Clinical efficacy and pharmacokinetic profiles of intranasal and oral cetirizine in a repeated allergen challenge model of allergic rhinitis.

Background: Intranasal and oral antihistamines are effective in treating allergic rhinitis. Studies comparing these routes of administration of an antihistamine regarding efficacy and pharmacokinetic profile are lacking.

Objective: To compare topical and oral routes of administration of cetirizine regarding efficacy, plasma exudation, and systemic drug levels in a repeated allergen challenge model of allergic rhinitis.

Onset of action of a topical antihistamine as assessed by histamine challenge-induced plasma exudation responses.

Background: Although usually administered orally, antihistamines are available also for topical use in allergic rhinitis. Information on onset of action of these drugs is incomplete.

Objective: To examine onset of action of topical cetirizine-dinitrate on plasma exudation evoked by repeated nasal histamine challenges.