Formulary
Methenamine hippurate: Indications, Dosing, Side Effects and Interactions
Methenamine hippurate is a urinary antiseptic which requires an acidic urine for its action.
MedNext Academy | 3 min read
Methenamine hippurate: Indications, Dosing, Side Effects and Interactions
Methenamine hippurate is a urinary antiseptic which requires an acidic urine for its action.
Drug action
Methenamine hippurate is a urinary antiseptic which requires an acidic urine for its action. It has decreased effect on urea-degrading bacteria e.g. Pseudomonas and some strains of Proteus ; these organisms usually affect patients with complicated urinary tract infections.
Indications and dose
**Prophylaxis of uncomplicated lower urinary-tract infection**
- **Adult** (By Mouth): 1 g twice daily, seek specialist advice if considering use for prophylaxis during pregnancy, in male patients, or for recurrent upper UTI or recurrent complicated lower UTI (lack of evidence to inform when methenamine hippurate may be beneficial in these patients).
**Prophylaxis of uncomplicated lower urinary-tract infections in patients with a catheter**
- **Adult** (By Mouth): 1 g 2-3 times a day.
**Prophylaxis of uncomplicated lower urinary-tract infection for methenamine hippurate**
- **Child 16-17 years** (By mouth): 1 g twice daily, seek specialist advice if considering use for prophylaxis during pregnancy, in male patients, or for recurrent upper UTI or recurrent complicated lower UTI (lack of evidence to inform when methenamine hippurate may be beneficial in these patients).
Contraindications
Gout; metabolic acidosis; renal parenchymal infection; severe dehydration
Side effects
Uncommon Gastrointestinal discomfort; nausea; skin reactions; vomiting Frequency not known Diarrhoea
Interactions
**Other interactions (2):**
- Methenamine hippurate should not be given/administered concurrently with sulphonamides because of the possibility of crystalluria, or with alkalising agents such as potassium citrate.
- Concurrent use with acetazolamide should be avoided as the desired effect of hexamine will be lost.
Pregnancy
Specialist sources indicate not known to be harmful, however limited human data available.
Breast feeding
Amount too small to be harmful. M (recommendation also supported by tertiary sources).
Hepatic impairment
Avoid M (risk of accumulation of ammonia metabolite).
Renal impairment
Risk of hippurate crystalluria. Avoid if creatinine clearance less than 10 mL/minute, M see Prescribing in renal impairment .
Medicinal forms
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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