Repeated Open Application Test (ROAT) Study With Hydroperoxides of Linalool

Study Overview
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Brief Summary
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Linalool is currently one of the most used fragrance substances in cosmetic and household products. Previous studies report a high prevalence (5.9-11.7%) of contact allergy to hydroperoxides of linalool (Lin-OOH)1.0% in pet. among patch tested patients. The optimal test concentration of Lin-OOH in patch tests is not known and requires further investigation. It is of great importance to establish the optimal test concentration and elicitation threshold of Lin-OOH to improve diagnosis and prevent development of Allergic Contact Dermatitis (ACD). We want to mimic real-life exposure to Lin-OOH, by conducting a ROAT (Repeated Open Application Test) study, on 40 adult participants (20 patients with confirmed contact allergy to Lin-OOH, and 20 healthy participants) to low doses of Lin-OOH using a simulated perfume, during a maximum of 21 days of exposure. With this knowledge, we aim to: Establish the optimal patch test concentration to diagnose ACD to Lin-OOH In case of confirmed contact allergy, examine the threshold value for the development of ACD upon daily exposure to a simulated leave-on cosmetic product

Official Title
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Allergic Contact Dermatitis to Hydroperoxides of Linalool - a Repeated Open Application Test (ROAT) Study

Conditions
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Allergic Contact Dermatitis

Intervention / Treatment
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* Diagnostic Test: ROAT


Participation Criteria
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Eligibility Criteria
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Allergic participants: Inclusion criteria Positive (at least one reading) or doubtful patch test (at least two readings) result to hydroperoxides of Linalool within the last ten years Aged 18 years or older Received written and verbal information of the study Signed written consent form Exclusion criteria Active eczema in test areas (volar forearms) Pregnancy or breast feeding Treatment with topical corticosteroids or other immune suppressants on/near test areas within two weeks prior to study start Systemic immune-suppressant treatment within seven days prior to study start UV exposure of test areas within three weeks prior to study start Unable to cooperate or communicate with the investigators Healthy controls: Inclusion criteria Aged 18 years or older Received written and verbal information of the study Signed written consent form Exclusion criteria Known or possible contact allergy to hydroperoxides of Linalool Known contact allergy to other fragrance allergens Active eczema or other known relevant skin diseases Pregnancy or breast feeding Treatment with topical corticosteroids or other immune suppressants on/near test areas within four weeks prior to study start. Systemic immune-suppressant treatment within four weeks prior to study start. UV exposure of test areas within three weeks prior to study start. Participation in other clinical studies within four weeks prior to study start. Unable to cooperate or communicate with the investigators.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 110 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Allergic participants<br> | Diagnostic Test: ROAT<br>* Repeated Open Application Test<br>* Other names: Patch testing and punch biopsies;|
| Experimental: Healthy participants<br> | Diagnostic Test: ROAT<br>* Repeated Open Application Test<br>* Other names: Patch testing and punch biopsies;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Establish the optimal patch test concentration to diagnose allergic contact dermatitis to hydroperoxides of linalool via a Repeated Open Application Test | Establish the optimal patch test concentration to diagnose allergic contact dermatitis to hydroperoxides of linalool via Repeated Open Application Test | 6 months | 
| In case of confirmed contact allergy, examine the threshold value for the development of ACD upon daily exposure to a simulated leave-on cosmetic product | In case of confirmed contact allergy, examine the threshold value for the development of ACD upon daily exposure to a simulated leave-on cosmetic product | 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The Lin-OOH chemicals can penetrate the skin barrier and reside in the local skin tissue | Chemical analysis of skin punch biopsies from the exposed skin of the patients' lower back: time of flight secondary ion mass spectrometry (ToF-SIMS) analysis of Lin-OOH in the skin. | 12 months |