PHARM_OVERVIEW Flashcards
what is the predominant tone of the GI system?
parasympathetic (cholinergic)
what is the effect of ganglionic blockade of the parasympathetic nervous system in the GI tract?
reduced tone & motility
constipation
decreased gastric and pancreatic secretions
what is DUMBBELLS
Diarrhea Urination Miosis (constriction of pupil) /muscle weakness Bronchorrhea Bradycardia Emesis Lacrimation Sweating
what is the probable role of Ach in the GI nervous system?
a primary excitatory transmitter to smooth muscle and secretory cells in the ENS. Probably also the major neuron-to-neuron ganglionic transmitter in the ENS
what is the role of dopamine in the GI nervous system?
A modulatory transmitter in the ENS
what is the role of Enkephalin and related opioid peptids in the GI nervous system?
present in some secretomotor and interneurons in ENS. Inhibits ACh release & peristalsis. May stimulate secretion
what is the function of serotonin in the GI nervous system?
an important transmitter or cotransmitter at excitatory neuron to neuron junctions in the ENS
what is metoclopramide, and what is it used for?
used to treat N/V and has gastrokinetic actions
-results in coordinated contractions that enhance transit
the effects of metoclopramide are limited to what part of the GI tract?
upper GI, where it increases LES tone & stimulates antral & small intestinal contractions
what is one of the proposed explanations for the etiology of irritable bowel syndrome?
serotonin disequilibrium
- excess 5-HT–>D-IBS
- insufficient 5-HT–> C-IBS
what kind of serotonin antagonist would you want to use that would normalize the activity rather than totally override the activity?
a weak partial agonist
what are the pharmacologic treatments of constipation in IBS?
stool softeners
what are the pharmacologic treatments of diarrhea in irritable bowel syndrome?
antidiarrheal agents
what are the pharmacologic treatments of abdominal pain and discomfort in Irritable bowel syndrome?
antispasmodics
TCAs
SSRIs
how can probiotics improve management of IBS?
can improve barrier function of epithelium, inhibit pathogenic bacteria, acidify colon, improve dysmotility
what is the explanation for the etiology of IBD?
dysbiosis of normal intestinal homeostatic relationship b/w intestinal mucosa and normal microbiome–>inflamm. rxn
whats the name of the TNF-alpha blocker that block TNF-alpha1, TNF-alpha2, and soluble TNF-alpha receptors?
infliximab
what are the clinical effects of opioids on the gallbladder?
biliary pain, delayed digestion
what are the clinical effects of opioids on the gastroduodenum?
anorexia, nausea, emesis
what are the clinical effects opioids on the small bowel?
constipation, delayed digestion, hard, dry stool
what are the clinical effects of opioids on the colon?
constipation, hard, dry stools, bloating & distension, spasm, cramps, pain
what are the clinical effects of opioids on the anorectum?
incomplete evacuation, straining constipation
How can drugs cause osmotic diarrhea?
caused by medications that draw water into the GI tract
How can drugs cause secretory diarrhea?
caused by meds that impair Na+ absorption & Cl- & HCO3 ions ar esecreted into the GI lumen
how can drugs cause disordered motility?
drugs affecting cholinergic tone
how can drugs cause inflammatory diarrhea?
disruption of colonic flora precipitating C. Diff colitis, or following direct damage of the gastric mucosa
how can drugs cause C. Diff diarrhea?
drugs that disrupt acid-base environment or epithelial homeostasis or immune system function
- PPIs, H2 antagonists, & immunosuppressants
- NSAIDS: direct epithelial damage & +/- Na+ perm.
how can drugs cause fatty diarrhea (steatorrhea)?
orlistat & alli
metformin–> decrease Glucose absorption
Octreotide–>paradoxical fatty diarrhea
what kind of pts get pill-induced esophagitis?
old pts
what is pill-induced esophagitis?
a feeling that pill is stuck in throat: pts may complain of burnin and retrosternal pain
-damage usually heals in days, but can lead to esophageal perf., hemorrhage, & death
what are the drug risk factors related to pill-induced esophagitis?
prescription of gelatin capsules, and ER or sustained released products
what class of drugs must you avoid if you have a pt with pill-induced esophagitis?
anticholinergics
what 2 enzymes are the major regulator s of drug bioavailability?
P-GP/MDR & CYP3A (participate in 1st pass metab. in the intestinal wall)
antacids can chelate which class of drugs?
Doxycycline, tetracycline, most fluoroquinolones
which class of drugs can cause constipation or diarrhea and can alkalinize the urine?
antacids
all proton pump inhibitors are substrates of what CYP enzyme?
CYP2C19
