Levocetirizine dihydrochloride

Levocetirizine hydrochloride is the (R)-enantiomer of the histamine H1 receptor antagonist and antihistamine agent cetirizine. It binds to the H1 receptor with higher affinity than cetirizine and is 25,000-100,000-fold selective for H1 receptors over muscarinic M1-M5 receptors. Intranasal administration dose-dependently decreases histamine-induced nasal rubbing and sneezing in mice. Has been used in the treatment of allergic rhinitis and chronic idiopathic urticaria.