Biochem/physiol Actions Cetirizine hydrochloride is an orally active and selective H1-receptor antagonist. Antihistaminic; Piperazines. Non-sedating type histamine H1-receptor antagonist; major metabolite of hydroxyzine. Pharmacological activity resides primarily in the (R)-isomer. 法律信息 Zyrtec 注册商标 UCB Pharma, S.A.