14- GI II Flashcards
how does 5ht stimulate gastric motility?
induces release of Ach onto smooth muscle (muscarinic receptors)
how does dopamine effect gastric motility?
activates presynaptic reeptors to decrease firing of ENS neurons —> decrease gastric motility
prokinetic mechanism of metoclopramide
D2 antagonist
adverse effects metoclopramide
CNS drowsiness, anxiety
parkinsonian symptoms
MOA bethanechol
M3 agonist
MOA neostigmine
AchE inhibtor
MOA erythromycin
motilin receptor agonist
what type of laxative is methylcellulose?
bulk forming
what type of laxative is glycerin
surfactant
what type of laxative is lactulose
osmotic
what type of laxative is senna
stimulant
what happens when you stimulate 5HT4 receptors
- promote NT release in ENS resulting in motility
- decrease firing of extrinisc sensory neurons to CNS (blcok pain)
how does activation of chloride channels a laxative mechanism
increase luminal concentration of chlroide –> sodium and water go to lumen too
–> stool soft and motility easier
when should you use mu-opiod receptor antagonist?
when using opiod agonist to treat pain post surgically
mu-opiod antagonist doesn’t go to CNS = pain relieved and no constipation
what type of laxative tegaserod?
5HT partial agonist
what type of laxative lubiprostone?
chloride channel activator
what are the two mu-opiod receptor antagonists used as laxatives?
methylnaltrexone and alvimopan
treat opiod-induced constipation during palliative care
methylnaltrexone
treat postop patients with bowel resevtion
alvimopan **only 7 days of high chance MI
why can an opiod antagonist be used to treat diarrhea?
opiod decrease peristaltic contraction and increase sphincters and segmental contractions, decrease GI distension perception
what effects of bismuth subsalicylate are antidiarrheal?
inhibiton of prostaglandin synthesis in intestines and absorption of bacteria
*stimulates in stomach
how is octeotide an antidiarrheal?
acts as a somatostatin agonist
MOA ondansetron
5HT3 antagonist
direct antiemetic
— constipation
MOA scopolamine
M1 antagonist
direct antiemetic
*** motion sickness
what two anitemetics are good for motion sickness?
scopolamine and dimenhydrinate
MOA metoclopramide
D2 antagonist
direct antiemetic
— parkisonian symptoms
MOA dimenhydrinate
H1 antagonist
*** motion sickness
— drowsiness
MOA aprepitant
NK1 antagonist
— drug-drug interaction
MOA prochlorperazine
M1D2H1 antagonist
***only severe nausea and drowsiness , lots of adverse effects
MOA lorazepam
GABA agonist
indirect antiemetic
***anxiety
MOA nabilone
cannabinoid agonist
indirect antiemetic
**chemo
— dysphoria (high)
MOA dexamethasone
clucorticoid agoinst
indirect antiemetic
–> increases 5HT antagonist
— steroid side effects
