Itch, Lidocaine
Conditions
Brief summary
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).
Interventions
DRUGEMLA (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.
Sponsors
Aalborg University
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Masking description
The participant are blind about the location of EMLA and placebo application
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
Yes
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Pain to Supra-threshold Heat Stimuli | Change from baseline, up to three days after the first session | The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device |
| Superficial blood perfusion | Change from baseline, up to three days after the first session | is measured by a Speckle contrast imager (FLPI, Moor Instruments, England). |
| Warm Detection Thresholds and Heat Pain Thresholds | Change from baseline, up to three days after the first session | The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device |
| Pain rating | only on day 3 (third session) | 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'. |
| Alloknesis | Change from baseline, up to three days after the first session | Alloknesis is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force). |
| Mechanical Pain Thresholds and Sensitivity | Change from baseline, up to three days after the first session | 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 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Itch rating | only on day 3 (third session) | 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'. |
Countries
Denmark
Outcome results
None listed