Gastrointestinal Drugs

Question 1

Name some Proton Pump Inhibitors

Answer 1

Omeprazole, Lansoprazole, Rabeprazole, Esomeprazole and Pantoprazole

Question 2

When are PPI’s used?

Answer 2

In treatment of GORD, PUD and Zellinger-Ellison Syndrome

Question 3

How do PPI’s work?

Answer 3

Irreversible inhibition of H+/K+ATPase at parietal cells, decreasing secretion of acid into the stomach.

Question 4

What are some ADRs of PPI use?

Answer 4

GI upset, headache and gastric atrophy.

Question 5

Name some Histamine Receptor Antagonists

Answer 5

Cimetidine and Ranitidine

Question 6

How do Histamine Receptor Antagonists work?

Answer 6

Antagonise H2 receptors, preventing amplification of parietal cell stimulation, reducing acid output into the stomach.

Question 7

What are some ADRs of Histamine Receptor Antagonists?

Answer 7

Dizziness, fatigue, gynaecomastia and rash.

Question 8

When are Histamine Receptor Antagonists best taken?

Answer 8

At night, as there is less food to buffer stomach acid, worsening GORD/PUD.

Question 9

Name some Oral Bulk Laxatives

Answer 9

Ispaghula, Bran and Methylcellulose

Question 10

When are bulk laxatives used?

Answer 10

For constipation with hard faeces

Question 11

What are contraindications for bulk laxative use?

Answer 11

Dysphagia, intestinal obstruction or ulceration, colonic atony, faecal impaction.

Question 12

What is the mechanism of action for bulk laxatives?

Answer 12

Increase volume of non-absorbable residue in the gut, stimulating gut wall stretch receptors, increasing peristalsis.

Question 13

What are ADRs of bulk laxatives?

Answer 13

Flatulence, abdominal distension, and gastrointestinal obstruction.

Question 14

Name some Faecal Softeners and how they are given?

Answer 14

Arachis Oil, as an enema, and Glycerol, given as a rectal suppository.

Question 15

What are faecal softeners used for?

Answer 15

Haemorrhoids, constipation, faecal impaction, and anal fissures.

Question 16

What are contraindications for faecal softener use?

Answer 16

Age below 3 years.

Question 17

What is the mechanism of action faecal softeners?

Answer 17

Lubricate and soften stool.

Question 18

Name some osmotic laxatives and their method of administration

Answer 18

Lactulose (oral), Magnesium and Sodium salts (rectal) and Movial (oral powder).

Question 19

When are osmotic laxatives used?

Answer 19

For hard faecal constipation.

Question 20

What is the mechanism of action for osmotic laxatives?

Answer 20

Increase osmosis and water movement into the bowel lumen. Specifically in Lactuloses case, lactulose is fermented by gut flora to acetic and lactic acid, having an osmotic effect.

Question 21

What are ADRs for osmotic laxatives?

Answer 21

Flatulence, cramps, abdominal discomfort and intestinal obstruction.

Question 22

When specifically are Magnesium and Sodium Salts used?

Answer 22

For rapid relief of severe constipation.

Question 23

When are irritant/stimulant Laxatives used?

Answer 23

For soft faecal clearance before operations or medical procedures.

Question 24

What are some examples of irritant/stimulant laxatives?

Answer 24

Senna, Danthron, and Bisacodyl

Question 25

What is a contraindication for irritant/stimulant laxative use?

Answer 25

Intestinal obstruction

Question 26

What is the mechanism of action for irritant/stimulant laxative use?

Answer 26

Increase GI peristalsis and water/electrolyte secretion from the mucosa.

Question 27

What are ADRs of irritant/stimulant laxatives?

Answer 27

Hypokalaemia and Colonic Atony

Question 28

Name some oral Anti-motility Antidiarrhoeals

Answer 28

Codeine and Imodium

Question 29

How do Codeine and Imodium work?

Answer 29

Act as opioid receptor agonsts, which decrease colonic motility and increase anal tone.

Question 30

What are contraindications for codeine or imodium use?

Answer 30

Toxic Megacolon (in IBD)

Question 31

What are ADRs for codeine or imodium?

Answer 31

Constipation, drowsiness and abdominal cramps.

Question 32

What is an example of a bulk forming antidiarrhoeal and when is it used?

Answer 32

Ispaghula, and used in IBS or ileostomy patients.

Question 33

What is a contraindication for bulk forming antidiarrhoeal use?

Answer 33

Intestinal obstruction

Question 34

How do bulk forming antidiarrhoeals work?

Answer 34

Absorb faecal fluid.

Question 35

When is mebeverine used and how does it work?

Answer 35

Decreases colonic hypermotility, to treat symptoms of Irritable Bowel Syndrome

Question 36

What type of drugs can be used as anti-emetics?

Answer 36

Dopamine D2 Receptor Antagonists, Serotonin Antagonists, Anti-muscarinics, Histamine H1 Receptor Antagonists, cannabinoids (nabilone) and benzodiazapines.

Question 37

Hoiw do Dopamine Antagonists work?

Answer 37

Act on the postrema of 4th ventricle floor (vomiting centre), and increase the rate of stomach emptying.

Question 38

Name some dopamine antagonists used in antiemesis

Answer 38

Domperidone, Metoclopremide

Question 39

What is an ADR of dopamine antagonist use?

Answer 39

Prolactin release, Extra-pyramidal dystonia

Question 40

What serotonin antagonists can be used for anti-emesis?

Answer 40

Ondansetron, Granisetron

Question 41

When are serotonin antagonists likely to be used?

Answer 41

For post-op, chemoptherapy and radiotherapy.

Question 42

What is the mechanism of action for serotonin antagonists?

Answer 42

Deactivate the vomiting centre, and decrease vagus nerve activity.

Question 43

What are ADRs of serotonin antagonist use?

Answer 43

Constipation, flushing and headache.

Question 44

What Anti-muscarinic (M1 antagonist) can be used, and when is it likely to be used?

Answer 44

Hyoscine, and used for motion sickness.

Question 45

What ADRs can arise from Hyoscine use?

Answer 45

Bradycardia, dry mouth, dyshydrosis

Question 46

What Histamine (H1) antagonist is likely to be used for anti-emesis?

Answer 46

Cyclizine or Phenothiazine

Question 47

What contraindication exists for cyclizine?

Answer 47

Any history of myocardial ischaemia.

Question 48

What ADRs occur from cyclizine?

Answer 48

Sedation and QT prolongation.