Clinical trial NCT04515056: Characterization of New Human Models of Non-histaminergic Itch
Official title: Characterization of New Human Models of Non-histaminergic Itch and Their Interaction With the TRPM8 Receptor
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Papain
Itch
Skin Prick Test (SPT)
Lead sponsor: Aalborg University
Sponsor class: OTHER
First posted: 2020-08-17
Enrollment: 20
Sex: ALL
Minimum age (years): 18
Maximum age (years): 60
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: SINGLE_GROUP
Primary purpose: BASIC_SCIENCE

Brief summary: In this experiment the investigators would like to test a new new human itch model based on papain, and to characterize the sensory quality and temporary aspects of papain skin prick test (SPT) in comparison to the inactivated-cowhage delivery system.

Detailed description: The most used model of non-histaminergic itch is cowhage but this models presents several problems, such us the impossibility of standardizing the amount of the spicules inserted in the skin and the difficulty of obtaining the substance. These aspects bring us the necessity to find a new and more standardized model of non-histaminergic itch.

Papain is a cysteine protease extracted from papaya plant that is known to cause itch if applied to the skin. For these reasons the investigators would like to test a new new human itch model based on papain, and to characterize the sensory quality and temporary aspects of papain skin prick test (SPT) in comparison to the inactivated-cowhage delivery system.

Eligibility criteria: 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, dermatological, immunological musculoskeletal, cardiac disorder or mental illnesses that may affect the results (e.g. neuropathy, muscular pain in the upper extremities, etc.).
* 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
* Moles, scars or tattoos in the area to be treated or tested.
* Hypersensitivity to papaya and mango fruit, cashew nuts, rubber latex
* Consumption of alcohol or painkillers 24 hours before the study days and between these
* Acute or chronic pain
* Participation in other trials within 1 week of study entry (4 weeks in the case of pharmaceutical trials)

Primary outcomes:
measure: Superficial blood perfusion
timeFrame: 15 minutes
measure: Measuring itch intensity by computerized Visual Analog Scale Scoring
timeFrame: 15 minutes
measure: Measuring pain intensity by computerized Visual Analog Scale Scoring
timeFrame: 15 minutes
measure: Measuring Alloknesis
timeFrame: 15 minutes
Secondary outcomes:
measure: Measurement of Cold Detection Thresholds (CDT)
timeFrame: 15 minutes
measure: Measurement of Cold Pain Thresholds (CPT)
timeFrame: 15 minutes
measure: Measurement of Warm Detection Thresholds (WDT)
timeFrame: 15 minutes
measure: Measurement of Heat Pain Thresholds (HPT)
timeFrame: 15 minutes
measure: Measurement of Pain to Supra-threshold Heat Stimuli
timeFrame: 15 minutes
measure: Measurement of Mechanical Pain Thresholds (MPT)
timeFrame: 15 minutes
measure: Measurement of Mechanical Pain Sensitivity (MPS)
timeFrame: 15 minutes
measure: Touch Pleasantness (TP)
timeFrame: 15 minutes
Other outcomes:
Locations:
city: Aalborg
country: Denmark
facility: Aalborg University
state: Nordjylland
Study officials:
affiliation: Aallborg University
name: Silvia Lo Vecchio
role: PRINCIPAL_INVESTIGATOR
References: