Amoxicillin-Clavulanate 500/125 mg for Uncomplicated UTI Treatment
For uncomplicated urinary tract infections, amoxicillin-clavulanate 500/125 mg should be administered three times daily for 5-7 days, taken at the start of meals to minimize gastrointestinal intolerance. 1, 2
Dosing Regimen Details
The 500/125 mg formulation of amoxicillin-clavulanate (Augmentin) refers to:
- 500 mg of amoxicillin
- 125 mg of clavulanic acid
Administration Guidelines:
- Frequency: Every 8 hours (three times daily)
- Duration: 5-7 days for uncomplicated UTIs
- Timing: Take at the start of a meal to enhance absorption of clavulanate and reduce GI side effects 2
Evidence Supporting This Recommendation
The World Health Organization recommends amoxicillin-clavulanic acid as a first-choice treatment for lower UTIs when first-line agents are contraindicated, with the specific dosing of 500/125 mg three times daily for 5-7 days 1.
According to the FDA label, the usual adult dose for more severe infections is one 500/125 mg tablet every 8 hours 2. Clinical studies have demonstrated efficacy of this dosing regimen in urinary tract infections.
Alternative Dosing Options
For patients who cannot tolerate the three-times-daily regimen, an alternative is:
- 875/125 mg twice daily (every 12 hours) 2
This higher-dose, less frequent regimen has shown comparable efficacy to the 500/125 mg three times daily regimen in clinical trials for UTIs, with potentially fewer gastrointestinal side effects. The FDA label notes that in pivotal trials comparing these regimens for complicated UTIs, both showed similar bacteriological success rates (81% vs 80% at 2-4 days post-therapy) 2.
Special Considerations
Renal Impairment
- Dose adjustment may be necessary for patients with severe renal impairment
- For patients with creatinine clearance <30 mL/min, consider extending the dosing interval
Potential Side Effects
- Diarrhea is the most common adverse effect (14-15% of patients)
- The 875/125 mg twice daily regimen has shown statistically lower rates of severe diarrhea compared to the 500/125 mg three times daily regimen (1% vs 2%) 2
Treatment Efficacy
Clinical studies have demonstrated varying efficacy rates for amoxicillin-clavulanate in UTIs:
- Microbiological cure rates of 84% one week after treatment and 67% one month later in patients with recurrent UTIs 3
- For UTIs caused by beta-lactamase-producing bacteria, cure rates of 63.6% overall were observed, with higher rates (77.7%) when using higher doses of clavulanic acid 4
Important Caveats
- Obtain urine culture before starting antibiotics to confirm the causative pathogen and determine susceptibility 1
- Amoxicillin-clavulanate may be less effective than fluoroquinolones for uncomplicated cystitis, with one study showing clinical cure rates of 58% vs 77% for ciprofloxacin 5
- For ESBL-producing organisms, higher doses may be required, though this should be guided by susceptibility testing 6
- Two 250/125 mg tablets should not be substituted for one 500/125 mg tablet, as they contain the same amount of clavulanic acid but different amounts of amoxicillin 2
Follow-up
- Consider repeat urine culture 1 week after completing therapy to confirm cure, especially in complicated cases or recurrent infections 1
- If symptoms persist or recur, reevaluate with urine culture and consider alternative antibiotics based on susceptibility testing