CH4 | Urinary Tract Infections Flashcards
What is a major issue with fluoroquinolones and cotrimoxazole in treating urinary tract infections?
There is high resistance in common pathogens like E. coli, so new drugs had to be introduced.
What are the most commonly used urinary antiseptics?
- Methenamine.
- Nitrofurantoin.
What is a key characteristic of urinary tract antiseptics like Methenamine and Nitrofurantoin?
They have high efficacy against common pathogens and achieve high concentrations in urine.
What is the purpose of using urinary tract antiseptics?
For treatment or suppression of recurrence of urinary tract infections.
Explain how Methenamine’s hydrolysis in acidic urine contributes to its antibacterial effect.
Methenamine is hydrolyzed to ammonia and formaldehyde in acidic urine (pH ≤ 5.5).
What happens to formaldehyde in the context of Methenamine’s action?
Formaldehyde denatures proteins and nucleic acids, leading to bacterial cell death.
What weak acids does Methenamine combine with to maintain acidity?
Hippuric acid and mandelic acid.
What is the primary use of Methenamine?
For chronic suppressive therapy to reduce the frequency of UTIs.
Which bacteria does Methenamine target?
E. coli, Enterococcus spp., Staphylococcus spp., and has some activity against Proteus and Pseudomonas aeruginosa.
Why does Methenamine not select for resistant organisms?
It lacks selection for resistant organisms.
How is Methenamine absorbed in the body?
It is orally absorbed, but enteric coating is needed to avoid 30% decomposition.
How does Methenamine reach the urine?
Through tubular secretion and glomerular filtration.
What should be avoided when using Methenamine?
Use in hepatic insufficiency due to ammonia production.
What are the adverse effects of Methenamine?
GIT distress, albuminuria, hematuria, and rashes at high doses.
In which patients is Methenamine mandelate contraindicated?
Patients with renal insufficiency due to the risk of acid precipitation.
