Montelukast

Montelukast

Clinical data
Trade names	Singulair
AHFS/Drugs.com	Monograph
MedlinePlus	a600014
Pregnancy category	AU: B1 US: B (No risk in non-human studies)
Routes of administration	Oral
ATC code	R03DC03 (WHO)
Legal status
Legal status	AU: S4 (Prescription only) CA: ℞-only UK: POM (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	63% to 73%
Protein binding	99%
Metabolism	Hepatic (CYP2C8-major, CYP3A4 and CYP2C9-minor)
Biological half-life	2.7-5.5 hours
Excretion	Biliary
Identifiers
IUPAC name (R,E)-2-(1-((1-(3-(2-(7-Chloroquinolin-2-yl)vinyl)phenyl)-3-(2-(2-hydroxypropan-2-yl)phenyl)propylthio)methyl)cyclopropyl)acetic acid
CAS Number	158966-92-8 Y
PubChem CID	5281040
IUPHAR/BPS	3340
DrugBank	DB00471 Y
ChemSpider	4444507 Y
UNII	MHM278SD3E
KEGG	D08229 Y
ChEBI	CHEBI:50730 Y
ChEMBL	CHEMBL787 Y
ECHA InfoCard	100.115.927
Chemical and physical data
Formula	C35H36ClNO3S
Molar mass	586.184 g/mol
3D model (Jmol)	Interactive image
SMILES O=C(O)CC1(CC1)CS[C@@H](c2cccc(c2)\C=C\c3nc4cc(Cl)ccc4cc3)CCc5ccccc5C(O)(C)C
InChI InChI=1S/C35H36ClNO3S/c1-34(2,40)30-9-4-3-7-25(30)13-17-32(41-23-35(18-19-35)22-33(38)39)27-8-5-6-24(20-27)10-15-29-16-12-26-11-14-28(36)21-31(26)37-29/h3-12,14-16,20-21,32,40H,13,17-19,22-23H2,1-2H3,(H,38,39)/b15-10+/t32-/m1/s1 Y Key:UCHDWCPVSPXUMX-TZIWLTJVSA-N Y

Montelukast (trade name Singulair) is a leukotriene receptor antagonist (LTRA) used for the maintenance treatment of asthma and to relieve symptoms of seasonal allergies. Montelukast comes as a tablet, a chewable tablet, flash tablet and granules to take by mouth. Montelukast is usually taken once a day with or without food. Montelukast is a CysLT₁ antagonist; it blocks the action of leukotriene D4 (and secondary ligands LTC4 and LTE4) on the cysteinyl leukotriene receptor CysLT₁ in the lungs and bronchial tubes by binding to it. This reduces the bronchoconstriction otherwise caused by the leukotriene and results in less inflammation.

Because of its mechanism of action, it is not useful in the treatment of acute asthma attacks.

Another leukotriene receptor antagonist is zafirlukast (Accolate). Zileuton (Zyflo), an asthma drug, blocks leukotriene synthesis by inhibiting 5-lipoxygenase, an enzyme of the eicosanoid synthesis pathway.

The Mont in Montelukast stands for Montreal, the place where Merck developed the drug.

Montelukast is used for a number of conditions including asthma, exercise induced bronchospasm, allergic rhinitis, primary dysmenorrhoea (i.e. dysmenorrhoea not associated with known causes; see dysmenorrhea causes), and urticaria. It is mainly used as a complementary therapy in adults in addition to inhaled corticosteroids, if they alone do not bring the desired effect. It is also used to prevent allergic reactions and asthma flare-ups during the administration of intravenous immunoglobulin.