Inhibition of histamine or allergen-induced wheals by a single dose of acrivastine, fexofenadine or cetirizine

Cetirizine, a potent H-1-blocking agent,is often recommended as an emergenc y drug in anaphylactic reactions because of its well documented fast onset of action. In this randomized, cross-over study we compared the onset of ac tion after a single dose of two recently introduced antihistamines, acrivas tine and fexofenadine, with that of cetirizine. The inhibition of the wheal -and-flare reaction produced by skin prick test with histamine in 20 health y volunteers and with a relevant pollen allergen in 20 atopic patients, res pectively were measured before and at regular intervals up to 60 min alter the ingestion of acrivastine (8 mg and 16 mg), fexofenadine (120 mg) and ce tirizine (10 mg and 20 mg). Wheal-and-flare reaction were significantly inh ibited 20 min alter the intake of 16 mg acrivastine in atopic patients and 30 min alter intake of 8 mg acrivastine in healthy volunteers, whereas ceti rizine produced a significant inhibition of the wheal-and-flare reaction wi thin 40-60 min. No significant inhibition could be observed within 60 min a fter fexofenadine intake. Therefore, in clinical settings when a fast onset of the H-1-blocking action is mandatory (e.g., after insect stings or for short-term prophylaxis) we recommend acrivastine.