GI Pharm ( 5% )

Question 1

Antiemetics; which is incorrect

• diphenoxylate
• dexamethasone
• THC
• Ondansetron
• Diphenhydramine

Answer 1

diphenoxylate – opioid agonist – antidiarrhoeal – not antiemetic.

• dexamethasone – augments antiemetic effects of eg ondansetron
• THC - also antiemetic.
• Ondansetron - serotonin receptor antagonist
• Diphenhydramine – antihistamine – motion sickness, used for extrapyamidal sx etc

Question 2

Metoclopramide; which is correct

• decreases lower oesophageal sphincter tone
• increases antral contractility
• decreases ileal peristalsis
• is a dopamine agonist

Answer 2

increases antral contractility - yes

• increases lower oesophageal sphincter tone
• no effect on small intestine motility
• is a dopamine antagonist

Question 3

regarding antiemetics

• metoclopramide increased lower oesophageal sphincter tone
• metoclopramide is a dopamine agonist
• THC works at the chemoceptor trigger zone

Answer 3

metoclopramide increased lower oesophageal sphincter tone

Is a dopamine antagonist

Question 4

Cimitidine

• blocks both H1 and H2 receptors
• t1/2 is 22 hours
• inhibits cytochrome P450
• never causes gynaecomastia

Answer 4

inhibits cytochrome P450

• blocks only H2 receptors
• t1/2 is 6-10hours
• may cause gynaecomastia, as increases oestradiol and prolactin levels.

Question 5

Regarding antiulcer/antireflux drugs

• Oral antiacids completely safe in people with renal failure

Answer 5

Oral antiacids can cause alkalosis in patients with renal failure