Itch Sensation Induced by Simultaneous Application of Pruritogens (Spatial Summation)

Aalborg University

Status: Enrolling

Conditions: Cowhage; Histamine

Treatments: Other: Cowhage; Other: Histamine

Study type: Interventional

Funder types: Other

Identifiers

NCT06328530

N-20210046 3rd project

Details and patient eligibility

About

In This experiment, the investigators would like to design a new itch model based on the spatial summation of pruritic stimuli. The hypothesis behind this study (spatial summation) is that two simultaneous applications of pruritogens will result in higher itch sensation compared with a single application of pruritogen.

Full description

Chronic itch affects approximately a fifth of the global population and is associated with substantial negative consequences for the affected individuals. Furthermore, there is a lack of efficient treatment options for chronic itch. In order to mimic a clinical itch condition as presented in patients, the aim of the project is to investigate a new itch model based on the spatial summation of pruritic stimuli. The aim of this experiment is to assess the itch sensation induced by simultaneous application of pruritogens (spatial summation). In particular, the purpose is to evaluate if a single application of cowhage/histamine (non-histaminergic and histaminergic itch respectively) results in a lower itch sensation compared to two simultaneous applications of the pruritogens, on the same arm or in different arms.

Enrollment: 24 estimated patients

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 addictive drugs
• Previous or current history of neurological (e.g. neuropathy), immunological (e.g. asthma, immune deficiencies, arthritis) musculoskeletal (e.g. muscular pain in the upper extremities,), cardiac disorder, or mental illnesses that may affect the results
• Lack of ability to cooperate
• Current use of medications that may affect the trial such as antihistamines, antipsychotics, and pain killers, as well as systemic or topical steroids
• Skin diseases (e.g. atopic dermatitis, pruritus nodularis, eczema, psoriasis)
• Moles, scars, or tattoos in the area to be treated or tested.
• Consumption of alcohol or painkillers 24 hours before the study days and between these
• Acute or chronic pain
• Participation in other trials within one week of study entry (four weeks in the case of pharmaceutical trials)

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Single Group Assignment

Masking: Single Blind

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24 participants in 2 patient groups

1st pruritogen

Experimental group

Description:

The subproject consists of 2 sessions 3 days apart. Each session consists of 3 parts. In the first session, 3 test areas (4x4 cm) will be selected on the subject's forearms. In part 1, we will apply cowhage in one area. In part 2, we will apply cowhage in two areas on the same arm. In part 3, we will again apply cowhage in 2 areas, one on each arm. In each part, the itch intensity will be measured using a VAS (visual analog scale) for 10 min from the cowhage application. After removal of the cowhage, alloknesis and mechanically evoked itch will be measured in the area selected in part 1.

Treatment:

Other: Cowhage

2nd pruritogen

Other group

Description:

The second session will take place 3 days after the first one and will follow the same procedure as session 1. However, histamine will be applied instead of cowhage. The order of the two sessions will be randomized.

Treatment:

Other: Histamine