Construction of an environmental exposure unit and investigation of the effects of cetirizine hydrochloride on symptoms of cedar pollinosis in Japan.
BACKGROUND
Cedar pollinosis is a widespread seasonal allergy that is unique to Japan. Environmental exposure units (EEU) assist in the development of effective therapeutic and preventive measures because outdoor studies are limited by seasonal variation in pollen exposure.


OBJECTIVE
We constructed an EEU to conduct a randomized cross-over double-blind placebo-controlled study of the efficacy of cetirizine (Zyrtec), a second-generation antihistamine.


METHODS
The spatial and temporal homogeneity of pollen distribution in the EEU was evaluated by counting the number of pollen grains on petroleum-jelly-smeared glass slides and by real-time pollen monitors. In the clinical study, 20 volunteers with known cedar pollinosis were exposed to pollen for 5 hours, randomly allocated to receive either cetirizine hydrochloride or placebo 30 minutes after exposure. Symptoms and the degree of somnolence were recorded every 30 minutes for 5.5 hours. As a measure of psychomotor performance, the Uchida-Kraepelin test was used to determine work quantity and error rate.


RESULTS
The cedar pollen grains were scattered evenly in the exposure room. In the clinical study, symptom scores were elevated in both groups, showing significant symptom induction 30 minutes after exposure. Test drugs were administered 30 minutes after exposure, and 1 hour later patients in the cetirizine hydrochloride group experienced a significant decrease in sneezing, nose-blowing frequency, and nasal congestion compared with the placebo group. There were no significant differences between the 2 groups in terms of subjective somnolence or objective psychomotor performance.


CONCLUSIONS
The first EEU in Japan was used successfully to evaluate cetirizine as a treatment for cedar pollinosis. The results confirmed those from studies in other countries, except for the degree of somnolence, which increased in both groups and may have been related to postprandial sleepiness.
Enomoto
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Department of Otolaryngology, Red Cross Society, Wakayama Medical Center, Wakayama-City, Japan. t-enomoto@mud.biglobe.ne.jp
Ide
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Ogino
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D000328:Adult; D028203:Cedrus / Q000009:adverse effects; D017332:Cetirizine / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004781:Environmental Exposure; D005260:Female; D039563:Histamine H1 Antagonists, Non-Sedating / Q000627:therapeutic use*; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000188:drug therapy*; D007159:Immunologic Tests / Q000379:methods*; D007564:Japan; D008297:Male; D008875:Middle Aged; D011058:Pollen / Q000009:adverse effects
D039563:Histamine H1 Antagonists, Non-Sedating; D017332:Cetirizine