Pharmacological modulation by cetirizine and loratadine of antigen and histamine-induced skin weals and flares, and late accumulation of eosinophils

In a double-blind, randomized, crossover study performed in atopic subjects, the inhibitory effects of single doses of 10 mg cetirizine and 10 mg loratadine on histamine- and grass pollen-induced skin reactions were evaluated 4 h after drug intake. Cetirizine significantly inhibited histamine- and antigen-induced skin reactions, as well as the accumulation of eosinophils measured 24 h after antigen challenge. Loratadine, however, did not significantly inhibit the skin reactions induced by histamine and grass pollen, nor eosinophil accumulation.