GI Pharmacology

Question 1

antacids

Answer 1

• e.g aluminium hydroxides, magnesium hydroxide
• neutralise stomach acid
• treat GORD, dyspepsia
• side effects of constipation, diarrhoea

Question 2

PPIs

Answer 2

• e.g omeprazole
• pumps on the apical membrane blocked
• used in GORD, peptic ulcers, zollinger ellison, H.pylori eradication
• side effects..
  constipation
  diarrhoea
  headache

Question 3

H2 receptor antagonists

Answer 3

• block action of histamine secreted by enterochromaffin like cells, which decrease HCl production
• used in GORD, dyspepsia, peptic ulcers
• side effects..
  hypotension
  headaches
  diarrhoea
  constipation

Question 4

mucosal strengtheners

Answer 4

• e.g sucralfate, bismuth chelate
• binds to +ve charger ulcer base and forms a protective mucosal barrier
• used in GORD, ulcers
• side effects..
  constipation

Question 5

anti motility drugs

Answer 5

• e.g leporamide, codeine
• morphine opaite based drugs that cause…
  decreased peristalsis and segmentation (causing constipation)
  sphincter constriction
  increased fluid absorption
• used for diarrhoea
• side effects..
  drowsiness
  constipation
  urinary retention

Question 6

5 - ASAs

Answer 6

• e.g sulfasaline, mesalazine
• used in UC (anti inflam)
• side effects..
  diarrhoea
  nausea
  cramps

Question 7

Laxatives/Purgatives are used when… (5)

Answer 7

• straining is bad for health
• painful defecation
• clearing bowel before procedures
• drug induced constipation
• constipation in elderly/bed ridden

Question 8

types of laxatives/purgatives

Answer 8

• bulk forming e.g methyl cellulose
• stimulant e.g bisocadyl
• faecal softeners e.g docusate sodium
• osmotic e.g Mg sulphate/hydroxide

Question 9

dopamine D2 receptor antagonists

Answer 9

• e.g metaclopramide, domperidone
• blocks dopamine receptors in chemoreceptor trigger zone, which increases LOS tone
• used in drug induced vomiting, GORD, gastroparesis
• side effects…
  drowsy
  physiological disturbance
  avoid in GI obstruction

Question 10

what does meclopramide do

Answer 10

increase gastric emptying

Question 11

what conditions are corticosteroids used

Answer 11

UC, hepatitis, Crohns

Question 12

5 HT3 receptor antagonists

Answer 12

• e.g ondansetron
• blocks 5HT3 receptors, which are prevalent in chemoreceptor trigger zones
• used in chemo/radiotherapy/post op induced emesis
• side effects…
  headache
  constipation

Question 13

Muscarinic ACh Antagonists

Answer 13

• e.g hyoscine, scopolamine, mebeverine
• block muscarinic receptors at vomiting centre, causing the inhibition of GI movement and relaxation (anti spasmodics)
• used in IBS, motion sickness
• side effects..
  dry mouth
  blurred vision
  sedation
  urinary retention

Question 14

Histamine H1 antagonists

Answer 14

• e.g cyclizine
• blocks H1 receptors in the nucleus tractus solitarius and vestibular nuclei
• used for motion sickness and acute labyrinthitis (inner ear disorder)
• side effects…
  drowsiness