A Mechanistic Evaluation of the Nociceptive Desensitizing Properties of Topical Capsaicin

NCT ID: NCT03587220

Last Updated: 2020-04-20

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 44 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2018-08-01
• Study Completion Date: 2019-12-31

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.

Conditions

Capsaicin; Ultaviolet B Light Burn; Neuropathic Pain; Lidocaine

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: SINGLE

Study Groups

Capsaicin+UVB group

All subjects will be treated with capsaicin, placebo + UVB, or Capsaicin+UVB.

Group Type: EXPERIMENTAL

Capsaicin Topical

Intervention Type: DRUG

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.

Ultraviolet-B (UVB) irradiation

Intervention Type: RADIATION

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).

Capsaicin + EMLA group

All subjects will be pre-treated with lidocain cream before capsaicin application

Group Type: EXPERIMENTAL

Capsaicin Topical

Intervention Type: DRUG

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.

Histamine 1%

Intervention Type: OTHER

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.

Lidocaine

Intervention Type: DRUG

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)

Interventions

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.

Intervention Type: DRUG

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).

Intervention Type: RADIATION

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.

Intervention Type: OTHER

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)

Intervention Type: DRUG

Eligibility Criteria

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.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Aalborg University

OTHER

Sponsor Role: lead

Responsible Party

Silvia Lo Vecchio

Biologist, PhD

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

Silvia Lo Vecchio

Aalborg, North Denmark, Denmark

Countries

Denmark

Other Identifiers

N-20180034

Identifier Type: -

Identifier Source: org_study_id