indication

Used to treat respiratory tract, urinary and soft tissue infections.

pharmacology

Roxithromycin is a semi-synthetic macrolide antibiotic. It is very similar in composition, chemical structure and mechanism of action to erythromycin, azithromycin, or clarithromycin. Roxithromycin has the following antibacterial spectrum in vitro: Streptococcus agalactiae, Streptococcus pneumoniae (Pneumococcus), Neisseria meningitides (Meningococcus), Listeria monocytogenes, Mycoplasma pneumoniae, Chlamydia trachomatis, Ureaplasma urealyticum, Legionella pneumophila, Helicobacter (Campylobacter), Gardnerella vaginalis, Bordetella pertussis, Moraxella catarrhalis (Branhamella Catarrhalis), and Haemophilus ducreyi. Roxithromycin is highly concentrated in polymorphonuclear leukocytes and macrophages, achieving intracellular concentrations greater than those outside the cell. Roxithromycin enhances the adhesive and chemotactic functions of these cells which in the presence of infection produce phagocytosis and bacterial lysis. Roxithromycin also possesses intracellular bactericidal activity.

mechanism of action

Roxithromycin prevents bacteria from growing, by interfering with their protein synthesis. Roxithromycin binds to the subunit 50S of the bacterial ribosome, and thus inhibits the translocation of peptides. Roxithromycin has similar antimicrobial spectrum as erythromycin, but is more effective against certain gram-negative bacteria, particularly Legionella pneumophila.

toxicity

Most common side-effects are gastrointestinal; diarrhoea, nausea, abdominal pain and vomiting. Less common side-effects include headaches, rashes, abnormal liver function values and alteration in senses of smell and taste.

biotransformation

Hepatic. Roxithromycin is only partially metabolised, more than half the parent compound being excreted unchanged. Three metabolites have been identified in urine and faeces: the major metabolite is descladinose roxithromycin, with N-mono and N-di-demethyl roxithromycin as minor metabolites. The respective percentage of roxithromycin and these three metabolites is similar in urine and faeces.

absorption

Very rapidly absorbed and diffused into most tissues and phagocytes.

half life

12 hours