NCT03132142

Desensitization of Nociceptive Afferents by Application of Topical Capsaicin, Trans-cinnamaldehyde and L-menthol

Temporal Profile of the Nociceptive Desensitization Induced by 8% Topical Capsaicin and the Functional Independence of Transient Receptor Potential Ankyrin 1 (TPRA1)- and Vanilloid 1 (TRPV1)-Expressing Nociceptive Afferents

• Status: Unknown
• Phase: N/A
• Study type: Interventional
• Enrollment: 22 (estimated)
• Sponsor: Aalborg University · Academic / Other
• Sex: All
• Age: 18 Years – 60 Years
• Healthy volunteers: Accepted

Summary

The purpose of this study is to investigate the potential desensitising effects of repeated applications of capsaicin, trans-cinnamaldehyde and L-menthol on thermal, mechanical and chemical sensory stimulations.

Detailed description

Capsaicin, the compound responsible for the pungency of chili peppers, can induce desensitization to nociceptive (1) and pruriceptive (2) stimuli when topically applied. The purpose of this study is to determine whether repeated topical applications of trans-cinnamaldehyde and L-menthol result in decreased responses to various nociceptive and non-nociceptive thermal and mechanical stimuli and to compare potential alterations with those caused by repeated topical application of capsaicin. Furthermore, this study investigates the temporal profile of said alterations. Capsaicin 8% patches, trans-cinnamaldehyde 10%, L-menthol 40% and inert vehicle patches will each be applied to 4 4x4 cm predefined areas on the skin of the volar forearms for 1 hour 4 times on 4 consecutive days. Before each application and the day after the last application, cold detection threshold (CDT), warmth detection threshold (WDT), cold pain threshold (CPT) and heat pain threshold (HPT) will be assessed using a Medoc Pathway (Medoc, Israel) equipped with a 3x3 cm contact thermode. On the last day, mechanical detection threshold (MDT) is assessed using a series of von Frey filaments and mechanical pain threshold (MPT) and mechanical pain sensitivity (MPS) is assessed using a series of standardized pinprick stimulators (Aalborg University). Furthermore, full-field laser perfusion imaging (FLPI) will be used to assess the degree of neurogenic inflammation in each predefined area before and after each substance application and at the last session. 1. F. Henrich et al. 2015 "Capsaicin-sensitive C- and A-fibre nociceptors control long-term potentiation-like pain amplification in humans" 2. H.H. Andersen et al. 2017 "Antipruritic effect of pretreatment with 8% topical capsaicin on histamine- and cowhage-evoked itch in healthy volunteers - a randomized placebo-blinded proof-of-concept trial"

Conditions

• Pain
• Pruritus
• Neuropathic Pain
• Dermatology/Skin - Other

Interventions

Type	Name	Description
DRUG	Capsaicin	4x4 cm patch of 8% topical capsaicin applied to the skin of the volar forearm for 1 hour 4 times on 4 consecutive days
DRUG	Trans-cinnamaldehyde	1mL of 10% trans-cinnamaldehyde applied to the skin of the volar forearm for 1 hour 4 times on 4 consecutive days
DRUG	L-Menthol	1mL of 40% L-menthol applied to the skin of the volar forearm for 1 hour 4 times on 4 consecutive days
DRUG	Vehicle patch	Inert vehicle patch applied to the skin of the volar forearm for 1 hour 4 times on 4 consecutive days

Timeline

• Start date: 2017-04-01
• Primary completion: 2017-08-01
• Completion: 2017-08-01
• First posted: 2017-04-27
• Last updated: 2017-04-27

Locations

1 site across 1 country: Denmark