What is the dosage of Co-amoxiclav (amoxicillin/clavulanic acid) 475mg/5ml syrup for a 3-month-old patient weighing 5.9 kilograms, given 2 times a day for 7 days?

Co-amoxiclav Dosing for a 3-Month-Old Infant

For a 3-month-old infant weighing 5.9 kg requiring co-amoxiclav 475mg/5ml (amoxicillin/clavulanic acid) suspension twice daily, administer 2.5 ml per dose (providing approximately 45 mg/kg/day of amoxicillin component), given every 12 hours for 7 days.

Dosing Calculation and Rationale

Standard Pediatric Dosing

• The recommended dose of amoxicillin/clavulanic acid for most pediatric infections is 45 mg/kg/day of the amoxicillin component divided into 2 doses 1
• For this 5.9 kg infant: 45 mg/kg/day × 5.9 kg = 265.5 mg/day total, divided into 2 doses = 132.75 mg per dose
• Your suspension contains 475 mg amoxicillin per 5 ml, which equals 95 mg/ml
• To deliver 132.75 mg per dose: 132.75 mg ÷ 95 mg/ml = 1.4 ml per dose

Higher-Dose Considerations

• For more severe infections or suspected resistant organisms (particularly β-lactamase-producing Haemophilus influenzae or penicillin-resistant Streptococcus pneumoniae), the dose can be increased to 90 mg/kg/day in 2 divided doses 1, 2
• For this infant at high-dose: 90 mg/kg/day × 5.9 kg = 531 mg/day ÷ 2 = 265.5 mg per dose
• This equals: 265.5 mg ÷ 95 mg/ml = 2.8 ml per dose

Practical Recommendation

• Start with 2.5 ml twice daily (approximately 237.5 mg per dose, or ~80 mg/kg/day), which provides adequate coverage for most common pediatric infections while remaining within safe dosing parameters 1
• This intermediate dose balances efficacy against common pathogens with tolerability 2

Administration Instructions

Timing and Frequency

• Administer every 12 hours (e.g., 8 AM and 8 PM) to maintain consistent drug levels 1
• Can be given with or without food, though administration with meals may improve gastrointestinal tolerability 2, 3
• Complete the full 7-day course even if symptoms improve earlier 1

Preparation and Storage

• Shake the suspension well before each dose to ensure uniform distribution 3
• Store reconstituted suspension in refrigerator and discard after 10 days 3
• Use an oral syringe for accurate measurement rather than household spoons 2

Clinical Monitoring

Expected Response

• Clinical improvement should be evident within 48-72 hours of initiating therapy 1
• If the infant's condition deteriorates or shows no improvement within 48-72 hours, further investigation is warranted 1

Common Pitfalls to Avoid

• Do not underdose: The 475 mg/5ml concentration requires careful calculation to avoid subtherapeutic dosing in small infants 4
• Do not use adult dosing: Always calculate weight-based dosing for pediatric patients 1
• Monitor for diarrhea: This is the most common adverse effect, occurring more frequently with three-times-daily dosing than twice-daily regimens 2, 3
• Watch for hypersensitivity: Skin rash is a common adverse effect; discontinue if severe reaction occurs 5

Infection-Specific Considerations

If Treating Community-Acquired Pneumonia

• For outpatient CAP in infants >3 months, amoxicillin/clavulanic acid at 90 mg/kg/day in 2 doses is preferred when β-lactamase-producing organisms are suspected 1
• In this case, use the 2.8 ml per dose calculation above

If Treating Otitis Media or Other Infections

• Standard dosing of 45 mg/kg/day (1.4 ml per dose) is typically adequate for uncomplicated infections 2
• High-dose formulations (90 mg/kg/day) are reserved for recurrent or persistent infections after amoxicillin failure 2

Safety Profile

• Amoxicillin/clavulanic acid is generally well tolerated in infants, with a low incidence of serious adverse events (3.6% in large pediatric studies) 2
• Gastrointestinal disturbances (nausea, vomiting, diarrhea) are the most frequent side effects but are usually mild 2, 5, 3
• The clavulanic acid component is more strongly associated with GI side effects and Clostridioides difficile infection risk than amoxicillin alone 3