Class Explorer · Anti-infectives
Macrolides
Bind the 50S ribosomal subunit and block translocation. Bacteriostatic, excellent intracellular and atypical coverage, and the interaction profile of a CYP3A4 inhibitor.
Members
AzithromycinA three-day course that keeps working for a week.ClarithromycinAn effective antibiotic and a potent CYP3A4 inhibitor in the same tablet.
Also in this class: Erythromycin. Full pages arrive as the library grows.
Compare the members
Azithromycin
- CYP3A4
- Minimal inhibition
- Half-life
- Very long, tissue
- Niche
- Short courses, fewer interactions
Clarithromycin
- CYP3A4
- Potent inhibitor
- Half-life
- 3 to 7 h
- Niche
- H. pylori regimens
Shared across the class
- Indications
- Community-acquired pneumonia, atypical cover · Pertussis · Chlamydia · H. pylori eradication (clarithromycin)
- Adverse effects
- Gastrointestinal upset · QT prolongation · Hepatotoxicity, uncommon
- Contraindications
- Known QT prolongation with other risk factors · Concurrent drugs with dangerous CYP3A4 dependence
- Monitoring
- QT where other QT-prolonging drugs are in play · INR if the patient is on warfarin · Clinical response
What makes each agent different
- Clarithromycin is a potent CYP3A4 inhibitor and the source of the statin, calcium-channel-blocker and warfarin interactions this class is known for. Azithromycin barely touches CYP3A4, which is its main practical advantage.
- Azithromycin's tissue half-life is measured in days, which is what allows three- and five-day courses that keep working after the last tablet.
The macrolide plus statin combination is a rhabdomyolysis question every time: with clarithromycin the usual answer is to hold the statin for the course.
Both raise cardiovascular risk slightly through QT effects; in a patient already collecting QT-prolonging drugs, doxycycline is often the quieter choice.
Last reviewed 2026-08-16 · Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed.