Characterization of New Human Models of Non-histaminergic Itch

NCT04515056 | Completed DMC

• 1 other identifier: N-20200005
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

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.

Conditions

Papain; Itch; Skin Prick Test (SPT)

Outcome Measures

Primary Outcomes (4)

• Superficial blood perfusion

  Superficial blood perfusion is measured by a Speckle contrast imager (FLPI, Moor Instruments, England).

  15 minutes

• Measuring itch intensity by computerized Visual Analog Scale Scoring

  The subjects will 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" and similarly for sensations of stinging/pricking and burning, both of which are frequently associated with the sensation of itch.

  15 minutes

• Measuring pain intensity by computerized Visual Analog Scale Scoring

  The subjects will 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".

  15 minutes

• Measuring Alloknesis

  Alloknesis is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 milliNewton of force). This stimulator is applied 0.5 cm outside the area of itch provocation.

  15 minutes

Secondary Outcomes (8)

• Measurement of Cold Detection Thresholds (CDT)

  15 minutes

• Measurement of Cold Pain Thresholds (CPT)

  15 minutes

• Measurement of Warm Detection Thresholds (WDT)

  15 minutes

• Measurement of Heat Pain Thresholds (HPT)

  15 minutes

• Measurement of Pain to Supra-threshold Heat Stimuli

  15 minutes

Study Arms (2)

Papain dosage

EXPERIMENTAL

In the 1st session, each of the middle forearms of the subject will be divided into two squared areas (4x4 cm). The two areas will be located 4 cm apart. Three areas will be exposed to 10, 50 or 100 µg of papain, while the last area will be used as control (exposed to a vehicle).

Drug: Papain 10 µg; Drug: Papain 50 µg; Drug: Papain 100 µg; Other: Vehicle

Papain SPT

EXPERIMENTAL

Each forearm of the subject will be divided into two squared areas (4x4 cm). The provocations of three areas will be performed with 100 µg of papain by SPT lancets. To assess the potential importance of repeated pricks, papain will be applied by 1, 5 or 25 SPT pricks thought the skin. The last area will be exposed to cowage spicules (made chemically inert by autoclaving) soaked in 5 mg/ml papain solution.

Drug: Papain 1 SPT; Drug: Papain 5 SPT; Drug: Papain 25 SPT; Other: Cowhage

Interventions

Papain 10 µg DRUG

The area will be exposed to 10 µg of papain.

Papain dosage

Papain 50 µg DRUG

The area will be exposed to 50 µg of papain.

Papain dosage

Papain 100 µg DRUG

The area will be exposed to 100 µg of papain.

Papain dosage

Vehicle OTHER

The area will be exposed to vehicle

Papain dosage

Papain 1 SPT DRUG

Papain will be applied by 1 SPT prick thought the skin

Papain SPT

Papain 5 SPT DRUG

Papain will be applied by 5 SPT pricks thought the skin

Papain SPT

Papain 25 SPT DRUG

Papain will be applied by 25 SPT pricks thought the skin

Papain SPT

Cowhage OTHER

The last area will be exposed to cowage spicules (made chemically inert by autoclaving) soaked in 5 mg/ml papain solution.

Papain SPT

Eligibility Criteria

• Age: 18 Years - 60 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy men and women
• years
• Speak and understand English

You may not qualify if:

• 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)

Sponsors & Collaborators

• Aalborg University: lead

Study Sites (1)

Aalborg University

Aalborg, North Denmark, 9000, Denmark

Location

MeSH Terms

Conditions

Pruritus

Interventions

Papain

Condition Hierarchy (Ancestors)

Skin Diseases; Skin and Connective Tissue Diseases; Skin Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Cysteine Endopeptidases; Cysteine Proteases; Peptide Hydrolases; Hydrolases; Enzymes; Enzymes and Coenzymes; Endopeptidases

Study Officials

• Silvia Lo Vecchio

  Aallborg University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: PhD, Assistant Professor

Study Record Dates

• First Submitted: August 13, 2020
• First Posted: August 17, 2020
• Study Start: September 1, 2020
• Primary Completion: June 1, 2021
• Study Completion: June 1, 2021
• Last Updated: July 9, 2021

Record last verified: 2021-07

Locations

DK (1)