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

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.

Study Overview

• Status: Recruiting
• Conditions: Pain, Burning; Capsaicin
• Intervention / Treatment: Other: Cowhage

Detailed 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.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Denmark
  • Aalborg, Denmark, 9220
    • Recruiting
    • Aalborg University
    • Contact: Silvia Lo Vecchio; Phone Number: +4521397785; Email: slv@hst.aau.dk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Pain; 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.	Other: Cowhage; 25 spicules will be inserted in the center of the predefined skin area on the mandibular area. The spicules will be gently rubbed for 15-20 seconds in circular motion to facilitate epidermal penetration.
Experimental: Capsaicin; 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.	Other: Cowhage; 25 spicules will be inserted in the center of the predefined skin area on the mandibular area. The spicules will be gently rubbed for 15-20 seconds in circular motion to facilitate epidermal penetration.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Assessment of itch intensity using a VAS scale	Immediately following the itch provocations, participants will be instructed to rate the itch intensity for 10 minutes using a digital visual analogue scale (VAS; eVAS Software: Aalborg, University, Denmark), on a tablet. The scale will be measured from 0 to 100, where 0 represents 'no itch' and 100 'worst itch imaginable'.	1 minute post itch provocation
Assessment of pain intensity using a VAS scale	Immediately following the itch provocations, participants will be instructed to rate the pain intensity for 10 minutes using a digital visual analogue scale (VAS; eVAS Software: Aalborg, University, Denmark), on a tablet. The scale will be measured from 0 to 100, where 0 represents 'no pain' and 100 'worst pain imaginable'.	1 minute post itch provocation
Retrospective rating of the pain perceived on a NRS	After 10 minutes of pruritogens application, a retrospective rating of the pain perceived from the thermal pain/capsaicin will be provided by the subject using a numeral rating scale (NRS)	10 minutes post itch provocation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Alloknesis	Alloknesis sensation is measured using a standardized sensory brush (SENSELab Brush-05, Somedic AB, Hörby, Sweden) exerting a force of 200 to 400 mN.	12 minutes post itch provocation
Mechanically evoked itch	Mechanically evoked itch is measured using three von Frey filaments of 4.08, 4.16 and 4.31 (1.0, 1.4, 2.0 g, respectively) (North Coast Medical, Gilroy, CA). The center of the skin area is stimulated by 3 pricks, repeated 3 times in short succession. After a total of 9 stimulations, the participants will report the itch elicited on a numerical rating scale (NRS) from 0 to 10 (0 = "no itch"; 10 = "worst imaginable itch").	15 minutes post itch provocation

Collaborators and Investigators

• Sponsor: Aalborg University

Study record dates

Study Major Dates

• Study Start (Actual): December 15, 2023
• Primary Completion (Estimated): December 31, 2024
• Study Completion (Estimated): June 30, 2025

Study Registration Dates

• First Submitted: November 20, 2023
• First Submitted That Met QC Criteria: December 14, 2023
• First Posted (Actual): December 29, 2023

Study Record Updates

• Last Update Posted (Actual): December 29, 2023
• Last Update Submitted That Met QC Criteria: December 14, 2023
• Last Verified: December 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neurologic Manifestations; Pain
• Other Study ID Numbers: N-20210046 2nd project

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No