Anti-allergic drug testing in an environmental challenge chamber is suitable both in and out of the relevant pollen season

Background An environmental challenge chamber (ECC) is a useful tool to expose allergic patients to relevant allergens in a controlled indoor setting and to test anti-allergic treatment. Hitherto, ECC studies with grass pollen are conducted primarily outside of the pollen season to avoid the influence of natural pollen exposure. Objective To investigate whether an established anti-allergic treatment, a combination of cetirizine (CET) and pseudoephedrine (PSE), shows an equivalent treatment effect within and outside of the grass pollen season when tested in an ECC. Methods In a randomized, placebo-controlled, double-blind, four-way crossover study, the effect of a combination of 10 mg CET and 120 mg PSE compared with placebo on nasal symptoms, nasal flow, and nasal secretion was investigated in 70 patients with seasonal allergic rhinitis. Subjects underwent four 6-hour pollen challenges in an ECC with administration of the drugs after 2 hours. Two challenges were conducted within the grass pollen season and two out of the grass pollen season. Results The active treatment significantly improved nasal symptoms and nasal flow and significantly reduced the amount of nasal secretion compared with placebo both within and outside of the pollen season ( P P > .05). Conclusion Controlled allergen provocation in an ECC can be used to test anti-allergic treatment both within and outside of the grass pollen season.