What is the appropriate dose and dosing interval of Augmentin (amoxicillin/clavulanate) 200 mg/28.5 mg mL⁻¹ suspension for a 6.58‑kg infant?

Augmentin 200-28.5 mg/mL Dosing for a 6.58 kg Infant

For an infant weighing 6.58 kg who is ≥3 months old, administer 3 mL of Augmentin 200-28.5 mg/5 mL suspension twice daily (every 12 hours) for standard respiratory or ear infections, providing 45 mg/kg/day of the amoxicillin component. 1, 2

Critical Age Restriction

• Augmentin should NOT be used in infants younger than 3 months of age unless under specialist consultation, as safety and efficacy data are limited in this population. 2, 3
• For neonates and infants <3 months with suspected serious bacterial infection, intravenous regimens (ampicillin + gentamicin or cefotaxime) are preferred over oral Augmentin. 2
• The FDA-approved dosing for infants <12 weeks is 30 mg/kg/day divided every 12 hours, but the 125 mg/5 mL formulation is recommended rather than the 200 mg/5 mL strength. 4

Standard Dosing Algorithm (For Infants ≥3 Months)

Mild to Moderate Infections

• Dose: 45 mg/kg/day divided every 12 hours 1, 2, 4
• For a 6.58 kg infant: 45 mg/kg/day × 6.58 kg = 296 mg/day total
• Per dose: 148 mg every 12 hours
• Volume: 3 mL of 200-28.5 mg/5 mL suspension twice daily 4
• This provides approximately 120 mg amoxicillin per dose (240 mg/day total)

Severe Infections or High-Risk Factors

• Dose: 90 mg/kg/day divided every 12 hours 1, 2
• For a 6.58 kg infant: 90 mg/kg/day × 6.58 kg = 592 mg/day total
• Per dose: 296 mg every 12 hours
• Volume: 7.5 mL of 200-28.5 mg/5 mL suspension twice daily 2

High-dose regimen is indicated when: 2

• Age <2 years with acute otitis media
• Recent antibiotic use within past 30 days
• Daycare attendance
• Incomplete Haemophilus influenzae type b vaccination
• Geographic area with high pneumococcal resistance (>10%)
• Severe presentation or treatment failure

Indication-Specific Dosing

Acute Otitis Media (Age ≥3 months, <2 years)

• 90 mg/kg/day divided every 12 hours for 10 days 2
• Volume: 7.5 mL twice daily for 6.58 kg infant
• High-dose formulation achieves middle ear fluid concentrations adequate to overcome penicillin-resistant S. pneumoniae and β-lactamase-producing organisms. 2

Community-Acquired Pneumonia (Age ≥3 months)

• 90 mg/kg/day divided every 12 hours for 10 days 1, 2
• Volume: 7.5 mL twice daily for 6.58 kg infant
• Use if incomplete H. influenzae type b vaccination or concurrent purulent otitis media. 2

Less Severe Respiratory Infections

• 45 mg/kg/day divided every 12 hours for 7-10 days 1, 4
• Volume: 3 mL twice daily for 6.58 kg infant

Administration Guidelines

• Give at the start of meals to enhance clavulanate absorption and minimize gastrointestinal intolerance. 3, 4
• Use a calibrated oral syringe (3 mL or 5 mL) for accurate dosing—never use household spoons. 3
• The suspension may be given without regard to meals if necessary, though food improves tolerability. 3

Treatment Duration

• Acute otitis media: 10 days 2, 3, 4
• Community-acquired pneumonia: 10 days 2, 3
• Most respiratory infections: 7-10 days 3

Monitoring Clinical Response

• Clinical improvement should be evident within 48-72 hours of starting therapy. 1, 2, 3
• If no improvement or worsening occurs after 48-72 hours, reevaluate the diagnosis and consider switching antibiotics or investigating for complications. 2
• Fever typically resolves within 24-48 hours for pneumococcal infections, though cough may persist longer. 1

Common Pitfalls to Avoid

• Do NOT use the 250 mg/62.5 mg formulation interchangeably with other strengths—the clavulanate ratios differ significantly. 4
• Do NOT substitute two 250 mg/125 mg tablets for one 500 mg/125 mg tablet—they contain different amounts of clavulanate. 4
• Verify the suspension concentration before dispensing (200-28.5 mg/5 mL vs. 400-57 mg/5 mL) to avoid dosing errors. 2
• Do NOT prescribe for viral upper respiratory infections—most URTIs are viral and do not benefit from antibiotics. 2
• Using standard doses (45 mg/kg/day) when high-dose therapy is indicated leads to treatment failure with resistant organisms. 2

Adverse Effects

• Common adverse effects include diarrhea (25% vs. 15% placebo), nausea, vomiting, and diaper dermatitis (51% vs. 35% placebo). 2
• The 14:1 ratio formulation (90/6.4 mg/kg/day) causes less diarrhea than other amoxicillin-clavulanate preparations while maintaining efficacy. 2
• Hypersensitivity reactions, including anaphylaxis, have been reported postmarketing. 5

Maximum Dose Considerations

• The maximum daily dose of amoxicillin should not exceed 4000 mg/day regardless of weight. 1
• For this 6.58 kg infant, even the high-dose regimen (592 mg/day) is well below the maximum threshold.