Itch Sensation Induced by Multiple Applications of Pruritogens (temporal Summation)

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

In This experiment, the investigators would like to design a new itch model based on the temporal summation of pruritic stimuli. The hypothesis behind this study (temporal summation) is that two overlapped applications of pruritogens will result in a higher itch sensation compared with a single application.

Study Overview

• Status: Recruiting
• Conditions: Histamine; Cowhage
• Intervention / Treatment: Other: Cowhage; Other: Histamine

Detailed 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 the multiple applications of pruritogens (temporal summation). In particular, the purpose is to evaluate if a single application of cowhage/histamine (non-histaminergic and histaminergic itch, respectively) results in a lower itch sensation compared with two overlapped applications of the pruritogens on the same area.

• Study Type: Interventional
• Enrollment (Estimated): 26
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Silvia Lo Vecchio, PhD; Phone Number: +4521397785; Email: slv@hst.aau.dk
• Study Contact Backup: Name: Giulia Erica Aliotta, PhD; Phone Number: 50290580; Email: gea@hst.aau.dk

Study Locations

• Denmark
  • Aalborg, Denmark, 9260
    • Recruiting
    • Aalborg University
    • Contact: Silvia Lo Vecchio, PhD
    • Contact: Silvia Lo Vecchio, PhD; Phone Number: 0045+21397785; 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 Englis

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: Randomized
• Interventional Model: Single Group Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 1st pruritogen; The subproject is conducted in 1 session (approx. 3 hours in total) divided into two parts. In the first part, 3 test areas (3x3 cm) will be selected on one forearm of the subject. The 3 areas will be randomly treated with 1 application of cowhage, 2 applications of cowhage (the second application will be conducted 90 seconds after the first one in the same area), and 2 applications of cowhage (the second application will be conducted 180 seconds after the first one in the same area). Itch will be monitored using a VAS (visual analog scale) for 15 min in each session. After the removal of cowhage, FLPI, alloknesis, and mechanically evoked itch will be measured.	Other: Histamine; Histaminergic itch will be evoked by a 1% histamine solution. A droplet of histamine solution will be placed on the predetermined area on the forearm, and the SPT lancet will be pierced through the histamine.
Experimental: 2nd pruritogen; The second part will be conducted 20 minutes after the first part, and the procedure will be the same, but using histamine instead of cowhage. The two parts will be randomized between subjects.	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	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 after every itch inductions
Assessment of pain	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 after every itch inductions

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Microvascular reactivity	The evoked cutaneous inflammation (quantified by superficial blood perfusion) will be measured by full-field laser perfusion imaging.	10 minutes after every itch inductions
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 after every itch inductions
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 after every itch inductions

Collaborators and Investigators

• Sponsor: Aalborg University

Study record dates

Study Major Dates

• Study Start (Actual): November 1, 2024
• Primary Completion (Estimated): December 31, 2025
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: March 19, 2024
• First Submitted That Met QC Criteria: March 22, 2024
• First Posted (Actual): March 25, 2024

Study Record Updates

• Last Update Posted (Estimated): November 22, 2024
• Last Update Submitted That Met QC Criteria: November 20, 2024
• Last Verified: November 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Histamine Agents; Neurotransmitter Agents; Histamine Agonists; Histamine
• Other Study ID Numbers: N-20210046 4th project

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No