Itch
Conditions
Brief summary
The aim of our 2nd sub-project is to clarify if the capsaicin receptor TRPV1 is implicated in the mechanism of morphine-induced mast cell degranulation. Moreover, we also aim to clarify if the mechanism of opioid-induced itch relay on the histaminergic pathway by using the antihistamine (diphenhydramine) to suppress the release of histamine from peripheral mast cells.
Interventions
DRUGCapsaicin
A capsaicin patch will be applied on a 3x3 cm squared area on the volar forearm. The patch will be left in place for 24h after which it will be removed.
DRUGDiphenhydramine
Diphenhydramin cream 1% (Restamine®) will be applied on a 3x3 cm squared predetermined area on the volar forearm for 24 hours.
Morphine solution (0.1mg/ml, Morphine Hydrochloride) 50 μl will be applied intradermally to the center of a predetermined area on the volar forearm by a 1 ml syringe.
DRUGIsotonic saline
injections of isotonic saline (0.05 ml, 0.9%) as vehicle will be performed.
DRUGHistamine
A small drop of histamine dihydrochloride (1%, in saline) will be applied to a previously determined area on the volar forearm followed by a prick through the drop.
Sponsors
Aalborg University
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
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
* Participants with any clinically significant abnormalities that in the opinion of the investigator may increase the risk associated with trial participation or may interfere with the interpretation of the trial results. * Pregnancy or lactation * Drug addiction defined as any use of cannabis, opioids or other addictive drugs * 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. * Participants with known allergy/discomfort to the opioid morphine and antihistamine. * Skin diseases * 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 1 week of study entry (4 weeks in the case of pharmaceutical trials)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Measuring itch intensity by computerized Visual Analog Scale Scoring | For 10 minutes | We will ask the subjects to 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. |
| Measuring pain intensity by computerized Visual Analog Scale Scoring | For 10 minutes | We will ask the subjects to 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. |
| Superficial blood perfusion measurement | After 15 minutes | Superficial blood perfusion is measured by a Speckle contrast imager |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| While size | After 15 minutes | While size will be assessed using a ruler |
Countries
Denmark
Outcome results
None listed