In this study the investigators wish to investigate whether halophyte-based cream applied to the skin can reduce itch applied by means of small needles from the plant mucuna pruriens (also called cowhage) or by histamine (an itch-evoking substance formed in the human body). Further, the investigators wishes to investigate whether long-term application of halophyte-based cream has a pain-relieving effect on heat/cold and pinprick stimulations.
Salt-tolerant plants (also called halophytes) can grow in saline soil or directly in salt water (e.g. along coasts). For centuries, these plants have been used in folk medicine, and among other things they are believed to have pain-relieving and anti-inflammatory effect. Even though experiments have already investigated halophytes as a pain relieving substance, the mechanisms in relation to pain and/or itch are still unknown. Therefore, the investigators wish to investigate whether halophyte-based cream applied to the skin can reduce itch applied by means of small needles from the plant mucuna pruriens (also called cowhage) or by histamine (an itch-evoking substance formed in the human body). Further, the investigators wishes to investigate whether long-term application of halophyte-based cream has a pain-relieving effect on heat/cold and pinprick stimulations.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
32
The concentration of active aqueous extract will be in the range of 2% to 30% (v/v) by cold emulsification. A 2 gram amount of Halophytes-based cream will be applied under occlusion (TegaDerm tape) in a 4x4 cm squared area.
The concentration of active aqueous extract will be in the range of 2% to 30% (v/v) by cold emulsification. A 2 gram amount of Halophytes-based cream will be applied under occlusion (TegaDerm tape) in a 4x4 cm squared area.
A 2 gram amount of vehicle cream will be applied under occlusion (TegaDerm tape) in a 4x4 cm squared area.
Aalborg University
Aalborg, Denmark
Superficial blood perfusion
Superficial blood perfusion is measured by a Speckle contrast imager (FLPI, Moor Instruments, England).
Time frame: Day 0
Superficial blood perfusion
Superficial blood perfusion is measured by a Speckle contrast imager (FLPI, Moor Instruments, England).
Time frame: 24 hours after cream application
Superficial blood perfusion
Superficial blood perfusion is measured by a Speckle contrast imager (FLPI, Moor Instruments, England).
Time frame: 48 hours after cream application
Itch intensity
The subject will rate the itch sensation on a 100 millimeter Visual Analog Scale from 0 to 100., where 0"indicates no itch and "100" worst itch imaginable
Time frame: Day 0
Itch intensity
The subject will rate the itch sensation on a 100 millimeter Visual Analog Scale from 0 to 100., where 0"indicates no itch and "100" worst itch imaginable
Time frame: 24 hours after cream application
Itch intensity
The subject will rate the itch sensation on a 100 millimeter Visual Analog Scale from 0 to 100., where 0"indicates no itch and "100" worst itch imaginable
Time frame: 48 hours after cream application
Pain intensity
The subject will rate the pain sensation on a 100 millimeter Visual Analog Scale from 0 to 100., where 0"indicates no pain and "100" worst pain imaginable
Time frame: Day 0
Pain intensity
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A 2 gram amount of vehicle cream will be applied under occlusion (TegaDerm tape) in a 4x4 cm squared area.
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.
The insertion of cowhage spicule(s) rapidly and consistently produces itch with no or very little flare reaction. This insertion is conducted by forceps using a stereo-microscope, and 30-35 spicules are gently rubbed into a 1 cm diameter skin area.
The subject will rate the pain sensation on a 100 millimeter Visual Analog Scale from 0 to 100., where 0"indicates no pain and "100" worst pain imaginable
Time frame: 24 hours after cream application
Pain intensity
The subject will rate the pain sensation on a 100 millimeter Visual Analog Scale from 0 to 100., where 0"indicates no pain and "100" worst pain imaginable
Time frame: 48 hours after cream application
Measuring Alloknesis
Alloknesis is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force).
Time frame: Day 0
Measuring Alloknesis
Alloknesis is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force).
Time frame: 24 hours after cream application
Measuring Alloknesis
Alloknesis is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force).
Time frame: 48 hours after cream application
Trans-epidermal Water Loss (TEWL)
TEWL is a non-invasive and pain free measuring technique in which a 2x2 cm hollow probe with two small humidity gauges and two thermometers is placed lightly on the skin for 10-25 seconds. These collectively establish a precise humidity gradient in a 2 cm vicinity of the skin, representative for the point-loss of water though the epidermis.
Time frame: Day 0
Trans-epidermal Water Loss (TEWL)
TEWL is a non-invasive and pain free measuring technique in which a 2x2 cm hollow probe with two small humidity gauges and two thermometers is placed lightly on the skin for 10-25 seconds. These collectively establish a precise humidity gradient in a 2 cm vicinity of the skin, representative for the point-loss of water though the epidermis.
