Azithromycin Dosage Recommendations for Bacterial Infections
For adults with bacterial infections, azithromycin is dosed at 500 mg on day 1 followed by 250 mg daily for days 2-5 for most respiratory and skin infections, while pediatric dosing is weight-based at 10 mg/kg on day 1 followed by 5 mg/kg for days 2-5 for respiratory infections. 1
Adult Dosing Regimens
Respiratory Tract Infections
- Community-acquired pneumonia (mild severity): 500 mg as a single dose on day 1, followed by 250 mg once daily on days 2-5 1
- Acute bacterial exacerbations of COPD (mild to moderate):
- Option 1: 500 mg once daily for 3 days
- Option 2: 500 mg on day 1, followed by 250 mg once daily on days 2-5 1
- Acute bacterial sinusitis: 500 mg once daily for 3 days 1
Skin and Skin Structure Infections
- Uncomplicated infections: 500 mg as a single dose on day 1, followed by 250 mg once daily on days 2-5 1
- Clinical studies have shown this regimen to be as effective as dicloxacillin 250 mg four times daily for 7 days, with clinical resolution rates of approximately 83% 2
Sexually Transmitted Infections
- Non-gonococcal urethritis and cervicitis: One single 1 gram dose 1
- Gonococcal urethritis and cervicitis: One single 2 gram dose 1
- Genital ulcer disease (chancroid): One single 1 gram dose 1
Pharyngitis/Tonsillitis
- Adults: 500 mg as a single dose on day 1, followed by 250 mg once daily on days 2-5 1
- Higher dosages (500 mg daily for 3 days) have shown better efficacy in adults with Group A streptococcal tonsillopharyngitis compared to 5-day regimens 3
Pediatric Dosing Regimens
Acute Otitis Media (age ≥6 months)
- Option 1: 30 mg/kg as a single dose
- Option 2: 10 mg/kg once daily for 3 days
- Option 3: 10 mg/kg on day 1, followed by 5 mg/kg/day on days 2-5 1
Community-Acquired Pneumonia (age ≥6 months)
- 10 mg/kg as a single dose on day 1, followed by 5 mg/kg on days 2-5 1
- For suspected Mycoplasma pneumoniae, combination therapy with a β-lactam antibiotic is recommended 4
Acute Bacterial Sinusitis (age ≥6 months)
- 10 mg/kg once daily for 3 days 1
Pharyngitis/Tonsillitis (age ≥2 years)
- 12 mg/kg once daily for 5 days (maximum: 500 mg/day) 1
- Higher dosages (60 mg/kg total course) have shown superior efficacy compared to lower dosages (30 mg/kg total course) for Group A streptococcal tonsillopharyngitis 3
Special Populations
Renal Impairment
- No dosage adjustment needed for GFR 10-80 mL/min
- Use caution in severe renal impairment (GFR <10 mL/min) as AUC increases by 35% 1
Hepatic Impairment
- No specific dosage recommendations available for hepatic impairment
- Use caution as pharmacokinetics have not been established in these patients 1
Administration Considerations
- Azithromycin can be taken with or without food 1
- When taken with food, absorption may be reduced by up to 50% 5
- The unique pharmacokinetics of azithromycin allow for shorter treatment courses due to high, sustained tissue concentrations that remain above MICs for common pathogens for up to 10 days after completion of therapy 6
Clinical Pearls and Pitfalls
- Tissue penetration: Azithromycin has excellent tissue distribution (volume of distribution 23 L/kg) with intracellular accumulation, allowing for shorter treatment courses 5
- Elimination: Biphasic elimination with terminal half-life of up to 5 days, primarily through biliary excretion 5
- Resistance concerns: Consider local resistance patterns when prescribing, particularly for Streptococcus pneumoniae in respiratory infections 4
- Monitoring: Clinical improvement should be evident within 48-72 hours of starting appropriate therapy 4
- Combination therapy: For suspected atypical pneumonia in children, consider combination therapy with a β-lactam antibiotic 4
By following these dosage recommendations based on infection type, patient age, and special considerations, clinicians can optimize azithromycin therapy for bacterial infections while minimizing the risk of treatment failure and antimicrobial resistance.