Gastrointestinal

Question 1

What are the indications for the use of PPIs?

Answer 1

• Peptic ulcers
• GORD
• H.pylori treatment

Question 2

What is the MOA for PPIs?

Answer 2

• irreversibly bind to H+/K+ ATPase in gastric parietal cells
• Inhibits the release of H+ ions
• Reduces production of stomach acid

Question 3

What are some side effects of PPIs?

Answer 3

• Headache
• GI disturbance
• Hypomagnesaemia
• May cause C.diff infections

Question 4

Warnings for PPIs?

Answer 4

• May disguise symptoms of gastro-oesophageal cancer (as about red flag symptoms)
• Increased risk of fractures in the elderly - osteoporosis

Question 5

What drug is omeprazole though to interact with?

Answer 5

Clopidogrel

• It is thought to reduce the antiplatelet effect of clopidogrel by decreasing its activation by cytochrome P450

Question 6

What is the treatment for H.pylori?

Answer 6

• PPI (omeprazole)
• Amoxicillin
• Clarithromycin

If there is a penicillin allergy give:
- Metronidazole

Question 7

What is an example of a H2 receptor antagonist?

Answer 7

Ranitidine

Question 8

What is the MOA of ranitidine?

Answer 8

• Blocks H2 receptors on gastric parietal cells
• Reduces gastric acid production
• However this doesn’t completely suppress gastric acid production (H2 receptors can be stimulated by other pathways)

Question 9

What is the one advantage of H2 receptor antagonist over PPIs?

Answer 9

• They have a more rapid onset of effect
• Used pre-operatively to reduce symptoms of significant GORD
• Prevents possible aspiration of gastric acid causing pneumonitis

Question 10

What is an example of a bulk-forming laxative?

Answer 10

Ispaghula husk

Question 11

What medication can help with short-term diarrhoea?

Answer 11

Loperamide

Question 12

What are examples of osmotic laxatives?

Answer 12

• Lactulose
• Macrogol
• Phosphate enema

Question 13

What are the indications of osmotic laxatives?

Answer 13

• Constipation or faecal impaction
• Bowel preparation before surgery
• Hepatic encephalopathy

Question 14

What is the MOA of osmotic laxatives?

Answer 14

• Osmotic agents pull water form surrounding tissues using osmosis
• They hold water in the stool, main thing its volume
• Stimulates peristalsis

Lactulose is also involved in the reduction of ammonia producing bacteria

Question 15

What is a specific warning with phosphate enemas?

Answer 15

Electrolyte disturbances

• Should be cautioned in people with heart failure and heart failure
• Glycerol suppositories are less likely to cause electrolyte disturbance

Question 16

What type of laxative can be prescribed alongside opioid analgesia?

Answer 16

Stimulant laxatives

• Reduces the constipation that opioid analgesia causes

Question 17

What is the MOA for stimulant laxatives?

Answer 17

• They irritate the intestinal cells causing the intestine to contract
• They also promote water influx to the intestine, which promotes bowel movement

Question 18

What are examples of stimulant laxatives?

Answer 18

• Senna
• Bisacodyl
• Glycerol suppositories
• Docusate sodium

Question 19

What advice should be given to patients taking laxatives?

Answer 19

Aim to drink 6-8 glasses of liquid per day

Question 20

What are examples of anti motility drugs?

Answer 20

• Loperamide

- Codeine phosphate

Question 21

When should codeine phosphate be used over loperamide?

Answer 21

When both analgesia + treatment of diarrhoea are required

Question 22

What is the MOA of loperamide?

Answer 22

• Opioid receptor agonist (doesn’t act on the CNS)
• Acts on the mu opioid receptors in the myenteric plexus large intestines
• This reduces propulsive contractions of the gut smooth muscle and increases non-propulsive contractions
• Slows transit and allows greater water absorption

Question 23

What are the warnings of using loperamide?

Answer 23

1) Acute ulcerative colitis - increases the risk of mega colon and perforation
2) C. Diff colitis - increases the risk of mega colon and perforation
3) Acute bloody diarrhoea - haemolytic uraemic syndrome

Question 24

What type of medication is metoclopramide?

Answer 24

It is an antiemetic( anti sickness medication)

Question 25

What are the different antiemetics?

Answer 25

1) Dopamine D2 receptor antagonists - metoclopramide (GI issues,opioids)
2) Histamine H1 receptor antagonists - cyclising, cinnarizine,promethazine ( motion sickness & vertigo)

Serotonin 5-HT3 receptor antagonists - ondansetron, granisetron (general anaesthesia, chemotherapy)