Vitamin C and Hiprex in rUTI

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

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

Study Overview

• Status: Not yet recruiting
• Conditions: Urinary Tract Infections
• Intervention / Treatment: Drug: Methenamine Hippurate 1g BD; Drug: Methenamine Hippurate 1g BD + Vitamin C 1g BD

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Early Phase 1

Contacts and Locations

• Study Contact: Name: Aviva Ogbolosingha; Phone Number: 01782 675380; Email: aviva.ogbolosingha@uhnm.nhs.uk

Study Locations

• United Kingdom
  • Staffordshire
    • Stoke-on-Trent, Staffordshire, United Kingdom, ST4 6QG
      • University Hospitals of North Midlands NHS Trust

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Treatment phase A; Methenamine Hippurate 1g BD for 6 months	Drug: Methenamine Hippurate 1g BD; Methenamine Hippurate 1g BD for 6 months
Experimental: Treatment phase B; Methenamine Hippurate 1g BD + Vitamin C 1g BD for 6 months	Drug: Methenamine Hippurate 1g BD + Vitamin C 1g BD; Methenamine Hippurate 1g BD + Vitamin C 1g BD for 6 months
Experimental: Treatment phase C; Methenamine 1g BD for 6 months	Drug: Methenamine Hippurate 1g BD; Methenamine Hippurate 1g BD for 6 months

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Frequency of UTIs	The incidence of symptomatic UTI during each six-month treatment phase of either methenamine hippurate alone or methenamine hippurate plus vitamin C	24 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Urine pH	Measurement of urine pH during each treatment phase	24 months

Collaborators and Investigators

• Sponsor: University Hospitals of North Midlands NHS Trust

Study record dates

Study Major Dates

• Study Start (Estimated): January 1, 2027
• Primary Completion (Estimated): August 1, 2027
• Study Completion (Estimated): January 1, 2028

Study Registration Dates

• First Submitted: November 26, 2024
• First Submitted That Met QC Criteria: November 26, 2024
• First Posted (Actual): November 29, 2024

Study Record Updates

• Last Update Posted (Actual): February 11, 2026
• Last Update Submitted That Met QC Criteria: February 10, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Urogenital Diseases; Male Urogenital Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Infections; Urinary Tract Infections; Organic Chemicals; Carbohydrates; Sugar Acids; Acids, Acyclic; Carboxylic Acids; Hydroxy Acids; Ascorbic Acid; methenamine hippurate
• Other Study ID Numbers: 3399

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No