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Additional Information  |  Mode of Action

Mode of Action

Effective treatment from a range of once-daily formulations1

Resources Watch the ZITHROMAX® Mode of Action Video Watch now LoadingZITHROMAX Mode of Action
  • ZITHROMAX is an azalide, a sub-class of the macrolide antibiotics1,2; it is chemically different2-4 and has a substantially longer half-life compared with other macrolide antibiotics3–7
  • ZITHROMAX is the only once-daily antibiotic in this class1,4-6
  • ZITHROMAX inhibits protein synthesis at ribosomes within susceptible bacterial cells1
  • ZITHROMAX concentrations are markedly higher in tissues than in plasma – up to 50 times the maximum observed concentration in plasma2
  • Concentrations in target tissues, such as lung, tonsil, and prostate, exceed the MIC90 for likely pathogens after a single dose of 500 mg2
  • Macrophages and polymorphonuclear leucocytes concentrate ZITHROMAX at levels greater than those found in tissues,7 delivering high concentrations at the site of infection; phagocytosis then enables release of ZITHROMAX in high concentrations2
  • Once-daily regimens help optimize patient adherence to antibiotic treatment in outpatient/ambulatory settings8

The most recent local resistance data available must always take precedence when selecting antimicrobial therapy; in settings where local resistance data are not available, national and international guidelines can help inform antimicrobial choice.
As with erythromycin and other macrolides, rare serious allergic  reactions, including angioedema and anaphylaxis (rarely fatal), Dermatologic reactions including Acute Generalized Exanthematous Pustulosis (AGEP), Stevens-Johnson Syndrome (SJS), Toxic Epidermal Necrolysis (TEN) (rarely fatal), and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) have been reported. Some of these reactions with azithromycin have resulted in recurrent symptoms and required a longer period of observation and treatment. If an allergic reaction occurs, the drug should be discontinued and appropriate therapy should be instituted. Physicians should be aware that reappearance of the allergic symptoms may occur when symptomatic therapy is discontinued1

You might also be interested in...Resources Pediatrics: How to Properly Administer ZITHROMAX® Watch now LoadingReferences:Pfizer Malaysia ZITHROMAX Prescribing Information. Available at: Accessed January 2024.Data on file, Pfizer. Azithromycin Core Data Sheet Version 14.0, April 2016.Drew RH, et al. Pharmacotherapy. 1992;12(3):161–73.Amsden GW. Clin Ther. 1996;18(1):56–72.Erythrocin 500 Tablets Summary of Product Characteristics. Available at:
. Accessed June 2023.
Clarithromycin 250 mg Film-coated Tablets Summary of Product Characteristics. Available at: https://
. Accessed June 2023.
Lode H. Eur J Clin Microbiol Infect Dis. 1991;10(10):807–12.Kardas P. J Antim Chem. 2007;59:531–6.
Additional Information ZITHROMAX® Safety Information Find out more Loading
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