Chem Basis CPN structures 1

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Chem Basis CPN structures 1
2014-01-26 15:18:14
Chem Basis CPN structures

Chem Basis CPN structures 1
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  1. If you swap a C for the S in the CPN pharmacophore, is it tolerated?
    Yes, called a carbacephem

  2. What is the benefit to having this ring structure
    Essential for activity and enhanced B-lactamase resistance
  3. How does the 3-cephem ring compare to a PCN?
    Less strained

  4.  (True/False) This is a 7-aminocephalosporonic acid.

  5. (True/False) This structure contains a beta-lactam and dihydrothiazine structure (i.e. 3-cephem).

  6. (True/False) Substituting the -S with a -C produces a cephamycin
    False, produces a Carbacephem

  7. is this structure essential for activity?

  8. Which drugs are cephamycins?
    Cefoxiten and Cefotetan

  9. What is the advantage of a cephamycin?
    Broader resistance to B-lactamases

  10. Is the COOH essential for activity?

  11. How does the COOH work to maintain activity of the CPN?
    Anchors the CPN to the cell wall and orients it to acylate the transpeptidase

  12. Can the COOH of CPNs form water soluble salts?
  13.  For all marketed forms of CPNs, what form is the COOH in and why?
    Na+ salt, for IV administration

  14. What characteristics of the CPN are affected by R1?
    Spectrum, B-lactamas ressitance, oral bioavailability

  15. Is acid stability affected by R1?

  16. Like with penicillins, does a lipophilic R group cause increased G+ activity?

  17. What generation of CPNs would have a lipophilic ring at R or R’?
    1st and 2nd generation

  18. What generation of CPNs would ou expect to see more polar rings at R or R’?
    3rd and 4th generation

  19. What is this potential R group called?
    2-amino thiazole

  20. Most 3rd and 4th generation CPNs have what group for R’?

  21. What is this group?

  22. These methoxyimine variations have what effect as an R’ group on a CPN?
    Add G- coverage due to polarity

  23. Polar groups at R1 have what effect on oral absorption?
    Enhance oral absorption in acid stable compounds

  24. Comparing an NH2 and a methoxyimine at R’, which one would be better at preventing intermolecular opening of the B-lactam ring (enhancing stability of the B-lactam)?

  25. How do methoxyimine variations enhance B-lactamase resistance of a CPN?
    Steric hindrance

  26. How can a Methoxyimine group be further modified to enhance B-lactamase resistance?
    Add a polar functional group to it (e.g. COOH)