GI Tract Pharmacology

Question 1

what is GERD

Answer 1

movement of gastric contents into esophagus
caused by relaxation of lower esophageal sphincter

Question 2

what is PUD

Answer 2

peptic ulcer disease
ulcers in upper Gi tract
causes: h. pylori, NSAIDs, stress

Question 3

Antacid “OIAs”

Answer 3

Use: neutralize gastric activity (primarily for acid reflux)
Dosing: frequent
Side Effects: minimal (constipation from aluminum/calcium, diarrhea from magnesium)
Interactions: binds to other drugs/reduces effectiveness

Question 4

Histamine-2 Receptor Antagonists “OIAs”

Answer 4

Uses: Inhibit histamine, gastrin, and ACh stimulated acid release; helps with basal and meal-related acids.
Dosing: Usually once to twice a day dosing.
Side Effects: Diarrhea, dizziness, muscle pain, rashes; Cimetidine has multiple drug interactions.
Interactions: Upregulation of receptors may diminish effectiveness with long-term use; cessation may lead to rebound acid secretion.

Question 5

Proton Pump Inhibitors (PPIs) “OIAs”

Answer 5

Uses: Irreversibly inhibit the H+/K+-ATPase pump on parietal cell membrane, stopping the final step of acid secretion; very effective at healing ulcers and preventing stress ulcer formation.
Dosing: Once daily dosing; need an acidic environment to function.
Side Effects: Similar to H2 Blockers; concerns with long-term use include decreased calcium absorption and increased risk for infection.
concern w/ longterm use causes decrease in calcium absorption/increased risk of infection

Question 6

neural mechanism for N/V - CTZ

Answer 6

chemoreceptor trigger zone
Senses toxins and drugs in blood and cerebrospinal fluid.
Involves dopamine, serotonin (5HT3), neurokinin, and opioid receptors.

Question 7

neural mechanism for N/V - vestibular

Answer 7

Responsible for motion sickness.
Involves muscarinic and histamine-1 receptors

Question 8

how do anticholinergics work for nausea

Answer 8

binds to ACh receptors in vestibular nuclei to block messages in vomiting center

Question 9

how do neuroleptic drugs work for nausea

Answer 9

similar to antipsychotic agents - blocks dopamine in CTZ

Question 10

how do antihistamines work for nausea

Answer 10

H1-blocking agents that inhibit vestibular input to the CTZ, blocks Ach binding to H1 in vestbiular nuclei

Question 11

how do prokinetic drugs work for nausea

Answer 11

block dopamine at CTZ - side use stimulate peristalsis in the stomach

Question 12

how do serotonin blockers work for nausea

Answer 12

blocks serotonin receptors in GI tract, CTZ, and vomiting center

Question 13

what is diarrhea

Answer 13

frequent passage of loose stools, either acute or chronic
mostly due to electrolyte imbalances in intestinal tract
chronic diarrhea have underlying GI conditions

Question 14

how do adsorbents work for diarrhea

Answer 14

coats GI tract, binds to diarrhea causing bacteria and reduces irritation providing relief

Question 15

how do opiates (lite) work for diarrhea

Answer 15

decreases GI motility and propulsion by increasing absorption of electrolytes and water
reduces pain w/ diarrhea

Question 16

what is constipation

Answer 16

movement disorder of colon/rectum = infrequent and painful defecation of sense of incomplete evacuation

Question 17

how do bulk-forming laxatives work for constipation

Answer 17

increases water absorption to soften/bulk up stool and stimulates paristalsis

Question 18

how do emollient laxatives work for constipation

Answer 18

facilitate water and fat absorption into the stool, reabsorption of water back into the body is blocked

Question 19

how do hyperosmotic laxatives work for constipation

Answer 19

works in large intestine by drawing fluid into colon

Question 20

how do saline laxatives work for constipation

Answer 20

increases osmotic pressure by increasing electrolyte and water concentrations in small bowel. increases peristalsis but with watery stools

Question 21

how do stimulant laxatives work for constipation

Answer 21

stimulates enteric nervous system and peristalsis.

Question 22

key facts about IBS?

Answer 22

• 3 types - IBS-C, IBS-D, IBS-M (rare)
• idiopathic etiology
• affects women 2:1, often btwn ages 20-30
• 10-15% of population has it, but only 15% of that seek help

Question 23

symptoms of IBS

Answer 23

• lower abd. pain
• bloating
• diarrhea sx >3 days
• constipation sx >3 weeks (straining, incomplete)
• fatigue, anxiety, depression

Question 24

what is IBD?

Answer 24

split betwen Crohn’s and Ulcerative Colitis.
chronic inflammatory multisystem condition

Question 25

what is ulcerative colitis

Answer 25

confined to rectum and colon
causes continuous lesions affecting mucosa and submucosa

Question 26

what is crohn’s

Answer 26

can affect any part of GI tract
causes discontinuous lesions leading to perforations/fistulas

Question 27

sx of UC?

Answer 27

cramping, frequent bowel movements, wt loss, arthritis, red nodules, hemorrhoids, fissures

Question 28

sx of crohn’s?

Answer 28

malaise/fever, abdom. pain, frequent bowel movements, fistula, wt loss, malnutrition, abdom. mass/tenderness

Question 29

whats the first treatment line for pts w/ UC?

Answer 29

aminosalicylates

these are NOT recommended for crohn’s

Question 30

what is Tumor Necrosis Factor (TNF-α)

Answer 30

Acts as a pro-inflammatory mediator
• Binds to TNF receptors on immune cells
• Increases activity of helper and regulatory T-Cells
• Contributes to inflammation in Crohn’s disease

Question 31

how do Anti-TINF Monoclonal antibodies work

Answer 31

binds to TNF and prevents it from biding to receptors
• Also bind to membrane-bound TNF and reduce its cell signaling

Question 32

What is Reyes Syndrome

Answer 32

ages 18 and under
allows viruses to go across the BBB and lead to brain damage and encephalopathy

Question 33

What leads to Reyes Syndrome

Answer 33

ages 18 and under taking salicylates (aspirin, pepto-bismol [Bismuth subsalicylate])

Question 34

what GI drugs not to use with pregnant women

Answer 34

amitzia/lubiprostone