2865 Hydroxyzine A histamine H1 receptor antagonist that is effective in the treatment of chronic urticaria, dermatitis, and histamine-mediated pruritus. Unlike its major metabolite cetirizine, it does cause drowsiness. It is also effective as an antiemetic, for relief of anxiety and tension, and as a sedative. 68-88-2 3658 C21H27ClN2O2 374.176110 White powder. 193°C < 700 mg/mL Oral, Intramuscular. Rapidly absorbed from the gastrointestinal tract Hydroxyzine competes with histamine for binding at H₁-receptor sites on the effector cell surface, resulting in suppression of histaminic edema, flare, and pruritus. The sedative properties of hydroxyzine occur at the subcortical level of the CNS. Secondary to its central anticholinergic actions, hydroxyzine may be effective as an antiemetic. Hepatic Half Life: 20 to 25 hours Oral, rat LD₅₀: 950 mg/kg. No indication of carcinogenicity to humans (not listed by IARC). For symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states in which anxiety is manifested. Useful in the management of pruritus due to allergic conditions such as chronic urticaria. Symptoms of overexposure include hypersedation. If vomiting has not occurred spontaneously, it should be induced. Immediate gastric lavage is also recommended. General supportive care, including frequent monitoring of the vital signs and close observation of the patient, is indicated. Hypotension, though unlikely, may be controlled with intravenous fluids and norepinephrine or metaraminol. Do not use epinephrine as hydroxyzine hydrochloride counteracts its pressor action. There is no specific antidote. It is doubtful that hemodialysis would be of any value in the treatment of overdosage with hydroxyzine. However, if other agents such as barbiturates have been ingested concomitantly, hemodialysis may be indicated. (L1712) 2009-07-21T20:27:08Z 2014-12-24T20:25:51Z Hydroxyzine C07045 5818 Hydroxyzine DB00557 true OCCOCCN1CCN(CC1)C(C1=CC=CC=C1)C1=CC=C(Cl)C=C1 C21H27ClN2O2 InChI=1/C21H27ClN2O2/c22-20-8-6-19(7-9-20)21(18-4-2-1-3-5-18)24-12-10-23(11-13-24)14-16-26-17-15-25/h1-9,21,25H,10-17H2 InChIKey=ZQDWXGKKHFNSQK-UHFFFAOYNA-N 374.904 374.176105825 Exogenous Solid 2.7 HMDB14697 CHEMBL896 3531 <p>U.S. Patent 2,899,436.</p>