Efficacy and Mechanism of Action of Methenamine Hippurate (Hiprex™) in Women With Recurring Urinary Tract Infections.

February 9, 2026 updated by: Philippe Zimmern, University of Texas Southwestern Medical Center

Efficacy and Mechanism of Action of Methenamine Hippurate (Hiprex™) in the Management of Recurrent Urinary Tract Infections in Women

The purpose of this study is to measure the concentration of formaldehyde in the urine of women with recurrent urinary tract infections on Hiprex; and then, assuming its urinary presence is confirmed at the proper acid urinary pH, evaluate if such a therapy has favorable effects in decreasing the rate of recurrent urinary tract infections over time.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Terminated

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
14

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • Texas
      • Dallas, Texas, United States, 75390
        • UT-Southwestern Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

50 years to 85 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Female
  2. Age 50 - 85
  3. Have RUTIs (at least 2 UTIs within the past 6 months or 3 within the past year) -

Exclusion Criteria:

  1. Being on antibiotics at baseline (i.e. suppressive therapy or antibiotic therapy for urinary or non-urinary infections)
  2. Neurogenic bladder condition
  3. Using urinary catheters (including Foley catheter, intermittent catheterization, and suprapubic catheter)
  4. Uncontrolled diabetes (HbA1c > 9)
  5. Chronic renal failure defined as serum creatinine > 1.5 mg/dL
  6. History of liver disease
  7. Patients from out of town, in whom follow-up will not be possible
  8. Pregnancy
  9. Allergy to Hiprex
  10. Inability to take Hiprex reliably at home, such as having psychosis, dementia, or swallowing disorders
  11. Non-English speakers -

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Group 1 - Patients with negative and positive urine culture
Drug: Hiprex
Patients with negative urine culture will be prescribed Hiprex 1 g PO BID x 1 yr and patients with a positive urine culture will be prescribed antibiotics.
Other Names:
  • Methenanime hippurate

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Number of Urinary Tract Infections
Time Frame: 1 year
It would be measured by counting the positive urine cultures, or UTI-like episodes requiring antibiotic treatment during the 1 year of the study period.
1 year

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Frequency of Oral Antibiotic Use
Time Frame: 1 year
Total number of calendar days on which a participant received one or more doses of an oral antibiotics
1 year
Number of Participants That Used Oral Anti-biotic
Time Frame: 1 year
Number of participants who used oral-antibiotics to treat symptomatic UTI episodes during 1 year of Hiprex administration
1 year
Number of Hospital Re-admissions at 1 Year
Time Frame: 1 year
Number of hospital re-admissions at 1 year due to urosepsis and pyelonephritis.
1 year
Frequency and Severity of Adverse Events Related to Hiprex
Time Frame: 1 year
Number of participants who experienced adverse events >= Grade 3, as defined by Common Terminology Criteria for Adverse Events by CTCA version 5.0
1 year
Urine Acidity Levels
Time Frame: 1 year
Urine acidity levels will be measured by urinary pH at each visit. Lower pH will yield a better outcome.
1 year
Number of Urinary Tract Infection Episodes
Time Frame: up to 1 year
Number of UTI episodes will be measured for this outcome.
up to 1 year
Number of Urinary Tract Infection Episodes
Time Frame: up to 2 years
Number of UTI episodes will be measured for this outcome.
up to 2 years
Severity of UTI Symptoms as Measured by the UTI Symptom Assessment Questionnaire
Time Frame: 1 year
UTI Symptom Assessment questionnaire measures severity of UTI symptoms. Possible score range from 0 to 3 (0= Did not have 1= Mild 2=Moderate, and 3=Severe), higher score indicates higher severity of UTI symptoms
1 year
Duration of Intervals Between UTI Episodes
Time Frame: 1 year
Duration of intervals will be measured between one UTI episode to the next UTI episode
1 year

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Texas Southwestern Medical Center

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Philippe Zimmern, MD, University of Texas Southwestern Medical Center

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 4, 2021

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2024

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 17, 2020

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 12, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 14, 2021

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 24, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 9, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • STU-2020-0725

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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