Evaluation of the Effect Induced by Repeated Administration of Topical Local Anaesthetic (EMLA) on Itch

A Mechanistic Evaluation of the Nociceptive Desensitization Induced by Repeated Administration of Topical Local Anaesthetic Mixture of Lidocaine and Prilocaine (EMLA) in a Model of Histaminergic and Non-histaminergic Itch.

In this experiment, the investigators would like to study if the repeated application of local cuaneous anaesthetic EMLA cream will reduce itch induced by small needles from the plant mucuna pruriens (also known as cowhage) and histamine (an itch proving substance formed in the body).

Study Overview

• Status: Completed
• Conditions: Itch; Lidocaine
• Intervention / Treatment: Drug: EMLA (lidocaine) +Itch (Histamine and cowhage)

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

Contacts and Locations

Study Locations

• Denmark
  • Nordjylland
    • Aalborg, Nordjylland, Denmark, 92200
      • Aalborg University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 60 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

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 drugs
• Previous or current neurologic, musculoskeletal or mental illnesses
• Lack of ability to cooperate
• Current use of medications that may affect the trial
• Skin diseases
• 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)
• Known history of anaphylactic shock, or local allergy (contact dermatitis) to lidocaine, prilocaine or other local anaesthetics of the amide type.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: EMLA

Drug: EMLA (lidocaine) +Itch (Histamine and cowhage); Cutaneous anaesthesia: will be topically induced by using EMLA cream 5%, a local anaesthetic cream consisting of equal parts of lidocaine and prilocaine (1g contains 25 mg of lidocaine and 25 mg of prilocaine, AstraZeneca A/S, Albertslund, Denmark). Histamine: To deliver histamine, standard allergy skin prick test (SPT) lancets are applied. Cowhage: Cowhage spicules are 1-2 mm in length and have diameter of 1-3 um at their tip, once inserted into the epidermis, the spicules evoke a moderate sensation of itch and to a lesser extent sensations of burning and stinging pain.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Superficial blood perfusion	is measured by a Speckle contrast imager (FLPI, Moor Instruments, England).	Change from baseline, up to three days after the first session
Warm Detection Thresholds and Heat Pain Thresholds	The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device	Change from baseline, up to three days after the first session
Pain to Supra-threshold Heat Stimuli	The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device	Change from baseline, up to three days after the first session
Alloknesis	Alloknesis is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force).	Change from baseline, up to three days after the first session
Mechanical Pain Thresholds and Sensitivity	This test is performed using a pin-prick set (Aalborg University, Aalborg). The set consists of 8 needles each having a diameter of 0.6 mm and different force applications: 0.8, 1.6, 3.2, 6.4, 12.8, 25.6, 50.1 and 60.0 g	Change from baseline, up to three days after the first session
Pain rating	The subject will rate the pain for 9 min by using a a visual analog scale (VAS) on a tablet. This scale goes from 0 to 100. 0 indicates 'no pain' and 100 indicates 'worst imaginable pain'.	only on day 3 (third session)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Itch rating	The subject will rate the itch for 9 min by using a a visual analog scale (VAS) on a tablet. This scale goes from 0 to 100. 0 indicates 'no itch' and 100 indicated 'worst imaginable itch'.	only on day 3 (third session)

Collaborators and Investigators

• Sponsor: Aalborg University
• Investigators: Principal Investigator: Silvia lo Vecchio, Aalborg University

Study record dates

Study Major Dates

• Study Start (Actual): October 15, 2019
• Primary Completion (Actual): October 1, 2020
• Study Completion (Actual): January 1, 2021

Study Registration Dates

• First Submitted: August 30, 2019
• First Submitted That Met QC Criteria: August 30, 2019
• First Posted (Actual): September 3, 2019

Study Record Updates

• Last Update Posted (Actual): January 15, 2021
• Last Update Submitted That Met QC Criteria: January 13, 2021
• Last Verified: January 1, 2021

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Anti-Arrhythmia Agents; Central Nervous System Depressants; Peripheral Nervous System Agents; Sensory System Agents; Anesthetics; Membrane Transport Modulators; Anesthetics, Local; Voltage-Gated Sodium Channel Blockers; Sodium Channel Blockers; Histamine Agents; Histamine Agonists; Lidocaine; Histamine
• Other Study ID Numbers: N-20190043

Drug and device information, study documents

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