What is the recommended dose of Azithromycin in pediatric patients?

Azithromycin Dosing in Pediatric Patients

For most pediatric respiratory infections, administer azithromycin 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg (maximum 250 mg) once daily on days 2-5. 1

Standard Dosing by Indication

Community-Acquired Pneumonia and Atypical Pneumonia

• The preferred regimen is 10 mg/kg (max 500 mg) on day 1, then 5 mg/kg (max 250 mg) daily for days 2-5 for children ≥6 months with community-acquired pneumonia, particularly when caused by atypical pathogens (Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia trachomatis) 1, 2
• This 5-day regimen is recommended by both the American Academy of Pediatrics and the Infectious Diseases Society of America 1
• Alternative 3-day regimen: 10 mg/kg once daily for 3 days is also FDA-approved and equally effective 2, 3

Acute Otitis Media

• Three FDA-approved options exist: 2
  • Single 30 mg/kg dose (maximum 1500 mg)
  • 10 mg/kg once daily for 3 days
  • 10 mg/kg on day 1, then 5 mg/kg daily for days 2-5
• All three regimens demonstrate comparable efficacy 2, 3

Acute Bacterial Sinusitis

• 10 mg/kg once daily for 3 days is the recommended regimen 1, 2

Streptococcal Pharyngitis/Tonsillitis

• Azithromycin is second-line therapy only—penicillin or amoxicillin remain first-line 1
• When used, the dose must be 12 mg/kg once daily for 5 days (maximum 500 mg/day) due to high recurrence rates with standard 10 mg/kg dosing 1
• Studies demonstrate inferior bacteriologic eradication (65% vs. 82%) with 10 mg/kg for 3 days compared to penicillin V, though clinical outcomes remain similar 4

Pertussis Treatment and Prophylaxis

• Infants <6 months: 10 mg/kg once daily for 5 days 1
• Children ≥6 months: 10 mg/kg (max 500 mg) on day 1, then 5 mg/kg (max 250 mg) daily for days 2-5 1
• Azithromycin is the preferred macrolide for infants under 1 month due to superior safety profile compared to erythromycin 1

Intravenous Azithromycin Dosing

For pediatric patients requiring IV therapy, administer 10 mg/kg once daily (maximum 500 mg) on days 1-2, then transition to oral therapy as soon as clinically feasible. 1

• IV azithromycin is specifically indicated for atypical pathogens when parenteral therapy is required 1
• Common pitfall: Avoid prolonged IV therapy beyond 2 days when oral therapy is feasible 1
• Important caveat: Typical bacterial pneumonia requires beta-lactam antibiotics as first-line therapy, not azithromycin 1

Weight-Based Dosing for Chronic Therapy

For conditions requiring prolonged therapy (e.g., cystic fibrosis exacerbations), weight-based daily dosing: 1

• 15-25 kg: 200 mg once daily
• 26-35 kg: 300 mg once daily
• 36-45 kg: 400 mg once daily
• ≥46 kg: 500 mg once daily

Special Populations and Considerations

Adolescents with Chlamydial Infections

• Single 1 gram oral dose for uncomplicated urethritis or cervicitis caused by Chlamydia trachomatis 1

MAC Prophylaxis in HIV-Infected Children

• 20 mg/kg (maximum 1200 mg) once weekly 1

Maximum Dose Considerations

• Oral doses should never exceed adult doses regardless of weight: maximum 500 mg on day 1 and 250 mg daily for the standard 5-day respiratory regimen 1

Safety and Tolerability

• Azithromycin has fewer gastrointestinal side effects compared to erythromycin 1
• Treatment-related adverse events occur in approximately 9% of patients, mostly mild-to-moderate gastrointestinal complaints 5
• Common side effects include abdominal discomfort, diarrhea, nausea, vomiting, headache, and dizziness 1
• Drug interaction warning: Do not administer simultaneously with aluminum- or magnesium-containing antacids, as they reduce absorption 1
• Monitor for QT interval prolongation when used with other QT-prolonging medications 1
• Higher doses (30 mg/kg single dose or 20 mg/kg/day for 3 days) are associated with more adverse effects but remain well-tolerated 5

Clinical Pearls

• Azithromycin can be taken with or without food 2
• The 3-day and 5-day regimens demonstrate comparable efficacy and tolerability for respiratory infections 3
• For infants under 1 month with pertussis, the benefits of treatment outweigh potential risks, though monitoring for infantile hypertrophic pyloric stenosis (IHPS) is recommended 1
• No dosage adjustment needed for renal impairment (GFR ≥10 mL/min), though caution is advised for severe renal impairment (GFR <10 mL/min) 2