Clarithromycin (6-O-methyl erythromycin) is a macrolide antibiotic used to treat pharyngitis, tonsillitis, acute maxillary sinusitis, acute bacterial exacerbation of chronic bronchitis, pneumonia (especially atypical pneumonias associated with Chlamydophila pneumoniae), skin and skin structure infections. In addition, it is sometimes used to treat legionellosis, Helicobacter pylori, and lyme disease. Recently there has been research towards whether Clarithromycin can be used to effectively treat idiopathic hypersomnia. Clarithromycin has a fairly rapid first-pass hepatic metabolism in human liver. Its major metabolites include N-desmethylclarithromycin and 14-(R)-hydroxyclarithromycin. 14-(R)-hydroxy clarithromycin is an active metabolite. Compared to clarithromycin, it is less potent against Mycobacterial tuberculosis and Mycobacterial avium complex.