It is produced by the strain of erythromycin. Clarithromycin, a CYP3A4 inhibitor, is a macrolide antibiotic used to treat pharyngitis, tonsillitis, acute maxillary sinusitis, acute bacterial exacerbation of chronic bronchitis, pneumonia, skin and skin structure infections. It prevents bacteria from growing by interfering with their protein synthesis and binds to the subunit 50S of the bacterial ribosome and thus inhibits the translation of peptides. It has similar antimicrobial spectrum as erythromycin, but is more effective against certain Gram-negative bacteria, particularly Legionella pneumophila. It also has bactericidal effect on certain strains, such as Haemophilus influenzae, Streptococcus pneumoniae and Neisseria gonorrhoeae.