Repetitive Applications of Pruritogens and Effects of a Cutaneous-induced Pain Stimulation on Nonhistaminergic Itch Perception

Aalborg University

Status: Enrolling

Conditions: Pain, Burning; Capsaicin

Treatments: Other: Cowhage

Study type: Interventional

Funder types: Other

Identifiers

NCT06185582

N-20210046 2nd project

Details and patient eligibility

About

In This experiment, the investigators would like to test following hypotheses:

the pain stimulation applied at the same time of a pruriceptive stimulus will decrease the itch perception. Moreover, also the effect of the cutaneous pain stimulus location (same forearm of the pruriceptive stimulus versus the opposite forearm) on histaminergic and non-histaminergic itch will be investigated.

Full description

The phenomenon that pain inhibits pain is a well-known mechanism, but it is not known if pain is inhibiting itch. In this context, the aim of this project is to investigate the extent to which thermal or neurogenic short cutaneous pain can affect the itch perception. In particular, the project aims to understand any differences in itch perception when the painful stimulation is applied on the same forearm versus the opposite forearm. The hypothesis is that by applying a painful stimulus at the same time of an itchy stimulus, the itch sensitivity will decrease; probably due to an inhibitory process conducted by interneurons (Bhlbb5 interneuron) at central level.

Enrollment: 30 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: Non-Randomized

Interventional model: Single Group Assignment

Masking: Single Blind

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30 participants in 2 patient groups

Pain

Experimental group

Description:

A thermode stimulator of 3x3 cm will be placed on the areas and kept in place by means of Velcro tape. The temperature raises 1°C per second from a starting temperature of 32°C until itch reach or 46.5 °C. This temperature will be maintained for 2 minutes. Then the temperature will return to baseline temperature at a rate of 5°C /s.

Treatment:

Other: Cowhage

Capsaicin

Experimental group

Description:

Capsaicin patches (dosage form: transdermal patch 8% Qutenza, Astellas) will be applied on one squared area (4x4 cm2). The patch will be left in place for 20 minutes after which it will be removed.

Treatment:

Other: Cowhage