Drug: Saline<br>* 10 units of the Saline vehicle will be intradermally injected into one 4x4cm area on the contralateral volar forearm on the 1st study visit.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Itch by VAS Itch Intensity at Baseline (Visit 1) | The primary endpoint is to test the antipruritic effect of Botox using an itch visual analog scale (VAS) intensity scale as an outcome measure. The itch VAS intensity scale ranges from a minimum of 0 (no itch - best) to a maximum of 10 (maximum itch - worst). Participants will rate itch intensity after itch is induced with cowhage. | Baseline (Visit 1) | 
| Itch by VAS Itch Intensity at 1 Week (Visit 2) | The primary endpoint is to test the antipruritic effect of Botox using an itch visual analog scale (VAS) intensity scale as an outcome measure. The itch VAS intensity scale ranges from a minimum of 0 (no itch - best) to a maximum of 10 (maximum itch - worst). Participants will rate itch intensity after itch is induced with cowhage. | 1 week from Baseline | 
| Itch by VAS Itch Intensity at 1 Month (Visit 3) | The primary endpoint is to test the antipruritic effect of Botox using an itch visual analog scale (VAS) intensity scale as an outcome measure. The itch VAS intensity scale ranges from a minimum of 0 (no itch - best) to a maximum of 10 (maximum itch - worst). Participants will rate itch intensity after itch is induced with cowhage. | 1 Month from Baseline | 
| Itch by VAS Itch Intensity at 3 Months (Visit 4) | The primary endpoint is to test the antipruritic effect of Botox using an itch visual analog scale (VAS) intensity scale as an outcome measure. The itch VAS intensity scale ranges from a minimum of 0 (no itch - best) to a maximum of 10 (maximum itch - worst). Participants will rate itch intensity after itch is induced with cowhage. | 3 Months from Baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Heat Pain Relief by VAS Pain Intensity Reporting After 1 Week, 1 Month, and 3 Months After Treatment | A secondary endpoint is to see if Botox has a relieving effect on heat pain using a pain visual analog scale (VAS) intensity scale as an outcome measure. The pain VAS intensity scale ranges from a minimum of 0 (no pain - best) to a maximum of 10 (maximum pain - worst). Participants will rate pain intensity after pain is induced with a heat thermode. | Baseline, 1 week, 1 month, 3 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Itch, Botox, Healthy Volunteers