Class
Macrolide antibiotic
Pharmacodynamics
- Inhibits bacterial protein synthesis by binding to 50S ribosomal RNA
Pharmacokinetics
- PO or IV administration
- Rapidly absorbed orally
- Penetrates into most tissues (except CSF) and phagocytic cells extremely well
- Tissue concentrations exceed serum concentrations 10-100 fold
- Drug is slowly released from tissues (tissue half life 2-4 days), elimination half-life thus ~3 days
- Permits infrequent dosing and short courses of treatment
- No CYP interactions, unlike erythromycin and clarithromycin
Antimicrobial activity of macrolide antibiotics
- Gram positive organisms e.g. pneumococci, strep, staph
- Mycoplasma pneumoniae, L pneumophila, Chlamydophila pneumoniae, Listeria monocytogenes
- Gram negative organisms e.g. neisseria, bordatella pertussis, campylobacter
- Treponema pallidum
- Azithromycin specifically:
- Highly active against Chlamydophila sp.
- Active against Toxoplasma gondii
- Slightly less active against staph and strep
- Slightly more active against H influenzae
Adverse effects
- Prolonged QT interval
Further reading
- Buttner R. Pharm 101: Erythromycin. LITFL
References
- Katzung BG. Basic and Clinical Pharmacology. 14e. 2018: 820, 824
Pharmacology 101
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MBBS FACEM DDU (Emergency) CCPU. Emergency Physician in Melbourne, Australia. Co-Ultrasound Lead for Emergency Medicine at The Alfred Hospital. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor of the LITFL ECG Library.
