A Mechanistic Evaluation of the Nociceptive Desensitizing Properties of Topical Capsaicin

Neuropathic Pain Clinical Trial

Official title:

En undersøgelse af Mekanismerne Bag Nociceptiv Desensibilisering forårsaget af Topikal Capsaicin

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT03587220
• Other study ID #: N-20180034
• Status: Completed
• Phase: N/A
• Start date: August 1, 2018
• Est. completion date: December 31, 2019

Study information

• Verified date: April 2020
• Source: Aalborg University
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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.

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 information / eligibility

• Status: Completed
• Enrollment: 44
• Est. completion date: December 31, 2019
• Est. primary completion date: August 31, 2019
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 60 Years

Eligibility

Inclusion criteria:

• Healthy men and women

• 18-60 years

• Caucasian descent (only in sub-study 1)

• 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

• Moles or tattoos in the area to be treated or tested.

• Exposure of the irradiated area to UV radiation (e.g., sun) 48 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.

Related Conditions & MeSH terms

• Capsaicin
• Lidocaine
• Neuralgia
• Neuropathic Pain
• Ultaviolet B Light Burn

Intervention

Drug:
• Capsaicin Topical
Capsaicin patches (dosage form: patch 8% Qutenza) will be applied on 4x4 cm squared areas on the volar forearm. The patches will be left in place for 24h and 3 hours after which they will be removed.

Radiation:
• Ultraviolet-B (UVB) irradiation
Two circular areas (Ø 2 cm) on the forearm are irradiated with 2 x MED (Minimal Erythema Dose) dose of UVB using a calibrated UVB machine (290-320nm wavelength), Saal Mann Multi Tester (Mann Saal, LT SBC 400 Herford, Germany).

Other:
• Histamine 1%
To deliver histamine, standard allergy skin prick test (SPT) lancets are applied. The lancets have a 1 mm shouldered tip adapt to introduce a small amount of test substance extremely locally and approximately at the dermo-epidermal junction.

Drug:
• Lidocaine
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)

Locations

Country	Name	City	State
Denmark	Silvia Lo Vecchio	Aalborg	Nordjylland

Sponsors (1)

Lead Sponsor	Collaborator
Aalborg University

Country where clinical trial is conducted

Denmark, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Superficial blood perfusion measured by a Speckle contrast imager (FLPI, Moor Instruments, England).		Changes from baseline to 7 days after intervention
Primary	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
Primary	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
Primary	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
Primary	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	assessment of pain rating by using a visual analog scales (VAS)	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').	Change from baseline to 24 h
Secondary	Itch rating by using a visual analog scales (VAS)	Itch is monitored for 9 minutes using a visual analog scale from 0 indicating 'no itch' to100 indicating 'worst imaginable itch.	Changes from baseline to 7 days after intervention