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34 Cards in this Set
- Front
- Back
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Maximally active sulfonamides are almost completely ionized at physiological pH so as to resemble what?
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-Para-aminobenzoic acid (PABA)
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What is the mechanism of action for sulfonamide?
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-Block formation of folates by competitively inhibiting formation of Dihydropteroate from PABA + 6-Pyrophosphoryl-methyl-7,8-dihydropteroin by Dihydropteroate synthetase.
-Note: Block in folate synthesis leads to inhibition of DNA, RNA, protein synthesis |
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Sulfonamide is bacteristatic (T/F)
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True: When DNA, RNA, protein is inhibited, but bacteriocidal when DNA is inhibited (Thymine-less = death)
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Purine and Pyrmidine are synthesize with the help of what product from the Folatic acid RXN?
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-Tetrahydrofolate
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Describe the rxn of folate metabolism?
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Pteridine + PABA --> Dihydropteroic acid -- (Glumate)--> Dihydrofolic acid --(NADPH -->NADP)--> Tetrahydrofolic acid --> FAH4 cofactors --> Thymidine, Purines, Methoionine
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What is 2 ways to make dTMP?
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-dUMP
-Made from nucleoside + Phosphate |
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can Sulfamide affect human like they affect bacteria?
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-No human don't have Dihydropteroate Synthetase.
-Since we get Folic acid from diet -Does affect us using Tetrahydrofolate |
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How is sulfonamides adminstrator?
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-Oral, peak in 2-4 hrs
-Sulfamides bind to albumin irreversibly) |
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What is the problem with Sulfonamide binding?
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-Problem w/ newborn
-Compete w/ bilirubin on Albumin. So bilirubin will be displaced by sulfamides so it moves into BBB = Kerniterus (Ataxia + movements involved) -DON'T use on newborn, pregnant, nursing |
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Where is Sulfonamide metabolized?
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-Kidney. [ ] of Sulfonamide in urine is higher than plasma
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What is the problem with the high [ ] of Sulfonamide in urine?
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-Crystallera: many Sulfonamide have poor solubility = can form crystal
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What is the way to prevent Crystallera?
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-Drink a lot of water
-Take bicarbonates |
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What is the other TX to use beside Sulfonamide?
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-Trisulfamide: 3 Sulfonamide. Given 1/3 of each 3
-Sulfizoxazole: greater solubility. But still need to drink lot of water |
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What is the toxicity of Sulfonamide drugs?
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-Hypersensitivity to drugs: 2% (Steven Johnson syndrome: Lack of Glucose-6-Dehydrogenase)
-GI disruption -Crystalluria -Blood dyscrasias |
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What is the usages of Sulfonamide?
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-Acute UTI (Urinary Tract Infection)
-E. coli -Klebsiella -Proteus -Nocardiosis (pulmonary abscess occur) |
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What drug selectively inhibit FH2 Reductase (No: NADPH -->NADP)?
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-Trimethoprim: affect on human is non-existing
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What other drug is often combined with Trimethoprim?
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-Sulfamethoxazole (Bactrim + Septra)
-Synergistic affect |
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What is the usages of Trimethoprim + Sulfamethoxazole?
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-Acute or Chronic UTI
-Middle Ear Infeciton in children -Haemphilus Influenza -Strep. Pneumonae -Toxoplamosis -Pneumocystis carniae: (AID pt. die from these infection) -Note: Same toxicity as Sulfamide |
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Differences b/t Human and Bacteria?
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-bacteria have cell wall b/c the cell is hyperosmotic to enivornment --> Required rigid cell wall to prevent cell lysis (incoming water)
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How does B-Lactam inhibit bacteria?
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-Inhibit synthesis of Bacteria cell wall = Break Open cell = Dead
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Peptidoglycan can be made up of what?
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-NAM: N-Acetylmuranic acid
-NAG: N-Acetylglucosamine |
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How does one alternating NAM+NAG structure link to one other?
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-3rd AA of one NAM+NAG strand will link to 4th AA of another NAM+NAG strand via 5-glycine
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What are the general structures of B-Lactam Antibiotics
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-Penicillins
-Cephalosporins -Monobactams -Carbapenems |
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Refer to Paper notescard for RXN of membrane?
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-Look at Notecards
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What is the function of D-cycloserine?
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-Inhibit Alanine racemase (L-alanine --> D-alanine
-Inhibit D-alanyl-D-alanine Synthetase (D-alanine --> D-alanyl-D-alanine) |
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Describe the RXN that occur the cytoplasm?
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-1-P-N-Acetylglucosamine --(UTP -->PP)--> UDP-X --> UDP-Y --(L-ala, D-glu, L-Lys)--> UDP -Y-(5 A.A.)
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Where does Vancomycin inhibit?
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-Bind to 2x D-alanine and stop the chain from growing
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Where does Bacitracin inhibit?
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-Bind Phosphatase & inhibit cell wall synthesis
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What enzyme is used to link the 5-glycine to the 3rd a.a. of one strand to the 4th a.a of another strand?
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-Transpeptidase: In addition also remove the 1 XS D-alanine from the NAM-5aa to become NAM-4aa
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How does B-Lactam response to Transpeptidase?
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B-Lactam look like 2x- D-ala: So transpeptidase will bind to B-Lactam bond = Covalent = Inactivating it.
Note: Cell wall synthesis stop and it breakdown = Cell lysis |
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How does bacteria counteract the affect of B-Lactam?
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-Replacing D-alanine (2x) --> D-alanine-D-Lactate = Decrease binding og Vancomycin by 1000X
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What is an example of Pen. Binding Protein = PBP's?
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Transpeptidase
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What are the properties of Pen. G?
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-It is given in unit = 0.6 mg
-Can be given oral or parentally |
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How effective is Pen. G when given orally?
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- 20%-33% is active b/c Pen G. is acid-labile. HCl will inactivate Pen.G
-Must be given 4-5X parental dose -Must be given 1hr before meal or 2hs after meal to minimize food absorption of drugs |
