The Effect of Levocetirizine on Inflammatory Mediators in Dermatographism

Levocetirizine (Xyzal®), the active levorotatory enantiomer of cetirizine (Zyrtec®), is a FDA-approved drug used in the treatment of symptoms associated with seasonal and perennial allergic rhinitis and chronic idiopathic urticaria. The parent compound, cetirizine was shown to be effective against experimental dermatographism, however no study has been conducted so far on the effect of levocetirizine on the inhibition of dermatographism. It is known that cetirizine is a mast-cell stabilizer and decreases histamine levels and the number of tryptase positive mast cells. Cetirizine inhibits the production of interleukin 8 (IL8) and leukotriene B4 (LTB4) by immune cells - two potent chemoattractants - and induces the release from monocytes of prostaglandin E2 (PGE2), a suppressor of antigen presentation and MHC class II expression. However, the effects of the most active enantiomer levocetirizine on these inflammatory mediators have not been evaluated so far. Therefore, we aim to conduct a study in humans with dermatographism and chronic idiopathic urticaria to evaluate the effect of levocetirizine on the above-mentioned mediators. The study will involve the use of skin microdialysis, a minimally invasive technique to measure inflammatory mediators in the extracellular space in dermis.