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28 Cards in this Set
- Front
- Back
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What are the 2 classes of Energy metabolism agents?
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-Sulfonamides
-Trimethoprim |
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What is the mechanism by which the Sulfonamides inhibit bacteria?
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They competitively inhibit Dihydropteroate Synthetase by acting as analogs of PABA
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How does the mechanism of the Sulfonamides not block human cell metabolism?
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Humans don't rely on folate synthesis; we get it from the diet.
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Are the sulfonamides bacteriostatic or cidal?
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Bacteriostatic
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What are the 2 resistance mechanisms to the Sulfonamides?
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-Reduced uptake of the drug
-Mutations in dihydropteroate synthetase |
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What has happened to the ability of the sulfonamides to act as broad spectrums?
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It is much decreased due to overuse
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How are the sulfonamides used now?
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In combination with other antibacterials
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What are the 2 sulfonamides to know?
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-Sulfamethoxazole
-Silver sulfadiazine |
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Why is Sulfamethoxazole the one that is always used synergistically with Trimethoprim?
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Because it is the best pharmacokinetic match
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What are the 3 infections that Sulfamethoxazole/Trimethoprim are given for?
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-UTI's
-Bacillary dysentery -Typhoid fever |
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What organism causes
-Bacillary dysentery -Typhoid fever |
BDysentery = Shigella
Typhoid fever = Salmonella |
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What is Silver sulfadiazine used for?
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Preventing infection in burn patients
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How is Silver sulfadiazine administered for preventing burn infections?
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Topically
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How are the sulfonamides metabolized?
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By N-acetyltransferase in the liver
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What type of enzyme is N-acetyltransferase (NAT)?
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Phase II
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What can happen as a result of the NAT metabolism of the sulfonamides? Why?
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Crystallization in renal tubules and renal damage - the acetyl group decreases their water solubility
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So what are 5 adverse side effects of Sulfonamides?
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GRiPH
-GI disturbance -Renal damage (crystals) -Inhibit Cyp2C9 -Potentiate other drugs -Hypersensitivity - rash |
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What makes the rash caused by sulfonamides worse?
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Sunlight
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What is Trimethoprim an analog of?
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Dihydrofolate
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So what is the mechanism of Trimethoprim?
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Competitive inhibition of Dihydrofolate reductase so it inhibits folate synthesis
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How does the combination of Sulfamethoxazole and Trimethoprim work synergisticly?
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-Smx decreases the amount of dihydrofolate produced
-Trimethoprim can much more easily outcompete with the DHF for DHF reductase |
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Is Trimethaprim alone cidal or static?
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Static
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What is the effect of Bactrim?
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Static + Static = Cidal!
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What are 2 resistance mechanisms to Trimethoprim?
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-Decreased permeability
-Mutations in DHF reductase |
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What is Bactrim the FIRST choice empiric therapy for?
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Uncomplicated UTIs caused by Staphs and enterics
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What else is Bactrim the 1st CHOICE for?
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Treatment and prophylaxis of Pneumocystis jiroveci
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What are 2 other indications for Bactrim?
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-Resp tract (h. flu/strep pneumo)
-Ear infections (moraxella) -GI infections with enterics |
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In addition to GI effects, rashes, inhibiting Cyp2C9, and renal damage, what can long-term bactrim cause?
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Bone marrow suppression
More nausea/vomiting, etc.. |
