What is the appropriate amoxicillin‑clavulanate dose for a 9‑year‑old boy weighing 30 kg?

Amoxicillin-Clavulanate Dosing for a 9-Year-Old, 30 kg Child

For a 9-year-old boy weighing 30 kg, the appropriate amoxicillin-clavulanate dose depends on the indication: for standard infections use 45 mg/kg/day (1,350 mg/day) divided into two doses of 675 mg every 12 hours, but for respiratory tract infections, acute otitis media, or if the child has risk factors (daycare attendance, recent antibiotic use, or moderate-to-severe illness), use the high-dose regimen of 90 mg/kg/day (2,700 mg/day) divided into two doses of 1,350 mg every 12 hours. 1, 2

Weight-Based Dosing Algorithm

Standard-Dose Regimen (45 mg/kg/day)

• For a 30 kg child, the standard dose equals 1,350 mg total daily (45 mg/kg × 30 kg), administered as 675 mg every 12 hours. 1
• This regimen is appropriate for uncomplicated infections in children ≥2 years without risk factors for resistant organisms. 1

High-Dose Regimen (90 mg/kg/day)

• For a 30 kg child, the high-dose equals 2,700 mg total daily (90 mg/kg × 30 kg), administered as 1,350 mg every 12 hours. 1, 2
• This high-dose regimen is indicated when ANY of the following risk factors are present:
  • Age <2 years 1
  • Daycare attendance 1
  • Recent antibiotic use within the past 30 days 1
  • Geographic area with >10% penicillin-resistant Streptococcus pneumoniae 1
  • Moderate-to-severe illness at presentation 1
  • Respiratory tract infections (pneumonia, acute bacterial sinusitis) 1, 2
  • Acute otitis media 1

Practical Administration

Tablet Formulation

• Since this child weighs 30 kg (less than 40 kg), use pediatric formulations rather than adult 250/125 mg tablets. 3
• The FDA label specifies that 250/125 mg tablets should not be used until the child weighs at least 40 kg due to different amoxicillin-to-clavulanate ratios. 3

Suspension Formulation

• For standard-dose (675 mg per dose): Use approximately 8.4 mL of 400 mg/5 mL suspension twice daily. 3
• For high-dose (1,350 mg per dose): Use approximately 16.9 mL of 400 mg/5 mL suspension twice daily. 1, 3
• The 400 mg/5 mL (or 200 mg/5 mL) suspension formulations provide the optimal 14:1 ratio of amoxicillin to clavulanate, which minimizes diarrhea while maintaining efficacy. 1

Indication-Specific Recommendations

Respiratory Tract Infections (Pneumonia, Sinusitis)

• Use the high-dose regimen (90 mg/kg/day = 2,700 mg/day in 2 doses) for community-acquired pneumonia or acute bacterial sinusitis. 1, 2
• This dosing achieves middle-ear and sinus fluid concentrations adequate to overcome penicillin-resistant S. pneumoniae with MICs up to 2–4 mg/L. 1

Acute Otitis Media

• Use the high-dose regimen (90 mg/kg/day) for 10 days, especially if the child has recent antibiotic exposure, daycare attendance, or severe presentation. 1

Less Severe Infections (Skin, Soft Tissue)

• Use the standard-dose regimen (45 mg/kg/day = 1,350 mg/day in 2 doses) for uncomplicated infections without risk factors. 1, 3

Treatment Duration

• Respiratory infections: 10 days for pneumonia and acute otitis media. 1, 2
• Acute bacterial sinusitis: Continue for 7 days after symptom resolution, with a minimum total of 10 days. 1
• Most other infections: 7–10 days depending on clinical response. 2

Clinical Monitoring

• Clinical improvement should occur within 48–72 hours of starting appropriate therapy. 1, 2
• If no improvement or worsening after 48–72 hours:
  • Reassess the diagnosis 1
  • Consider atypical pathogens and add a macrolide 1
  • Evaluate for complications or alternative diagnoses 1
  • Consider switching to broader-spectrum antibiotics 1

Administration Timing

• Amoxicillin-clavulanate may be taken without regard to meals, but administration at the start of a meal enhances clavulanate absorption and minimizes gastrointestinal intolerance. 3

Common Pitfalls to Avoid

• Do not substitute two 250/125 mg tablets for one 500/125 mg tablet, as they contain the same amount of clavulanate (125 mg each) but different amounts of amoxicillin. 3
• Verify the suspension concentration (125/31,250/62, or 400/57 mg per 5 mL) before calculating volume to avoid dosing errors. 1
• Do not underdose—subtherapeutic concentrations fail to eradicate resistant organisms and promote antimicrobial resistance. 1, 4
• For children weighing ≥40 kg, dose according to adult recommendations. 3