Pharm- Anti-peptic Diseases Flashcards
What is the mechanism of histamine binding to parietal cells to cause the H+/K+ ATP to be brought to the membrane?
Histamine binds to H2 –> increase in cAMP –> PKA activation –> tubovesicles with pumps brought to apical membrane
Which cells secrete gastrin?
G cells
ez to remember lol
Gastrin activates which type of receptors?
CCK(B) receptors
Which receptors does Ach activate on the gut?
M3
Gastrin and Ach therefore work on what G-protein pathway to increase intracellular Ca++?
Gq (activates PLC)
This is the phase of gastric acid secretion when sights, smells, or thoughts stimulate gastrin secretion and vagal stimulation which leads to an increase in gastric acid secretion
Cephalic phase
pavlov what UPPP
This is the phase of gastric acid secretion when stretching of the stomach wall and ingestion of amino acidds causes gstrin release.
Gastric phase
This is the phase of gastric acid secretion when digested proteins further in the GI tract stimulates gastric acid secretion.
Intestinal phase
True or false: prostaglandins stimulate mucous secretion.
True
True or false: NSAIDs inhibit mucous secretion.
True
What are the 2 most common causes of ulcers?
NSAID use and H. pylori
What is the enzyme that H. pylori uses to convert urea to NH3, thus buffering stomach acid?
Urease
So yeah, H. pylori is bad, but how does NSAIDs cause ulcers?
Remember, NSAIDs inhibit prostaglandins, and prostagandins stimulate mucous secretion. No prostaglandins –> no mucous –> gastric wall damage from lack of protection
This is the condition where there is excess gastrin secretion by a gastrinoma leading to excess gastric acid production.
Zollinger Ellison syndrome
These are types of ulcers caused by head trauma leading to heightened vagal tone.
Cushings ulcers
How can H2-blockers inhibit acid secretion?
remember histamine blocks to H2 receptors on the parietal cell, so if u block the R, the parietal cell never releases HCl
What is the suffix for H2-blockers?
“-tidine”
like cimetidine and ranitidine
Case: a hep C + pt presents with GERD and you are contemplating on prescribing an H2-blocker. Should you prescribe Nizatidine? Why or why not?
Yes cuz nizatidine is the only H2 blocker that is eliminated primarily in the kidney.
This is the class of drugs that directly inhibit the H/K ATPase, thus decreasing gastric acid secretions.
Proton-pump inhibitors (PPI)
True or False: PPI’s are secreted in the active form as to allow immediate inhibition when they enter the stomach.
False! They’re given as a prodrug and activated when they hit the stomach acid.
The gastric acid converts the prodrug PPI into what form?
Sulfanemide form
Which residue on the H/K ATPase forms a covalent bond with the sulfanemide PPI?
Cysteine
What are the 3 indications to use a PPI?
1) H. pylori-associated ulcers
2) Hemorrhagic ulcers
3) To allow the continued use of NSAIDs in patients with peptic ulcers.
ULCERS
Why should you use H2 blockers instead of PPI’s in a pregnant chick?
Because PPI’s cross the placenta. cimetidine does too but other H2 blockers dont.
