Inhibition of histamine-induced nasal symptoms by the H1 antihistamine chlorpheniramine maleate: demonstration of topical effect.

To study whether a histamine H1 receptor antagonist inhibits allergic rhinitis symptoms by a peripheral or a central mode of action 21 normal volunteers were challenged with 500 micrograms histamine chloride in the right nasal cavity on four occasions after bilateral pretreatment with an H1 antihistamine spray and a placebo spray in various combinations. The H1 antihistamine (chlorpheniramine maleate, 0.5 mg) significantly inhibited histamine-induced tickling (P less than 0.01), sneezing (P = 0.01) and discharge (P less than 0.01), but only when it was given on the same side as histamine. This is highly suggestive of a local effect on sensory nerve endings, which prompts further studies on the topical use of antihistamines in the nose.