PPIs

• What role does acetylcholine play in the function of parietal cells?

  Acetylcholine stimulates acid secretion in parietal cells.
• What must happen to the proton pump for it to function properly?

  It must be activated by various stimuli.
• What is the primary function of the proton pump in parietal cells?

  It secretes hydrogen ions into the stomach.
• How many cysteine residues are present in the proton pump?

  28 cysteine residues.
• How does histamine affect parietal cells?

  Histamine binds to receptors on parietal cells to stimulate acid secretion.
• What is the primary function of the proton pump in relation to hydrogen ions?

  It pumps hydrogen ions out of the parietal cells into the stomach.
• Name one example of a proton pump inhibitor (PPI).

  Examples include omeprazole and pantoprazole.
• Why are weak bases not effective in acidic conditions?

  They are not converted to their active form in acidic conditions.
• What is the significance of targeting cysteine residues in the proton pump?

  Targeting cysteine residues can inhibit the proton pump's activity.
• What is the importance of the stability of PPIs in the gastrointestinal tract?

  PPIs must be stable enough to survive the gut's acidic environment.
• What is the advantage of the S-enantiomer of omeprazole?

  The S-enantiomer has better potency and pharmacokinetic profile.
• How does the CYP2C19 enzyme affect the metabolism of omeprazole?

  It leads to less hydroxylation of the S-enantiomer, enhancing its effectiveness.
• What is the primary role of proton pumps in gastric acid secretion?

  They secrete hydrogen ions into the gastric lumen.
• What is the mechanism of action of proton pump inhibitors?

  They irreversibly inhibit the proton pump, reducing gastric acid secretion.
• Why is omeprazole considered a well-balanced PPI?

  It is reactive enough for activation but stable enough to survive the gastrointestinal tract.
• What does stereoselectivity in drug metabolism imply?

  It implies different metabolic outcomes for R- and S- isomers.