Pharm: Motility Disorders Flashcards
What changes can cause achalasia?
Degeneration of:
(1) inhibitory myenteric plexus neurons
(2) vagal branches
(3) dorsal vagal nucleus
What are the possible aims of esophageal motility drugs?
(1) reduce LES pressure
(2) reduce vigor of distal esophageal smooth muscle contractions
What is the only effective medication used to treat achalasia?
Botulinum toxin, which inhibits release of acetylcholine at the NMJ.
What are the most effective treatments for achalasia?
(1) Heller myotomy
(2) pneumatic dilation
(3) peroral endoscopy myotomy
What medication is used to reduce muscular vigor in the distal esophagus?
5’ phosphodiesterase inhibitors.
What is the MoA of 5’ phosphodiesterase inhibitors?
They block NO degradation, prolonging smooth muscle relaxation and reducing contractile amplitude and propagation velocity.
In what part of the body can a majority of one’s serotonin be found?
In the GI tract, 95%.
What are the possible aims of gastric motility drugs?
(1) delay gastric emptying
(2) accelerate gastric emptying
(3) improve fundic accommodation
What is another name for a drug the accelerates gastric motility?
A prokinetic.
What is a notable prokinetic?
Metoclopramide. It is also used as an antiemetic.
What is the MoA of metoclopramide?
(1) 5HT4-receptor agonist
(2) D2-receptor antagonist
What 2 types of drugs delay gastric emptying?
(1) anticholinergics
(2) somatostatin analogues
J: This class of drugs includes dicyclomine and hyoscyamine.
What are anticholinergics?
What is the MoA of octreotide as a delayer of emptying?
It’s a somatostatin analogue that inhibits the release of serotonin and motilin.
J: This drug is commonly used to improve fundic accommodation.
What is buspirone?
What is the MoA of buspirone?
It is a 5HT1A-receptor agonist. As such, it:
(1) inhibits ACh release in the myenteric plexus
(2) promotes NO release
When is fiber an appropriate treatment for constipation?
When the constipation is only mild or moderate.
What is the MoA of fiber as a treatment of constipation?
It increases stool weight.
What are 3 classes of laxatives and what are the MoAs?
(1) magnesium, sulfate, phosphate: create hyperosmolar luminal environment
(2) polyethylene glycol: binds water molecules
(3) anthraquinones & diphenylmethanes: mucosal afferent nerve fiber irritants
What is lubiprostone?
A treatment for constipation that increases intestinal fluid secretion and transit by activating chloride channels.
What is tegaserod?
A 5HT4-receptor partial agonist used to treat constipation.
Why should tap water enemas be avoided?
Water intoxication.
Why should soap suds enemas be avoided?
Colitis and necrosis.
What are the important receptors on excitatory enteric motor neurons?
(1) 5HT3 receptor
(2) 5HT4 receptor
What are the important receptors on inhibitory enteric motor neurons?
(1) 5HT1A receptor
(2) 5HT1D receptor
(3) 5HT7 receptor
What cells in the GI tract are responsible for the release of serotonin?
Enterochromaffin cells.
In what layers of the colon can interstitial cells of Cajal be found?
(1) submucosa
(2) within the circular smooth muscle layer
(3) between the circular and longitudinal muscle layers
What is the simplest way to attempt to relieve constipation?
Drink water.
What is the most notable antiemetic discussed? What is its MoA?
Odansetron, which is a 5HT4-receptor antagonist.
What is a side effect of odansetron?
Constipation.