Time frame: 24 hours after cream application
Trans-epidermal Water Loss (TEWL)
TEWL is a non-invasive and pain free measuring technique in which a 2x2 cm hollow probe with two small humidity gauges and two thermometers is placed lightly on the skin for 10-25 seconds. These collectively establish a precise humidity gradient in a 2 cm vicinity of the skin, representative for the point-loss of water though the epidermis.
Time frame: 48 hours after cream application
Measurement of Warm Detection Thresholds (WDT)
The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. A thermode stimulator of 3x3 cm will be placed on the treated/placebo areas and kept in place by means of Velcro tape. During the first 8 seconds, the temperature raises 1°C per second from a starting temperature of 32°C until the subject perceives a temperature change (warm sensation) and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 52°C will be used.
Time frame: Day 0
Measurement of Warm Detection Thresholds (WDT)
The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. A thermode stimulator of 3x3 cm will be placed on the treated/placebo areas and kept in place by means of Velcro tape. During the first 8 seconds, the temperature raises 1°C per second from a starting temperature of 32°C until the subject perceives a temperature change (warm sensation) and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 52°C will be used.
Time frame: 24 hours after cream application
Measurement of Warm Detection Thresholds (WDT)
The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. A thermode stimulator of 3x3 cm will be placed on the treated/placebo areas and kept in place by means of Velcro tape. During the first 8 seconds, the temperature raises 1°C per second from a starting temperature of 32°C until the subject perceives a temperature change (warm sensation) and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 52°C will be used.
Time frame: 48 hours after cream application
Measurement of Cold Detection Thresholds (CDT)
The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. A thermode stimulator of 3x3 cm will be placed on the treated/placebo areas and kept in place by means of Velcro tape. During the first 8 seconds, the temperature decreases 1°C per second from a starting temperature of 32°C until the subject perceives a temperature change (cold sensation) and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 0°C will be used.
Time frame: Day 0
Measurement of Cold Detection Thresholds (CDT)
The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. A thermode stimulator of 3x3 cm will be placed on the treated/placebo areas and kept in place by means of Velcro tape. During the first 8 seconds, the temperature decreases 1°C per second from a starting temperature of 32°C until the subject perceives a temperature change (cold sensation) and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 0°C will be used.
Time frame: 24 hours after cream application
Measurement of Cold Detection Thresholds (CDT)
The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. A thermode stimulator of 3x3 cm will be placed on the treated/placebo areas and kept in place by means of Velcro tape. During the first 8 seconds, the temperature decreases 1°C per second from a starting temperature of 32°C until the subject perceives a temperature change (cold sensation) and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 0°C will be used.
Time frame: 48 hours after cream application
Measurement of Heat Pain Thresholds (HPT)
The tests for thermal sensation will all be performed using the same PATHWAY ATS thermal sensory testing device as above. The stimulations are again applied on the treated/placebo areas. During the first 8 seconds, the temperature raises 1°C per second from a starting temperature of 32°C until the subject detects a painful sensation and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 52°C will be used.
Time frame: Day 0
Measurement of Heat Pain Thresholds (HPT)
The tests for thermal sensation will all be performed using the same PATHWAY ATS thermal sensory testing device as above. The stimulations are again applied on the treated/placebo areas. During the first 8 seconds, the temperature raises 1°C per second from a starting temperature of 32°C until the subject detects a painful sensation and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 52°C will be used.
Time frame: 24 hours after cream application
Measurement of Heat Pain Thresholds (HPT)
The tests for thermal sensation will all be performed using the same PATHWAY ATS thermal sensory testing device as above. The stimulations are again applied on the treated/placebo areas. During the first 8 seconds, the temperature raises 1°C per second from a starting temperature of 32°C until the subject detects a painful sensation and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 52°C will be used.
Time frame: 48 hours after cream application
Measurement of Cold Pain Thresholds (CPT)
The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. A thermode stimulator of 3x3 cm will be placed on the treated/placebo areas and kept in place by means of Velcro tape. During the first 8 seconds, the temperature decreases 1°C per second from a starting temperature of 32°C until the subject detects a painful sensation and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 0°C will be used.
Time frame: Day 0
Measurement of Cold Pain Thresholds (CPT)
The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. A thermode stimulator of 3x3 cm will be placed on the treated/placebo areas and kept in place by means of Velcro tape. During the first 8 seconds, the temperature decreases 1°C per second from a starting temperature of 32°C until the subject detects a painful sensation and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 0°C will be used.
