Topographical Distribution of Itch and Pain Receptors

NCT07122973 | Recruiting DMC

• 1 other identifier: N-20250017 Project 4
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

The experiment consists of three experimental sessions conducted on three consecutive days. In all experimental sessions, the participant will fill in a series of questionnaires about how you perceive itch and pain, and about some traits of your personality, such as depression, anxiety and stress. In the first session, we will mark six test areas in your face (three on each side on jaw, cheek, and temple, respectively). Thent a series of measure-ments in each test area will be conducted:measurement of the blood flow in the skin and sensitivity tests to pressure, pinprick and stroke with a brush. In the second session, histamine will be applied in one side of the face. On the other side, cowhage spicules will be applied. After 10 minutes, all the tests will be conducted again. The third session will be identical to the second. However, instead of histamine and spicules, patches containing capsaicin will be applied. In the other side, we will apply patches with placebo (i.e., a non-active patch). After 20 minutes all the tests will be conducted again.

Conditions

Pain; Itch

Outcome Measures

Primary Outcomes (4)

• Measuring pain by computerized Visual Analog Scale Scoring

  We will ask the subjects to rate the sensation of pain on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no pain" and 100 indicates "worst pain imaginable".

  Baseline

• Measuring itch by computerized Visual Analog Scale Scoring

  We will ask the subjects to rate the sensation of itch on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no itch" and 100 indicates "worst itch imaginable".

  Baseline

• Measuring pain by computerized Visual Analog Scale Scoring

  We will ask the subjects to rate the sensation of pain on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no pain" and 100 indicates "worst pain imaginable".

  Immediately after the intervention

• Measuring itch by computerized Visual Analog Scale Scoring

  We will ask the subjects to rate the sensation of itch on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no itch" and 100 indicates "worst itch imaginable".

  Immediately after the intervention

Secondary Outcomes (30)

• Superficial blood perfusion

  Baseline

• Superficial blood perfusion

  Immediately after the intervention

• Alloknesis

  Baseline

• Alloknesis

  Immediately after the intervention

• Mechanically evoked itch (MEI)

  Baseline

Study Arms (1)

Itch and pain

EXPERIMENTAL

Other: Histamine; Other: Cowhage; Other: Capsaicin 8% Patch; Other: Demo patch

Interventions

Histamine OTHER

To deliver histamine, standard allergy skin prick test (SPT) lancets are applied

Itch and pain

Cowhage OTHER

The spicules will be manually inserted. Approximately 30-35 spicules are gently rubbed into a 1 cm diameter skin area on the forearm/face

Itch and pain

Capsaicin 8% Patch OTHER

Capsaicin patches (dosage form: transdermal patch 8% Qutenza, Astellas) will be applied on 3 squared areas in the face.

Itch and pain

Demo patch OTHER

Placebo patch (demo patch, containing the same formulation as the active treatment with the exception of capsaicin) will be applied on 3 squared areas in the face.

Itch and pain

Eligibility Criteria

• Age: 18 Years - 60 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy men and women
• years
• Speak and understand English

You may not qualify if:

• Pregnancy or lactation
• Drug addiction defined as any use of cannabis, opioids, or other drugs
• Previous or current history of neurological, immunological, musculoskeletal, cardiac disorder or psychiatric diagnoses that may affect the results (e.g., neuropathy, muscular pain in the upper extremities, anxiety, depression, schizophrenia, etc.)
• Moles, wounds, scars, or tattoos in the area to be treated or tested
• Current use of medications that may affect the trial such as antihistamines and pain killers
• Skin diseases
• Consumption of alcohol or painkillers 24 hours before the study days and between these
• Acute or chronic pain and itch
• Participation in other trials within 1 week of study entry (4 weeks in the case of pharmaceutical studies)
• Contraindications to capsaicin, including intolerance to chili or burns or wounds at the application site
• The subject is assessed as unable to engage in the necessary cooperation required by the study

Sponsors & Collaborators

• Aalborg University: lead

Study Sites (1)

Aalborg University

Gistrup, Aalborg, 9260, Denmark

RECRUITING

MeSH Terms

Conditions

Pain; Pruritus

Interventions

Histamine; Capsaicin; Transdermal Patch

Condition Hierarchy (Ancestors)

Neurologic Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Skin Diseases; Skin and Connective Tissue Diseases; Skin Manifestations

Intervention Hierarchy (Ancestors)

Biogenic Monoamines; Biogenic Amines; Amines; Organic Chemicals; Ethylamines; Imidazoles; Azoles; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Autacoids; Inflammation Mediators; Biological Factors; Polyunsaturated Alkamides; Amides; Alkenes; Hydrocarbons, Acyclic; Hydrocarbons; Catechols; Phenols; Benzene Derivatives; Hydrocarbons, Aromatic; Hydrocarbons, Cyclic; Solanaceous Alkaloids; Alkaloids; Fatty Acids, Monounsaturated; Fatty Acids, Unsaturated; Fatty Acids; Lipids; Equipment and Supplies

Central Study Contacts

Silvia Lo Vecchio

CONTACT

+4521397785; slv@hst.aau.dk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Study Record Dates

• First Submitted: August 13, 2025
• First Posted: August 14, 2025
• Study Start: September 17, 2025
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2028
• Last Updated: October 1, 2025

Record last verified: 2025-09

Locations

DK (1)