Methenamine huppurate Flashcards
What drug classification is methenamine hippurate?
‘other - antimicrobials’
aka hexamine hippurate
What is the MOA of methenamine hippurate?
Hydrolysed in acidic pH to ammonia and formaldehyde, which is bactericidal against Gram-positive and Gram-negative bacteria, and fungi in vitro.
What is the indication for treatment with methenamine hippurate?
Prophylaxis of chronic or recurrent lower UTIs
What are the precautions to methenamine hippurate?
- Severe dehydration - contraindicated
- Gout - urate crystals may precipitate in urine
- Renal
- Hepatic
What is the renal precaution associated with methenamine hippurate?
Ineffective in renal impairment because of inadequate concentrations in renal tubules (also risk of hippurate crystalluria in severe impairment).
What is the hepatic precaution associated with methenamine hippurate?
Contraindicated in severe impairment (stomach acid hydrolyses methenamine, producing ammonia).
Is methenamine hippurate safe in pregnancy or breastfeeding patients?
Safe to use
What are the adverse effects of methenamine hippurate?
- nausea
- vomiting
- diarrhoea
- rash
- dysuria (discomfort/painful urination)
What is the counselling points for methenamine hippurate?
Avoid taking medications like sodium bicarbonate, Ural® or Citravescent® as they make methenamine less effective.
Is methenamine hippurate effective for UTI prevention?
•evidence for efficacy in preventing UTIs is poor; it is not effective for:
◦suppressing infection associated with indwelling urinary catheters
◦preventing infections due to Proteus and some Pseudomonas spp., which increase urinary pH, inhibiting the production of formaldehyde
•it is not effective for treating UTIs (refer symptomatic patients to a doctor in preference to supplying OTC)
Is methenamine hippurate effective for treating a UTI?
•it is not effective for treating UTIs (refer symptomatic patients to a doctor in preference to supplying OTC)
Which vitamin may affect the efficacy of methenamine hippurate?
•urinary pH <5.5 is required for its activity; ascorbic acid (4–12 g over 24 hours) may lower urinary pH but its effect is short-lived
