Effect of loratadine on mouse models of atopic dermatitis associated pruritus.

To confirm the effectiveness of loratadine for relieving pruritus in atopic dermatitis, we examined the effect of this drug using animal models of atopic dermatitis associated pruritus in ICR and hairless mice. As for the results, in ICR mice, single oral administration of loratadine at a dose of 5 or 10 mg/kg significantly inhibited the dorsal scratching behavior induced by histamine or an antigen, and the effect of loratadine was more potent than that of fexofenadine and chlorpheniramine. In hairless mice, oral administration of loratadine at a dose of 10 mg/kg for 6 days significantly inhibited the facial scratching behavior induced by the feeding of a low magnesium diet. Furthermore, oral administration of loratadine at a dose of 10 mg/kg for 7 days also significantly inhibited the histamine-induced scratching behavior in the same animals. These results indicate that loratadine may be effective in preventing pruritus associated with atopic dermatitis.