Lecture 20 - GI Pharmacology

Question 1

What is the most common location of pain for gastric or duodenal ulcers?

Answer 1

Epigastric pain

Question 2

What are some symptoms of gastric or peptic ulcerations?

Answer 2

Bleeding
Perforation
Scarring and possible obstruction

Question 3

What are some risk factors of gastric acid or peptic ulcers?

Answer 3

Early gastric emptying
Imbalance between normal acid levels and feedback
Helicobacter pylori
NSAIDs
Smoking and alcohol delay healing of ulcers.

Question 4

Why do NSAIDs increase risk of gastric ulceration?

Answer 4

Reduced prostaglandins which normally inhibit the production of gastric acid

Question 5

What cells produce histamine stimulating gastric acid production?

Answer 5

Enterochromaffin cells

Question 6

What are the 3 main stimulatory transmitters for gastric acid production?

Answer 6

ACh
Histamine
Gastrin

Question 7

What is an example of a combined alginates and antacids?

Answer 7

Gaviscon

Question 8

What is the purpose of antacids and alginates?

Answer 8

Antacids = buffering stomach acid
Alginic acid = inc stomach content viscosity and reduce reflux

Question 9

What is contained in gaviscon?

Answer 9

Alginic acid = sodium alginate
Antacids = aluminium hydroxide/magnesium carbonate

Question 10

What are the adverse effects of magnesium salt and then aluminium salts used as antacids?

Answer 10

Mg salts = diarrhoea
Aluminium salts = constipation

AC
MD

Question 11

Why are aluminium hydroxide. And magnesium carbonate both taken at the same time if they are both antacids?

Answer 11

Mg salts cause diarrhoea and Aluminium salts can cause constipation

So balance the side effects

Question 12

What are the warnings and contraindications to alginates and antacids?

Answer 12

Na+ and K+ containing preparations should be carefully used in renal failure

High conc sucrose in some solutions so be careful with hyperglycaemia in DM

Question 13

What are the important drug drug interactions of alginates and antacids?

Answer 13

Reduce absorption of many drugs
Can inc urine alkalinity increasing aspirin excretion

Question 14

What are some proton pump inhibtors?

Answer 14

Omeprazole
Lansoprazole

Question 15

What is the mechanism of action of proton pump inhibitors like omeprazole and lansoprazole?

Why are they so effective?

Answer 15

Irreversibly inhibit the H+/K+ ATPase in gastric parietal cells

Inhibit the final stage in stomach acid production

Question 16

What are some adverse effects of proton pump inhibtors like omeprazole and lansoprazole?

Answer 16

GI disturbance (abdominal pain, constipation, diarrhoea)
Headache , dizziness
Drowsiness/confusion

Question 17

What are some warnings and contraindications of proton pump inhibitors?

Answer 17

Mask symptoms of gastro-oesophageal cancer
Osteoporosis - fracture risk

Question 18

What are some importnat drug drugs interactions of omeprazole?

Answer 18

CYP inhibitor so omeprazole reduces clopidogrel activation

PPIs can increase effects of warfarin and phenytoin

Question 19

What are PPIIs often prescribed alongside with?

Answer 19

NSAID
Steroid

Question 20

What is an example of H2 receptor antagonists?

Answer 20

Famotidine

Question 21

How do H2 receptor antagonists work?
(Famotidine)

Answer 21

Inhibts H2 receptors since histamine release contributes to proton pump. Activation

Question 22

How do H2 receptor anatagonists like Famotidine compare in their action to proton pump inhibtors like omeprazole and lansoprazole?

Answer 22

PPIs act at the final step of acid production so are very effective

H2 receptor antagonists dont act as far down the pathway so only partially reduce acid secretion

Question 23

What are the adverse effects of Famotidine? (H2 receptor antagonists)

Answer 23

Generally well tolerated
Diarrhoea
Headache

Question 24

What are the warnings/contrainidactions of Famotidine? (H2 receptor antagonists)

Answer 24

Mask symptoms of gastro-oesophageal cancers
Renal impairment

Question 25

What are the DDIs of Famotidine? (H2 receptor antagonists)

Answer 25

Very few

Question 26

When should Helicobacter pylori infection be suspected?

Answer 26

Duodenal or gastric ulcerations

Question 27

What test is used to determine a Helicobacter pylori infection?

Answer 27

Urea breath test Breath in C13 and H-pylori will convert urea to ammonia and ammooonia will be breathed out containing C13

Question 28

How is Helicobacter pylori infection treated?

Answer 28

One week triple therapy PPI + 2 anti bacterial agents

Question 29

What mediations are given for Helicobacter pylori infection?

Answer 29

Lansoprazole + Clarithromycin + Amoxicillin Lansoprazole + Clarithromycin + Metronidazole (when allergic to penicillin)

Question 30

What are some examples of aminosalicylates?

Answer 30

Mesalazine Sulfalazine

Question 31

What is the first line treatment for ulcerative colitis?

Answer 31

Mesalazine

Question 32

What is the mechanism of action of Mesalazine in ulcerative colitis?

Answer 32

Enteric coated tablet limits gastric breakdown leading to release of 5-amino salicylic acid topical action at the colon

Question 33

Why does Mesalazine not work in rheumatoid arthritis but sulfasalazine does?

Answer 33

Sulfa group good for RA

Question 34

What are the adverse effects of aminosalicylates (Mesalazine)?

Answer 34

GI disturbance (nausea and dyspepsia) Leukopenia (rare)

Question 35

What are the warning/contraindications to Mesalazine (aminosalicylates)?

Answer 35

They’re like aspirin so may have similar hypersensitivity to them

Question 36

What aer some DDI for Mesalazine (aminosalicylates)?

Answer 36

Using PPIs may lead to the enteric coated tablets breaking down quicker due to. Increased PH