Itch Sensation Induced by Multiple Applications of Pruritogens (temporal Summation)

Repetitive Applications of Pruritogens and Effects of a Cutaneous-induced Pain Stimulation on Nonhistaminergic Itch Perception

In This experiment, the investigators would like to design a new itch model based on the temporal summation of pruritic stimuli. The hypothesis behind this study (temporal summation) is that two overlapped applications of pruritogens will result in a higher itch sensation compared with a single application.

Chronic itch affects approximately a fifth of the global population and is associated with substantial negative consequences for the affected individuals. Furthermore, there is a lack of efficient treatment options for chronic itch. In order to mimic a clinical itch condition as presented in patients, the aim of the project is to investigate a new itch model based on the multiple applications of pruritogens (temporal summation). In particular, the purpose is to evaluate if a single application of cowhage/histamine (non-histaminergic and histaminergic itch, respectively) results in a lower itch sensation compared with two overlapped applications of the pruritogens on the same area.

Inclusion Criteria:

• Healthy men and women
• 18-60 years
• Speak and understand Englis

Exclusion Criteria:

• Pregnancy or lactation
• Drug addiction defined as any use of cannabis, opioids, or other addictive drugs
• Previous or current history of neurological (e.g. neuropathy), immunological (e.g. asthma, immune deficiencies, arthritis), musculoskeletal (e.g. muscular pain in the upper extremities,), cardiac disorder, or mental illnesses that may affect the results
• Lack of ability to cooperate
• Current use of medications that may affect the trial such as antihistamines, antipsychotics, and pain killers, as well as systemic or topical steroids
• Skin diseases (e.g. atopic dermatitis, pruritus nodularis, eczema, psoriasis)
• Moles, scars, or tattoos in the area to be treated or tested.
• Consumption of alcohol or painkillers 24 hours before the study days and between these
• Acute or chronic pain
• Participation in other trials within one week of study entry (four weeks in the case of pharmaceutical trials)