What is the dosage of amoxicillin (amoxicillin-clavulanate) in pediatric patients?

Amoxicillin-Clavulanate Pediatric Dosing

For most pediatric respiratory infections, use high-dose amoxicillin-clavulanate at 90 mg/kg/day of the amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into 2 doses (maximum 4000 mg/day amoxicillin). 1

Standard Dosing Regimens by Age

Infants Under 3 Months

• 30 mg/kg/day divided every 12 hours based on the amoxicillin component 2, 3
• Use the 125/31 mg per 5 mL suspension formulation 1
• Due to immature renal function, do not exceed this dose 2

Children 3 Months and Older

High-Dose Regimen (Preferred for Most Infections):

• 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in 2 divided doses 1, 4
• This provides a 14:1 ratio of amoxicillin to clavulanate 1
• Maximum daily dose: 4000 mg amoxicillin 4
• Maximum single dose: 2000 mg per dose 1

Standard-Dose Regimen (For Uncomplicated Infections Without Risk Factors):

• 45 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in 2 divided doses 1, 4
• Alternative: 40 mg/kg/day divided every 8 hours 2, 3

Age-Based Volume Dosing (Alternative Approach)

• Less than 1 year: 2.5 mL of 125/31 suspension three times daily 1
• 1-6 years: 5 mL of 125/31 suspension three times daily 1
• 7-12 years: 5 mL of 250/62 suspension three times daily 1
• 12-18 years: 1 tablet (250/125) three times daily 1

Indications for High-Dose Therapy

Always use the high-dose regimen (90 mg/kg/day) when ANY of these risk factors are present: 1, 4

• Age less than 2 years 1
• Daycare attendance 4
• Recent antibiotic use within 30 days 1, 4
• Moderate to severe illness 1
• Geographic area with >10% penicillin-resistant Streptococcus pneumoniae 1, 4
• Incomplete Haemophilus influenzae type b vaccination (less than 3 injections) 1
• Concurrent purulent acute otitis media 1
• Concurrent conjunctivitis (suggests Moraxella catarrhalis) 4
• Treatment failure with standard-dose amoxicillin 1

Specific Clinical Indications

Acute Otitis Media

• 90 mg/kg/day in 2 divided doses for 10 days 1, 5
• The high-dose formulation achieves middle ear fluid concentrations adequate to overcome penicillin-resistant S. pneumoniae 1

Community-Acquired Pneumonia

• Children under 5 years: 90 mg/kg/day in 2 doses for 10 days 1
• Children under 3 years without risk factors: Consider amoxicillin alone at 80-100 mg/kg/day first; add clavulanate if treatment fails 1
• With incomplete Hib vaccination or concurrent purulent otitis media: 80 mg/kg/day of amoxicillin component 1

Acute Bacterial Rhinosinusitis

• With risk factors: 80-90 mg/kg/day of amoxicillin with 6.4 mg/kg/day clavulanate in 2 doses 4
• Without risk factors: 45 mg/kg/day in 2 doses 4
• Duration: 10-14 days for children (longer than adults) 4

Respiratory Infections with β-lactamase Producing Organisms

• 45 mg/kg/day in 3 doses OR 90 mg/kg/day in 2 doses 1

Treatment Duration

• Most respiratory infections: 10 days 1
• Acute bacterial sinusitis: 10-14 days in children 4
• Bacterial pneumonia: 10 days 1
• Continue for 7 days after symptom resolution 1
• Streptococcal infections: Minimum 10 days to prevent acute rheumatic fever 2, 3

Renal Impairment Dosing (Children >40 kg and Adults)

• GFR 10-30 mL/min: 500 mg/125 mg every 12 hours 2, 3
• GFR <10 mL/min: 500 mg/125 mg every 24 hours 2, 3
• Hemodialysis: 500 mg/125 mg every 24 hours, with additional dose during and after dialysis 2, 3
• Do NOT use 875 mg/125 mg dose if GFR <30 mL/min 2, 3

Critical Clinical Considerations

Pharmacokinetic Advantages of High-Dose Regimen

• Serum amoxicillin levels increase linearly with dose 1
• The 14:1 ratio formulation (90/6.4 mg/kg/day) causes less diarrhea than other amoxicillin-clavulanate preparations 1, 4
• High-dose therapy (80-90 mg/kg/day) exceeds the MIC for intermediately resistant S. pneumoniae and many highly resistant serotypes 1
• Predicted clinical efficacy of high-dose therapy is 90-92% in both adults and children 4

Common Pitfalls to Avoid

Critical Dosing Errors:

• Never substitute two 250/125 mg tablets for one 500/125 mg tablet - they contain the same amount of clavulanate but different amounts of amoxicillin 3
• Verify suspension concentration (125/31 vs 250/62) before calculating volume to avoid dosing errors 1
• Using standard doses when high-dose therapy is indicated leads to treatment failure with resistant organisms 1
• Subtherapeutic doses fail to achieve adequate tissue concentrations and promote antimicrobial resistance 1

Administration Guidelines

• Take at the start of a meal to minimize gastrointestinal intolerance and enhance clavulanate absorption 2, 3
• Shake oral suspension well before each use 2
• Refrigeration is preferable but not required 2
• Discard reconstituted suspension after 14 days 2

Monitoring and Treatment Failure

• Expect clinical improvement within 48-72 hours 1
• If no improvement or worsening after 72 hours: Reassess diagnosis, consider atypical pathogens, evaluate for complications, or switch antibiotics 1, 4

Adverse Effects

• Most common: diarrhea, nausea, vomiting, rash 1
• The twice-daily high-dose regimen is associated with significantly less diarrhea than three-times-daily dosing 3, 6
• Diaper dermatitis occurs in approximately 21% with reduced-clavulanate formulations vs 33% with standard formulations 6

Important Context: Antibiotic Stewardship

Most upper respiratory tract infections are viral and do not require antibiotics 1. Before prescribing, ensure the child meets criteria for bacterial infection such as:

• Persistent symptoms >10 days without improvement 1
• Severe symptoms (high fever ≥39°C, purulent nasal discharge) 1
• "Double sickening" (worsening after initial improvement) 1