What is the recommended dosage of coamoxiclav (amoxicillin/clavulanic acid) for children?

Recommended Dosage of Co-Amoxiclav in Children

For most pediatric infections requiring co-amoxiclav, use high-dose therapy: 90 mg/kg/day of the amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into 2 doses daily (maximum 4000 mg/day amoxicillin). 1

Standard Dosing Framework

The dosing of co-amoxiclav in children depends critically on the clinical scenario and local resistance patterns:

High-Dose Regimen (Preferred for Most Situations)

Use 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day clavulanate in 2 divided doses when: 1

• Child is <2 years old 1
• Recent antibiotic use within past 30 days 1
• Daycare attendance 1
• Moderate to severe illness 1
• Areas with >10% prevalence of penicillin-resistant Streptococcus pneumoniae 1
• Incomplete Haemophilus influenzae type b vaccination (<3 injections) 1
• Treatment of acute otitis media, community-acquired pneumonia, or acute bacterial rhinosinusitis 1

This high-dose formulation provides a 14:1 ratio of amoxicillin to clavulanate, which achieves adequate middle ear fluid concentrations to overcome penicillin-resistant organisms while causing less diarrhea than other formulations. 1

Standard-Dose Regimen (Limited Use)

Use 45 mg/kg/day divided into 3 doses OR 90 mg/kg/day divided into 2 doses for β-lactamase producing organisms when high-dose criteria are not met. 1 However, this lower dosing is increasingly inadequate given current resistance patterns. 2

Age-Based Practical Dosing (When Weight-Based Calculation Not Feasible)

For situations where precise weight-based dosing cannot be calculated: 1

• <1 year (1-12 months): 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

Critical caveat: These age-based doses provide substantially lower amoxicillin amounts than the recommended 90 mg/kg/day high-dose regimen and should only be used when weight-based dosing is impossible. 1

Intravenous Dosing

For severe infections requiring IV therapy: 30 mg/kg three times daily IV for all pediatric ages. 1

Duration of Therapy

• 10 days for most pediatric infections including acute otitis media, community-acquired pneumonia, and acute bacterial rhinosinusitis 1
• Continue for 7 days after resolution of signs and symptoms 1

Critical Clinical Considerations

Why High-Dose Matters

Standard 40-45 mg/kg/day dosing is inadequate to eradicate resistant S. pneumoniae, particularly during viral coinfection, which reduces antibiotic penetration into middle ear fluid. 2 Research demonstrates that amoxicillin middle ear fluid concentrations are lowest in virus-infected children (2.7 μg/mL) compared to bacterial-only infection (5.7 μg/mL). 2

Using standard doses when high-dose therapy is indicated leads to inevitable treatment failure with resistant organisms. 1

Pharmacokinetic Rationale

High-dose amoxicillin (80-90 mg/kg/day) exceeds the minimum inhibitory concentration for intermediately resistant S. pneumoniae and many highly resistant serotypes. 1 The 14:1 ratio formulation maintains efficacy while causing less diarrhea than other amoxicillin-clavulanate preparations. 1

Serum levels of amoxicillin increase linearly with dose, and the difference in adverse effects between lower and higher doses is generally negligible. 1

Common Pitfalls to Avoid

• Verify suspension concentration (125/31 vs 250/62) before calculating volume to prevent dosing errors 1
• Do not use subtherapeutic doses as they fail to achieve adequate tissue concentrations and promote antimicrobial resistance 1
• Ensure the indication truly requires antibiotics - most upper respiratory tract infections are viral and do not benefit from antibiotics 1
• Maximum single dose is 2 grams regardless of weight 1

Special Populations

Drug-Resistant Tuberculosis

In the specific context of drug-resistant tuberculosis in children, co-amoxiclav is classified as a Group 5 agent with unclear efficacy. Dosing is 10-15 mg/kg/day of the amoxicillin component when used as part of multi-drug regimens for MDR-TB. 3 Common adverse events include gastrointestinal intolerance, hypersensitivity reactions, seizures, and liver/renal dysfunction. 3