Placebo Effect in the Treatment of Atopic Dermatitis

Study Overview
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Brief Summary
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The study is initiated in the indication of atopic dermatitis to study the impact of placebo in the treatment of pruritus. Classical conditioning and expectation via instructions/anticipation maintain the effect of placebo.

Official Title
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Placebo Effect in Atopic Dermatitis - Increase the Pharmacological Effect of Itching Caused by Classical Conditioning and Expectancy Processes: A Randomized Controlled Trial

Conditions
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Atopic Dermatitis

Intervention / Treatment
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* Drug: dimetindene
* Behavioral: instruction
* Other: conditioning


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: SCORAD-Score < 50 points basic experimental pruritus >= 3 points on a numeric rating scale no acute eczema on their forearms no systemic treatments for skin diseases for at least four weeks no topical treatment on their arms for at least two weeks Exclusion Criteria: intake of antihistamines pregnancy and lactation serious dysfunctions of the liver, kidneys or thyroid prostatic hyperplasia patients with tumors, major cardiovascular diseases, immunosuppression glaucoma

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: verum, instruction, conditioning<br>This group received dimetindene and instructions about dimetindene and its effectiveness. One classical conditioning process with saline was applied during the skin prick test procedures. | Drug: dimetindene<br>* receiving either dimetindene or a placebo (saline) via infusion<br>Behavioral: instruction<br>* information about the drug dimetindene and its efficacy versus no information and unawareness of treatment influencing expectations of an efficient treatment<br>Other: conditioning<br>* classical conditioning; experiencing and observing the efficiency of a drug manipulated by a conditioning process versus no learning experience.<br>* Other names: learning experience;|
| Experimental: verum, instruction, no conditioning<br>This group received dimetindene and instructions about dimetindene and its effectiveness. No conditioning process were applied | Drug: dimetindene<br>* receiving either dimetindene or a placebo (saline) via infusion<br>Behavioral: instruction<br>* information about the drug dimetindene and its efficacy versus no information and unawareness of treatment influencing expectations of an efficient treatment<br>|
| Experimental: placebo, instruction, conditioning<br>This group received a placebo (saline) as intravenously administered substance. But instructions about receiving dimetindene and its effectiveness were given. One classical conditioning process was applied during the skin prick test procedures. | Behavioral: instruction<br>* information about the drug dimetindene and its efficacy versus no information and unawareness of treatment influencing expectations of an efficient treatment<br>Other: conditioning<br>* classical conditioning; experiencing and observing the efficiency of a drug manipulated by a conditioning process versus no learning experience.<br>* Other names: learning experience;|
| Experimental: verum, no instruction, no conditioning<br>Dimetindene was covertly administered (unawareness of treatment). No instruction and no conditioning were given. | Drug: dimetindene<br>* receiving either dimetindene or a placebo (saline) via infusion<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of the experimental pruritus intensity on a 10-point-rating scale between the groups | The pruritus intensity is assessed at different time points during a time frame of 2 days. The results are compared between the groups. | assessed over a time frame of 2 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of the severity of atopic dermatitis (SCORAD) and comparison between the groups | Change of SCORAD is assessed on day 1 and day 2. | assessed over a time frame of 2 days | 
| Changes of Wheal sizes experimentally provoked by skin prick test. | The changes of wheal sizes due to the administered intervention at different time point during a time frame of 2 day is assessed in square millimeters. The results are compared between the groups. | assessed over a time frame of 2 days | 
| Changes of clinical, atopic itch intensity on a 10-point-rating scale | Changes of clinical itch intensity assessed on day 1 and day 2. | assessed over a time frame of 2 days |