Amoxicillin-Clavulanate (Amoxyclav/Augmentin) Dosing
For adults with respiratory infections, use 875 mg/125 mg twice daily for standard cases, but escalate to 2000 mg/125 mg twice daily when antibiotic resistance is likely or infection is moderate-to-severe. 1
Adult Dosing Regimens
Standard-Dose Therapy
- 875 mg/125 mg twice daily OR 500 mg/125 mg three times daily for uncomplicated respiratory infections 1, 2
- Treatment duration: 5-7 days for acute bacterial rhinosinusitis, 7-10 days for community-acquired pneumonia 1, 2
- The twice-daily regimen (875/125 mg) is equally effective as three-times-daily dosing (500/125 mg) but causes less diarrhea 3, 4
High-Dose Therapy (When Resistance is Likely)
- 2000 mg/125 mg twice daily for patients with risk factors 1, 5
- This high-dose regimen achieves adequate serum concentrations to eradicate penicillin-resistant Streptococcus pneumoniae with MICs up to 4-8 mg/L 1, 5
- Predicted clinical efficacy: 90-92% versus 83-88% for standard dosing 2
Risk Factors Requiring High-Dose Therapy
Use 2000 mg/125 mg twice daily if ANY of the following are present: 1, 5
- Antibiotic use within the past 30 days (most critical factor)
- Age >65 years
- Recent hospitalization or close contact with healthcare environment
- Immunocompromised status or comorbidities (diabetes, chronic cardiac/pulmonary/renal/hepatic disease)
- Geographic area with >10% prevalence of penicillin-resistant S. pneumoniae
- Moderate-to-severe infection (fever ≥39°C, frontal/sphenoidal sinusitis)
- Smoking or household smoker exposure
- Close contact with daycare facilities
Pediatric Dosing Regimens
Standard-Dose Therapy
- 45 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into 2 doses every 12 hours 1, 2
- Alternative: 40 mg/kg/day every 8 hours for less severe infections 1
- Treatment duration: 10-14 days for acute bacterial rhinosinusitis (longer than adults), 5 days for uncomplicated pneumonia 1, 2
High-Dose Therapy (When Resistance is Likely)
- 90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into 2 doses 1, 2
- Maximum daily dose: 4000 mg of amoxicillin 2
- The 14:1 ratio formulation causes less diarrhea than other preparations 2
Pediatric Risk Factors Requiring High-Dose Therapy
Use 90 mg/kg/day if ANY of the following are present: 1, 2
- Age <2 years
- Daycare attendance
- Antibiotic use within the past 30 days
- Concurrent conjunctivitis (otitis-conjunctivitis syndrome)
- Geographic area with >10% prevalence of penicillin-resistant S. pneumoniae
- Pneumonia not responding to amoxicillin alone
Intravenous Dosing
Adults
- 1.2 g (1000 mg/200 mg) three times daily IV for severe pneumonia requiring hospitalization 1
- 2 g/0.2 g every 8 hours for intra-abdominal infections in non-critically ill patients 1
- Switch to oral formulation as soon as clinically appropriate 1
Pediatrics
- 30 mg/kg three times daily IV for all ages 1
- Increase to four times daily for severe infections in patients >3 months 1
Critical Dosing Considerations and Pitfalls
Avoid underdosing in high-resistance areas: In regions where >10% of S. pneumoniae isolates are penicillin-resistant, always use high-dose formulations from the start 1, 5
Reassess at 48-72 hours: If no clinical improvement occurs within 48-72 hours, consider changing antibiotics or reevaluating the diagnosis with imaging or cultures 1, 2
Do NOT use macrolides or TMP-SMX as alternatives: These have >40% and 50% resistance rates respectively against S. pneumoniae 5
Clavulanate limits maximum amoxicillin dose: The clavulanate component causes more gastrointestinal side effects and limits how much amoxicillin can be given in combination formulations 6
Standard dosing may be insufficient for severe infections: Only 65% of hospitalized patients reach the pharmacodynamic target (40% time above MIC) with standard dosing for organisms with MIC of 8 mg/L; consider increasing frequency to 6 times daily for severe Enterobacteriaceae infections 7