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

Capsaicin Clinical Trial

Official title:

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

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT06185582
• Other study ID #: N-20210046 2nd project
• Status: Recruiting
• Phase: N/A
• Start date: December 15, 2023
• Est. completion date: June 30, 2025

Study information

• Verified date: December 2023
• Source: Aalborg University
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

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.

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.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 30
• Est. completion date: June 30, 2025
• Est. primary completion date: December 31, 2024
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 60 Years

Eligibility

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)

Related Conditions & MeSH terms

• Capsaicin
• Pain
• Pain, Burning

Intervention

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.

Locations

Country	Name	City	State
Denmark	Aalborg University	Aalborg

Sponsors (1)

Lead Sponsor	Collaborator
Aalborg University

Country where clinical trial is conducted

Denmark, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	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
Primary	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
Primary	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	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
Secondary	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