Augmentin Dosing for Urinary Tract Infections
For complicated UTIs, Augmentin should be dosed at 875 mg/125 mg twice daily for 5-10 days, based on FDA-approved regimens demonstrating comparable efficacy to three-times-daily dosing with significantly lower rates of severe diarrhea. 1
Key Dosing Recommendations
Adults with Complicated UTIs
- Standard regimen: 875 mg/125 mg orally twice daily 1
- Alternative regimen: 500 mg/125 mg orally three times daily 1
- Treatment duration: 5-10 days 2
The FDA clinical trial data in 629 patients with pyelonephritis or complicated UTIs demonstrated that the 875 mg/125 mg twice-daily regimen achieved bacteriologic cure rates of 81% at 2-4 days post-therapy, 58% at 5-9 days, and 52% at 2-4 weeks, which were comparable to the three-times-daily regimen 1. Critically, the twice-daily dosing had a statistically significant advantage with only 1% severe diarrhea/withdrawal rate versus 2% for the three-times-daily regimen 1.
Pediatric Dosing
- 20-40 mg/kg/day divided into 3 doses 2
- The 45 mg/kg/day divided every 12 hours formulation showed significantly lower diarrhea rates (14%) compared to 40 mg/kg/day every 8 hours (34%) in pediatric trials 1
Important Clinical Context
When Augmentin Is NOT Recommended
Augmentin is notably absent from the 2024 European Association of Urology guidelines for empiric treatment of both uncomplicated and complicated UTIs. 3 The guidelines recommend fluoroquinolones and cephalosporins as first-line agents for uncomplicated pyelonephritis, with extended-spectrum cephalosporins or penicillins (specifically piperacillin/tazobactam) for hospitalized patients 3. This omission reflects concerns about resistance patterns and the availability of more effective alternatives.
Resistance Considerations
- Local antimicrobial resistance patterns must guide therapy selection 2
- Susceptibility testing should be performed to adjust therapy 2
- Historical data from the 1980s-1990s showed 70-84% success rates for amoxicillin-resistant organisms 4, 5, but contemporary resistance patterns may differ significantly
- Augmentin is not recommended for asymptomatic bacteriuria 2
Clinical Scenarios Where Augmentin May Be Appropriate
Complicated UTIs with Known Susceptibility
- Use 875 mg/125 mg twice daily when culture confirms susceptibility 1
- Duration should be 5-10 days based on clinical response 2
Recurrent UTIs
- Historical studies showed 67% cure rates at 1 month in recurrent UTI patients using 250 mg/125 mg three times daily for 7 days 5
- Short-course therapy (3 days) with Augmentin was more effective than single-dose trimethoprim for uncomplicated lower UTIs (92.8% vs 58.8% cure rates) 6
Common Pitfalls to Avoid
- Do not use Augmentin as empiric first-line therapy for pyelonephritis or complicated UTIs without considering local resistance patterns and guideline recommendations 3
- Do not use for multidrug-resistant organisms without documented susceptibility, as alternative agents are required 2
- The lower 500 mg/125 mg three-times-daily regimen has higher gastrointestinal side effects without improved efficacy 1
- Avoid in patients with chronic renal insufficiency without dose adjustment, though historical data showed tolerability in patients with GFR 55-70 mL/min 7