Effect of the H1 Antihistamine Chlorpheniramine Maleate on Histamine‐Induced Symptoms in the Human Conjunctiva

Abstract

Earlier studies have shown that intranasal chlorpheniramine (0.77%) can inhibit histamine‐induced tickling, sneezing, and hypersecretion by a local effect on nerve fibres. The aim of the present study was to examine whether this solution has local anaesthetic or parasympatholytic properties. If nether of these properties are present it suggests that the anti‐pruritic effects of the solution are caused by inhinbition of H₁ receptors, which in turn is indirect evidence for the presence of H₁ receptors on nerve fibres. In a double‐blind design 15 normal subjects were provoked with histamine in the eye after pretreatment with chlorpheniramine or with a local anaesthetic, oxybuprocain. Both drugs inhibited itching, but the H₁ antihistamine was significatly more effective than the local anaesthetic (P1 receptors in the mucous membranes of the eye and airways, and has extended its application in animals to also include man.