What is the recommended dosage of IV Azithromycin (intravenous Azithromycin) for pediatric patients?

IV Azithromycin Dosing for Pediatric Patients

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

Standard IV Dosing Protocol

• Initial IV dose: 10 mg/kg once daily, infused over 1 hour, with a maximum single dose of 500 mg 1, 2
• Duration of IV therapy: Typically limited to days 1 and 2 of treatment, with transition to oral therapy when the patient can tolerate it 1
• Age range: This dosing has been validated in children from 6 months to 16 years of age 2

Transition to Oral Therapy

Once the patient can tolerate oral medications, switch to:

• Day 1 oral dose (if starting oral): 10 mg/kg (maximum 500 mg) 1, 3
• Days 2-5 oral dose: 5 mg/kg once daily (maximum 250 mg) 1, 3

Indication-Specific Considerations

Community-Acquired Pneumonia (Atypical Pathogens)

For Mycoplasma pneumoniae, Chlamydia trachomatis, or Chlamydophila pneumoniae:

• IV azithromycin is the preferred agent when parenteral therapy is required 1
• The 10 mg/kg IV dosing on days 1-2 applies, with early transition to oral therapy 1
• Alternative IV agents include erythromycin lactobionate (20 mg/kg/day divided every 6 hours) or levofloxacin for older children 1

Pharmacokinetic Profile Supporting This Dosing

• The 10 mg/kg IV dose achieves a mean Cmax of 2.4 mcg/mL and AUC₀₋₇₂ of 8.2 mcg·h/mL 2
• Elimination half-life is approximately 65 hours, supporting once-daily dosing 2
• Pharmacokinetics are comparable across pediatric age groups from 6 months to 16 years 2
• Sustained serum concentrations persist for days after administration due to extensive tissue distribution 4

Critical Safety Considerations

• Infusion rate: Administer over 60 minutes (1 hour) to minimize infusion-related reactions 2
• QT prolongation risk: Monitor ECG in patients with cardiac risk factors or those receiving other QT-prolonging medications 3
• Drug interactions: Avoid concurrent aluminum- or magnesium-containing antacids, which reduce absorption of oral formulations 3
• Tolerability: IV azithromycin is generally well-tolerated with no serious adverse events reported in pediatric pharmacokinetic studies 2

Common Pitfalls to Avoid

• Prolonged IV therapy: Do not continue IV azithromycin beyond 2 days when oral therapy is feasible—the guideline explicitly recommends early transition 1
• Underdosing: Ensure the full 10 mg/kg dose is given (not rounding down excessively), as lower doses may compromise efficacy 1
• Inappropriate use for typical bacterial pneumonia: IV azithromycin is specifically indicated for atypical pathogens; typical bacterial pneumonia (S. pneumoniae, H. influenzae) requires beta-lactam antibiotics as first-line therapy 1

Age-Specific Nuances

For infants under 6 months with pertussis or other indications:

• Oral azithromycin at 10 mg/kg once daily for 5 days is preferred over IV when feasible 3
• IV formulation pharmacokinetics have not been specifically studied in infants under 6 months, though the oral formulation is recommended by CDC for this age group 3