Urinary Tract InfectionsPhase 4NCT04709601
Efficacy and Mechanism of Action of Methenamine Hippurate (Hiprex™) in Women With Recurring Urinary Tract Infections.
A Phase 4 study testing Hiprex in people with Urinary Tract Infections, run by University of Texas Southwestern Medical Center at 1 site in United States.
Trial summary
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… Read more about this study
- Who is it for?
- Ages 50 to 85 years, women only
- Conditions the study is for
- Urinary Tract Infections
- What is being tested?
- Hiprex
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 14 participants
- Where
- 1 siteUnited States
- Study dates
- 4 Jan 2021to 31 Dec 2024
- Phase
- Phase 4
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 50 to 85 years
- Women only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Female
- Age 50 - 85
- Have RUTIs (at least 2 UTIs within the past 6 months or 3 within the past year) -
Who cannot join
- Being on antibiotics at baseline (i.e. suppressive therapy or antibiotic therapy for urinary or non-urinary infections)
- Neurogenic bladder condition
- Using urinary catheters (including Foley catheter, intermittent catheterization, and suprapubic catheter)
- Uncontrolled diabetes (HbA1c > 9)
- Chronic renal failure defined as serum creatinine > 1.5 mg/dL
- History of liver disease
Show all 11Show fewer
- Patients from out of town, in whom follow-up will not be possible
- Pregnancy
- Allergy to Hiprex
- Inability to take Hiprex reliably at home, such as having psychosis, dementia, or swallowing disorders
- Non-English speakers -
Trial locations and contacts
1 site in 1 country.
About this study
Official title: 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.
- Conditions
- Urinary Tract Infections
- Being tested
- Hiprex
- Medical subject headings
- Urinary Tract Infections
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
HiprexDrug
Also called Methenanime hippurate
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.
| Study group | Role | What they receive |
|---|---|---|
| Group 1 - Patients with negative and positive urine culture | Experimental | Not described Receives: Drug: Hiprex |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of Urinary Tract Infections
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.
Measured: 1 year
Secondary outcomes (9)
Frequency of Oral Antibiotic Use
Total number of calendar days on which a participant received one or more doses of an oral antibiotics
Measured: 1 year
Number of Participants That Used Oral Anti-biotic
Number of participants who used oral-antibiotics to treat symptomatic UTI episodes during 1 year of Hiprex administration
Measured: 1 year
Number of Hospital Re-admissions at 1 Year
Number of hospital re-admissions at 1 year due to urosepsis and pyelonephritis.
Measured: 1 year
Frequency and Severity of Adverse Events Related to Hiprex
Number of participants who experienced adverse events >= Grade 3, as defined by Common Terminology Criteria for Adverse Events by CTCA version 5.0
Measured: 1 year
Urine Acidity Levels
Urine acidity levels will be measured by urinary pH at each visit. Lower pH will yield a better outcome.
Measured: 1 year
Number of Urinary Tract Infection Episodes
Number of UTI episodes will be measured for this outcome.
Measured: up to 1 year
Number of Urinary Tract Infection Episodes
Number of UTI episodes will be measured for this outcome.
Measured: up to 2 years
Severity of UTI Symptoms as Measured by the UTI Symptom Assessment Questionnaire
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
Measured: 1 year
Duration of Intervals Between UTI Episodes
Duration of intervals will be measured between one UTI episode to the next UTI episode
Measured: 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Jan 2021
- Study start4 Jan 2021
- Primary completion31 Dec 2024
- Study completion31 Dec 2024
Why it stopped: Because the study investigator is no longer following these patients as part of this study. They are followed as part of SOC as the study investigator's patients.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Urinary Tract InfectionsStudies of the same condition, open and under way.
- More trials run by University of Texas Southwestern Medical CenterThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 14 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Texas Southwestern Medical Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Philippe Zimmern, University of Texas Southwestern Medical Center
- Investigators
- Philippe Zimmern, MD, Principal investigator, University of Texas Southwestern Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04709601
- Sponsor's protocol ID
- STU-2020-0725
- Status last verified
- Feb 2026
- First submitted
- 17 Dec 2020
- Last updated
- 24 Feb 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 24 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Efficacy and Mechanism of Action of Methenamine Hippurate (Hiprex™) in the Management of Recurrent Urinary Tract Infections in Women
- ClinicalTrials.gov ID
- NCT04709601
- Acronym / sponsor ID
- STU-2020-0725
- Conditions
- Urinary Tract Infections
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Because the study investigator is no longer following these patients as part of this study. They are followed as part of SOC as the study investigator's patients.
- Enrolment
- 14 participants (actual)
- Lead sponsor
- University of Texas Southwestern Medical CenterUniversity, hospital or other
- Study start
- 4 Jan 2021 (actual)
- Primary completion
- 31 Dec 2024 (actual)
- Study completion
- 31 Dec 2024 (actual)
- First posted
- 14 Jan 2021 (actual)
- Results
- Posted 24 Feb 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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 design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Group 1 - Patients with negative and positive urine culture | Experimental | Drug: Hiprex |
Who may qualify
- Ages
- 50 to 85 years
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Female
- Age 50 - 85
- Have RUTIs (at least 2 UTIs within the past 6 months or 3 within the past year) -
Key exclusion criteria (11 listed)
- Being on antibiotics at baseline (i.e. suppressive therapy or antibiotic therapy for urinary or non-urinary infections)
- Neurogenic bladder condition
- Using urinary catheters (including Foley catheter, intermittent catheterization, and suprapubic catheter)
- Uncontrolled diabetes (HbA1c > 9)
- Chronic renal failure defined as serum creatinine > 1.5 mg/dL
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| HiprexAlso: Methenanime hippuratePatients 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. | Drug | Group 1 - Patients with negative and positive urine culture |
Primary outcome
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.
9 secondary outcomes
Frequency of Oral Antibiotic Use
Time frame: 1 year
Number of Participants That Used Oral Anti-biotic
Time frame: 1 year
Number of Hospital Re-admissions at 1 Year
Time frame: 1 year
Frequency and Severity of Adverse Events Related to Hiprex
Time frame: 1 year
Urine Acidity Levels
Time frame: 1 year
Number of Urinary Tract Infection Episodes
Time frame: up to 1 year
Number of Urinary Tract Infection Episodes
Time frame: up to 2 years
Severity of UTI Symptoms as Measured by the UTI Symptom Assessment Questionnaire
Time frame: 1 year
Duration of Intervals Between UTI Episodes
Time frame: 1 year
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Feb 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Philippe Zimmern, MD principal investigator
University of Texas Southwestern Medical Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Hiprex in people with Urinary Tract Infections, run by University of Texas Southwestern Medical Center at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 24 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 24 Feb 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of Urinary Tract Infections (time frame: 1 year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Feb 2026.