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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)
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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
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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
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(True/False) both the unionized and ionized conjugates of the pyridine nitrogen play a role in proton pump inhibition.
True
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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
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What is the role of the Unionized conjugate of the Pyridine Nitrogen?
Traps the inhibitor in the canaliculus
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What is the role of the Ionized conjugate of the Pyridine Nitrogen?
Responsible for activating inhibitor via nucleophilic attack at benzimidazole C2
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Reactivity of PPIs is directly related to what?
The nucleophilic character of the pyridine nitrogen atom
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What does pKa1 refer to?
pKa of the Pyridine Nitrogen
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What does pKa 2 refer to?
pKa of the Benzimidazole Nitrogen
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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
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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
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Reactivity of PPIs is directly related to what?
The extent of protonation of the benzimidazole nitrogen
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What form of the pyridine N1 is needed to activate the PPI molecule?
Unionized
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What form of the pyridine N1 is needed to activate the PPI molecule?
Cationic
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What form of the pyridine N1 is present at the stomach pH?
Cationic
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What form of the pyridine N1 is present at the stomach pH?
Unonized
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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
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