Effects of acrivastine, loratadine and cetirizine on histamine-induced wheal and flare responses D. Bayramgu ¨ rler, N. Bilen, R. Apaydy ´ n, L. Altıntas ¸,* G. Sal, S ¸ . Do ¨kmeci and T. Utkan† Departments of Dermatology and *Pharmacology, Faculty of Medicine, University of Kocaeli, I ˙ zmit, Turkey, †Department of Public Health, Faculty of Medicine, University of I ˙ stanbul, Turkey Summary It is accepted that studies evaluating histamine-induced wheal and flare reactions in the skin represent a simple and reliable method for demonstrating pharmacodynamic activity and pharmacokinetics of the H 1 -receptor antagonists. In this study, the effects of single oral doses of acrivastine (8 mg), loratadine (10 mg) and cetirizine (10 mg) on the histamine-induced wheal and flare reactions were compared in 60 healthy volunteers. The wheal and flare responses were produced by prick test using 1% histamine solution. Measurements were performed before the ingestion of antihista- mines (baseline values) and afterwards at 15, 30, 90, 240, 360 min and 24 h. The values obtained for each antihistamine were compared with each other and with baseline values. Cetirizine was found to be superior to acrivastine and loratadine for the suppression of wheal and flare responses at 240, 360 min and 24 h (P < 0.05) and acrivastine was superior to the other two antihistamines for the suppression of flare response at 30 min (P < 0.05). Our results indicate that a single dose of cetirizine provides a more effective and long acting suppression on wheal and flare reactions in urticaria when compared to acrivastine and loratadine. Introduction Oral antihistamines are the most widely used drugs for the treatment of allergic disorders. 1–5 The first genera- tion H 1 -receptor antagonists that was discovered more than 50 years ago are poorly tolerated by most patients because of sedative and anticholinergic effects. 5,6 The second generation H 1 -receptor antagonists were devel- oped to reduce significantly the incidence of centrally mediated side-effects while maintaining the effectiveness of their predecessors. 4,6 The aim of present investigator-blinded, cross-over study was to compare the effects of single oral doses of acrivastine (8 mg), loratadine (10 mg), and cetirizine (10 mg) on the histamine-induced wheal and flare reactions in healthy volunteers. Materials and methods Subjects This investigator-blinded, single dose, cross-over study was performed in 60 healthy volunteers between May and September 1997. Thirty male and 30 female adults aged 22–52 years (mean, 28.68  0.74 years) were included in the study. The mean weight of the study population was 64.78  13.34 kg. Ethical approval was granted for all experiments carried out in the study and all volunteers gave informed consent to the procedures performed. Haematological and biochemical tests were normal in all subjects. Subjects were excluded if they had any acute or chronic illness, if they had taken an H 1 or H 2 -receptor antagonist, systemic corticosteroid, mast cell stabilizator Experimental dermatology • Original article  1999 Blackwell Science Ltd • Clinical and Experimental Dermatology , 24, 407–411 407 Correspondence: D. Bayramgu ¨ rler, Kocaeli U ¨ niversitesi Tıp Faku ¨ ltesi, Dermatoloji ABD 41900 Sopalıc ¸ iftlig ˘i, Kocaeli, Turkey. Tel.: þ90 2622335474. Fax: þ 90 2622335461. Note: This study was presented at 7th Congress of the European Academy of Dermatology and Venereology, 7–11 October 1998, Nice, France. Accepted for publication 4 April 1999