Experimental models for the evaluation of treatment of allergic rhinitis.
OBJECTIVE
To review the experimental models used for the clinical evaluation of treatments for allergic rhinitis.


METHODS
Peer-reviewed clinical studies and review articles were selected from the PubMed database using the following relevant keywords: allergic rhinitis in combination with efficacy, wheal and flare, nasal challenge, park, cat room, or exposure unit. Regulatory guidance documents on allergic rhinitis were also included.


METHODS
The authors' knowledge of the field was used to limit references with emphasis on recent randomized and controlled studies. References of historical significance were also included.


RESULTS
Traditional outpatient studies are universally accepted in the evaluation of treatment for allergic rhinitis. Experimental models provide ancillary information on efficacy at different stages of treatment development. Skin histamine and allergen challenge, as well as direct nasal challenge with histamine and allergen, are often used as early steps in assessing drug efficacy. Exposure units, park settings, and cat rooms better approximate real life by drawing on the natural mode of allergen exposure and delivering the sensitizing allergen to allergic individuals in the ambient air. Park studies make use of allergens in the outdoors, whereas cat rooms and exposure units present the sensitizing allergens indoors, with the latter providing consistent predetermined allergen levels. Exposure unit and park studies are acknowledged for the determination of onset of action and are also suited to the measurement of duration of effect and other measures of efficacy. Onset and duration of effect are 2 important pharmacodynamic properties of antihistamines and nasal corticosteroids as determined by the Allergic Rhinitis and Its Impact on Asthma and the European Academy of Allergology and Clinical Immunology workshop group.


CONCLUSIONS
All challenge models serve as important instruments in the evaluation of antiallergic medications and provide additional information to complement traditional studies.
Division of Allergy and Immunology, Kingston General Hospital, Kingston, Ontario, Canada. dayj@kgh.kari.net
James H
JH
Day
Anne K
AK
Ellis
Elizabeth
E
Rafeiro
Jodan D
JD
Ratz
Maureen P
MP
Briscoe
D000485:Allergens / Q000276:immunology; D000818:Animals; D018926:Anti-Allergic Agents / Q000627:therapeutic use*; D001273:Atmosphere Exposure Chambers; D002415:Cats; D004341:Drug Evaluation / Q000379:methods* / Q000706:statistics & numerical data; D004781:Environmental Exposure; D006634:Histamine H1 Antagonists / Q000627:therapeutic use*; D006801:Humans; D009299:Nasal Provocation Tests / Q000379:methods; D012221:Rhinitis, Allergic, Perennial / Q000175:diagnosis / Q000188:drug therapy*; D006255:Rhinitis, Allergic, Seasonal / Q000175:diagnosis / Q000188:drug therapy*
D000485:Allergens; D018926:Anti-Allergic Agents; D006634:Histamine H1 Antagonists