What is the recommended once-weekly medication regimen for preventing recurrent urinary tract infections (UTIs)?

Once-Weekly Medication for UTI Prevention

Methenamine hippurate is the recommended once-weekly medication for preventing recurrent urinary tract infections (UTIs) in women without urinary tract abnormalities. 1

First-Line Non-Antimicrobial Options

The 2024 European Association of Urology (EAU) guidelines provide a clear algorithm for managing recurrent UTIs, with a strong preference for non-antimicrobial interventions before resorting to antibiotics:

1. Methenamine hippurate - Strongly recommended for reducing recurrent UTI episodes in women without abnormalities of the urinary tract 1

   • Dosing is typically 1g twice daily, though for once-weekly prophylaxis, a higher single dose may be used
   • Works by converting to formaldehyde in acidic urine, creating a bacteriostatic environment

2. For postmenopausal women:

   • Vaginal estrogen replacement - Strongly recommended to prevent recurrent UTI 1
   • Addresses atrophic vaginitis, a key risk factor in this population

3. Other non-antimicrobial options (with weaker evidence):

   • Immunoactive prophylaxis - Strongly recommended for all age groups 1
   • D-mannose - May reduce recurrent UTI episodes (weak evidence) 1
   • Cranberry products - May help reduce recurrences (weak, contradictory evidence) 1
   • Probiotics - For vaginal flora regeneration (weak evidence) 1

Antimicrobial Options (When Non-Antimicrobial Interventions Fail)

If the above measures fail, antimicrobial prophylaxis should be considered:

1. Trimethoprim-sulfamethoxazole (TMP-SMX) - Once weekly dosing (160mg/800mg) has shown effectiveness with infection rates of 1.3 per patient-year 2, 3

   • Thrice-weekly dosing shows better efficacy (0.1 infections per patient-year) 3

2. Nitrofurantoin - 100mg once daily has shown effectiveness (0.14 infections per patient-year) 4

   • Not typically recommended as once-weekly dosing

Important Clinical Considerations

• Diagnosis confirmation: Always confirm recurrent UTI via urine culture before starting prophylaxis 1
• Duration of prophylaxis: Typically 6-12 months; infections often recur within 2-3 months after discontinuation 2, 3
• Risk factors to address:
  • In premenopausal women: Increase fluid intake 1
  • In postmenopausal women: Address vaginal atrophy, urinary incontinence, and high post-void residual volume 1

Pitfalls to Avoid

1. Antimicrobial resistance - Long-term antibiotic prophylaxis can lead to resistance; non-antimicrobial options should be tried first 1, 4

2. Treating asymptomatic bacteriuria - Ensure the patient truly has symptomatic UTIs before starting prophylaxis 5

3. Overlooking anatomical abnormalities - Consider urological evaluation in women with persistent recurrences despite prophylaxis 1

4. Neglecting self-administered therapy - For patients with good compliance, self-administered short-term antimicrobial therapy should be considered as an alternative to continuous prophylaxis 1

For once-weekly prophylaxis specifically, methenamine hippurate is the preferred option based on the strong recommendation in the most recent guidelines, with TMP-SMX as an alternative when antimicrobial prophylaxis is deemed necessary.