Characterization of the Toll-like Receptor 7-agonist Imiquimod 3.75% As a New Surrogate Model of Itch

Aalborg University

Status: Withdrawn

Conditions: Itch

Treatments: Drug: Prudoxin; Other: Cowhage; Other: L-menthol; Other: Histamine; Other: Trans-cinnamaldehyde (CA); Drug: Zyclara 3.75 % Topical Cream

Study type: Interventional

Funder types: Other

Identifiers

NCT03943407

N-20190029

Details and patient eligibility

About

The aim of this research project is to design a new model of human itch by application of Zyclara cream. Further, the aim is to characterize the model and to verify if the mechanism of action of imiquimod follows the histaminergic or non-histaminergic pathway by using the anti-histamine drug doxepin. The last goal is to evaluate the interaction between the activation of TLR7 receptor and the activation of TRPA1 and TRPM8 receptors, which are two of the most important receptors involved in the transduction of noxious stimuli, and to evaluate to which extent these three channel populations functionally overlap.

Sex: All

Ages: 18 to 60 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Healthy men and women
• 18-60 years
• Speak and understand English

Exclusion criteria

• Pregnancy or lactation
• Drug addiction defined as any use of cannabis, opioids or other drugs
• Previous or current neurologic, musculoskeletal or mental illnesses
• Lack of ability to cooperate
• Current use of medications that may affect the trial
• Skin diseases
• Consumption of alcohol or painkillers 24 hours before the study days and between these
• Acute or chronic pain
• Participation in other trials within 1 week of study entry (4 weeks in the case of pharmaceutical trials)

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

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0 participants in 4 patient groups

Zyclara/vehicle

Experimental group

Description:

All subjects will be treated with Zyclara cream (Imiquimod 3.75%) and vehicle.

Treatment:

Drug: Zyclara 3.75 % Topical Cream

Zyclara/Doxepin

Experimental group

Description:

All subjects will be treated with the topical antihistamine cream (Prudoxin, containing 5% doxepin hydrochloride, Healthpoint, San Antonio, TX) or a placebo cream. After removal, subjects will be treated with Zyclara cream

Treatment:

Drug: Zyclara 3.75 % Topical Cream

Drug: Prudoxin

Zyclara/Histamine/Cowage

Experimental group

Description:

All subjects will be treated with Zyclara cream, vehicle cream, histamine and cowhage

Treatment:

Drug: Zyclara 3.75 % Topical Cream

Other: Histamine

Other: Cowhage

Zyclara/L-menthol/trans-cinnamaldehyde

Experimental group

Description:

All subjects will be treated with Zyclara cream (Imiquimod 3.75%) and vehicle. After removal, subjects will be treated with L/menthol and trans-cinnamaldehyde

Treatment:

Other: Trans-cinnamaldehyde (CA)

Drug: Zyclara 3.75 % Topical Cream

Other: L-menthol