Laxatives, Anti-Darrheals, IBS

Question 1

ACh vs. Somatostatin general actions?

Answer 1

ACh increases motility and secretion

Somatostatin decreases both

Question 2

5HT effect on motility?

Answer 2

Increases

Acts as sensory nt that activates the nerve plexi

Question 3

SSRI effect on gastric emptying/motility?

Answer 3

Increases motility (Diarrhea)
Increased afferent limb of peristaltic reflex

Question 4

Polycarbophil
Psyllium
Methylcellulose
Dietary fiber all act how?

Answer 4

Bulk Laxatives

Increase luminal P –> Activation of peristaltic reflex

Question 5

What is necessary for bulk laxatives to be functional?

Answer 5

Intact reflexes/myenteric plexus

Question 6

When shouldn’t you give bulk laxatives and why?

Answer 6

For unknown causes of constipation

It could just cause an obstruction if the enteric nervous system is not functional

Question 7

Anthraquinones
Bisacodyl
Castor Oil all act how?

Answer 7

Contact Cathartics that irritate the mucosa, activating peristaltic reflex

Question 8

Which contact cathartic is given as a pro-drug and needs 6hrs to activate?

Answer 8

Bicosadyl

Question 9

Which contact cathartic(s) act only on the large intestine?

Answer 9

Bicodasyl

Anthraquinones

Question 10

Which contact cathartic(s) act on both small in and large intestine?

Answer 10

Castor Oil

Question 11

Which contact cathartic is most potent, with most SE?

Answer 11

Castor Oil

Question 12

Melanosis coli is caused by what contact cathartic?

Answer 12

Anthraquinone

Question 13

Which contact cathartic causes uterine contractions and dehydration?

Answer 13

Castor Oil

Question 14

5HT agonist vs antagonist?

Answer 14

Agonist = Cisapride, Tegaserod
Antagonist = Alosetron

Agonist will increase motility
Antagonist will decrease motility

Question 15

Cisapride does what?

Who Gets?

Answer 15

5HT agonist –> Increased presynaptic CGRP –> Increased peristaltic reflex

Diabetic Gastroparesis patients

Question 16

Tegaserod does what?

Who gets it?

Answer 16

5HT agonist –> Increased presynaptic CGRP –> Increased peristaltic reflex

Constipation-IBS

Question 17

Alosetron is metabolised by what enzyme?

Answer 17

CYP1A2

Question 18

Cisapride is metabolized by what enzyme?

Answer 18

CYP3A4

Question 19

Which 5HT drug is associated with ischemic colitis?

Answer 19

Alosetron

Question 20

Which 5HT drug is associated with cardiac toxicity when administered with drugs like warfarin?

Answer 20

Cisapride

Question 21

Enkephalins act how?

Answer 21

Inhibit peristaltic reflex arc (Decrease motility)

Question 22

Dopamine acts how?

Answer 22

Dopamine inhibits ACh release (Decreased motility)

Question 23

Opioids act how?

Answer 23

Inhibit ACh and VIP release in peristaltic reflex (Decreased motility)

Question 24

Diphenoxylate and Loperamide are what class of drug?
What do the cause in GI system?

