OTC Digestion

Question 1

what are 4 common maladies of the GI tract that can be treated w OTC drugs?

Answer 1

peptic ulcers, gastroesophageal reflux disease (GERD, heartburn), nausea/vomiting, GI motility problems (constipation, diarrhea)

Question 2

what are acid-peptic diseases?

Answer 2

excessive acid secretion or erosion of mucosal lining of GI tract (GERD, peptic ulcers, gastritis)

Question 3

what do drugs that treat acid-peptic diseases do? (3)

Answer 3

decr GI acidity by decr acid secretion, incr mucosal defense, or eradicate H. pylori

Question 4

what bacteria is associated with peptic ulcers?

Answer 4

Helicobacter pylori (breaks down mucosal barrier)

Question 5

what drugs can cause peptic ulcers?

Answer 5

NSAIDs

Question 6

what cells in the stomach secrete H+?

Answer 6

parietal cells (in the fundus)

Question 7

what are the 2 regions of the stomach?

Answer 7

fundus (top) and antrum (bottom)

Question 8

what pump do parietal cells use to make the stomach acidic?

Answer 8

H+/K+ ATPase pump (H+ against conc. grad.)

Question 9

what 3 compounds control acid production from parietal cells?

Answer 9

gastrin, histamine, acetylcholine

Question 10

how does gastrin stimulate acid production from parietal cells?

Answer 10

G cells in antrum detect protein/a.a. and release gastrin which binds to CCK receptors on P cells

Question 11

how does histamine stimulate acid production from parietal cells?

Answer 11

gastrin stimulates enterochromaffin cells (H cells) in fundus to release histamine which binds to H2 receptors on P cells

Question 12

how does ACh stimulate acid production from parietal cells?

Answer 12

vagus nerve (parasymp.) stimulates postgang. neurons of ENS to release ACh which binds to muscarinic (M3) receptors on P cells

Question 13

what is the negative feedback loop to decr acid production from P cells?

Answer 13

D cells in antrum detect low pH (<3) and release somatostatin which inhibits gastrin release from G cells

Question 14

what are the dangers of excess acid production in stomach?

Answer 14

erodes mucosal layer and LES

Question 15

what can lead to acid in eso. (GERD)?

Answer 15

loss of LES integrity (from pregnancy, obesity, etc.)

Question 16

what are antacids?

Answer 16

weak bases that neutralize stomach acid by reacting w H+

Question 17

what are antacids used to treat?

Answer 17

peptic ulcers (decr recurrence rate if taken frequently and in high doses)

Question 18

what are 2 popular antacids?

Answer 18

magnesium hydroxide (Mg[OH]2) and aluminum hydroxide (Al[OH]3)

Question 19

what are the diff side effects of Mg(OH)2 and Al(OH)3?

Answer 19

(both not absorbed from bowel)
Mg(OH)2: laxative effect
Al(OH)3: constipation action

Question 20

what are proton pump inhibitors?

Answer 20

lipophilic weak bases that diffuse into P cells and inactivate H+/K+ ATPase

Question 21

what is an example of a proton pump inhibitor?

Answer 21

Omeprezole

Question 22

what can prolonged use of proton pump inhibitors cause?

Answer 22

hypergastrinemia (acid secretion inhibits gastrin) which can incr cancer risk

Question 23

what is a side effect of proton pump inhibitors?

Answer 23

decr bioavailability of vit B12 or other drugs that require acidity to be absorbed

Question 24

what are OTC drugs called that treat nausea and vomiting caused by motion sickness or other conditions?

Answer 24

antiemetics

Question 25

what is bismuth subsalicylate?

Answer 25

antiemetic, active ingredient in Pepto Bismol

Question 26

what happens to bismuth subsalicylate in the stomach?

Answer 26

hydrolyzes to bismuth oxychloride (salt) and salicylic acid

Question 27

what does salicylic acid do (from bismuth subsalicylate)?

Answer 27

is absorbed by gut and acts as a COX2 inhibitor (anti-inflammatory)

Question 28

what do bismuth salts do (from bismuth subsalicylate)?

Answer 28

not absorbed by gut but has antibacterial effects (can bind to toxins from E. Coli and H. pylori)

Question 29

what are 3 other effects of bismuth subsalicylate?

Answer 29

weak antacid properties, slows gut motility, stimulates fluid absorption

Question 30

what is dimenhydramine?

Answer 30

competitive antagonist at H1 receptor (active ingr in Gravol)

Question 31

what does dimenhydramine do?

Answer 31

block histamine activity in vestibular system

Question 32

what is the ENS?

