macrolide antibiotic roxithromycin Roxithromycin is a semi-synthetic, 14-carbon ring macrolide antibiotic derived from erythromycin. It is used to treat respiratory tract, urinary and soft tissue infections. Roxithromycin may possess bacteriocidal activity, particularly at higher concentrations by binding to the 50S subunit of the bacterial 70S rRNA complex, protein synthesis and subsequently structure/function processes critical for life or replication are inhibited. PubChem:6915744 antibiotic_resistance ChEMBL:CHEMBL1214185 ChEBI:48844 ARO:0000027