Clarithromycin and azithromycin: new macrolide antibiotics.

Area of Science:

• Pharmacology
• Infectious Diseases
• Microbiology

Background:

• Clarithromycin and azithromycin are novel macrolide antibiotics structurally related to erythromycin.
• They exhibit distinct antimicrobial spectrums compared to erythromycin, with enhanced activity against specific pathogens.

Purpose of the Study:

• To describe the chemistry, mechanism of action, spectrum, pharmacokinetics, efficacy, safety, and dosing of clarithromycin and azithromycin.
• To compare the properties and clinical applications of these new macrolides with erythromycin.

Main Methods:

• Review of existing literature on clarithromycin and azithromycin.
• Analysis of their chemical structures, antimicrobial activity, pharmacokinetic profiles, and clinical trial data.

Main Results:

• Clarithromycin shows increased activity against Staphylococcus aureus, streptococci, Legionella pneumophila, Moraxella catarrhalis, Chlamydia trachomatis, Mycobacterium avium complex, and Toxoplasma gondii.
• Azithromycin demonstrates enhanced gram-negative activity (e.g., Haemophilus influenzae) while retaining gram-positive coverage, and is effective against Chlamydia trachomatis.
• Both antibiotics possess good oral bioavailability, excellent tissue penetration, long half-lives allowing once or twice-daily dosing, and have shown efficacy in treating respiratory tract infections, skin infections, and Chlamydia trachomatis infections.

Conclusions:

• Clarithromycin and azithromycin represent advancements over erythromycin, with potential advantages in treating various infections, including those caused by resistant organisms and in immunocompromised patients.
• Further clinical trials are needed to fully establish their role in therapeutic guidelines.
• Common adverse effects include gastrointestinal disturbances such as nausea, diarrhea, and abdominal pain.