Cetirizine

Cetirizine

Clinical data
Trade names	Zyrtec
AHFS/Drugs.com	Monograph
MedlinePlus	a698026
License data	US FDA: Cetirizine
Pregnancy category	US: B (No risk in non-human studies)
Routes of administration	Oral
ATC code	R06AE07 (WHO)
Legal status
Legal status	AU: Unscheduled CA: OTC UK: General sales list (GSL, OTC) US: OTC
Pharmacokinetic data
Bioavailability	well absorbed
Protein binding	~93%
Metabolism	Excreted mainly unchanged
Biological half-life	8.3 Hours
Excretion	Urine (mainly), hepatic or excrement (Small amounts)
Identifiers
IUPAC name (±)-[2-[4-[(4-chlorophenyl)phenylmethyl]-1- piperazinyl]ethoxy]acetic acid
Synonyms	Alatrol, Alerid, Alzene, Cetirin, Cetirizin, Cetirizina, Cetzine, Cezin, Histazine, Humex, Letizen, Reactine, Razene, Triz, Zetop, Zirtec, Zirtek, Zodac, Zyllergy, Zynor, Zyrlek, Zyrtec
CAS Number	83881-51-0 Y
PubChem CID	2678
IUPHAR/BPS	1222
DrugBank	DB00341 Y
ChemSpider	2577 Y
UNII	YO7261ME24
KEGG	D07662 Y
ChEBI	CHEBI:3561 Y
ChEMBL	CHEMBL1000 Y
ECHA InfoCard	100.223.545
Chemical and physical data
Formula	C21H25ClN2O3
Molar mass	388.89 g/mol
3D model (Jmol)	Interactive image
SMILES Clc1ccc(cc1)C(c2ccccc2)N3CCN(CC3)CCOCC(=O)O
InChI InChI=1S/C21H25ClN2O3/c22-19-8-6-18(7-9-19)21(17-4-2-1-3-5-17)24-12-10-23(11-13-24)14-15-27-16-20(25)26/h1-9,21H,10-16H2,(H,25,26) Y Key:ZKLPARSLTMPFCP-UHFFFAOYSA-N Y

Cetirizine /sɛˈtɪrᵻziːn/ (trade names Zirtec, Zyrtec, Reactine, Triz) is a second-generation antihistamine used in the treatment of hay fever, allergies, angioedema, and urticaria. It is a major metabolite of hydroxyzine, and a racemic selective H₁ receptor antagonist.

Second-generation antihistamines like cetirizine are less able to cross the blood–brain barrier and therefore have diminished effects on the central nervous system compared to first-generation drugs: for instance they are less likely to induce drowsiness or to interfere with memory formation.

Cetirizine's primary indication is for hay fever and other allergies. Because the symptoms of itching and redness in these conditions are caused by histamine acting on the H1 receptor, blocking those receptors temporarily relieves those symptoms.

Cetirizine is also commonly prescribed to treat acute and (in particular cases) chronic urticaria, more efficiently than any other second-generation antihistamine.

Interleukin 6 and interleukin 8 have been shown to be elevated in acute respiratory distress syndrome. Cetirizine contains L- and D-stereoisomers. Chemically, levocetirizine is the active L-enantiomer of cetirizine. One recent study of airway epithelial cells showed that levocetirizine may have beneficial effects on the pathophysiologic changes related to human rhinovirus (HRV) infection.