Azithromycin Pediatric Dosing
For most pediatric infections, azithromycin should be dosed at 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg (maximum 250 mg) once daily on days 2-5, which is the standard 5-day regimen recommended by major guidelines and the FDA. 1, 2, 3
Standard Dosing by Indication
Community-Acquired Pneumonia (Atypical Pathogens)
- Oral therapy: 10 mg/kg (max 500 mg) on day 1, then 5 mg/kg (max 250 mg) daily for days 2-5 1, 2, 3
- IV therapy: 10 mg/kg (max 500 mg) once daily on days 1-2, then transition to oral therapy as soon as clinically feasible 1, 2
- This regimen is specifically indicated for Mycoplasma pneumoniae, Chlamydia trachomatis, and Chlamydophila pneumoniae 1, 2
Acute Otitis Media
The FDA approves three alternative regimens 3:
- 5-day regimen: 10 mg/kg day 1, then 5 mg/kg days 2-5 (preferred)
- 3-day regimen: 10 mg/kg once daily for 3 days
- Single-dose regimen: 30 mg/kg as a single dose
Acute Bacterial Sinusitis
- 3-day regimen: 10 mg/kg once daily for 3 days 3
Pharyngitis/Tonsillitis (Streptococcal)
- 12 mg/kg once daily for 5 days (maximum 500 mg/day) 2, 3
- Critical caveat: The standard 3-day regimen (10 mg/kg daily) is inadequate for streptococcal pharyngitis, with significantly higher recurrence rates compared to penicillin 4
- This is a second-line therapy; penicillin remains first-line 1
Pertussis (Treatment and Prophylaxis)
- Infants <6 months: 10 mg/kg once daily for 5 days 2
- Children ≥6 months: 10 mg/kg (max 500 mg) day 1, then 5 mg/kg (max 250 mg) days 2-5 2
Weight-Based Dosing Table (5-Day Regimen)
For the standard 5-day regimen 3:
| Weight | Day 1 Dose | Days 2-5 Dose | Total Course |
|---|---|---|---|
| 5 kg (11 lbs) | 50 mg | 25 mg | 150 mg |
| 10 kg (22 lbs) | 100 mg | 50 mg | 300 mg |
| 20 kg (44 lbs) | 200 mg | 100 mg | 600 mg |
| 30 kg (66 lbs) | 300 mg | 150 mg | 900 mg |
| 40 kg (88 lbs) | 400 mg | 200 mg | 1200 mg |
| ≥50 kg (≥110 lbs) | 500 mg | 250 mg | 1500 mg |
Never exceed adult doses regardless of calculated pediatric weight-based dosing 1
Age-Specific Considerations
Infants <1 Month
- Azithromycin is the preferred macrolide for pertussis treatment and prophylaxis at 10 mg/kg once daily for 5 days 2
- The risk of severe pertussis complications outweighs potential risks of azithromycin treatment in this age group 2
- Monitor for infantile hypertrophic pyloric stenosis (IHPS), though azithromycin has not been definitively associated with this condition 2
Children ≥6 Months
- All standard regimens are appropriate for this age group 3
- Azithromycin can be taken with or without food 3
Common Pitfalls to Avoid
Underdosing for Streptococcal Pharyngitis
- Do not use the standard 3-day regimen (10 mg/kg daily) for streptococcal pharyngitis 4
- This results in bacteriologic failure in 46% of cases compared to 14% with penicillin 4
- Must use 12 mg/kg once daily for 5 days for this indication 2, 3
Inappropriate Use for Typical Bacterial Pneumonia
- Azithromycin is not first-line for typical bacterial pneumonia caused by S. pneumoniae or H. influenzae 1
- Beta-lactam antibiotics (amoxicillin, amoxicillin-clavulanate) remain first-line for typical pathogens 1
- Reserve azithromycin for atypical pathogens or when atypical coverage is specifically needed 1, 2
Prolonged IV Therapy
- Limit IV azithromycin to days 1-2 only, then transition to oral therapy when feasible 1, 2
- Prolonged IV therapy beyond 2 days is unnecessary given azithromycin's excellent tissue penetration and long half-life 2
Drug Interactions and Safety
Administration Considerations
- Do not administer simultaneously with aluminum- or magnesium-containing antacids, as they reduce absorption 2
- Monitor for QT prolongation when used with other QT-prolonging medications 2
- Azithromycin has fewer gastrointestinal side effects than erythromycin 2, 5
Renal Impairment
- No dosage adjustment needed for mild to moderate renal impairment (GFR 10-80 mL/min) 3
- Exercise caution in severe renal impairment (GFR <10 mL/min), as AUC increases by 35% 3