Ondansetron

Ondansetron
Clinical data
Trade names	Zofran, others
AHFS/Drugs.com	Monograph
MedlinePlus	a601209
License data	US DailyMed: Ondansetron;
Pregnancy; category	AU: B1;
Routes of; administration	By mouth, rectal, intravenous, intramuscular, thin film
Drug class	Antiemetic;; 5-HT3 receptor antagonist;
ATC code	A04AA01 (WHO) ;
Legal status
Legal status	AU: S4 (Prescription only); CA: ℞-only; UK: POM (Prescription only); US: ℞-only; EU: Rx-only;
Pharmacokinetic data
Bioavailability	~60%
Protein binding	70–76%
Metabolism	Liver (CYP3A4, CYP1A2, CYP2D6)
Elimination half-life	5.7 hours
Excretion	Kidney
Identifiers
	IUPAC name (RS)-9-Methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-2,3-dihydro-1H-carbazol-4(9H)-one;
CAS Number	99614-02-5 ;
PubChem CID	4595;
IUPHAR/BPS	2290;
DrugBank	DB00904 ;
ChemSpider	4434 ;
UNII	4AF302ESOS;
KEGG	D00456 ;
ChEMBL	ChEMBL46 ;
CompTox Dashboard (EPA)	DTXSID8023393 ;
ECHA InfoCard	100.110.918
Chemical and physical data
Formula	C18H19N3O
Molar mass	293.370 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES O=C1c2c3ccccc3n(C)c2CCC1Cn4ccnc4C;
	InChI InChI=1S/C18H19N3O/c1-12-19-9-10-21(12)11-13-7-8-16-17(18(13)22)14-5-3-4-6-15(14)20(16)2/h3-6,9-10,13H,7-8,11H2,1-2H3 ; Key:FELGMEQIXOGIFQ-UHFFFAOYSA-N ;
	(verify)

Ondansetron, sold under the brand name Zofran among others, is a medication used to prevent nausea and vomiting caused by chemotherapy, radiation therapy, migraines, or surgery. It is also effective for treating gastroenteritis. It can be given orally (by mouth), intramuscularly (injection into a muscle), or intravenously (injection into a vein).

Common side effects include diarrhea, constipation, headache, sleepiness, and itchiness. Serious side effects include QT prolongation and severe allergic reaction. It appears to be safe during pregnancy but has not been well studied in this group. It is a serotonin 5-HT₃ receptor antagonist. It does not have any effect on dopamine receptors or muscarinic acetylcholine receptor and therefore does not cause akathisia.

Ondansetron was patented in 1984 and approved for medical use in 1990. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2022, it was the 61st most commonly prescribed medication in the United States, with more than 10 million prescriptions.