Azelastine

Azelastine
Clinical data
Trade names	Astelin, others
AHFS/Drugs.com	Monograph
MedlinePlus	a603009
License data	US DailyMed: Azelastine;
Pregnancy; category	AU: B3;
Routes of; administration	Eye drops, nasal spray, by mouth
ATC code	R01AC03 (WHO) R06AX19 (WHO), S01GX07 (WHO);
Legal status
Legal status	AU: S2 (Pharmacy medicine); UK: POM (Prescription only); US: ℞-only / OTC;
Pharmacokinetic data
Bioavailability	40% (intranasal)
Metabolites	desmethylazelastine (active)
Onset of action	Within 1 hour
Elimination half-life	22 hours
Duration of action	12 hours
Identifiers
	IUPAC name (RS)-4-[(4-Chlorophenyl)methyl]-2-(1-methylazepan-4-yl)-phthalazin-1-one;
CAS Number	58581-89-8 ; as HCl: 79307-93-0;
PubChem CID	2267; as HCl: 54360;
IUPHAR/BPS	7121;
DrugBank	DB00972 ; as HCl: DBSALT000013;
ChemSpider	2180 ; as HCl: 49103;
UNII	ZQI909440X; as HCl: 0L591QR10I;
KEGG	D07483 ; as HCl: D00659;
ChEBI	CHEBI:2950 ; as HCl: CHEBI:2951;
ChEMBL	ChEMBL639 ; as HCl: ChEMBL1200809;
CompTox Dashboard (EPA)	DTXSID6022638 ;
ECHA InfoCard	100.133.278
Chemical and physical data
Formula	C22H24ClN3O
Molar mass	381.90 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES Clc1ccc(cc1)CC\3=N\N(C(=O)c2ccccc2/3)C4CCCN(C)CC4;
	InChI InChI=1S/C22H24ClN3O/c1-25-13-4-5-18(12-14-25)26-22(27)20-7-3-2-6-19(20)21(24-26)15-16-8-10-17(23)11-9-16/h2-3,6-11,18H,4-5,12-15H2,1H3 ; Key:MBUVEWMHONZEQD-UHFFFAOYSA-N ;
	(verify)

Azelastine, sold under the brand name Astelin among others, is a H₁ receptor-blocking medication primarily used as a nasal spray to treat allergic rhinitis (hay fever) and as eye drops for allergic conjunctivitis. Other uses may include asthma and skin rashes for which it is taken by mouth. Onset of effects is within minutes when used in the eyes and within an hour when used in the nose. Effects last for up to 12 hours.

Common side effects include headache, sleepiness, change in taste, and sore throat. It is unclear if use is safe during pregnancy or breastfeeding. It is a second-generation antihistamine and works by blocking the release of a number of inflammatory mediators including histamine.

Azelastine was patented in 1971 and came into medical use in 1986. It is available as a generic medication. In 2022, it was the 124th most commonly prescribed medication in the United States, with more than 5 million prescriptions.