What is the recommended dosing regimen of amoxicillin/clavulanate (Augmentin) for adults and children, including adjustments for infection severity and renal impairment?

Amoxicillin-Clavulanate Dosing Guidelines

Adult Dosing

For adults with normal renal function, prescribe Augmentin 875 mg/125 mg twice daily for most respiratory and soft tissue infections, or escalate to 2000 mg/125 mg twice daily when antibiotic resistance is likely. 1

Standard Adult Regimen

• 875 mg/125 mg twice daily for 7 days is appropriate for uncomplicated respiratory tract infections in patients without resistance risk factors 1
• This regimen achieves clinical cure rates equivalent to 10-day courses while producing fewer adverse events 1

High-Dose Adult Regimen (2000 mg/125 mg twice daily)

Use the high-dose regimen when any of the following resistance risk factors are present: 1

• Antibiotic use within the past 30 days
• Healthcare environment exposure or contact with healthcare workers
• Previous antibiotic treatment failure for the current infection
• Smoking or household smoking exposure
• Community prevalence of penicillin-resistant S. pneumoniae >10%
• Age >65 years
• Significant comorbidities (diabetes, chronic cardiac/hepatic/renal disease)
• Immunocompromised status
• Moderate to severe infection severity
• Frontal or sphenoidal sinusitis
• Recurrent upper respiratory infections

The high-dose regimen achieves 90-92% predicted clinical efficacy versus 83-88% for standard dosing in patients with resistance risk factors. 1

Duration by Infection Type (Adults)

• Acute bacterial rhinosinusitis: 5-7 days 1
• Community-acquired pneumonia: 7-10 days 1
• Uncomplicated urinary tract infections: 3-7 days 1
• Intra-abdominal infections (with source control): 4-7 days 1

Intravenous Adult Dosing

• 1.2 g (1000 mg amoxicillin + 200 mg clavulanate) every 6-8 hours for moderate to severe infections 1
• For intra-abdominal infections with adequate source control, continue for 4-7 days based on clinical response 1

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Pediatric Dosing

For children ≥3 months with bacterial infections, prescribe 45 mg/kg/day divided every 12 hours for mild-moderate infections, or 90 mg/kg/day divided every 12 hours for severe infections or when resistance is likely (maximum 4000 mg/day). 1, 2

Standard Pediatric Regimen (Mild-Moderate Infections)

• 45 mg/kg/day of amoxicillin component divided every 12 hours 1
• Alternative: 40 mg/kg/day divided every 8 hours 1
• Appropriate for uncomplicated respiratory infections without resistance risk factors 2

High-Dose Pediatric Regimen (90 mg/kg/day)

Use 90 mg/kg/day with 6.4 mg/kg/day clavulanate in two divided doses (14:1 ratio formulation) when any of these factors are present: 1, 3

• Age <2 years
• Daycare attendance
• Antibiotic use within the past 30 days
• Incomplete Haemophilus influenzae type b vaccination (<3 doses)
• Geographic area with >10% penicillin-resistant S. pneumoniae
• Severe infection presentation
• Concurrent purulent acute otitis media
• Recent treatment failure
• Community-acquired pneumonia requiring coverage for resistant organisms

Age-Based Oral Suspension Dosing (Standard Infections)

For children without high-risk factors, age-based dosing may be used: 3

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

However, for respiratory infections requiring high-dose therapy, always calculate weight-based dosing at 90 mg/kg/day divided twice daily rather than using age-based regimens. 1, 3

Intravenous Pediatric Dosing

• 30 mg/kg three times daily for moderate infections 1, 3
• Increase to four times daily for severe infections in patients >3 months 1
• For severe infections with possible undrained abscesses, increase amoxicillin component up to 200 mg/kg/day divided every 6 hours 1

Duration by Infection Type (Pediatrics)

• Acute otitis media: 10 days (especially for children <6 years) 1, 3
• Acute bacterial rhinosinusitis: 10-14 days 1, 3
• Community-acquired pneumonia: 10 days 2, 3
• Group A streptococcal infections: 10 days 2

Clinical Monitoring

Evaluate clinical response within 48-72 hours of initiating 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 1, 3
• Fever typically resolves within 24-48 hours for pneumococcal infections, though cough may persist longer 2

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Renal Impairment Dosing Adjustments

In patients with renal impairment, reduce dosing frequency or dose amount to prevent drug accumulation, as amoxicillin clearance decreases more than clavulanate clearance with declining renal function. 1, 4

Adult Renal Dosing

• CrCl 10-30 mL/min: Reduce frequency to every 12 hours OR decrease dose by 50% 1
• CrCl <10 mL/min: Reduce frequency to every 24 hours OR decrease dose by 75% 1
• Hemodialysis: Administer supplemental dose after each dialysis session 1

Pediatric Renal Dosing

• Apply proportional dose reductions based on estimated creatinine clearance, mirroring adult adjustments 1
• Specific pediatric renal dosing guidelines are limited; consider nephrology consultation for severe impairment 1

The ratio of amoxicillin to clavulanate increases significantly with declining renal function (from 4.9:1 at GFR 75 mL/min to 14.7:1 in hemodialysis patients), which helps maintain adequate clavulanate concentrations while preventing amoxicillin accumulation. 4

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Critical Dosing Considerations and Common Pitfalls

Avoid Underdosing in High-Resistance Areas

In communities with >10% penicillin-resistant S. pneumoniae, always use high-dose formulations (2000 mg/125 mg twice daily for adults or 90 mg/kg/day for children) to achieve adequate serum concentrations against strains with amoxicillin MICs up to 4-8 mg/L. 1

Verify Suspension Concentration

Always verify the suspension concentration (125/31 vs 250/62 vs 600/42.9 mg per 5 mL) before calculating volume to avoid dosing errors. 3

Maximum Doses

• Pediatric maximum: 4000 mg/day of amoxicillin component regardless of weight 2, 3
• Single-dose maximum (pediatrics): 2000 mg per dose 3

Minimum Age

Augmentin may be initiated in children ≥3 months of age; for infants <3 months with suspected serious bacterial infection, use intravenous regimens (ampicillin + gentamicin or cefotaxime) instead. 3

Gastrointestinal Adverse Events

Expect diarrhea in 15-40% of patients, but discontinuation is rarely required 1. The 14:1 ratio high-dose formulation (90/6.4 mg/kg/day) causes less diarrhea than other amoxicillin-clavulanate preparations while maintaining efficacy 3.

Augmented Renal Clearance in Critically Ill Children

In critically ill pediatric patients with augmented renal clearance, standard dosing results in subtherapeutic concentrations; consider four-hourly dosing of 25 mg/kg with 1-hour infusions rather than bolus dosing. 5