The aim: of the study was to estimate the skin microcirculation reactivity after histamine administration in patients treated with 10mg daily dose of cetirizine for 180 days.
Material and methods: Twenty six patients suffering from persistent rhinitis (28+11 years) were randomized into two groups which received 10 mg/day of cetirizine or placebo respectively. Twenty patients completed the study. The skin microcirculation reaction after 10 mg/ml histamine administration was estimated visually on the forearm (diameter of wheal and flare) and by laser Doppler flowmetry before and after study drug or placebo administration 24 hours and every 30 days during the time of the study. The blood flow was measured by Periflux PF3, using a skin probe 5 mm away from the histamine-induced point.
Results: Statistically significant inhibition of skin reaction (over 90%) and blood flow (over 80%) in relation to the start values in cetirizine group as well as between the groups which received cetirizine or placebo (p<0,001), remained at the same level all the time during the examination.
Conclusion: Tachyphylaxis phenomenon for antihistamine effect of 10 mg/day cetirizine wasn't observed during the whole 180-days treatment.