methenamine hippurate: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
methenamine hippurate: clinical details
Prescribing considerations
- Confirm that acute infection has received appropriate assessment and treatment before preventive use.
- Review medicines and supplements that alkalinise urine because activity depends on acidic urinary conditions.
- Breakthrough UTI symptoms require reassessment; methenamine does not guarantee complete prevention.
- Consider renal and hepatic status and hydration before prescribing.
Contraindications and cautions
- Hypersensitivity to methenamine hippurate or an excipient
- Hepatic dysfunction
- Renal parenchymal infection or severe renal failure
- Severe dehydration
- Metabolic acidosis
- Gout
- Concurrent sulphonamide or urinary-alkalising treatment
Monitoring
- Assess renal and hepatic function when impairment is known or suspected.
- Review clinical recurrence and obtain urine culture when clinically indicated.
- Warn laboratories about possible interference with specified urine assays.
Clinical pharmacology
Methenamine hippurate is absorbed gastrointestinally and excreted renally. Acid-dependent hydrolysis releases bactericidal formaldehyde in urine, supplemented by the bacteriostatic activity of hippuric acid.
Formulation and product differences
- The selected Hiprex product is a scored, oblong tablet that may be halved or crushed.
- Its listed excipients are magnesium stearate, povidone and colloidal anhydrous silica.
- The selected product is supplied in a tightly closed glass bottle and should not be stored above 30°C.
methenamine hippurate preparations and strengths
Tablet
Route: Oral
Strengths: 1 g
methenamine hippurate interactions
Check prescribed, over-the-counter and urinary-symptom products before combining them with methenamine hippurate.
Sulphonamide antibiotics
Concurrent use is contraindicated because crystals may form in the urine.
Urinary alkalising agents, including potassium citrate
They raise urinary pH and can prevent methenamine from working effectively.
Acetazolamide
It can reduce the required urinary acidity and should be avoided with methenamine hippurate.
Certain urine laboratory tests
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.