The effect of 5-days of cetirizine, desloratadine, fexofenadine 120 and 180 mg, levocetirizine, loratadine treatment on the histamine-induced skin reaction and skin blood flow--a randomized, double-blind, placebo controlled trial

Objective: of this study was to compare the effect of the following antihistamines: cetirizine 10mg, desloratadine 5mg, fexofenadine 120 and 180mg, levocetirizine 5mg, loratadine 10mg, and placebo, administered in the recommended doses over the period of 5 days, on the visually assessed histamine-induced skin reaction, using the Laser Doppler flowmetry (LDF).

Methods: Forty two volunteers (aged 18-22) who gave a written consent before entering the study, were randomized in seven groups of six subjects each. The skin prick test with histamine solution of 10mg/ml was performed on the ventral forearm, 10 cm from the elbow, before and at 2, 4, 6, 8, 10, 12, 18, and 24 hours after drug administration, as well as once daily for the next 4 days of antihistamine drug or placebo intake, and 9 days following the treatment. Diameters of wheal and flare as well as the LDF index measured with Periflux PF3 flowmeter and skin probe, 5mm from the histamine-provoked area, were assessed 10 minutes after performing the above-mentioned skin prick test.

Results: The current study revealed that during the 5-day treatment with recommended doses of cetirizine, desloratadine, fexofenadine, levocetirizine, and loratadine, a significant reduction of histamine-induced wheal, flare and the LDF index was observed as compared to the initial values and placebo intake, reaching the maximum value within the first 24 hours, weakening on the next day, and then gradually increasing during the following days. After the 5-day treatment drugs used for the study were lined up according to the volume of reduction in histamine-induced skin reaction (largest>smallest): levocetirizine > cetirizine > fexofenadine 180mg = fexofenadine 120mg > loratadine = desloratadine.

Conclusions: Following the end of the treatment, the effect of the antihistamines on skin reaction was subsiding in such an order: after 24 hours in case of loratadine and desloratadine, after two days for both doses of fexofenadine, and 3-4 days for cetirizine and levocetirizine.