A comparison of the anti-inflammatory properties of intranasal corticosteroids and antihistamines in allergic rhinitis

Allergic rhinitis manifests itself clinically due to the local release of m ediators from activated cells within the nasal mucosa. Treatment strategies aim either to reduce the effects of these mediators on the sensory neural and vascular end organs, or to reduce the tissue accumulation of the activa ted cells that generate them. Corticosteroids intervene at a number of step s in the inflammatory pathway, and, by reducing the release of cytokines an d chemokines, inhibit cell recruitment and activation. These effects are ev ident both in vivo and in vitro. While antihistamines also have some anti-i nflammatory effects in vitro, these require higher concentrations than with corticosteroids and are not consistently reproduced in vivo. In addition, although antihistamines and corticosteroids might appear to have complement ary mechanisms of action, clinical trials suggest that their co-administrat ion does not confer any additional long-term benefits compared with that ac hieved with corticosteroids alone. Topical corticosteroids are therefore th e preferred anti-inflammatory therapy for persistent allergic rhinitis.