What is the recommended dose of co-amoxiclav (amoxicillin/clavulanic acid) for a 9-year-old, 35 kg child with a suspected bacterial infection and no penicillin allergy, based on common suspension preparations?

Co-Amoxiclav Dosing for a 9-Year-Old, 35 kg Child

For a 9-year-old child weighing 35 kg with a suspected bacterial infection, the recommended dose is 5 mL of 250/62 suspension three times daily, providing approximately 750 mg of amoxicillin per day. 1

Standard Age-Based Dosing Algorithm

For children aged 7-12 years, the established dosing regimen is:

• 5 mL of 250/62 suspension three times daily 1, 2
• This provides approximately 250 mg of amoxicillin per dose 1
• Total daily amoxicillin dose: approximately 750 mg 1

This age-based approach is the standard recommendation from the American Academy of Pediatrics for routine infections in this age group 1. The 250/62 formulation is specifically indicated for children over 6 years of age 1.

When High-Dose Therapy Is Required

If the child has specific risk factors, switch to high-dose therapy: 90 mg/kg/day of amoxicillin component divided into 2 doses. 1

For a 35 kg child, this calculates to:

• 90 mg/kg/day × 35 kg = 3,150 mg total daily (divided into 2 doses)
• 1,575 mg per dose, twice daily 1

Risk Factors Requiring High-Dose Regimen:

• Age <2 years 1
• Daycare attendance 1
• Recent antibiotic use within the past 30 days 1
• Incomplete Haemophilus influenzae type b vaccination 1
• Geographic area with high prevalence (>10%) of penicillin-resistant Streptococcus pneumoniae 1
• Moderate to severe illness 1
• Concurrent purulent acute otitis media 1

The high-dose formulation provides a 14:1 ratio of amoxicillin to clavulanate, which achieves middle ear fluid concentrations adequate to overcome penicillin-resistant organisms 1. Using standard doses when high-dose therapy is indicated leads to treatment failure with resistant organisms 1.

Practical Suspension Preparation Considerations

Critical: Verify the suspension concentration before dispensing to avoid dosing errors 1:

• 125/31 suspension: Used for children 1-6 years (5 mL three times daily) 1, 2
• 250/62 suspension: Used for children 7-12 years (5 mL three times daily) 1, 2
• 457 mg/5 mL preparation: Can be used for twice-daily high-dose dosing 1

Treatment Duration

• Standard duration: 7-10 days for most respiratory and soft tissue infections 1
• Pneumonia: 10 days 1
• Acute bacterial rhinosinusitis: 10-14 days 1

Clinical improvement should be evident within 48-72 hours; if no improvement or worsening occurs, reevaluation and consideration of switching antibiotics or further investigation is necessary 1.

Intravenous Alternative for Severe Infections

If severe infection requires IV therapy:

• 30 mg/kg three times daily IV 1, 2
• For a 35 kg child: 1,050 mg IV every 8 hours 1

Common Pitfalls to Avoid

• Do not use adult formulations for children, as this leads to dosing errors 2
• Do not underdose: Subtherapeutic doses fail to achieve adequate tissue concentrations and promote antimicrobial resistance 1
• Do not confuse suspension concentrations: Always verify whether you're using 125/31 or 250/62 before calculating volume 1
• The medication can be given with or without food, though administration with meals may improve gastrointestinal tolerability 2

Adverse Effects to Monitor

Common side effects include 1, 2:

• Diarrhea (less frequent with twice-daily dosing) 1
• Nausea and vomiting 1, 2
• Rash 1, 2
• Hypersensitivity reactions 2

The 14:1 ratio high-dose formulation causes less diarrhea than other amoxicillin-clavulanate preparations while maintaining efficacy 1.