The GI system, from pharmacology’s perspective

Question 1

Gastrointestinal Tract Smooth Muscle
Sympathetic Effect/Receptor
Walls

Answer 1

Relaxes

alpha-2 & Beta-2

Question 2

Gastrointestinal Tract Smooth Muscle
Sympathetic Effect/Receptor
Sphincters

Answer 2

Contracts

alpha-1

Question 3

Gastrointestinal Tract Smooth Muscle
Parasympathetic Effect/Receptor
Walls

Answer 3

Contracts

M3

Question 4

Gastrointestinal Tract Smooth Muscle
Parasympathetic Effect/Receptor
Sphincters

Answer 4

Relaxes

M3

Question 5

Gastrointestinal Tract Smooth Muscle
Parasympathetic Effect/Receptor
Secretions

Answer 5

Increases

M3

Question 6

Gastrointestinal Tract

Predominate Tone:

Answer 6

Parasympathetic (cholinergic)

Question 7

Gastrointestinal Tract

Effect of Ganglionic Blockade

Answer 7

Reduced tone & motility; constipation; decreased gastric & pancreatic secretions.

Question 8

DUMBBBELS

Cholinergic Agonists or AchE Inhibitors

Answer 8

Diarrhea/Defecation: relaxation internal anal sphinc
Urination:
Miosis: pupil constriction
Bronchorrhea
Bronchospasm
Bradycardia
Emesis: Vomiting
Lacrimation:
Salivation:

Question 9

Some medications that are taken for non-­‐G.I. conditions have anticholinergic activity that can lead
to?

Answer 9

Constipation as an ADE.

Question 10

The processes of mixing, propulsion, & absorption of nutrients in the GI tract are controlled locally through a restricted part of the peripheral nervous system called?

Answer 10

The enteric nervous system (ENS).

Question 11

The ENS is involved in sensorimotor control & thus consists of both afferent sensory neurons & a number of motor nerves & interneurons that are organized principally into two nerve plexuses:

Answer 11

The myenteric (Auerbach’s) plexus & the submucosal (Meissner’s) plexus.

Question 12

The myenteric plexus, located between the

Answer 12

Longitudinal & circular muscle layers, plays an important role in the contraction & relaxation of GI smooth muscle.

Question 13

The submucosal plexus is involved with

Answer 13

Secretory & absorptive functions of the GI epithelium, local blood flow, & neuroimmune activities.

Question 14

Within the enteric nervous system a large number of neuromodulators play a role in

Answer 14

Regulating autonomic control over the semi-­‐autonomous functioning of the G.I. smooth muscle & secretory glands

Question 15

The enteric nervous system lining with G.I. tract has as its principal neurotransmitter

Answer 15

acetylcholine

Question 16

Co-­‐transmicers & modulators that serve to provide local control over prevailing central neural tone?

Answer 16

Dopaminergic & opiate receptors (Enkephalin) can be modulated by drug therapy.

Question 17

Metoclopramide is an older drug that is used to treat

Answer 17

N/V & is also used for its gastrokinetic actions, in other words it is used to treat gastroparesis.

Question 18

The mechanisms of action of metoclopramide are complex & involve

Answer 18

5­‐HT4 receptor agonism, vagal & central 5-­HT3 antagonism, & possible sensitization of muscarinic receptors on smooth muscle, in addition to DA receptor antagonism.

Question 19

Metoclopramide administration results in

Answer 19

Coordinated contractions that enhance transit. Its effects are confined largely to the upper digestive tract, where it increases lower esophageal sphincter tone & stimulates antral & small intestinal
contractions.

Question 20

Irritable Bowel Syndrome (IBS) is multifactorial condition involving episodes of both constipation & diarrhea, has been attributed,

Answer 20

in part, to dysfunction in serotonergic signaling in the G.I. tract.

Question 21

In IBS it would appear that the use of partial agonists or antagonists, rather than full agonist/antagonist would be

Answer 21

The most appropriate option for treatment.

Question 22

The chronic debilitating illness known as irritable bowel syndrome is characterized by

Answer 22

Recurring pain & discomfort in the lower abdomen, & by functional impairment of G.I. motility.

Question 23

Studies indicate that defense mechanism in IBS is

Answer 23

Compromised

Question 24

Inflammatory Bowel Disease (IBD) most common components are

Answer 24

Ulcerative colitis & Crohn’s disease.

Question 25

In IBD the intestinal microflora is implicated in the

Answer 25

Genesis of this condition, & TNF alpha has been identified as playing a pivotal role in the inflammatory response.

Question 26

TNF alpha inhibitors, are the drugs of choice for both

Answer 26

Crohn’s disease & ulcerative colitis.

Question 27

One of the most significant & persistent adverse effects of chronic opiate therapy is

Answer 27

Constipation.

Question 28

Opiate receptors are found in the enteric nervous system where their activation leads to

Answer 28

Gastroparesis.

Question 29

The opiate receptors are found throughout the G.I. tract & their activation by the narcotic analgesics not only promotes (blank) but also (blank).

Answer 29

Nausea & Vomiting,

Constipation & Incomplete Evacuation.

Question 30

Drug-­‐induced diarrhea can occur through any one of a number of mechanisms, such as

Answer 30

Attracting or retaining excess water, modification to normal motility signaling, & disruption of the microflora.

Question 31

Disruption of the microflora can be due to the use of

Answer 31

Antimicrobial agents, or simply through effects on the microbes micro-­environment, such as drug-induced changes in pH, epithelial integrity, or immune system function.

Question 32

The weight-­loss product orlistat&cholestyramine used for hypercholesterolemia produce

Answer 32

diarrhea

Question 33

Octreotide, a drug that blocks the affects of many GI hormones is useful in controlling many types of

Answer 33

secretory diarrhea including patients with GI carcinoid tumors & in HIV­‐associated diarrhea.

Question 34

The common antidiabetic drug metormin produces diarrhea in almost 50% of patients taking the drug; this is thought due to

Answer 34

Inhibition of glucose in the GI tract, thus producing large quantities of unabsorbed material that produces osmotic diarrhea. Diarrhea is also a symptom of lactic acidosis, the major adverse effect of this drug.

Question 35

Pill­‐induced esophagitis:

Answer 35

A problem primarily experienced by older patients & one that can lead to esophageal perforation & hemorrhage in extreme situations.

Question 36

Pill­‐induced esophagitis most commonly it is seen with

Answer 36

sustained or extended release products or gelatin capsules which catch in the throat of older patients who by virtue of their age, are producing less saliva to aid in swallowing.

Question 37

Most commonly in regards to G.I. bleed, we think about

Answer 37

nonsteroidal anti‐inflammatory drugs.

Question 38

Recall that both CYP3A & P­‐GP are to be found in the intestinal wall where they modulate

Answer 38

bioavailability & participate in 1st­‐pass metabolism.

Question 39

The 3 ways in which gastric acidity can be modulated:

Answer 39

Antacids, proton pump inhibitors, & H2 histamine blockers.

Question 40

Some drugs rely on gastric acidity to be

Answer 40

Absorbed, so a simple change in pH can reduce their bioavailability.

Question 41

Antacids have the capacity to

Answer 41

chelate, that is to bind up & prevent absorption of a number of drugs.

Question 42

Most commonly chelated drugs we think about

Answer 42

Doxycycline, tetracycline, & fluoroquinolones.

Question 43

For the H2‐blockers & proton pump inhibitors the change in pH can also impact

Answer 43

bioavailability of concurrent medications.