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Azithromycin
Systematic (IUPAC) name
9-deoxy-9a-aza-9a-methyl-9a- homoerythromycin A
Identifiers
CAS number	83905-01-5
ATC code	J01FA10
PubChem	55185
DrugBank	APRD00397
Chemical data
Formula	C38H72N2O12
Mol. mass	748.88
SMILES	eMolecules & PubChem
Pharmacokinetic data
Bioavailability	38% for 250 mg capsules
Metabolism	hepatic
Half life	68 hours
Excretion	biliary, renal (4.5%)
Therapeutic considerations
Pregnancy cat.	B1(AU) B(US)
Legal status
Routes	oral (capsule), ophthalmic

Azithromycin is an azalide, a subclass of macrolide antibiotics. Azithromycin (brand names Zithromax® in Italy, The United Kingdom, The United States, Australia, Portugal and Belgium; ATM® in India, Vinzam® / Zitromax® in Spain; Zmax®; Sumamed®; Aztrin®, Zitrocin®, Azibiot®, Azifine®,AziCip®) is one of the world's best-selling antibiotics, and is derived from erythromycin; however, it differs chemically from erythromycin in that a methyl-substituted nitrogen atom is incorporated into the lactone ring, thus making the lactone ring 15-membered. Azithromycin is used to treat certain bacterial infections, most often those causing middle ear infections, tonsillitis, throat infections, laryngitis, bronchitis, pneumonia and sinusitis. It is also effective against certain sexually transmitted infectious diseases, such as non-gonococcal urethritis and cervicitis. Recent studies have also indicated it to be effective against late-onset asthma, but these findings are controversial and not widely accepted yet.