Histamine: To deliver histamine, standard allergy skin prick test (SPT) lancets are applied
Cowhage: 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: Capsaicin patches (dosage form: transdermal patch 8% Qutenza, Astellas) will be applied on 3 squared areas in the face.
Demo patch: 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.
Study 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.
Eligibility
Sex
ALL
Min age
18 Years
Max age
60 Years
Healthy volunteers
Accepted
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
Primary outcome measure(s)
Measuring pain by computerized Visual Analog Scale Scoring — 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".
Measuring itch by computerized Visual Analog Scale Scoring — 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".
Measuring pain by computerized Visual Analog Scale Scoring — 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".
Measuring itch by computerized Visual Analog Scale Scoring — 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".
This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.
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