Suppression of histamine-induced skin reactions by loratadine and cetirizine diHCl.

The skin reactivity to histamine was measured in 10 healthy and 10 atopic subjects after the ingestion of single doses of loratadine 10 mg, cetirizine diHCl 10 mg and placebo, in a double-blind cross-over randomized study. The anti-H1 effect of cetirizine diHCl proved to be significantly more rapid, more pronounced and longer lasting than that of loratadine.