GI Pharm Flashcards
ranitidine
H2 histamine receptor antagonist - competitive inhibitors
used to treat gastric ulcers and associated problems - inhibits secretion of gastric acid
Which cells synthesize and store histamine?
ECL cells
What are the side effects of ranitidine?
diarrhea, dizziness, muscle pain, skin rash, gynecomastia, CNS effects, drug interxns (p450 inhibition - prolongs life of other drugs)
Omeprazole
inhibits H/K ATPase
used to treat gastric ulcers and associated problems - inhibits gastric acid from any agents –> rapid healing!
How does omeprazole work?
prodrug requires activation
protonated form inhibits pump - irreversible inhibition via covalent modification of SH groups
What is the therapeutic use of antacids?
good for duodenal ulcers, not gastric
treats GER but only symptoms, not dz course
Misoprostol
synthetic prostaglandin agonist that inhibits cAMP, increases production of mucus and bicarb
prevents ulcers caused by NSAIDs
bethanechol
cholinergic agonist - promotes gastric emptying and GI motility
metoclopramide
promotes GI motility antagonist at dopamine D2 receptors reduces inhibtion agonist at 5-HT3 and 5-HT4 receptors can cross BBB effects more in upper GI tract
What can restrict use of metoclopramide?
use >3 mos of high doses can lead to short term or permanent Tardive Tyskinesia
lactulose
osmotic laxative - not absorbed and resistant to digestion
lubiprostone
treatment of constipation
derivative or PG E1 that activates Cl channels - secretion of Cl with Na leads to more water to soften stools and increase motility
diphenoxylate/loperamide
opiate receptor agonists
anti-diarrheal effects w few central effects
act through mu receptors
cholestyramine
anion exchange resin
useful in bile-induced diarrhea
What can happen with misuse of laxatives?
excessive fluid and electrolyte loss
colonic inertia
steatorrhea
secondary aldosteronism due to volume depletion
