PERIPHERAL H-1-BLOCKADE EFFECT OF FEXOFENADINE

Background: Studies of the suppressive effect of H-1-receptor antagoni sts on the histamine-induced wheal and flare are useful for assessing peripheral H-1-blockade. Objective: To compare the peripheral H-1-bloc kade produced by fexofenadine, 60 mg twice daily or 120 mg once daily; loratadine, 10 mg once daily; and placebo during 24 hours. Methods: I n this randomized, double-blind, single-dose, crossover study in 20 su bjects, the wheals and flares produced by epicutaneous tests with hist amine phosphate 1 mg/mL were measured before and at intervals (20, 40, 60 minutes, hourly until 12 hours, and 24 hours) after the ingestion of fexofenadine, 60 mg twice daily; fexofenadine, 120 mg once daily; l oratadine, 10 mg once daily; or placebo. Results: All active medicatio ns effectively suppressed the histamine-induced wheal and flare for 23 hours compared with placebo. Fexofenadine 60 mg twice daily and fexof enadine 120 mg once daily had a faster onset of action than loratadine in this experimental model. Conclusions: Peripheral H-1-blockade stud ies are useful for investigation of the differences among H-1-receptor antagonists. They complement large clinical trials in which efficacy is subjectively assessed using symptom scores, and which are more like ly to demonstrate similarities among the different medications in this class, and among different doses of the same H-1-receptor antagonist.