Overview
Azithromycin is a broad-spectrum macrolide antibiotic used to treat various bacterial infections. It works by inhibiting bacterial protein synthesis and is particularly effective against respiratory, skin, and sexually transmitted infections. It has a long half-life allowing for once-daily dosing and shorter treatment courses compared to other antibiotics.
Mechanism of Action
Azithromycin binds to the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis by blocking transpeptidation/translocation steps. This bacteriostatic action prevents bacterial growth and replication.
Indications
- Acute bacterial exacerbations of COPD
- Community-acquired pneumonia
- Pharyngitis/tonsillitis
- Acute bacterial sinusitis
- Uncomplicated skin infections
- Urethritis and cervicitis
- Genital ulcer disease
- Acute otitis media
- Mycobacterium avium complex prophylaxis
Dosage
Typical adult dosage: 500 mg on day 1, followed by 250 mg daily on days 2-5. Alternative: 500 mg daily for 3 days. Pediatric dosage based on weight. Take 1 hour before or 2 hours after meals.
Contraindications
- Hypersensitivity to azithromycin, erythromycin, or other macrolides
- History of cholestatic jaundice/hepatic dysfunction with prior azithromycin use
- Concurrent use with pimozide
Side Effects
- Diarrhea
- Nausea
- Abdominal pain
- Headache
- Dizziness
- Rash
- Elevated liver enzymes
- QT prolongation
- Hearing impairment (rare)
Interactions
- Antacids (reduce absorption)
- Warfarin (increased INR)
- Digoxin (increased levels)
- Cyclosporine (increased levels)
- Nelfinavir (increased azithromycin levels)
- QT-prolonging drugs (additive effects)