H1-ANTIHISTAMINES SUPPRESS WHEAL-AND-FLARE REACTION AND SKIN BLOOD PERFUSION MEASURED BY LASER DOPPLER FLOWMETRY: RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED, CROSSOVER DESIGN STUDY

The aim of our study was to compare the influence of pre-treatment with H1-antihistamines (levocetirizine, desloratadine, clemastine, quifenadine, and sequifenadine) and a placebo on the histamine-induced weal and flare reaction, increase of skin blood perfusion and sedation. Thirty healthy volunteers were enrolled in the study. The study design was a prospective, randomised, double-blind, placebo-controlled, crossover, balanced clinical trial. Volunteers in randomised and double-blind order were treated with oral levocetirizine 5 mg, desloratadine 5 mg, clemastine 1 mg, quifenadine 50 mg, sequifenadine 50 mg or a placebo. Two hours after intake of medication, the histamine skin prick test was performed and skin blood perfusion was registered with further evaluation of sedative effect. We conclude that levocetirizine induced a significant and pronounced decrease of weal and flare reaction and skin blood perfusion compared to the placebo and the other H1-antihistamines. The effect of quifenadine and sequifenadine on weal reaction area was similar to desloratadine and clemastine. Regarding the sedative effect, we can conclude that second generation antihistamines appear to be not non-sedative but the least impairing, and the first generation antihistamines appear to be the most impairing on central nervous system function. There is a necessity to consider the sedating potential of antihistamines, along with other factors such as efficacy, when prescribing antihistamines to patients.