Gastrointestinal Disorders (Exam 3) Flashcards
Most common GI disorder in the US
GERD
major GI disorders in the US
GERD
IBS
Gallstones
Celiac disease
Crohn’s disease
Ulcerative colitis
Hemorrhoids
Diverticulosis
Colon cancer
cells in the GI tract
pit cell
stem cell
neck cell
parietal cell
chief cell
endocrine cell
which layer of the stomach wall does drugs typically act?
mucosa
types of enzymes in the small intestine
pancreatic enzymes
brush border enzymes
pancreatic enzymes
lipases, amylases, exopeptidase, nucleases
secreted into the intestine, in intestinal lumen
brush border enzymes
embedded in the absorptive cell membranes
carry digestive work, not in lumen
intestinal cells can absorb only
monosaccarhides
digestion of proteins begins in the
stomach
digestion and absorption of lipids
bile salts must emulsify the lipid droplets into smaller ones
micelle
cholesterol
monoglyceride
fatty acid
how does components of a micelle cross the membrane?
cholesterol - carrier protein
monoglycerides and fatty acids - simple diffusion
what happens when the components of a micelle cross the membrane?
triglycerides reform
cholesterol, TG, proteins form chylomicrons
chylomicrons released into lacteal
what types of drugs are used to treat GI disorders?
drugs that neutralize acids
drugs that decrease acid output
drugs that affect GI motility
histamine
produced in enterochromaffin-like cells, mast cells, basophils and neurons
histamine has an important role in
gastric secretion
site of histamine storage is mainly in
mast cells
serotonin
modulation of platelet function and neurotransmission
important role in the gut
serotonin is produced in
enterochromaffin cells, neurons
serotonin is not produced in _____________, only stored there
platelets
precursor of serotonin
tryptophan
5HT1 subtypes and where they act
A-F - brain
P - enteric NS
5HT2 subtypes and where they act
2A - platelets, smooth muscle
2B - stomach
where does 5HT3 act?
vomiting centers - CNS
stomach
what stimulates gastric acid secretion?
acetylcholine, histamine, gastrin
G cells are
gastrin producers
D cells are
somatostatin producers
somatostatins role
inhibits G cell
inhibits gastrin secretion
nerve involved in gastric acid secretion
vagus preganglionic nerve
acetylcholine is present in
D cells
ECL cells
Parietal cells
where is the proton pump located and what is its official name?
in parietal cells
H+K+ ATPase
drugs that neutralize acids
systemic antacids
nonsystematic antacids
systemic antacids
are soluble and reabsorbable
cause systemic alkalosis
example of systemic antacids
sodium bicarbonate
nonsystematic antacids
not absorbed into systemic circulation
do not produce systemic alkalosis
examples of nonsystematic antacids
aluminum containing antacids
calcium containing antacids
magnesium containing antacids
combination antacids
magaldrate
use to treat variety of conditions such as esophagitis, duodenal and gastric ulcers and GERD
mechanism of systemic antacids
in stomach: instantaneous interaction with HCl –> NaCl, water and CO2
in intestines: NaCl + HCO3 to Na+ HCO3
side effects of systemic antacids
hypernatremia
fluid retention
metabolic alkalosis
where part of the MOA of systemic antacids does absorption occur?
in intestines
NaHCO3 –> Na+ and HCO3
Nonsystemic antacids CaCO3 MOA
in stomach: CaCO3 + 2HCl –> CaCl2, water and CO2
in intestines: CaCl2 + HCO3 –> CaCO3 and HCl
CaCO3 reacts slower than
Na+ bicarbonate
side effects of CaCO3
hypercalcemia can trigger gastrin release –> acid rebound
how much of CaCO3 is absorbed (nonsystemic antacid)
about 10%
nonsystematic acids Mg(OH)2 and Al(OH)3 MOA
in stomach: reacts slowly with HCl –> MgCl2 and water
in intestines: MgCl2 and HCO3 –> Mg(OH)2 and HCl
Mg(OH)2 and Al(OH)3 are relatively
insoluble and slow neutralize acid
retention in stomach
side effects of Mg(OH)2
cathartic
can induce N/V
diarrhea
side effects of Al(OH)3
constipation
can bind to antibiotics, antifungals, iron supplements and prevent absorption
toxicity in renal insufficiency
nonsystemic antacids can be combined with
anticholinergic drugs to delay gastric emptying
common anticholinergics combined with nonsystemic antacids
pirenzepine, propantheline and mepenzolate
all act as M1 receptor antagonists
side effects of nonsystemic antacids with anticholinergics
blurry vision
contraindicated with glaucoma
potency of H2 receptor antagonists (from greatest to least)
famotidine > nizatidine = ranitidine > cimetidine
H2 receptor antagonists examples
cimetidine
nizatidine
famotidine
ranitidine (discontinued)
H2 receptor antagonists MOA
competitive H2 receptor antagonist
permissive and transmissive role of histamine
permissive role of histamine
presence of histamine permits action of acetylcholine and gastrin
transmissive role of histamine
histamine is basic and final requirement for acetylcholine and gastrin
how are H2 receptor antagonists metabolized?
hepatic metabolism
glomerular filtration
tubular secretion
H2 receptor antagonists are very effective at
inhibiting nocturnal H+ secretion
which H2 receptor antagonists has little first pass hepatic metabolism?
nizatidine
cimetidine inhibits
CYP450 hepatic drug metabolism
toxicity of H2 receptor antagonists from greatest to least
cimetidine > nizatidine > famotidine > ranitidine
toxicity of H2 receptor antagonists
inhibits dihydrotestosterone binding to androgen receptors
inhibits estradiol metabolism
increase serum prolactin levels
inhibition of hepatic alcohol metabolism
toxicity of H2 receptor antagonists can lead to
Gynecomastia in men
Galactorrhea in women
proton pump inhibitors examples
omeprazole
esomeprazole
rabeprazole
lansoprazole
pantoprazole
MOA of PPIs
non competitive inhibitors of the H+K+ ATPase
PPIs are _____________ and are activated in an _________ environment
prodrugs
acidic
PPIs must pass through the
stomach to be effectively absorbed
PPIs are absorbed in the _______ into ________________ and converted into the __________
intestine
PC vesicles
active form
omeprazole
Prilosec
metabolized in the liver by CYP2C19 and CYP3A4
CYP3A4 converts ___-omeprazole to _________________
S
3-hydroxyomeprazole
__ isomer of omeprazole is the conversion to _________________ by CYP______
R
5-hydroxyomperazole
CYP2C19