Roxithromycin is a semi-synthetic macrolide antibiotic. It is used to treat respiratory tract, urinary and soft tissue infections. Roxithromycin is derived from erythromycin, containing the same 14-membered lactone ring. However, an N-oxime side chain is attached to the lactone ring.

Roxithromycin is available under several brandnames, for example Surlid and Rulid

Roxithromycin
'"erythromycin-9-(-o-[2-methoxyethoxy]methyloxime)"
Molecular Weight	836.94
Empiric Formula	C41H76N2O15
ATC code	J01FA06
Metabolism	Liver
Pregnancy category	? (USA) B1 (Aus)

History

French pharmaceutical company Hoechst Uclaf brought out roxithromycin in 1987.

Available forms

Roxithromycin is commonly administered in tablets or oral suspension.

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 pneumophilae .

Pharmacokinetics

When taken before a meal, roxithromycin is very rapidly absorbed, and diffused into most tissues and phagocytes. Due to the high concentration in phagocytes, roxithromycin is actively transported to the site of infection. During active phagocytosis, large concentrations of roxithromycin are released.

Metabolism

Only a small portion of roxithromycin is metabolised. Most of roxithromycin is secreted unchanged into the bile and some in expired air. Under 10% is excreted into the urine. Roxithromycin's half-life is 12 hours.

Side effects

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.