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22 Cards in this Set
- Front
- Back
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What is the hx of beta lacta drugs?
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1929 - Fleming first isolated penicilln from the penicillium mold.
1941 - Introduced to clinical medicine at Yale and Mayo. |
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What does the general structure of Beta Lactam Antibiotics include? Draw.
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(1) Beta Lactam ring
(2) Beta Lactam Bond (3) Thiazolidine rng |
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What are the four beta-lactam antibiotics mentioned in class?
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(1) Penicillins
(2) Cephalosporins (3) Carbopenems (4) Monobactams |
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Bacteria have a cell wall and humans do not. What is the function of the cell wall?
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The cell wall provides a major framework from preventing the hyperosmotic interior condition from causing it to lyse.
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What is the mechanism of beta lactam drugs?
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Beta lactam drugs are bactericidal and inhibit cell wall synthesis.
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What is the major cell wall component?
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Peptidoglycan.
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What is peptidoglycan composed of?
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(1) Sugar molecules - N-acetylmuramic acd and N-acetylglucosamine
(2) Peptides |
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Draw the structure of bacterial cell wall.
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On the MurNAC, there is a peptide made of four amino acids. From the third amino acid, there is a chain of 5 glcyines that connects to the fourth amino acid.
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In studying the first set of reactions of bacterial cell wall synthesis, where does this reaction take place?
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Cytoplasm.
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What is the action of D-cycloserine?
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D-cycloserine sructurally resembles D-alanine and can inhibit L-ala -->D-ala and --> D-ala-D-ala
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Where does the second set of reactions occur for cell wall synthesis?
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Bacterial Membrane.
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What is the mechanism of vancomycin?
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Vancomycin binds to the last two D-alanines and inhibits the transfer of the y-x-5 aa-5 gly to the cell wall.
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How do bacteria resist the effect of vancomycin?
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To avoid the vancomycin, bacteria are able to make a peptide substituting D-ala-D-lactate into the last substrate of their chain. By doing this, they reduce the ability of vancomycin to bind by 1000-fold.
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How does bacitracin inhibit cell wall synthesis?
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To regenerate the Lipid-P, a phosphatase acts on lipid-P-P to extract a P.
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Where does the final step of cell wall synthesis occur?
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the Cell WAll.
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Where do beta lactam antibiotics act?
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(1) Transpeptidation
(2) Carboxypeptidation |
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What does the beta-lactam structure resemble?
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The two D-Ala together.
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Why is penicillin G give by unit of activity instead of weight?
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Because when it was first developed it was not pure and we did not know what the structure and how much was needed in that sense.
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How is penicillin G administered?
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(1) Orally
(2) Parenterally |
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When given orally, how much is Penicillin G absorbed? Why?
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When Penicillin-G is given orally, only about 1/5-1/3 of the administered dose gets absorbed. The reaso that this occurs is that the bond in penicillin G is acid labile. So HCl in the stomach will cleave the bond and inactvate the penicillin G. So if you are giving an oral dose of penicillin G, you have to give f-5 times the parental dose, in order to compensate for te acid lability of Penicillin G.
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Why must you administer penicilling G one hour before a meal r two hours after a meal?
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To minimize the problem of food absorption. Penicilling G aborbs to food.
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Can penicillin G be modivided to be more acid stable?
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Penicillin V is modified from Penicillin G and is more acid stable.
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