-5%
Zimax contains Azithromycin, an acid-stable macrolide antibiotic that is readily absorbed after oral administration. Since it is resistant to degradation by gastric acid, it does not require enteric protection. Absorption is enhanced when taken on an empty stomach, with peak plasma concentrations generally achieved within 2.1–3.2 hours.
Azithromycin is actively transported by phagocytic cells to sites of infection, where high intracellular concentrations are released during phagocytosis. Tissue concentrations may exceed plasma concentrations by more than 50-fold, contributing to prolonged antibacterial activity.
The drug has an extended elimination half-life of approximately 68 hours, allowing convenient once-daily dosing while maintaining therapeutic tissue concentrations for several days. Elimination occurs mainly through biliary excretion as an unchanged drug, with approximately 6% excreted unchanged in urine.
Azithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit of susceptible bacteria. This suppresses bacterial growth without interfering with nucleic acid synthesis.
It demonstrates activity against a broad spectrum of susceptible microorganisms, including:
Gram-positive bacteria
- Staphylococcus aureus
- Streptococcus pneumoniae
- Streptococcus pyogenes
- Streptococcus agalactiae
- Group C, F, and G streptococci
- Viridans streptococci
Gram-negative bacteria
- Haemophilus influenzae
- Haemophilus ducreyi
- Moraxella catarrhalis
- Neisseria gonorrhoeae
- Bordetella pertussis
- Legionella pneumophila
Other susceptible organisms
- Chlamydia trachomatis
- Chlamydia pneumoniae
- Mycoplasma pneumoniae
- Peptostreptococcus species
- Prevotella bivia
The presence of beta-lactamase enzymes does not significantly affect azithromycin activity.
Dosage & Administration
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Intravenous Administration (Adults)
Community-Acquired Pneumonia
- 500 mg IV once daily for at least 2 days, followed by 500 mg orally once daily to complete a 7–10-day treatment course.
Pelvic Inflammatory Disease
- 500 mg IV once daily for 1–2 days, followed by 250 mg orally once daily to complete a total of 7 days of therapy.
When anaerobic pathogens are suspected, an additional antimicrobial with anaerobic coverage should be administered.
The safety and efficacy of injectable azithromycin have not been established in children and adolescents younger than 16 years.