Chem Basis PPIs 8

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  1. The benzimidazole nitrogen (N3) has a pKa of 0.11-0.79, will it be primarily cationic or unionized at the stomach pH of 1.5?
    Unionized, because the pKa is lower than the pH, though a few molecules will be in the cationic form (i/u is transient)
  2. The pyridine nitrogen (N1) has a pKa of 3.83-4.53, will it be primarily cationic or unionized at the blood pH of 7.4?
    Unionized, because the pKa is lower than the pH
  3. The benzimidazole nitrogen (N3) has a pKa of 0.11-0.79, will it be primarily cationic or unionized at the blood pH of 7.4?
    Unionized, because the pKa is lower than the pH
  4. (True/False) both the unionized and ionized conjugates of the pyridine nitrogen play a role in proton pump inhibition.
    True
  5. Why is the i:u ration of the Pyridine nitrogen important?
    Because, both the unionized and ionized conjugates play a role in inhibition, Unionized: activates inhibitor, Ionized: traps inhibitor in the canaliculus
  6. What is the role of the Unionized conjugate of the Pyridine Nitrogen?
    Traps the inhibitor in the canaliculus
  7. What is the role of the Ionized conjugate of the Pyridine Nitrogen?
    Responsible for activating inhibitor via nucleophilic attack at benzimidazole C2
  8. Reactivity of PPIs is directly related to what?
    The nucleophilic character of the pyridine nitrogen atom
  9. What does pKa1 refer to?
    pKa of the Pyridine Nitrogen
  10. What does pKa 2 refer to?
    pKa of the Benzimidazole Nitrogen
  11. The cationic center of these ionized benzimidazole N3 has what effect on C2?
    Pulls electrons from benzimidazole C2, enhancing its d+ character, increasing rate of proton pump inhibitor activation
  12. Why does an ↑ in electrophilic (d+) character of C2 increases rate of proton pump inhibitor activation?
    Through nucleophilic attack by the unionized conjugate of the pyridine nitrogen
  13. Reactivity of PPIs is directly related to what?
    The extent of protonation of the benzimidazole nitrogen
  14. What form of the pyridine N1 is needed to activate the PPI molecule?
    Unionized
  15. What form of the pyridine N1 is needed to activate the PPI molecule?
    Cationic
  16. What form of the pyridine N1 is present at the stomach pH?
    Cationic
  17. What form of the pyridine N1 is present at the stomach pH?
    Unonized
  18. Electron donating groups on pyridine increase the ___________ and also increase the __________ of any unionized pyridine molecules
    • percent of ionized N1
    • and also increase the
    • nucleophilic character
Author:
kyleannkelsey
ID:
251729
Card Set:
Chem Basis PPIs 8
Updated:
2013-12-08 21:46:15
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Chem Basis PPIs 8
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