Trimethoprim-Sulfamethoxazole and Quinolones Flashcards
15.28
Trimethoprim-Sulfamethoxazole (TMP-SMX) - MOA
Antimicrobial
Inhibits 2 steps of the THF synthesis pathway; (1) sulfamethoxazole inhibits incorporation of PABA into dihydrofolic acid via competition; (2) trimethoprim inhibits the enzyme DHFR and prevents formation of tetrahydrofolic acid
Trimethoprim-Sulfamethoxazole (TMP-SMX) - Tx (4)
Tx and prophylactic use in women w/ frequent UTIs; also for uncomplicated cystitis, uncomplicated pyelonephritis, prostatitis (acute and chronic forms)
What is THF?
Tetrahydrofolic acid
Why is the THF synthesis pathway important?
Tetrahydrofolic acid needed to make purines, which is needed to make DNA
What does DHFR stand for?
Dihydrofolate reductase
Trimethoprim-Sulfamethoxazole (TMP-SMX) - Dosage
20:1 sulfamethoxazole:trimethoprim concentration; oral ;
Trimethoprim-Sulfamethoxazole (TMP-SMX) - MOR
Altered DHFR
Trimethoprim-Sulfamethoxazole (TMP-SMX) - Tox (3)
Myelosuppression, Stevens-Johnson syndrome, nausea/vomiting
What are the 2 quinolones?
Nalidixic acid; Cinoxacin
Nalidixic acid; Cinoxacin - MOA
Quinolones
Inhibits DNA gyrase and topoisomerase IV ; Given orally ;
Nalidixic acid; Cinoxacin - MOR
DNA gyrase mutation
Nalidixic acid; Cinoxacin - limitations (3)
- Compared to fluoroquinolones –> narrow spectrum (gram (-) bacteria only)
- Requires high doses
- Widespread resistance
Name the 4 fluoroquinolones?
Ciprofloxacin; Ofloxacin; Levofloxacin; Norfloxacin
Ciprofloxacin; Ofloxacin; Levofloxacin; Norfloxacin - MOA
Fluoroquinolones
Inhibits DNA gyrase (gram - bacteria) and topoisomerase IV (gram positive bacteria)
Given orally
Ciprofloxacin; Ofloxacin; Levofloxacin; Norfloxacin - Tx (3)
Use in complicated and uncomplicated cystitis, uncomplicated and complicated pyelonephritis (as empiric therapy), prostatitis (acute and chronic forms)
