(R)-Cetirizine (hydrochloride)

(R)-Cetirizine is the (R)-enantiomer of the histamine H1 receptor antagonist and second generation antihistamine cetirizine (Item No. 19686).{31604} (R)-Cetirizine binds to the H1 receptor with higher affinity than cetirizine (Kis = 3 and 6 nM, respectively) and is 25,000-100,000-fold selective for H1 receptors over muscarinic M1-M5 receptors.{39482} It decreases production of RANTES and eotaxin following antigen stimulation in mouse eosinophils in vitro in a concentration-dependent manner with a minimum effective concentration (MEC) of 0.05 µM.{39483} Intranasal administration of (R)-cetirizine (0.01-1%) dose-dependently decreases histamine-induced nasal rubbing and sneezing in mice.{39484} Formulations containing (R)-cetirizine have been used in the treatment of allergic rhinitis and chronic idiopathic urticaria.