Inhibition of histamine-induced nasal symptoms by the H1 antihistamine chloropheniramine maleate: Demonstration of topical effect

Abstract To study whether a histamine H 1 receptor antagonist inhibits allergic rhinitis symptoms by a peripheral or a central mode of action 21 normal volunteers were challenged with 500 μg histamine chloride in the right nasal cavity on four occasions after bilateral pretreatment with an H 1 antihistamine spray and a placebo spray in various combinations. The H 1 antihistamine (chlorpheniramine maleate, 0.5 mg) significantly inhibited histamine-induced tickling ( P P = 0.01) and discharge ( P