Pharmacology

Question 1

What is an example of a PPI?

Answer 1

omeprazole and lansoprazole

Question 2

How do PPIs work?

Answer 2

• Irreversibly block proton pump in apical membrane of parietal cells
• Reduce acid secretion (final common pathway of secretagogues)
• activated in an acidic environment (prodrugs)
• absorbed in the small intestine then transported back to the stomach

Question 3

What are PPIs used for?

Answer 3

• peptic ulcers
• relief of dyspepsia and GORD
• used to remove H. pylori (with clarithromycin and amox or metron)

Question 4

What is an example of a histamine type 2 receptor antagonist?

Answer 4

ranitidine

Question 5

How do histamine type 2 receptor antagonists work?

Answer 5

• Competitive antagonists of histamine channels on basolateral membrane
• Increase in cAMP which activates protein kinase A
  (-Less effective than PPIs)

Question 6

What are histamine type 2 receptor antagonists used for?

Answer 6

peptic ulcer disease or symptomatic relief of dyspepsia or GORD

Question 7

What is an example of an alginate/antacid?

Answer 7

gaviscon

Question 8

How do alginates/antacids work?

Answer 8

• short-term relief from dyspepsia
• proton buffers to increase pH of gastric juice
• Inactivates pepsin irreversibly
• Alginates produce foam for barrier so no reflux

Question 9

What are alginates/antacids used to treat?

Answer 9

symptoms of GORD and short-term dyspepsia

Question 10

What is an example of an antimuscarinic drug?

Answer 10

hyoscine butylbromide

Question 11

How do antimuscarinic drugs work?

Answer 11

• Competitive antagonist of muscarinic ACh receptors

- Blocks parasympathetic effect of ACh binding to M3

Question 12

What is an antimuscarinic drug used to treat?

Answer 12

Relieves muscle spasm in IBS

Question 13

What is the most common antimotility drug?

Answer 13

Ioperamide

Question 14

How do anti motility drugs work?

Answer 14

• Agonist of opioid

- Increase tone of smooth muscle and constricts sphincters to cause constipation with inhibition of peristalsis

Question 15

What are anti motility drugs used for?

Answer 15

acute diarrhoea for symptoms, for IBS symptoms or analgesia for acute pain

Question 16

What are the most common aminosalicylates?

Answer 16

Mesalazine and Balsalazide

Question 17

How do aminosalicylates work?

Answer 17

• Anti-inflammatory and immunosuppressive effects on the colon

Question 18

What are aminosalicylates used for?

Answer 18

UC or rheumatoid arthritis

Question 19

What is the most common bulk forming laxative?

Answer 19

Ispagula husk

Question 20

How do bulk forming laxatives work?

Answer 20

• Polymers which are not digested in SI so increase bulk of stool
• water moves into SI and colon so increases bulk and peristalsis
• 2-3 days to work

Question 21

What are bulk forming laxatives used to treat?

Answer 21

constipation and faecal impaction
mild chronic diarrhoea with diverticular disease
IBS

Question 22

What are main osmotic laxatives used?

Answer 22

lactulose
macrogols
phosphate

Question 23

How do osmotic laxatives work?

Answer 23

• They are sugars or alcohols that increase bulk and peristalsis
• Lactulose reduces ammonia absorption

Question 24

When are osmotic laxatives used?

Answer 24

• constipation
• faecal impaction
• bowel preparation before surgery or endoscopy and hepatic encephalopathy (lactulose)

Question 25

What is the most commonly used stimulant laxatives?

Answer 25

senna

Question 26

How do stimulant laxatives work?

Answer 26

• Increase electrolytes so water secretion from colon which stimulates peristalsis
• Act on enteric nervous system

Question 27

What are stimulant laxatives used to treat?

Answer 27

Constipation or faecal impaction

Question 28

What are the most common antiemetic dopamine D2 receptor antagonists?

Answer 28

domperidone and metoclopramide

Question 29

How do antiemetic dopamine D2 receptor antagonists work?

Answer 29

• Antagonist of dopamine receptors in CTZ outside of BBB

- Relaxes the stomach and LOS and disrupts gastroduodenal coordination

Question 30

What are the most common antiemetic histamine H1 receptor antagonists?

Answer 30

cyclising and cinnarizine

Question 31

How do antiemetic histamine H1 receptor antagonists work?

Answer 31

Competitive antagonism of H2 receptors in the vomiting centre and block of M1 ACh

Question 32

What are antiemetic H1 receptors antagonist used to treat?

Answer 32

Treats nausea and vomiting esp in motion sickness and post-operative

Question 33

What is the most commonly used antiemetic phenothiazine?

Answer 33

Prochlorperazine

Question 34

How does antiemetic phenothiazines work?

Answer 34

Competitive antagonism of dopamine, histamine and muscarinic receptors in the vomiting centre, vestibular system and in the gut

Question 35

What are antiemetic phenothiazines used to treat?

Answer 35

Nausea and vomiting eg vertigo, chemotherapy or psychiatric disorders

Question 36

What is the most common antiemetic 5-HT3 receptor antagonist?

Answer 36

ondansetron

Question 37

How do antiemetic 5-HT3 receptor antagonists work?

Answer 37

Competitive antagonism of inotropic 5-HT3 receptors in CTZ, NTS and on vagal afferents fibres of GI tract

Question 38

What are antiemetic 5-HT3 receptor antagonists used to treat?

Answer 38

nausea and vomiting with chemo and radiotherapy and after surgery with general