Urinary pH, Methenamine, and Formaldehyde Levels in the Management of Postmenopausal Women With Recurrent Urinary...

To evaluate urinary pH, methenamine (uME), and formaldehyde (uFA) levels from women with documented recurrent urinary tract infections (rUTIs) taking Hiprex and monitored these levels with rUTI incidence over time.

Following IRB-approval, non-neurogenic women, ages 50-85 years old, with a history of rUTIs, low urinary pH trends (<6), and interested in being monitored for UTI symptoms while taking Hiprex for 1 year were enrolled at a tertiary care center specializing in rUTI management. At the initial and six subsequent office visits, a urine sample was obtained prior to, and 1 hour after, taking 1 gm Hiprex. Urine pH, uME, and uFA levels were measured using commercially available kits, normalized to urinary creatinine.

Of 29 patients (mean age 71.4 years) screened, seven met study criteria and completed the 1-year study, with an additional year of follow-up. Methenamine was identified in the urine of each participant after Hiprex administration. Median uFA levels increased between 14% and 130% 1-hour following Hiprex administration. Most individuals (71%) consistently had a urine pH below 6. The majority remained UTI-free.

This study confirmed the durable presence of uME and uFA from those on Hiprex in a low urinary pH environment with clinical efficacy. A sustained increase in uFA was observed 1-hour following office-administered Hiprex. The uFA concentration was lower than deemed bactericidal in vitro; so, additional research is needed on the mechanism of Hiprex to better define its role in UTI prevention.