What is the recommended dosage of Azithromycin (macrolide antibiotic) for a 5-month-old child weighing 7.7 kg?

Azithromycin Dosage for a 5-Month-Old Weighing 7.7 kg

For a 5-month-old child weighing 7.7 kg, the recommended dosage of azithromycin is 10 mg/kg (77 mg) on day 1, followed by 5 mg/kg (38.5 mg) once daily for days 2-5. 1

Dosing Regimen

• The standard 5-day course for infants consists of:

  • Day 1: 10 mg/kg = 77 mg once daily 1
  • Days 2-5: 5 mg/kg = 38.5 mg once daily 1, 2

• This dosing regimen is supported by multiple clinical guidelines and is considered appropriate for infants in this age group 2, 1

• For liquid formulations, azithromycin is typically available as a 40 mg/mL suspension, meaning approximately 1.9 mL on day 1 and 1 mL on days 2-5 3

Clinical Indications

• This dosing regimen is appropriate for common pediatric infections including:

  • Community-acquired pneumonia, particularly atypical pneumonia caused by Mycoplasma or Chlamydia 2, 1
  • Pertussis treatment and post-exposure prophylaxis 1
  • Upper respiratory tract infections 3

• For infants under 6 months, azithromycin is preferred over other macrolides (like erythromycin) due to lower risk of infantile hypertrophic pyloric stenosis 4

Safety Considerations

• Azithromycin has fewer gastrointestinal side effects compared to other macrolides 4
• Common side effects include abdominal discomfort, diarrhea, nausea, and vomiting (occurring in approximately 9% of pediatric patients) 4, 3
• Do not administer with aluminum- or magnesium-containing antacids as they reduce absorption 4
• Monitor for potential drug interactions, particularly with medications that prolong QT interval 1

Administration Pearls

• Azithromycin can be administered without regard to meals, though administration with food may improve gastrointestinal tolerability 3, 5
• The once-daily dosing regimen improves compliance compared to other antibiotics requiring multiple daily doses 6, 5
• The 5-day course is sufficient for most indications due to azithromycin's long tissue half-life and persistent antimicrobial effects 3, 5

Clinical Advantages

• Azithromycin achieves high tissue concentrations despite relatively low serum levels 6
• It maintains effective tissue concentrations longer than many other antibiotics 5
• The short-course therapy (5 days) with once-daily dosing improves patient compliance 5, 7
• Activity against both typical and atypical respiratory pathogens makes it suitable for empiric therapy 3, 8

By following this dosing regimen, you can provide effective antimicrobial therapy for this 5-month-old infant while minimizing the risk of adverse effects.