Clinical trial NCT02570841: Pain Thresholds Under High-dose Topical Capsaicin
Official title: Heat-, Cold-, and Mechanical Pain Thresholds Under Exposition of High Dose Topical Capsaicin
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE4
Conditions: Pain
Keywords: Heat pain threshold
Cold pain threshold
Mechanical pain threshold
High dose Capsaicin
Lead sponsor: Medical University of Vienna
Sponsor class: OTHER
Collaborators: name: Astellas Pharma GmbH
First posted: 2015-10-07
Enrollment: 20
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: PREVENTION

Brief summary: Aim of the study is to determine heat pain thresholds (HPT in °C) and cold pain thresholds (CPT in °C) during topical capsaicin 8% application, and mechanical pain thresholds (MPT in g) immediately after to find out the exact skin temperature by which capsaicin initiates the application pain (heat pain threshold, HPT in °C) but also the temperature by which capsaicin does not yet trigger a cold pain (cold pain threshold, CPT in °C). Moreover the investigators want to find out the mechanical pain threshold in g from topical capsaicin and to verify a prolonged effect of capsaicin on the pain thresholds.

Detailed description: Capsaicin is the main pungent ingredient in chili peppers. Topical capsaicin 8% is used for the treatment of peripheral neuropathic pain. Application of capsaicin 8% provokes distinct pain by activating the transient receptor potential vanilloid 1 (TRPV1) receptor. Cooling the skin results in a reliable prevention of the application pain. However, the necessary cooling temperature and if cooling itself produces application pain, is unknown.

Materials and Methods: 10 female and 10 male healthy volunteers will be enrolled in a randomised, double blind, placebo controlled, cross-over study. The left or right forearm of each subject is going to be treated with a capsaicin 8% patch (QUTENZA, Astellas Pharma, Tokyo, Japan) of 9 cm² or a placebo patch (Demo patch, Astellas Pharma, Tokyo, Japan) of the same size for 60 min. Then the other forearm (which has not been tested before) will be treated with the remaining patch. During capsaicin and placebo exposure HPT in °C and CPT in °C are going to be obtained by the thermode of a thermal sensory analyser, TSA-II (Medoc Ltd., Ramat Yishai, Israel). Temperature increase/decrease of the thermode will be stopped, as soon as the subject presses a switch because of a beginning pain sensation. Immediately after exposure a pin prick test will be performed 5 times in a row by pressing a Mini-Spike (B. Braun Melsungen AG, Melsungen, Germany) slowly against the skin of the application areal to determine the pressure necessary to provoke a sharp pain (Mechanical pain threshold in g). 2 weeks later HPT, CPT, and MPT will be determined again in the areas of capsaicin and placebo exhibition.

Eligibility criteria: Inclusion Criteria:

* healthy volunteers 18 ore more years old

Exclusion Criteria:

* dermatologic or neurologic injuries on both thighs, (possible) pregnancy

Primary outcomes:
measure: Heat pain threshold (HPT) in degrees Celsius (°C)
timeFrame: 60 minutes during topical highdose Capsaicin/Placebo exposure
Secondary outcomes:
measure: Cold pain threshold (CPT) in degrees Celsius (°C)
timeFrame: 60 minutes during topical highdose Capsaicin/Placebo exposure
measure: Mechanical pain threshold (MPT) in grams (g)
timeFrame: Immediately after topical highdose Capsaicin/Placebo exposure
measure: HPT in degrees Celsius (°C)
timeFrame: 2 weeks after exposure
measure: CPT in degrees Celsius (°C)
timeFrame: 2 weeks after exposure
measure: MPT in grams (g)
timeFrame: 2 weeks after exposure
Other outcomes:
Locations:
city: Vienna
country: Austria
facility: Department of Anesthesia, Critical Care and Pain Medicine
Study officials:
affiliation: Department of Anesthesia, Critical Care and Pain Medicine
name: Erich Knolle, MD
role: PRINCIPAL_INVESTIGATOR
References: