Constipation and diarrhea

Question 1

Dioctyl sodium MOA

Answer 1

decrease water tension for easier passage of stool with no effect on intestinal peristalsis

Question 2

Dioctyl AE and CI

Answer 2

Dont use with abdominal pain, N/V, irritates mucosa and increase intestinal absorption of other drugs. Short term use

Question 3

What is the most potent class of laxatives?

Answer 3

stimulant laxatives

Question 4

Bisacodyl MOA

Answer 4

Stimulant laxative that acts predominantly on large bowel, increases mucosal permeability, increase back diffusion, increase propulsive contractility by stimulating myenteric plexus, stimulate PG synthesis. Prodrug converted by enteric bacteria

Question 5

Bisacodyl AE and CI

Answer 5

overdosing= fluid and electrolyte loss, enterocyte damage, colonic inflammatory response

Question 6

Lactulose MOA

Answer 6

disaccharide which is not absorbed and produces osmotic effect. Metabolized to formic and acetic acid by bacteria–> fecal acidifier traopping ammonium

Question 7

What drug is used in C-IBS?

Answer 7

Lubiprostone

Question 8

MOA of lubiprostone

Answer 8

Activation of Cl channel to increase permeability in an PKA independent fasion. Alleviates symptoms

Question 9

What does laxative abuse do?

Answer 9

leads to constipation requiring several days to accumulate bulk which people take even more laxatives for. Bowel become unresponsive.

Question 10

What anti-diarrheal is an absorber of etiological factors in the lumen?

Answer 10

Bismuth subsalicylate- absorb harmful bacteria, viruses, toxins

Question 11

What drug is used to prevent Traveler’s diarrhea?

Answer 11

bismuth subsalicylate

Question 12

MOA of opiates

Answer 12

Alter intestinal motility to increase contact time between ingested matter and intestinal epithelium. Decrease secretions, decrease motility, increase muscle tone, increase sphincter tone, anti-spasmodics, decrease cramps

Question 13

Loperamide MOA

Answer 13

interacts with intestinal opiod receptors and binds to and inhibits Ca binding protein calmodulin

Question 14

Describe neural control of emesis

Answer 14

Vomiting center is in the area postrema medulla and sends signals vomiting, swallow, and saliva. Receives signals from : limbic system of forebrain, motion via 8th nerve, taste, vagal and visceral afferents, chemoreceptor trigger zone. Limbic system sends signals for nausea

Question 15

What receptors aid in signal transmission to emetic center?

Answer 15

inner ear motion to cerebellum: M1, H1

Blood born emetics act on 5-HT3, D2, M1, substance P receptors

Question 16

Scopolamine MOA

Answer 16

anti-cholinergic muscarinic receptor blocker to prevent motion fibers signalling to CTZ. prophylactic only for motion sickness

Question 17

Scopolamine AE

Answer 17

sedation, extrapyramidal (dry mouth, drowsiness)

Question 18

Cyclzine MOA

Answer 18

H1 antihistamine to counter motion sickness

Question 19

Meclizine MOA

Answer 19

H1 antihistamine that exerts a depressant effect on hyperstimulation of labyrinthine function. Used for vestibular disturbances.

Question 20

Chlorpromazine MOA

Answer 20

centrally acting anticholinergic and anti-dopaminergic (at CTZ), used for N/V and intractable hiccoughs

Question 21

Droperidol MOA

Answer 21

blocks dopaminergic receptors in the CTZ. used for post-op N/V

Question 22

Metoclopramide MOA

Answer 22

Dopamine receptor antagonist that blocks chemotherapeutic induced activation of D2 receptors in CTZ. Stimulates gastric emptying. given prophylactically prior to cancer chemo and prevention of post op N/V

Question 23

Granisetron MOA

Answer 23

Antiemetic serotonin antagonist, potent, blocks receptors in stomach and small intestine, and CTZ

Question 24

What is the most effective anti-emetic?

Answer 24

serotonin antagonists

Question 25

Dolasetron MOA

Answer 25

Antiemetic serotonin antagonist with longer half life

Question 26

Methylprednisolone MOA

Answer 26

Corticosteroids have anti-emetic effect and reduce side effects. Prevent PG production.

Question 27

Aprepitant MOA

Answer 27

substance P/NK1 receptor antagonist that is used as an adjunct drug for preventing emesis by cytotoxic drugs. It crosses the BBB and inhibits emesis via central actions. Completely metabolized by CYP3A4

Question 28

Lorazepam MOA

Answer 28

benzodiazepine, used in adjunct to other antiemetic drugs, effective in pt with anticipatory vomiting, give 1 day prior to chemo

Question 29

Describe use of anti-emetics in cancer chemo

Answer 29

Combination of 5-HT3 + (dexamethasone, benzodiazepine, NK1 antagonist, or D2 antagonists are added)