Chem Basis - Penicillins 2

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kyleannkelsey
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257703
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Chem Basis - Penicillins 2
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2014-01-21 14:38:23
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Chem Basis Penicillins
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Chem Basis - Penicillins 2
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Chem Basis - Penicillins 2
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  1. What G+ bacteria are Natural penicllins particularly useful against?
    Non-penicillinase producing Streptococcus pneumonia; streptococci viridans; Enterococcus and Staphylococcus
  2. What G- bacteria are Natural penicllins particularly useful against?
    Non-penicillinase producing N. meningitides and N. gonorrhea.
  3. What bacteria are Penicillinase-resistant Penicillins particularly useful against?
    G+: Non-penicillinase producing Streptococcus pneumonia, streptococci viridans, Enterococcus, Staphylococcus G-: N. meningitides, N. gonorrhea and penicillinase-producing Staphylococcus
  4. What bacteria are Aminopenicillins particularly useful against?
    G+: Streptococcus pneumonia, streptococci viridans, Enterococcus, Staphylococcus G-: N. meningitides, N. gonorrhea, E. coli, P. mirabilis, H. influenza, Salmonella and Shigella
  5. What bacteria are Antipseudomonal penicillins particularly useful against?
    G+: Streptococcus pneumonia, streptococci viridans, Enterococcus, Staphylococcus G-: N. meningitides, N. gonorrhea, E. coli, P. mirabilis, H. influenza, Salmonella, Shigella and Pseudomonas aeruginosa
  6. Why is carbenicillin rarely used?
    Potency is low and large doses have to be given
  7. What bacteria are Extended spectrum penicillins particularly useful against?
    G+: Streptococcus pneumonia, streptococci viridans, Enterococcus, Staphylococcus G-: N. meningitides, N. gonorrhea, E. coli, P. mirabilis, H. influenza, Salmonella, Shigella, Pseudomonas aeruginosa, Klebsiella and Serratia
  8. What is the basic pharmacophore for penicillins?
    • 6-aminopenicillinic acid
  9. What is the name for the internal cyclic amide in a Pencillin?
    Beta lactam ring
  10. What does beta designate in the term “Beta-lactam ring”
    The position of the amine fused to a thiazolidine
  11. What is a thiazolidine?
    • A five membered saturated ring with a sulfur and a nitrogen
  12. Penicliins are acids with pKa's in the range of _____-_____.
    2.5-3.0
  13. Soidum and potassium salts of most of the penicillins allow for what properties?
    Water solubility, easy absorbtion
  14. (True/False) Free acid versions of Penicillins are fairly stable.
    False, unstable
  15. The beta-lactam ring has inherent strain due to the bond angle, which causes ___________of the penicillin in aqueous media.
    Decomposition
  16. Why do Natural penicillins have low stability in vitro in acid and base and in vivio in stomach acid?
    Because, the beta-lactam ring has inherent strain due to the bond angle
  17. What steps are included in the acid degradation of a Penicillin?
    • 1.) Protonation of lactam N
    • 2.) E- movement from C7 carbonyl, increasing δ+ on carbonyl C
    • 3.) Intramolecular nucleophilic attack by the side chain carbonyl oxygen at lactam carbonyl C
  18. The driving force for penicillin’s decomposition by acid is formation of a conjugated system, what is this conjugated system called?
    • Penicillennic acid
  19. So, penicillins without electron withdrawing R/ R'' groups have poor __________.
    Oral activity
  20. To prevent acid degredation R must be a (positive/negative) _____________ inducer OR R'' must be a (positive/negative) _____________ inducer.
    Negative for both
  21. Acid stability of a penicillin can be enhanced by refrigeration, storage in dry conditions and controlling the pH of aqueous solution by buffering, what pH is ideal?
    4-8
  22. (True/False) The process of acid decomposition of penicillins starts with protonation of the beta lactam nitrogen.
    True
  23. (True/False) The process of acid decomposition of penicillins involves electron movement from the -C7 carbonyl resulting in a more positive charge on the carbonyl carbon.
    True
  24. (True/False) The process of acid decomposition of penicillins involves intramolecular nucleophilic attack by the side chain O2 at the lactam carbonyl carbon.
    True
  25. (True/False) The process of acid decomposition of penicillins can be controlled by preventing the nucleophilic attack by electron donating groups on the alpha carbon.
    False
  26. (True/False) The process of acid decomposition of penicillins can be controlled by buffering the aqueous solution to a pH of 4-8 by or by refrigeration.
    True

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