Clarithromycin is a semi-synthetic macrolide antibiotic. Chemically it is 6-0 methylerythromycin. Like other macrolides, clarithromycin binds to the 50S subunit of the 70S ribosome, thereby blocking RNA-mediated bacterial protein synthesis. Clarithromycin can be bacteriostatic or bactericidal in action, depending on the concentration as well as the particular organism and its inoculum. The minimum inhibitory concentrations (MIC) of clarithromycin are generally two-fold lower than the MIC of erythromycin.