Conditions: Pruritus
Keywords: Itch Botox Healthy Volunteers
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 35
Healthy volunteers: yes

Brief summary:
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:
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.

Arms:
arm 1: 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. arm 2: 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.

Interventions: intervention 1: Botox intervention 2: Saline
Intervention descriptions: intervention 1: 10 units of Botox will be intradermally injected into one 4x4cm area on the volar forearm on 1st study visit. intervention 2: 10 units of the Saline vehicle will be intradermally injected into one 4x4cm area on the contralateral volar forearm on the 1st study visit.

Protocol document: