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The macrolides: erythromycin, clarithromycin, and azithromycin

S Alvarez-Elcoro1, M J Enzler

  • 1Division of Infectious Diseases and Internal Medicine, Mayo Clinic Jacksonville, Florida, USA.

Mayo Clinic Proceedings
|June 23, 1999
PubMed

Insights

New macrolides like azithromycin and clarithromycin offer improved stability and broader spectrum against infections such as Mycobacterium avium complex (MAC). However, increasing macrolide resistance is a growing concern for future antimicrobial effectiveness.

Area of Science:

  • Microbiology
  • Pharmacology
  • Infectious Diseases

Background:

  • Erythromycin has been a primary macrolide antibiotic, but newer agents offer distinct advantages.
  • Azithromycin and clarithromycin represent advancements in macrolide antibiotic therapy.

Purpose of the Study:

  • To compare the chemical stability, antimicrobial spectrum, pharmacokinetics, and clinical applications of azithromycin and clarithromycin versus erythromycin.
  • To highlight the efficacy of azithromycin and clarithromycin in treating specific infections, including Mycobacterium avium complex (MAC) and atypical respiratory pathogens.
  • To address the emerging issue of macrolide resistance and its potential impact on future treatment strategies.

Main Methods:

  • Comparative analysis of chemical stability and antimicrobial spectrum.
  • Pharmacokinetic profiling to assess dosing schedules and tissue penetration.
  • Review of clinical data regarding efficacy in MAC prophylaxis and treatment, respiratory tract infections, skin/soft tissue infections, community-acquired pneumonia, and pelvic inflammatory diseases.
  • Assessment of drug-drug interactions and pediatric tolerance.

Main Results:

  • Azithromycin and clarithromycin exhibit enhanced chemical stability and broader antimicrobial activity compared to erythromycin, particularly against MAC, H. influenzae, and C. trachomatis.
  • Both agents demonstrate excellent activity against atypical respiratory pathogens (C. pneumoniae, Mycoplasma) and Legionella species.
  • Pharmacokinetics allow for shorter dosing schedules; both are effective for MAC prophylaxis in AIDS patients, with azithromycin preferred due to fewer interactions.
  • Clarithromycin is crucial for treating active MAC disease; azithromycin offers advantages in pediatric compliance.
  • Increasing macrolide resistance in S. pneumoniae, group A streptococci, and H. influenzae is a significant concern.

Conclusions:

  • Azithromycin and clarithromycin are valuable macrolide antibiotics with improved profiles over erythromycin, offering effective treatment options for various infections.
  • Their pharmacokinetic properties and efficacy in specific patient populations (e.g., AIDS, children) enhance therapeutic utility.
  • The rising prevalence of macrolide resistance poses a threat to the long-term clinical effectiveness of this antibiotic class.

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