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

Aalborg University

Status: Completed

Conditions: Cowhage; Histamine

Treatments: Other: Cowhage; Other: Histamine

Study type: Interventional

Funder types: Other

Identifiers

NCT06154824

N-20210046 1st project

Details and patient eligibility

About

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

repetitive cutaneous administration of pruritogens will lead to a more robust and longer lasting itch sensation compared with a single application. The aim of this project is to investigate a new itch model based on repetitive administration of three different pruritogens: histamine (histaminergic itch), cowhage, and BAM 8-22 (non-histaminergic itch).

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 repetitive administration of three different pruritogens: histamine (histaminergic itch), cowhage, and BAM 8-22 (non-histaminergic itch). The hypothesis is that repetitive cutaneous administration of pruritogens will lead to a more robust and longer-lasting itch sensation compared with a single application. This proposal for a new itch model could better mimic clinical itch conditions and be used to investigate fundamental mechanisms, new anti-pruritic drugs, and their possible mechanisms of action.

Enrollment: 30 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

1st pruritogen

Experimental group

Description:

The study takes place over two sessions over a period of 7 days. The duration of the sessions is approx. 4 hours in total. In the 1st session, a squared area of 4x4 cm will be selected at the center of each middle forearm of the subject. The two areas will be randomly treated with one of the following substances: cowhage, histamine, BAM 8-22 or vehicle. Each substance will be applied for 10 minutes, during which the pain/itch following the substance application will be monitored. Twenty minutes after each application, the measurements with FLPI will be conducted. Then the measurements of alloknesis and mechanically evoked itch, will be conducted. This procedure will be repeated three times for each substance; so in total each substance will be applied three times, each application lasting 10 minutes.

Treatment:

Other: Cowhage

2nd pruritogen

Experimental group

Description:

The study takes place over two sessions over a period of 7 days. The duration of the sessions is approx. 4 hours in total. In the 1st session, a squared area of 4x4 cm will be selected at the center of each middle forearm of the subject. The two areas will be randomly treated with one of the following substances: cowhage, histamine, BAM 8-22 or vehicle. Each substance will be applied for 10 minutes, during which the pain/itch following the substance application will be monitored. Twenty minutes after each application, the measurements with FLPI will be conducted. Then the measurements of alloknesis and mechanically evoked itch, will be conducted. This procedure will be repeated three times for each substance; so in total each substance will be applied three times, each application lasting 10 minutes.

Treatment:

Other: Histamine