Answer 32

intrinsic neural plexuses that control GI motility (= second brain)

Question 33

what modulates ENS?

Answer 33

CNS and ANS (para: vagus nerve and symp)

Question 34

what results from removing extrinsic ANS control from ENS?

Answer 34

disorganized gastric activity but returns to normal over time (by ENS)

Question 35

what are the 2 plexuses of the ENS?

Answer 35

myenteric and submucosal

Question 36

what does the myenteric plexus do?

Answer 36

provide motor innervation to muscular layer of gut (peristalsis)

Question 37

what does the submucosal plexus do?

Answer 37

provide secretomotor innervation to submucosa (induce gland to produce mucus)

Question 38

what type of neurons are in the ENS plexuses primarily?

Answer 38

cholinergic (also has serotonin and dopamine)

Question 39

what do pregang ANS neurons release?

Answer 39

ACh (cholinergic)

Question 40

what do postgang ANS neurons release?

Answer 40

para: ACh (cholinergic) symp: NA (adrenergic)

Question 41

what do pregang parasym neurons innervate?

Answer 41

postgang myenteric muscarinic (ACh) neurons in eso, stomach, and upper intest

Question 42

what does ACh binding to GI smooth muscle cause?

Answer 42

contraction (motility)

Question 43

what does vagus release of ACh also stimulate?

Answer 43

acid production from parietal cells

Question 44

what do postgang symp neurons innervate?

Answer 44

adrenergic myenteric and submucosal enteric neurons in intes and colon

Question 45

what receptors does NA from postgang symp neurons bind to?

Answer 45

alpha2 adrenergic receptors

Question 46

what is effect of sympathetic innervation of the GI tract?

Answer 46

inhibition of gut motility

Question 47

what is constipation?

Answer 47

less frequent bowel movements that are more difficult to pass

Question 48

what causes contipation?

Answer 48

low fiber diet and decr water intake

Question 49

what are laxatives?

Answer 49

substances that loosen stool or stimulate bowel movements

Question 50

what are 4 kinds of laxatives?

Answer 50

bulk-forming, osmotic, lubricant and stimulant

Question 51

what do bulk-forming laxatives do?

Answer 51

draw water into stool to make them larger and easier to pass by containing plant fibers such as psyllium and methyl cellulose (must take w/ water)

Question 52

what do osmotic laxatives do?

Answer 52

draw fluid into bowel from nearby tissues by containing polyethylene and Mg

Question 53

what do lubricant laxatives do?

Answer 53

coat surface of stool or anus to make it easier for stools to pass by containing glycerin suppositories (mineral oil)

Question 54

what do stimulant laxatives do?

Answer 54

cause bowels to squeeze stool out by containing senna and bisacodyl

Question 55

what is diarrhea?

Answer 55

loose, watery stool as colon doesn't absorb fluid from food

Question 56

what causes dairrhea?

Answer 56

bacterial or viral infections

Question 57

what are 2 common OTC treatments for diarrhea?

Answer 57

loperamide and bismuth subsalicylate

Question 58

what is loperamide?

Answer 58

full mu opioid agonist

Question 59

where are mu opioid receptors in GI tract?

Answer 59

submucosal and myenteric (mainly) plexus

Question 60

what are mu opioid receptors?

Answer 60

Gi GPCRs

Question 61

what does loperamide do?

Answer 61

binds to mu opioid receptors to slow peristalsis and inhibit secretion of water and mucus

Question 62

what is different btwn loperamide and other opioid agonists?

Answer 62

has weak analgesic effects (not rewarding/addicting, no resp depression)

Question 63

why can't loperamide cause any physiological effects in the brain?

Answer 63

is a substrate for P-gp (permeability-glycoprotein), which is a pump in the endothelial cells of the BBB that actively removes drugs from the brain

Question 64

what drugs interfere with P-gp?

Answer 64

tricyclic antidepressants (amitriptyline)

Question 65

what are some adverse effects of taking amitriptyline with loperamide?

Answer 65

respiratory depression and abuse as amitriptyline blocks P-gp allowing [loperamide] in brain to incr

Question 66

why are some OTC drugs for common digestive problems counterproductive?

Answer 66

bacterial or viral infections should be removed through vomiting/anal/urethral excretion

Question 67

Mucosal surface cells secrete mucous that provides a barrier btwn __________ and __________

Answer 67

Mucosa (top layer of stomach) and lumen

Question 68

what kind of receptors are alpha2 adrenergic receptors?

Answer 68

Gi GPCR