Time frame: 24 hours after cream application
Measurement of Cold Pain Thresholds (CPT)
The tests for thermal sensation will all be performed using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device. A thermode stimulator of 3x3 cm will be placed on the treated/placebo areas and kept in place by means of Velcro tape. During the first 8 seconds, the temperature decreases 1°C per second from a starting temperature of 32°C until the subject detects a painful sensation and presses a button that will terminate the measurement and return the temperature to baseline at a rate of 5°C /s. A cut-off temperature of 0°C will be used.
Time frame: 48 hours after cream application
Measurement of Pain to Supra-threshold Heat Stimuli:
Again, the tests will be performed by using the PATHWAY ATS thermal sensory testing device. The subjects will have to rate the pain to three suprathreshold heat pain stimuli (starting and ending at 34°C with an increase and decrease of 5°C and 4 s plateau at 50°C) applied on the treated/placebo areas .
Time frame: Day 0
Measurement of Pain to Supra-threshold Heat Stimuli:
Again, the tests will be performed by using the PATHWAY ATS thermal sensory testing device. The subjects will have to rate the pain to three suprathreshold heat pain stimuli (starting and ending at 34°C with an increase and decrease of 5°C and 4 s plateau at 50°C) applied on the treated/placebo areas .
Time frame: 24 hours after cream application
Measurement of Pain to Supra-threshold Heat Stimuli:
Again, the tests will be performed by using the PATHWAY ATS thermal sensory testing device. The subjects will have to rate the pain to three suprathreshold heat pain stimuli (starting and ending at 34°C with an increase and decrease of 5°C and 4 s plateau at 50°C) applied on the treated/placebo areas .
Time frame: 48 hours after cream application
Measurement of Mechanical Pain Thresholds (MPT)
This test is performed using a pin-prick set (Aalborg University, Aalborg). The set consists of 8 needles each having a diameter of 0.6 mm and different force applications: 0.8, 1.6, 3.2, 6.4, 12.8, 25.6, 50.1 and 60.0 g. Starting with the lightest, each stimulator is applied at a rate of 2 s on, 2 s off in an ascending order until the first perception of sharpness is reached. The final threshold is the geometric mean of five series of ascending and descending stimuli.
Time frame: Day 0
Measurement of Mechanical Pain Thresholds (MPT)
This test is performed using a pin-prick set (Aalborg University, Aalborg). The set consists of 8 needles each having a diameter of 0.6 mm and different force applications: 0.8, 1.6, 3.2, 6.4, 12.8, 25.6, 50.1 and 60.0 g. Starting with the lightest, each stimulator is applied at a rate of 2 s on, 2 s off in an ascending order until the first perception of sharpness is reached. The final threshold is the geometric mean of five series of ascending and descending stimuli.
Time frame: 24 hours after cream application
Measurement of Mechanical Pain Thresholds (MPT)
This test is performed using a pin-prick set (Aalborg University, Aalborg). The set consists of 8 needles each having a diameter of 0.6 mm and different force applications: 0.8, 1.6, 3.2, 6.4, 12.8, 25.6, 50.1 and 60.0 g. Starting with the lightest, each stimulator is applied at a rate of 2 s on, 2 s off in an ascending order until the first perception of sharpness is reached. The final threshold is the geometric mean of five series of ascending and descending stimuli.
Time frame: 48 hours after cream application
Measurement of Mechanical Pain Sensitivity (MPS)
This test is performed using the same pin-prick set as for the MPT test. Starting with the lightest, each stimulator is applied at a rate of 2 s on, 2 s off in an ascending order, and the subject will be asked to give a pain rating for each stimulus on a scale from 0-10 (where 0 indicates ''no pain'', and 10 indicates the ''worst imaginable pain''). This procedure will be repeated twice.
Time frame: Day 0
Measurement of Mechanical Pain Sensitivity (MPS)
This test is performed using the same pin-prick set as for the MPT test. Starting with the lightest, each stimulator is applied at a rate of 2 s on, 2 s off in an ascending order, and the subject will be asked to give a pain rating for each stimulus on a scale from 0-10 (where 0 indicates ''no pain'', and 10 indicates the ''worst imaginable pain''). This procedure will be repeated twice.
Time frame: 24 hours after cream application
Measurement of Mechanical Pain Sensitivity (MPS)
This test is performed using the same pin-prick set as for the MPT test. Starting with the lightest, each stimulator is applied at a rate of 2 s on, 2 s off in an ascending order, and the subject will be asked to give a pain rating for each stimulus on a scale from 0-10 (where 0 indicates ''no pain'', and 10 indicates the ''worst imaginable pain''). This procedure will be repeated twice.
Time frame: 48 hours after cream application