A Mechanistic Evaluation of the Nociceptive Desensitizing Properties of Topical Capsaicin
- Conditions
- LidocaineCapsaicinUltaviolet B Light BurnNeuropathic Pain
- Interventions
- Registration Number
- NCT03587220
- Lead Sponsor
- Aalborg University
- Brief Summary
The aim of this project is to study the role of transient receptor potential (TRP-) channel V1 (TRPV1+) fibers in the development of cutaneous inflammation induced by epidermal Ultraviolet-B damage. Moreover, in this project the investigators want to evaluate if the capsaicin-desensitization action can still be induced in a skin area pretreated with topical, local anesthetic lidocaine.
- Detailed Description
In this project the Ultraviolet- B pain model, a model using type B ultraviolet rays to induce a first-degree sunburn, will be used to induce a non-specific inflammation in the skin. This model is well-known to produce both peripheral and central hyperalgesia through sensitization of peripheral and central nociceptors. Capsaicin, the active substance in chili peppers, is currently used to treat peripheral neuropathic pain, and prolonged application of 8% capsaicin patch causes profound desensitization to painful heat stimuli and itch provocations. Therefore, the investigators would like to monitor the development of unspecific UVB-cutaneous inflammation and consequent neurogenic flare in a capsaicin pre-treated area. Moreover the investigators want to test if pre-treating the skin with lidocaine can reduce the pain associated with the capsaicin application without affecting its desensitization action.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 44
Not provided
Not provided
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description Capsaicin + EMLA group Capsaicin Topical All subjects will be pre-treated with lidocain cream before capsaicin application Capsaicin + EMLA group Histamine 1% All subjects will be pre-treated with lidocain cream before capsaicin application Capsaicin+UVB group Capsaicin Topical All subjects will be treated with capsaicin, placebo + UVB, or Capsaicin+UVB. Capsaicin+UVB group Ultraviolet-B (UVB) irradiation All subjects will be treated with capsaicin, placebo + UVB, or Capsaicin+UVB. Capsaicin + EMLA group Lidocaine All subjects will be pre-treated with lidocain cream before capsaicin application
- Primary Outcome Measures
Name Time Method Superficial blood perfusion measured by a Speckle contrast imager (FLPI, Moor Instruments, England). Changes from baseline to 7 days after intervention Measurement of Warm Detection Thresholds and Heat thresholds by using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. Changes from baseline to 7 days after intervention Measurement of Pain to Supra-threshold Heat Stimuli by using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. Changes from baseline to 7 days after intervention Measurement of Mechanical Pain Thresholds and Sensitivity using a pin-prick set consisting 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. Changes from baseline to 7 days after intervention Trans-epidermal Water Loss (TEWL) using a 2x2 cm probe to measure the humidity gradient of the skin. Changes from baseline to 7 days after intervention
- Secondary Outcome Measures
Name Time Method assessment of pain rating by using a visual analog scales (VAS) Change from baseline to 24 h The subject will report the peak and average of the perceived pain sensation during the last 24 hours (on a VAs scale from 0 indicating 'no pain' to100 indicating 'worst imaginable pain').
Itch rating by using a visual analog scales (VAS) Changes from baseline to 7 days after intervention Itch is monitored for 9 minutes using a visual analog scale from 0 indicating 'no itch' to100 indicating 'worst imaginable itch.
Trial Locations
- Locations (1)
Silvia Lo Vecchio
🇩🇰Aalborg, Nordjylland, Denmark