Azithromycin Dosing for a 28-lb Child
For a 28-lb (12.7 kg) child, give 5 mL (1 teaspoon) of Zithromax 200 mg/5 mL suspension on day 1, followed by 2.5 mL (½ teaspoon) once daily on days 2 through 5, for a standard 5-day regimen treating community-acquired pneumonia or atypical respiratory infections. 1
Weight-Based Calculation
- A 28-lb child weighs approximately 12.7 kg, which falls into the 10–15 kg weight band in pediatric dosing tables 1
- The FDA-approved 5-day regimen uses 10 mg/kg on day 1 (= 127 mg ≈ 125 mg = 5 mL of 200 mg/5 mL suspension), then 5 mg/kg daily on days 2–5 (= 63.5 mg ≈ 62.5 mg = 2.5 mL) 1
- This delivers a total course of 300 mg over 5 days 1
Indication-Specific Considerations
- This 5-day regimen (10 mg/kg day 1, then 5 mg/kg days 2–5) is the standard for community-acquired pneumonia and atypical respiratory infections caused by Mycoplasma pneumoniae, Chlamydia pneumoniae, or Chlamydia trachomatis 2, 1
- For acute otitis media, the FDA label offers three options: the same 5-day regimen above, a 3-day course of 10 mg/kg daily, or a single 30 mg/kg dose 1
- For streptococcal pharyngitis, azithromycin is second-line only (penicillin or amoxicillin remain first-line), and requires a higher dose of 12 mg/kg once daily for 5 days due to high recurrence rates with standard dosing 2
- Azithromycin should not be used as first-line monotherapy for typical bacterial pneumonia caused by Streptococcus pneumoniae or Haemophilus influenzae; amoxicillin 90 mg/kg/day is preferred 2
Administration and Safety
- Azithromycin suspension can be taken with or without food 1
- Do not give simultaneously with aluminum- or magnesium-containing antacids; separate by at least 2 hours, as antacids reduce absorption 2, 1
- Common adverse effects include gastrointestinal disturbances (abdominal discomfort, diarrhea, nausea, vomiting), dizziness, and headache 2
- Children on appropriate therapy should show clinical improvement within 48–72 hours; if no improvement or deterioration occurs, reassess the diagnosis and consider alternative pathogens or complications 2
Common Pitfalls to Avoid
- Do not underdose the initial 10 mg/kg loading dose on day 1; full dosing is essential to achieve therapeutic tissue levels 2
- Do not use azithromycin as first-line for typical bacterial pneumonia or strep throat, as β-lactam agents have superior outcomes and lower recurrence rates 2
- For strep pharyngitis specifically, the standard 5-day regimen has unacceptably high recurrence; use 12 mg/kg daily × 5 days or choose penicillin/amoxicillin instead 2