Methenamine for Preventing Recurrent UTI?

Educational Objectives

Summary

Methenamine Hippurate Works for Preventing Recurrent Urinary Tract Infections

A guideline from the American Urological Association allows for 1 year of low-dose antibiotics to suppress recurrent urinary tract infections (UTIs) despite concerns about contributing to antibiotic resistance (https://doi.org/10.1097/JU.0000000000000296). The nonantibiotic urinary antiseptic methenamine hippurate (which is hydrolyzed to bactericidal formaldehyde in the distal tubule) might be a useful alternative, but its effectiveness has not been studied adequately.

In a pragmatic noninferiority trial on the website of The BMJ (https://doi.org/10.1136/bmj-2021-0068229), investigators in the U.K. randomized 240 women with recurrent symptomatic UTIs (mean, 7 episodes in the past year) to receive either daily low-dose antibiotic prophylaxis (i.e., nitrofurantoin, trimethoprim, or cefalexin, at the discretion of the patient and clinician) or methenamine hippurate (100 mg twice daily) for 12 months. Patients could switch between antibiotics or between treatment strategies. Women who experienced UTI symptoms were advised to seek short courses of antibiotics from their usual clinicians.

In a modified intent-to-treat analysis, more symptomatic, antibiotic-treated UTIs (with or without bacteriologic confirmation) occurred in the methenamine hippurate group than in the antibiotic group (1.38 vs 0.89 per patient-year), but the confidence interval around the difference fell within the prespecified, noninferiority limit of 1 UTI per person-year. A similarly small difference was noted in the first 6 months after completion of treatment.

Methenamine hippurate appears to be a reasonable nonantibiotic alternative for patients with recurrent UTIs. Few adverse effects have been noted in short-term studies of methenamine hippurate, but its long-term safety has not been assessed fully.

Bruce Soloway, MD

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Disclosures

Acknowledgements

CME/CE INFO

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The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

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Lecture ID:

JW330820

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

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Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

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