What is the appropriate Augmentin (amoxicillin/clavulanate) dose for a child weighing 18.2 kg with normal renal function and no penicillin allergy?

Augmentin Dosing for 18.2 kg Child

For a child weighing 18.2 kg with normal renal function, administer Augmentin 400 mg/5 mL suspension at 4 mL twice daily (standard dose) or 8 mL twice daily (high-dose regimen for severe infections or resistant pathogens). 1, 2, 3

Weight-Based Calculation

• Standard dosing (45 mg/kg/day): 18.2 kg × 45 mg/kg = 819 mg/day of amoxicillin component, divided into 409.5 mg twice daily 1, 2, 3

  • Using 400 mg/5 mL suspension: approximately 4 mL twice daily provides 320 mg per dose (640 mg/day total) 3

• High-dose regimen (90 mg/kg/day): 18.2 kg × 90 mg/kg = 1,638 mg/day, divided into 819 mg twice daily 1, 2, 3

  • Using 400 mg/5 mL suspension: approximately 8 mL twice daily provides 640 mg per dose (1,280 mg/day total) 3

Indication-Specific Algorithm

Use standard dosing (4 mL of 400 mg/5 mL suspension twice daily) for:

• Mild to moderate respiratory tract infections without recent antibiotic exposure 1, 2
• Uncomplicated skin and soft tissue infections 1
• Urinary tract infections 3

Use high-dose regimen (8 mL of 400 mg/5 mL suspension twice daily) for:

• Community-acquired pneumonia in areas with >10% penicillin-resistant S. pneumoniae 1, 2
• Recent antibiotic exposure within the past 4-6 weeks 1, 2
• Daycare attendance (higher risk of resistant organisms) 2
• Treatment failure with standard-dose amoxicillin 4
• Severe infections requiring hospitalization 2
• Acute otitis media after failed initial therapy 4, 5

Treatment Duration

• 7-10 days for most respiratory infections 1, 6
• 10 days specifically for acute otitis media and pneumonia 1, 3
• Clinical improvement should occur within 48-72 hours; if not, reevaluation is mandatory 1, 6

Critical Pitfalls to Avoid

Do not underdose when resistant pathogens are suspected. The most common error is using standard dosing (45 mg/kg/day) when high-dose therapy (90 mg/kg/day) is indicated, leading to treatment failure with penicillin-resistant S. pneumoniae or β-lactamase-producing H. influenzae 1, 2, 4

Do not substitute formulations incorrectly. The 400 mg/57 mg per 5 mL suspension provides a 14:1 ratio of amoxicillin to clavulanate, which minimizes gastrointestinal side effects compared to older formulations 2, 7, 5

Do not use three-times-daily dosing. Twice-daily administration provides equivalent efficacy with significantly less diarrhea (9.6% vs 26.7%) and better compliance (82.8% vs 73.3%) compared to three-times-daily regimens 7, 5

Practical Administration

• Administer with food to minimize gastrointestinal upset 3
• Shake suspension well before each dose 3
• Use calibrated measuring device, not household spoons 3
• Complete the full course even if symptoms improve 1, 6

Monitoring Parameters

• Fever should resolve within 24-48 hours for pneumococcal infections, though cough may persist longer 6
• If no improvement by 48-72 hours, consider atypical pathogens and potentially add a macrolide 6
• Hospitalization should be considered after 5 days without improvement 6