An interventional study of Ketamine 0.5% and Amitriptyline in Itch, sponsored by Aalborg University. Completed at 1 site in Denmark. Open to participants aged 18 Years to 60 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-01-30.
Sponsored by Aalborg University · Not applicable, Interventional, and Basic science
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 treat-ment options for chronic itch. Topical ketamine cream has been used successfully to relieve various forms of pain, and we hypothesize that topical ketamine relieves itch through a mechanism of action comparable to that in pain relief.
The aim of this project is to evaluate the effects of ketamine both alone and in combination with amitriptyline on histaminergic and non-histaminergic itch induced by histamine and cowhage, respectively.
The main action of ketamine, 2-(2-chlorophenyl)-2-(methylamino)-cyclohexanone, is to antagonize the glutamate N-methyl-D-aspartate (NMDA) receptors. In the clinical setting, topical ketamine cream has been used successfully to relieve various pathogenic forms of pain. In addition to its pain-relieving effects, the cream was also reported to have itch-relieving properties in a very limited study. However, its efficacy on itch has not been established, and the mechanism of action remains uncertain. Ketamine cream is used not only by itself, but also in conjunction with other analgesics. One of these is amitriptyline, which may enhance the analgesic effects of ketamine. The aim of this human experimental study is to use the well-characterized anesthetic Ketamine, both alone and in combination with amitriptyline, as a tool to modulate different histaminergic and non-histaminergic itch modalities evoked by histamine and cowhage.
Aalborg University is the lead sponsor of 178 studies on the registry; 37 are open to participants now.
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This subproject will be conducted in two sessions one week apart. Each session will last approximately 3 hours. In each forearm of the participant, two 4x4 cm areas will be selected as Area of Interest (AOI). In these selected areas, the four different creams will be applied in a randomized position for 1½ hours. After the cream removal, itch will be induced using histamine in one session and cowhage in the other session (the order of histamine and cowhage will be randomized). During the application of the substances, the itch/pain elicited will be monitored for 10 minutes using a VAS (Visual analog scale). After the removal of the substances, measurements of SBP, TP, MEI, MPT, MPS, and thermal sensitivity will be conducted.
Drug: Ketamine 0.5% · Drug: Amitriptyline · Drug: ketamine + amitriptyline · Other: Vehicle · Other: Histamine · Other: Cowhage
Ketamine cream 0.5% will be applied in a 4x4 area in the forearm of each participant.
Amitriptyline cream 1% will be applied in a 4x4 area in the forearm of each participant.
A cream containing ketamine 0.5%, amitriptyline 1%, will be applied in a 4x4 area in the forearm of each participant.
A vehicle cream will be applied in a 4x4 area in the forearm of each participant.
After the cream removal, itch will be induced using histamine in the first session
After the cream removal, itch will be induced using cowhage in the second session
Measuring itch by computerized Visual Analog Scale Scoring
We will ask the subjects to rate the sensation of itch on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no itch" and 100 indicates "worst itch imaginable".
Time frame: Immediately after the intervention
Measuring pain by computerized Visual Analog Scale Scoring
We will ask the subjects to rate the sensation of pain on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no pain" and 100 indicates "worst pain imaginable".
Time frame: Immediately after the intervention
Superficial blood perfusion
Superficial blood perfusion (SBP) is measured by a Speckle contrast imager
Time frame: Immediately after the intervention
Touch Pleasantness
Pleasant touch sensation measured using a standardized sensory brush exerting a force of 200 to 400 mN.
Time frame: Immediately after the intervention
Mechanically evoked itch (MEI), intensity approach
MEI is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force).
Time frame: Immediately after the intervention
Mechanically evoked itch, spatial approach
The von-Frey filament that better evokes the itch sensation during the assessment of mechanically evoked itch as well as a template of soft plastic are used to map the area of hyperkinesis in the test areas (forearms).
Time frame: Immediately after the intervention
Mechanical Pain Thresholds (MPT)
This test is conducted using a pinprick set. The set consists of 7 needles each with a diameter of 0.6 mm and different force applications: 8, 16, 32, 64, 128, 256, and 512 mN.
Time frame: Immediately after the intervention
Mechanical Pain Sensitivity (MPS), intensity approach
This test is conducted with the same pinprick set used to test the MPT.
Time frame: Immediately after the intervention
Mechanical Pain Sensitivity (MPS), spatial approach
The pinprick that was selected in the MPT as well as a template of soft plastic are used to map the area of hyperalgesia in the test areas (forearms).
Time frame: Immediately after the intervention
Cold Detection Thresholds (CDT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
Warm Detection Thresholds (WDT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
Cold Pain Thresholds (CPT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
Heat Pain Thresholds (HPT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
Pain to Supra-threshold Heat Stimuli (STHS)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
Plan to share: No
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Aalborg University