Clarithromycin

Also known as: Biaxin, Klaricid, Klacid, Klabax, Fromilid

CAS Number: 81103-11-9

Semi-synthetic macrolide antibiotic — 6-O-methylerythromycin

Pharmacopeia Standards

USPBPEP

Mechanism of Action

Semi-synthetic macrolide (6-O-methylerythromycin) with greater acid stability, improved oral bioavailability (~55%), and broader spectrum than erythromycin. Binds 50S ribosomal subunit. Metabolized in vivo to active 14-hydroxyclarithromycin metabolite with complementary activity. Inhibits CYP3A4 — significant drug interactions (multiple statins, tacrolimus, warfarin).

Technical Specifications

Generic / INN Name	Clarithromycin
CAS Registry Number	81103-11-9
Molecular Formula	C38H69NO13
Molecular Weight	747.95 g/mol
Typical Purity	97.0–102.0%
Storage Conditions	Store below 25°C in a dry place, protected from light
Shelf Life	36 months from date of manufacture
Category	Macrolides

Specifications are indicative and intended for sourcing reference only. Always confirm against the supplier's Certificate of Analysis and the applicable pharmacopeial monograph before issuing a purchase specification.

Typical Applications

H. pylori eradication (cornerstone of triple/quadruple therapy with PPI and amoxicillin), community-acquired pneumonia (atypical organisms), COPD exacerbations, acute maxillary sinusitis, pharyngitis/tonsillitis, MAC treatment in HIV (with ethambutol), skin/soft tissue infections.