Answer 24

Opioids

Constipation

Question 25

``` Alvimopan and Methylnaltrexone are what class of drug? What do the do in the GI system? ```

Answer 25

mu opioid receptor antagonists | Relieve constipation caused by opioids

Question 26

Who gets toxic megacolon if they are given opioids?

Answer 26

People with severe ulcerative colitis

Question 27

Which opioid can cross the BBB? Which cannot?

Answer 27

Diphenoxylate crosses BBB | Loperamide does not

Question 28

Who takes alvimopan?

Answer 28

Post-op bowel resection patients taking opioids

Question 29

Who takes methylnaltrexone?

Answer 29

Pallative care patients with high doses of opioids

Question 30

What is Domperidone and metoclopramide's MOA?

Answer 30

Dopamine R antagonism, inhibiting DA's inhibition of motility, thus increasing motility

Question 31

Who takes domperidone or metoclopramide?

Answer 31

Patients suffering from delayed gastric emptying due to vagotomy or diabetic gastroparesis

Question 32

Which DA antagonist cross the BBB?

Answer 32

Metoclopramide

Question 33

Which DA does NOT cross BBB?

Answer 33

Domperidone

Question 34

Amitriptyline and Desipramine MOA and GI effect?

Answer 34

Tricyclics that Decrease ACh and increase DA, thus decreasing motility

Question 35

What is the relevance of atropine in GI treatment?

Answer 35

It is a muscarinic antagonist that is co-administered with opioid agonists to increases toxicity/unpleasant SE

Question 36

What does erythromycin do in the GI system?

Answer 36

Bind motilin receptors and activate the MMC, increasing motility

Question 37

Lubiprostone acts how?

Answer 37

ClC-2 agonist, increasing ClC-2 Cl secretion

Question 38

Major toxicity of Lubiprostone?

Answer 38

Increased fetal loss

Question 39

Linaclotide acts how?

Answer 39

GC-C activation --> increased cGMP --> increased CFTR action

Question 40

Who can't take Linaclotide?

Answer 40

Pregnant women | Pediatric patients

Question 41

Who does take lubiprostone or linaclotide?

Answer 41

Chronic idiopathic constipation | Constipation IBS

Question 42

Crofelemer MOA?

Answer 42

Inhibits CFTR channel action

Question 43

Who takes crofemeler?

Answer 43

HIV patients with Diarrhea

Question 44

Octreotide MOA?

Answer 44

Somatostatin analog

Question 45

Who takes octreotide?

Answer 45

Pts with carcinoid tumors and VIPomas

Question 46

toxicity of octreotide?

Answer 46

decreased pancreatic secretion - malabsorption - steatorrhea - Gall stones

Question 47

Who takes bismuth subsalicylate?

Answer 47

Prevention or treatment of travelers diarrhea

Question 48

Toxicity associated with bismuth subsalicylate?

Answer 48

Black tongue Black stool tinnitus

Question 49

bismuth subsalicylate two distinct MOA and active sites?

Answer 49

``` Bismuth = Increased PGE, bicarb, mucus IN STOMACH Salicylate = Decreased PGE and Cl in LI ```

Question 50

Lactulose MOA and associated toxicty?

Answer 50

Non-digested sugar that increases the osmotic pressure in lumen Digested by bacteria to produce severe cramps and farts

Question 51

Who takes lactulose?

Answer 51

Portal system encephalopathy | Decreases plasma ammonium

Question 52

Major toxicity of osmotic cathartics?

Answer 52

System absorption will cause intravascular volume depletion and electrolyte absorption

Question 53

Cholestyramine and Colestipol MOA and use?

Answer 53

Bile Acid Binding Resins used in patient with ilieal resection that have decreased Bile Acid Reabsorption. They decrease Luminal H2O secretion

Question 54

Docusate and mineral oil MOA?

Answer 54

Surfactant, increasing mixing of aqueous substance which SOFTENS STOOL

Question 55

Who doesn't get mineral oil and why?

Answer 55

Undiagnosed abdominal pain patients shouldn't take mineral oil, because if it is aspirated it will cause severe lipid pneumonitis

Question 56

Kaolin MOA? Use?

Answer 56

Natural MgAl silicate that may be useful in acute diarrhea

Question 57

Pectin MOA and Use?

Answer 57

Indigestible carbohydrate that maybe absorbs toxins?

Question 58

Which classes of laxatives have a mild efficacy and long latency?

Answer 58

``` Stool Softeners - Docusate - Mineral Oil Bulk Laxatives - Polycarbophil - Psyllium - Hemicellulose - Dietary Fiber ```

Question 59

Which drugs are only given as compassionate care?

Answer 59

Alosteron Cisapride Tegaserod Domperidone

Question 60

Which class of laxatives should be given to patients with moderate constipation?

Answer 60

Contact Cathartics - Bicosyl - Anthraquinones

Question 61

Which class of laxatives should be given for severe constipation and will cause a rapid watery evacuation?

Answer 61

``` Castor Oil Osmotic Cathartics - Lactulose - MgOH - Na phosphate - Polyethylene Glycol ```