Environmental exposure unit: a system to test anti-allergic treatment

Learning Objectives: Reading this article will enable readers to recognize the Environmental Exposure Unit (EEU), its historic development and its cur rent role as a system to test anti-allergic treatment; to recognize clinica l relevance of this test system and its relationship with other pollen chal lenge methods of evaluation of anti-allergic medication; and, to recognize variables associated with standard clinical studies of anti-allergic medica tion. Readers will review four studies of antihistamines tested in the Envi ronmental Exposure Unit, three studies on nasal corticosteroids, one on top ical eye drops and one on immunotherapy conducted in the EEU. Data Sources: The EEU has been in operation since 1985 preceded by a protot ype challenge system to assess respiratory effects of urea formaldehyde foa m insulation. A number of studies on the onset of action and efficacy of di fferent antihistamines and nasal corticosteroids as well as other treatment s have been completed producing accurate and consistent results influenced to some extent by study designs. Study Selection: Studies of commonly used antihistamines and nasal corticos teroids are discussed in detail and represent several of the studies undert aken to date in the EEU. Results: Controlled ragweed pollen exposure using the EEU has shown that so me antihistamines demonstrate an onset of action within 30 minutes while ot hers have taken up to 3 hours to produce significant effect. Nasal corticos teroids evidenced the onset of clinical improvement at 5 to 6 hours with si gnificance over placebo between 6 and 12 hours depending on dose. Conclusion: The EEU is an effective pollen delivery system that accurately and consistently determines the onset of action and efficacy of anti-allerg ic treatment in large groups of subjects. It eliminates variables associate d with various other methods of evaluation of these medications but does no t supplant the need for such evaluations.