Flashcards in Sulfonamides, Trimethoprim, & Fluoroquinolones Deck (18):
What is the mechanism of action of trimethoprim-sulfamethoxazole?
1. Synergistic inhibition of folic acid synthesis.
2. The combination is bactericidal - sequential blockade.
What is the clinical use of trimethoprim-sulfamethoxazole?
2. Respiratory, ear , and sinus infections
3. P.jiroveci pneumonia
What is the pharmacokinetics of trimethoprim-sulfamethoxazole?
1. Oral or IV administration
2. Renal clearance
3. Half-life - 8h
What is the toxicity of trimethoprim-sulfamethoxazole?
3. Bone marrow suppression
5. High incidence of adverse effects in AIDS
Mention some major folate antagonists?
2. Sulfadiazine (+/- pyrimethamine)
4. Pyrimethaprim (+/- sulfadoxine)
What is the mechanism of action of folate antagonists?
1. Sulfonamides inhibit dihydropteroate synthase.
2. Trimethoprim + pyrimethamine inhibit dihydrofolate reductase.
What is the clinical use of folate antagonists?
Sulfonamides --> simple UTI (orally), topical in burn or eye infections.
Sulfadiazine + pyrimethamine --> toxoplasmosis.
Sulfadoxine + pyrimethamine --> malaria.
What are the pharmacokinetics of sulfonamides?
Hepatic and renal clearance and extensive plasma protein binding of sulfonamides - displace bilirubin, methotrexate, and warfarin.
What is a common toxicity of sulfonamides?
Oral doses cause:
1. GI upset
2. Acute hemolysis
3. Possible crystalluria
5. Assume crossreactivity
What is the mechanism of action of ciprofloxacin?
Inhibits DNA replication via binding to DNA gyrase (gram (-)) and topoisomerase (gram (+)).
What is the clinical use of ciprofloxacin?
3. Respiratory infections
4. Rapidly declined activity versus gonococci
5. Limited use in TB
What are the pharmacokinetics of ciprofloxacin?
1. Oral, IV admin
2. Mostly renal clearance
3. Half-life 4h
4. Oral absorption impaired by cations
What is the toxicity of ciprofloxacin?
1. GI upsets
2. CNS effects (dizziness, headache)
3. Tendinitis due to effects of cartilage (try to avoid in young children and in pregnancy.
Mention 5 major fluoroquinolones.
What is the mechanism of action of fluoroquinolones?
Identical to that of ciprofloxacin.
What is the clinical use of fluroquinolones?
Norfloxacin and ofloxacin --> UTIs.
Levoflaxin and moxifloxacin --> gram (+) cocci and atypicals (chlamydia, mycoplasma).
What are the pharmacokinetics of fluroquinolones?
1. Oral and IV formas of levoffloxacin and moxifloxacin.
2. Mostly renal clearance - not moxifloxacin.
3. Long-halves lifes of gemifloxacin and moxifloxacin permit once-daily dosing.