indication

For the treatment of patients with mild to moderate infections caused by susceptible strains of the designated microorganisms in the specific conditions: H. influenzae, M. catarrhalis, S. pneumoniae, C. pneumoniae, M. pneumoniae, S. pyogenes, S. aureus, S. agal

pharmacology

Azithromycin, a semisynthetic antibiotic belonging to the macrolide subgroup of azalides, is used to treat STDs due to chlamydia and gonorrhea, community-acquired pneumonia, pelvic inflammatory disease, pediatric otitis media and pharyngitis, and Mycobacterium avium complex (MAC) in patients with advanced HIV disease. Similar in structure to erythromycin. azithromycin reaches higher intracellular concentrations than erythromycin, increasing its efficacy and duration of action.

mechanism of action

Azithromycin binds to the 50S subunit of the 70S bacterial ribosomes, and therefore inhibits RNA-dependent protein synthesis in bacterial cells.

toxicity

Potentially serious side effects of angioedema and cholestatic jaundice were reported

biotransformation

Hepatic. In vitro and in vivo studies to assess the metabolism of azithromycin have not been performed.

absorption

Bioavailability is 37% following oral administration. Absorption is not affected by food. Azithromycin is extensively distributed in tissues with tissue concentrations reaching up to 50 times greater than plasma concentrations. Drug becomes concentrated within macrophages and polymorphonucleocytes giving it good activity against Chlamydia trachomatis.

half life

68 hours

route of elimination

Biliary excretion of azithromycin, predominantly as unchanged drug, is a major route of elimination.

drug interactions

Acenocoumarol: Azithromycin may increase the anticoagulant effect of acenocoumarol by increasing its serum concentration.

Anisindione: Azithromycin may increase the anticoagulant effect of anisindione by increasing its serum concentration.

Artemether: Additive QTc-prolongation may occur. Concomitant therapy should be avoided.

Cyclosporine: The macrolide, azithromycin, may increase the effect of cyclosporine.

Dicumarol: Azithromycin may increase the anticoagulant effect of dicumarol by increasing its serum concentration.

Disopyramide: The macrolide, azithromycin, may increase the effect of disopyramide.

Lovastatin: The macrolide antibiotic, azithromycin, may increase the serum concentration of lovastatin by decreasing its metabolism. Monitor for changes in the therapeutic and adverse effects of lovastatin if azithromycin is initiated, discontinued or dose changed.

Lumefantrine: Additive QTc-prolongation may occur. Concomitant therapy should be avoided.

Vorinostat: Additive QTc prolongation may occur. Consider alternate therapy or monitor for QTc prolongation as this can lead to Torsade de Pointes (TdP).

Warfarin: Azithromycin may increase the anticoagulant effect of warfarin by increasing its serum concentration.

Ziprasidone: Additive QTc-prolonging effects may increase the risk of severe arrhythmias. Concomitant therapy is contraindicated.

Zuclopenthixol: Additive QTc prolongation may occur. Consider alternate therapy or use caution and monitor for QTc prolongation as this can lead to Torsade de Pointes (TdP).