Lec 17 GI Pharm II Flashcards
What fibers mediates vomitting?
vagus nerve and cholinergic fibers
What is the chemoreceptor trigger zone? What acts there?
located on floor of fourth ventricle outside BBB
opioids, dopa agonists, chemo drugs act there
What are 4 diseases associated with gastroparesis [slow gastric emptying]?
- diabetes [longstanding type I]
- hypothyroidism
- connective tissue [scleroderma]
- pregnancy
Of Dopamine, ACh, 5HT2, and 5HT4 which are pro-motility and which slow down gastric emptying?
ACh and 5HT4 stimulate gastric emptying
D2 and 5HT2 slow down gastric emptyin
[2 less that 4. more stimulates]
Ondasetron: mechanism
5-HT3 antagonist;
decreases vagal stimulation. Powerful central-acting antiemetic.
Ondasetron: clinical use
Control vomiting postoperatively and in patients undergoing cancer chemotherapy.
Ondasetron: toxicity
Headache, constipation
Ocreotide: mech?
somatostatin analog
Ocreotide: clinical use?
acute variceal bleeds, acromegaly, VIPoma, and carcinoid tumors.
Ocreotide: toxicity
nausea, cramps, steatorrhea
What are some causes of constipation?
- normal constipation
- IBS
- metabolic
- colonic inertia
- pelvic floor dysfunction
What are major types of treatment for diarrhea?
- opiates: slow motility, increase absorption
- a-agonists: increase basal fluid and electrollyte absorption
- somatostatin: inhibits secretions and motility
- Alosetron: inhibits 5HT3 receptors of small bowel to decrease motility and secretion
What is mech of action loperamide?
opioid receptor agonist
What is clinical use of loperamide?
use to treat diarrhea
usually give with diphenoxylate
What are some potential treatments for constipation?
- stool softening
- colonic irritants
- enemas to stimulate rectal evacuation
- fiber to increase stool bulk
