Comparison of Efficacy and Consistency of Action of Levocetirizine 5 mg Once Daily With Fexofenadine 60 mg Twice Daily in the Histamine Induced Wheal, Flare and Itch Response

This will be a randomized, double-blind, placebo-controlled study with intra-individual comparison of the histamine induced wheal and flare reaction. In September 2009, Fexofenadine was approved as an antihistamine against allergies in Japan and it is currently used widely. It has been approved in 120 countries, including the US, UK, France and Germany [11]. In Europe and the United States, fexofenadine is marketed at 120 mg once daily for allergic rhinitis and 180mg once daily for urticaria. In Japan, fexofenadine is marketed at 60 mg twice daily for both conditions. But is this dosage regimen as effective as levocetirizine, 5 mg once daily? The above described study from Takahashi et al, comparing 60 mg twice daily versus cetirizine 10 mg once daily suggests that it is not [4]. The aim of the study is to compare the efficacy and consistency of action of levocetirizine 5 mg once daily with fexofenadine 60 mg twice daily over a 24 hour period in the histamine induced wheal, flare and itch response. Furthermore, we would like to investigate whether a different between Japanese and Caucasian exists or not. Each volunteer will receive the study medication at time point 0 and 12 hour later. Skin Prick Test (SPT) will be performed in each volunteer using histamine (10 mg/ml), 15 minutes before drug admission (baseline) and at 0.5, 1, 2, 3, 4, 6, 8, 10, 12 and 24 hours afterwards. Volumetric optical scanning system and infrared camera will be used for objective evaluation of the wheal- and flare reduction. Additionally, measurement of the erythema diameter with a transparent ruler will be performed. The subjective intensity of itching will be assessed using a Visual Analogue Scale (VAS). To relate the pharmacokinetics of the drugs to their pharmacodynamics, blood samples for assay of drug concentrations will be taken at baseline and at 0.5, 1, 2, 3, 4, 6, 8, 10, 12 and 24 hours later. Subjects will undergo the same procedure on three separate occasions to receive each treatment option. The options are: placebo at time 0 hours + placebo at 12 hours, Levocetirizine 5mg at time 0 hours + placebo at 12 hours or fexofenadine 60mg at time 0 hours + fexofenadine 60mg at 12 hours. There will be a washout period of at least 6 days between the treatments.