50 The influence of cetirizine on symptom generation and nasal eosinophilia in seasonal allergic rhinitis

Eosinophils and the pathophysiology of allergic rhinitis

“…Although, for several reasons, it is not possible to use any pharmacological treatment as evidence of any causal relationship, this observation lends further support to the notion that the eosinophils are not primarily harmful in allergic disease. Moreover, there was no effect of treatment with cetirizine on the influx of eosinophils into the nasal mucosa during natural allergen exposure in a recent study by Howarth et al [71].…”

The therapeutic index of antihistamines

“…Local allergen challenge of the nose has provided variable results, one study (101) showing both terfenadine and cetirizine to be inactive whereas another (102) showed complete inhibition of eosinophilia. Similarly, in seasonal rhinitis in season, no reduction in eosinophilia has been reported by one group (103) whereas another reported a preferential inhibition of eosinophilia by cetirizine compared with terfenadine or astemizole (104). In asthma, only one study (10.5) using a rather high dose of cetirizine (1.5 mg twice daily) has appeared in the literature thus far.…”

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

“…Lavage studies also have produced contradictory findings ( 45, 46). In our own studies in naturally occurring seasonal rhinitis, cetirizine failed to show a clear anti‐inflammatory effect, at least as indicated by tissue eosinophil accumulation ( 47). Cetirizine, however, has been found to reduce nasal epithelial ICAM‐1 expression in naturally occurring disease ( 48).…”