Validation of Laser Doppler Flowmetry to Identify Allergic Rhinitis Patients With Pharmacogenetic Alterations in Histamine Metabolism

Study Overview
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Brief Summary
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The hypothesis to be proven is that histamine iontophoresis with measurement of microvascular blood flow by laser Doppler flowmetry can be used as a reliable marker to characterize the normal microvascular cutaneous response to histamine.

Detailed Description
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The specific aim of this study is to validate iontophoresis (with measurement of microvascular blood flow by laser Doppler flowmetry) in a pediatric cohort as a surrogate marker capable of reliably characterizing the normal physiologic response of the cutaneous microvasculature to histamine. In future studies laser Doppler flowmetry ultimately will be used to assess whether microvascular blood flow determined by a previously validated laser Doppler technique can be used as a reliable surrogate endpoint capable of functionally discriminating the effects of polymorphisms in the genes which are quantitatively important for histamine metabolism. The hypothesis to be proven is that histamine iontophoresis with measurement of microvascular blood flow by laser Doppler flowmetry can be used as a reliable marker to characterize the normal microvascular cutaneous response to histamine.

Official Title
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Histamine Pharmacodynamics in Patients With Allergic Rhinitis: Validation of Laser Doppler Flowmetry as a Surrogate Endpoint

Conditions
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Allergic Rhinitis

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: diagnosed with allergic rhinitis by an attending Pediatrician or Allergist (diagnosis made on clinical grounds or by positive skin test or RAST to environmental allergens, trees, grass, weeds, mold, animal dander, cockroach, dust mite) - Exclusion Criteria: history or evidence of McCune Albright syndrome, immunodeficiency, mastocytosis, receipt of allergy shots, chronic skin disease, liver or kidney disease, cancer, neurological movement disorders, uncontrolled ADHD, evidence of eczema currently or in the past 2 years, history of anaphylaxis or anaphylactic like episode, evidence of pregnancy (by urinary hCG) or lactation, use of antihistamines 10 days prior to skin testing, use of systemic corticosteroids or tricyclic antidepressants 30 days prior to skin testing, presence of condition that would cause difficulty in adherence with study procedure.

Ages Eligible for Study
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Minimum Age: 7 Years
Maximum Age: 18 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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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| comparison of histamine iontophoresis laser doppler monitoring with epicutaneous histamine testing in measuring the microvasculature response to histamine |  | one time point | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| intra-individual variability of histamine iontophoresis with laser doppler monitoring | Determine the intra-individual variability of histamine iontophoresis with laser doppler flowimetry. Twenty subjects will be asked to return for 2 more visits for histamine iontophoresis with laser doppler flowimetry and the intra-individual variability of the measurement will be determined. | at least 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Allergic, Rhinitis, Pharmacogenetics, Histamine