The anti‐inflammatory effects of the second‐generation antihistamines

Second‐generation histamines are widely used and effective drugs for the treatment of urticaria, atopic dermatitis, and in both seasonal and perennial allergic rhinitis. It has been recognized for some years that the newer antihistamines have a number of additional anti‐inflammatory effects which appear to be independent of their H 1 receptor antagonist effect. These include in vitro inhibitory effects on eosinophil activation, chemotaxis, and on platelet, lymphocyte, or neutrophil activation, while in vivo several researchers have documented protective effects on the changes induced by skin prick test with histamine or allergen, in the specific nasal provocation test, and also limited protection to the specific bronchial provocation test. Other effects are inhibition of the accumulation of proinflammatory cells at allergen‐challenged skin sites and downregulation of allergen‐induced expression of the adhesion molecule ICAM‐1 by epithelial cells. These additional properties may enhance the effects of these drugs in the treatment of allergic disease.