Levocetirizine Dihydrochloride (Xyzal Dihydrochloride) is a third-generation peripheral H1-receptor antagonist. Acting as an antihistaminic agent, it specifically targets the histamine H1-receptor. Levocetirizine Dihydrochloride is the R-enantiomer of Cetirizine, which gives it a higher affinity for the H1-receptor than the S-enantiomer. Due to this enhanced affinity, Levocetirizine Dihydrochloride is effective in treating allergic rhinitis and chronic idiopathic urticaria.

Levocetirizine Dihydrochloride（0.4 mg/kg；口服；雄性斯普拉格-道利大鼠）治疗显示，在斯普拉格-道利大鼠中Cmax、AUC0-t、AUC0-∞ 以及 t1/2 分别为 0.34 μg/mL、3.26 μg h/mL、3.67 μg h/mL 和 2.34 小时[1]。