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
试验速览
- 阶段
- 不适用
- 发起方
- 入组人数
- 22
- 试验地点
- 1
- 主要终点
- Cold Pain Threshold (CPT)
研究概览
简要总结
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.
详细描述
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.
- F. Henrich et al. 2015 "Capsaicin-sensitive C- and A-fibre nociceptors control long-term potentiation-like pain amplification in humans"
- 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"
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- Single (Participant)
入排标准
- 年龄范围
- 18 Years 至 60 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Speaks and understands English or Danish
- •18-60 years
排除标准
- •Pregnancy or lactation
- •Drug addiction
- •Previous or current dermatological, neurological, musculoskeletal or mental illnesses
- •Lack of ability to cooperate
- •Current use of medications that may affect the trial
研究组 & 干预措施
Capsaicin
Capsacin (8%) patches applied topically 4 times for 1 hour to a 4x4 cm predefined area on the skin of the volar forearms.
干预措施: Capsaicin (Drug)
Trans-cinnamaldehyde
Trans-cinnamaldehyde (10%, dissolved in 90% ethanol) applied topically 4 times for 1 hour to a 4x4 cm predefined area on the skin of the volar forearms on a cotton ball placed in a plastic chamber to limit evaporation.
干预措施: Trans-cinnamaldehyde (Drug)
L-menthol
L-menthol (40%, dissolved in 96% ethanol) applied topically 4 times for 1 hour to a 4x4 cm predefined area on the skin of the volar forearms on a cotton ball placed in a plastic chamber to limit evaporation.
干预措施: L-Menthol (Drug)
Vehicle patch
Inert vehicle patches applied topically 4 times for 1 hour to a 4x4 cm predefined area on the skin of the volar forearms.
干预措施: Vehicle patch (Drug)
结局指标
主要结局
Cold Pain Threshold (CPT)
时间窗: Assessed at 5 visits on 5 consecutive days
The pain threshold for cold stimulation assessed using a Medoc Pathway (Medoc, Israel) equipped with a 3x3 cm thermode. CPT is defined as the temperature at which cold induces pain and is expressed in °C.
Heat Pain Threshold (HPT)
时间窗: Assessed at 5 visits on 5 consecutive days
The pain threshold for heat stimulation
次要结局
- Pain During Application of Capsaicin(Assessed every 5 minutes during the 60 minute application of capsaicin at 4 visits on 4 consecutive days)
- Pain During Application of Trans-cinnamaldehyde(Assessed every 5 minutes during the 60 minute application of trans-cinnamaldehyde at 4 visits on 4 consecutive days)
- Vibration Detection Threshold(Assessed at day 5 (final visit))
- Neurogenic Inflammation Intensity(Assessed before and after application of substances at 5 visits on 5 consecutive days)
- Pain During Application of Inert Patch (Control)(Assessed every 5 minutes during the 60 minute application of the inert patch (control) at 4 visits on 4 consecutive days)
- Neurogenic Inflammation Area(Assessed before and after application of substances at 5 visits on 5 consecutive days)
- Cold Detection Threshold (CDT)(Assessed at 5 visits on 5 consecutive days)
- Pain During Application of L-menthol(Assessed every 5 minutes during the 60 minute application of L-menthol at 4 visits on 4 consecutive days)
- Warmth Detection Threshold (WDT)(Assessed at 5 visits on 5 consecutive days)
- Mechanical Detection Threshold (MDT)(Assessed at day 5 (final visit))
- Mechanical Pain Threshold (MPT)(Assessed at day 5 (final visit))
- Mechanical Pain Sensitivity (MPS)(Assessed at day 5 (final visit))
研究者
Hjalte Holm Andersen
MSc. Med., Phd. Stud.
Aalborg University