From the Guidelines
Methenamine hippurate is an antibiotic used to treat and prevent urinary tract infections (UTIs) by releasing formaldehyde in acidic urine, resulting in bacteriostasis 1.
Key Points
- The recommended dose is 1 gram orally every 12 hours 1.
- Methenamine hippurate is an appealing antimicrobial-sparing intervention to reduce UTIs in patients without incontinence and a fully functional bladder 1.
- It is essential to take the medication with a full glass of water and to maintain adequate hydration throughout the treatment period.
- Patients with renal impairment or those taking other medications that may interact with methenamine hippurate should be closely monitored 1.
- Methenamine hippurate has been found to be noninferior to antibiotics for the prevention of UTIs in women aged 18 years and older 1.
Important Considerations
- Methenamine hippurate works by releasing formaldehyde in acidic urine, thus resulting in bacteriostasis 1.
- Unlike conventional antibiotics, acquired resistance does not appear to develop with methenamine hippurate 1.
- Strategies that reduce antibiotic use may be important to decrease patient side effects and antibiotic resistance 1.
From the FDA Drug Label
Each yellow capsule-shaped tablet contains 1 g Methenamine Hippurate which is the hippuric acid salt of methenamine (hexamethylene tetramine). Methenamine hippurate is the hippuric acid salt of methenamine (hexamethylene tetramine), an antibacterial agent used to treat or prevent urinary tract infections 2.
- It has antibacterial activity due to the hydrolysis of methenamine to formaldehyde in acid urine.
- The hippuric acid component also has some antibacterial activity and helps keep the urine acid. Key points about methenamine hippurate include:
- Composition: hippuric acid salt of methenamine
- Mechanism of action: antibacterial activity through formaldehyde release and urine acidification
- Indications: prophylactic or suppressive treatment of frequently recurring urinary tract infections 2
From the Research
Definition and Use of Methenamine Hippurate
- Methenamine hippurate is a urinary antiseptic used as a preventive treatment for recurrent urinary tract infections (UTIs) in some Scandinavian countries 3.
- It is often used as an alternative to antibiotics for the prevention of UTIs 4, 5, 6.
Efficacy of Methenamine Hippurate
- Methenamine hippurate may be effective for preventing UTI in patients without renal tract abnormalities, particularly when used for short-term prophylaxis 4, 5.
- Subgroup analyses suggest that methenamine hippurate may have some benefit in patients without renal tract abnormalities, but not in patients with known renal tract abnormalities 4, 5.
- A systematic review and meta-analysis found that methenamine hippurate showed a non-statistically significant trend of benefit versus antibiotics and control in preventing UTIs 7.
Safety and Adverse Events
- The rate of adverse events associated with methenamine hippurate is low 4, 5, 7, 6.
- Methenamine hippurate is unlikely to be causing significant harm due to its low rate of adverse events 6.
Research Gaps and Future Studies
- There is a need for further large, well-conducted randomized controlled trials to clarify the effectiveness of methenamine hippurate in preventing UTIs, particularly for longer-term use in people without neuropathic bladder 4, 5, 7.
- Future studies should investigate the benefits and harms of methenamine hippurate in preventing UTIs and explore its potential as an alternative to antibiotic treatment for UTIs 7.