Vitamin C and Hiprex in rUTI

NCT06710899 — Early Phase 1, Not yet recruiting, 20 participants, University Hospitals of North Midlands NHS Trust

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Does Vitamin C Improve the Efficacy of Methenamine Hippurate (Hiprex®) in Prophylaxis of Recurrent Urinary Tract Infections? A Proof of Concept Study

Registry	NCT06710899
Status	Not yet recruiting
Phase	Early Phase 1
Study type	Interventional; non randomized, sequential, masking: none, treatment
Enrollment	20 (Estimated)
Sponsor	University Hospitals of North Midlands NHS Trust (Other)
Conditions	Urinary Tract Infections
Interventions	Methenamine Hippurate 1g BD, Methenamine Hippurate 1g BD + Vitamin C 1g BD (Drug)
Dates	start 2027-01-01 (estimated), primary completion 2027-08-01 (estimated), completion 2028-01-01 (estimated), first posted 2024-11-29, last updated 2026-02-11
Locations	1 site in United Kingdom

-Summary

A single centre proof of concept study to assess whether Vitamin C improves the efficacy of Methenamine Hippurate (Hiprex®) in the prophylaxis of recurrent urinary tract infections (rUTIs) in women

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+Arms and interventions

Arm	Type	Interventions	Description
Treatment phase A	Experimental	Drug: Methenamine Hippurate 1g BD	Methenamine Hippurate 1g BD for 6 months
Treatment phase B	Experimental	Drug: Methenamine Hippurate 1g BD + Vitamin C 1g BD	Methenamine Hippurate 1g BD + Vitamin C 1g BD for 6 months
Treatment phase C	Experimental	Drug: Methenamine Hippurate 1g BD	Methenamine 1g BD for 6 months

Methenamine Hippurate 1g BD (Drug): Methenamine Hippurate 1g BD for 6 months
Methenamine Hippurate 1g BD + Vitamin C 1g BD (Drug): Methenamine Hippurate 1g BD + Vitamin C 1g BD for 6 months

+Outcome measures

Primary outcomes

Frequency of UTIs [24 months]: The incidence of symptomatic UTI during each six-month treatment phase of either methenamine hippurate alone or methenamine hippurate plus vitamin C

Secondary outcomes

Urine pH [24 months]: Measurement of urine pH during each treatment phase

+Eligibility

Sex: Female, ages: 18 Years to any

Inclusion Criteria:

* Female
* Age ≥18 years
* Recurrent proven UTI, defined as "two or more proven infections in six months or three or more infections in six months"
* Willing and able to give fully informed consent
* Patients suitable for prophylaxis following discussion with their clinician.
* No contra-indications to treatment with methenamine hippurate or Vitamin C
* All women will have undergone standard diagnostic work-up and have followed routine conservative UTI prevention measures.
* A working email address to be used to submit urine pH results
* Willing and able to comply with the study procedures
* Females of childbearing potential must be willing to use a highly effective method of contraception (hormonal or barrier method of birth control; abstinence; sterilisation or vasectomised partner)

Exclusion Criteria:

* Males
* Women who are pregnant or breast-feeding
* Contraindications to methenamine hippurate as described in BNF: known allergy, gout, severe metabolic acidosis, severe dehydration, eGFR less than 10 ml/min, severe hepatic impairment
* Currently using vitamin C containing supplement or cranberry extract tablets
* Women using urinary alkalinisation agents, e.g potassium citrate, sodium bicarbonate
* Currently receiving any form of bladder instillation or intradetrusor Onabotulinum Toxin A injections
* Patients already on low-dose antibiotics or methenamine hippurate (due to delay that will be incurred by 3-month washout period)
* Indwelling urinary catheter in situ or performing clean intermittent self-catheterisation
* Correctable urinary tract abnormalities, e.g., urinary tract calculi, urinary retention
* Formation of ileal conduit or augmented bladder
* Neurogenic bladder dysfunction
* Hyperoxaluria

+Locations (1)

Facility	City	Country	Status
University Hospitals of North Midlands NHS Trust	Stoke-on-Trent, Staffordshire	United Kingdom