Generic name: Cetirizine hydrochloride. Chemical name: [2- [4- [(4-chlorophenyl) phenylmethyl] -1- piperazinyl] ethoxy]acetic acid, dihydrochloride. Cetirizine, a metabolite of hydroxyzine, is an antihistamine drug. Its main effects are achieved through selective inhibition of peripheral H1 receptors. Cetirizine was rapidly absorbed with a time to maximum concentration of about 1 hour after oral administration of tablets or syrup formulation in adult volunteers. Cetirizine hydrochloride syrup is indicated for the relief of symptoms associated with perennial allergic rhinitis due to allergens such as dust mites, animal dander and molds. Cetirizine is a second generation drug. Second generation antihistamines are developed to avoid or reduce the sedative effects of drug. Second-generation antihistamines cross the blood–brain barrier to a much lower degree than the first-generation antihistamines. Their main benefit is they primarily affect peripheral histamine receptors and therefore are less sedating.