Brands, Medical Use, Clinical Data
Brands / Synonyms
ROX; Rulid; Rulide; Surlid
Used to treat respiratory tract, urinary and soft tissue infections.
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.
Very rapidly absorbed and diffused into most tissues and phagocytes.
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.
Biotrnasformation / Drug Metabolism
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.
Known allergy to macrolides.
Concomitant administration of roxithromycin with vasoconstrictive ergot (alkaloid) derivatives is contra-indicated since symptoms of ergotism have been described with other macrolides.
Concomitant administration contra-indicated:
- Vasoconstrictive ergot alkaloids.
Concomitant administrations not recommended:
- Terfenadine and astemizole: Certain macrolides interact with terfenadine and astemizole leading to increased serum concentrations of the latter. This may result in severe ventricular arrhythmia, typically torsades de pointe. Although such a reaction has not been demonstrated with roxithromycin, concomitant administration of roxithromycin with terfenadine or astemizole is not recommended.
- Cisapride, pimozide: Other drugs such as cisapride or pimozide, which are metabolised by hepatic CYP3A isozymes have been associated with QT interval prolongation and/or cardiac arrythmias (typically torsades de pointe) as a result of increase in their serum level subsequent to interaction with significant inhibitors of the isozyme, including some macrolide antibacterials. Although such a risk is not verified for roxithromycin, combination of roxithromycin with such drugs is not recommended.