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NCT Number: NCT07122973

Topographical Distribution of Itch and Pain Receptors

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.

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Key information

Conditions

Pain Itch Neurologic Manifestations Pathological Conditions, Signs and Symptoms Pruritus Signs and Symptoms Skin Diseases Skin Manifestations Skin and Connective Tissue Diseases

Age range

18 year–60 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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 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

Treatment and study plan

Histamine

Other

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

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

Capsaicin 8% Patch

Other

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

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.

Primary outcomes

  1. Measuring pain by computerized Visual Analog Scale Scoring

    Time frame: Baseline

    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".

  2. Measuring itch by computerized Visual Analog Scale Scoring

    Time frame: Baseline

    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".

  3. Measuring pain by computerized Visual Analog Scale Scoring

    Time frame: Immediately after the intervention

    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".

  4. Measuring itch by computerized Visual Analog Scale Scoring

    Time frame: Immediately after the intervention

    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".

Secondary outcomes

  1. Superficial blood perfusion

    Time frame: Baseline

    Superficial blood perfusion (SBP) is measured by a Speckle contrast imager

  2. Superficial blood perfusion

    Time frame: Immediately after the intervention

    Superficial blood perfusion (SBP) is measured by a Speckle contrast imager

  3. Alloknesis

    Time frame: Baseline

    Measured using a standardized sensory brush exerting a force of 200 to 400 mN.

  4. Alloknesis

    Time frame: Immediately after the intervention

    Measured using a standardized sensory brush exerting a force of 200 to 400 mN.

  5. Mechanically evoked itch (MEI)

    Time frame: Baseline

    MEI is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force).

  6. Mechanically evoked itch (MEI)

    Time frame: Immediately after the intervention

    MEI is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force).

  7. Mechanical Pain Thresholds (MPT)

    Time frame: Baseline

    This test is conducted using a pinprick set. The set consists of 7 needles each with a diameter of 0.6 mm and different force applications: 8, 16, 32, 64, 128, 256, and 512 mN.

  8. Mechanical Pain Thresholds (MPT)

    Time frame: Immediately after the intervention

    This test is conducted using a pinprick set. The set consists of 7 needles each with a diameter of 0.6 mm and different force applications: 8, 16, 32, 64, 128, 256, and 512 mN.

  9. Mechanical Pain Sensitivity (MPS)

    Time frame: Baseline

    This test is conducted with the same pinprick set used to test the MPT.

  10. Mechanical Pain Sensitivity (MPS)

    Time frame: Immediately after the intervention

    This test is conducted with the same pinprick set used to test the MPT.

  11. Cold Detection Thresholds (CDT)

    Time frame: Baseline

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  12. Cold Detection Thresholds (CDT)

    Time frame: Immediately after the intervention

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  13. Warm Detection Thresholds (WDT)

    Time frame: Baseline

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  14. Warm Detection Thresholds (WDT)

    Time frame: Immediately after the intervention

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  15. Cold Pain Thresholds (CPT)

    Time frame: Baseline

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  16. Cold Pain Thresholds (CPT)

    Time frame: Immediately after the intervention

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  17. Heat Pain Thresholds (HPT)

    Time frame: Baseline

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  18. Heat Pain Thresholds (HPT)

    Time frame: Immediately after the intervention

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  19. Pain to Supra-threshold Heat Stimuli (STHS)

    Time frame: Baseline

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  20. Pain to Supra-threshold Heat Stimuli (STHS)

    Time frame: Immediately after the intervention

    The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device

  21. Pain Catastrophizing Scale (PCS).

    Time frame: Baseline

    The PCS assesses negative and exaggerated coping concerning anticipated or experienced painful stimuli. Thirteen items have to be answered on a 5-point Likert-type scale ranging from 0 (Not at all) to 4 (all the time).

  22. Itch Catastrophizing Scale (ICS).

    Time frame: Baseline

    The ICS assesses negative and exaggerated coping concerning anticipated or experienced itchy stimuli. Thirteen items have to be answered on a 5-point Likert-type scale ranging from 0 (Not at all) to 4 (all the time).

  23. Learned Helplessness Scale (LHS)

    Time frame: Baseline

    The questionnaire consists of 20 items, and the participant's response to each item is rated on a 4-point Likert scale ranging from strongly agree (1) to strongly disagree (4).

  24. Learned Helplessness Scale (LHS)

    Time frame: 10 minutes after every induction

    The questionnaire consists of 20 items, and the participant's response to each item is rated on a 4-point Likert scale ranging from strongly agree (1) to strongly disagree (4).

  25. Pain Catastrophizing Scale (PCS).

    Time frame: 10 minutes after induction

    The PCS assesses negative and exaggerated coping concerning anticipated or experienced painful stimuli. Thirteen items have to be answered on a 5-point Likert-type scale ranging from 0 (Not at all) to 4 (all the time).

  26. Itch Catastrophizing Scale (ICS).

    Time frame: 10 minutes after induction

    The ICS assesses negative and exaggerated coping concerning anticipated or experienced itchy stimuli. Thirteen items have to be answered on a 5-point Likert-type scale ranging from 0 (Not at all) to 4 (all the time).

  27. Depression, Anxiety, Stress Scale (DASS-21)

    Time frame: Baseline

    The questionnaire measures the magnitude of depression, anxiety, and stress. Each of these three subscales consists of 7 questions answered using a 0-3 Likert scale, with 0 meaning "it did not apply to me", and 3 meaning "it applied to me very much"

  28. Reinforcement Sensitivity Theory - Personality Questionnaire (RST-PQ).

    Time frame: Baseline

    The RST-PQ contains in total, 65 items must be answered on a 4-point Likert-type scale

  29. Difficulties in Emotion Regulation Scale Short Form (DERS-SF)

    Time frame: Baseline

    The questionnaire is an 18-item measure used to identify emotional regulation issues in adults. Participants rate each item on a 5-point Likert scale (from 1 to 5).

  30. Emotion Regulation Questionnaire (ERQ

    Time frame: Baseline

    This questionnaire is designed to assess individual differences in the habitual use of two emotion regulation strategies: cognitive reappraisal and expressive suppression. Respondents answer each item on a 7-point Likert-type scale ranging from 1 (strongly disagree) to 7 (strongly agree), where 4 means (neutral).

Study contacts

Contact information is provided by the study sponsor or research team.

Silvia Lo Vecchio

CONTACT

[email protected]

+4521397785

Sponsors and collaborators

Lead sponsor

Aalborg University

Other

Registry information

Official study title

Pain and Itch Neuromodulation: Effects of Offset Analgesia, Placebo, and Nocebo and Topographical Distribution of Itch and Pain Receptors

Important dates

Study start
2025
Primary completion
2026
Study completion
2028
First posted
Aug 14, 2025
Registry last updated
Oct 1, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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